Use @IntDef where possible.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=133932812

demo/src/main/java/com/google/android/exoplayer2/demo/PlayerActivity.java

@@ -316,15 +316,15 @@ public class PlayerActivity extends Activity implements OnClickListener, ExoPlay
     int type = Util.inferContentType(!TextUtils.isEmpty(overrideExtension) ? "." + overrideExtension
         : uri.getLastPathSegment());
     switch (type) {
-      case Util.TYPE_SS:
+      case C.TYPE_SS:
         return new SsMediaSource(uri, buildDataSourceFactory(false),
             new DefaultSsChunkSource.Factory(mediaDataSourceFactory), mainHandler, eventLogger);
-      case Util.TYPE_DASH:
+      case C.TYPE_DASH:
         return new DashMediaSource(uri, buildDataSourceFactory(false),
             new DefaultDashChunkSource.Factory(mediaDataSourceFactory), mainHandler, eventLogger);
-      case Util.TYPE_HLS:
+      case C.TYPE_HLS:
         return new HlsMediaSource(uri, mediaDataSourceFactory, mainHandler, eventLogger);
-      case Util.TYPE_OTHER:
+      case C.TYPE_OTHER:
         return new ExtractorMediaSource(uri, mediaDataSourceFactory, new DefaultExtractorsFactory(),
             mainHandler, eventLogger);
       default: {

library/build.gradle

@@ -55,6 +55,7 @@ dependencies {
     androidTestCompile 'com.google.dexmaker:dexmaker:1.2'
     androidTestCompile 'com.google.dexmaker:dexmaker-mockito:1.2'
     androidTestCompile 'org.mockito:mockito-core:1.9.5'
+    compile 'com.android.support:support-annotations:24.2.0'
 }
 
 android.libraryVariants.all { variant ->

library/src/main/java/com/google/android/exoplayer2/C.java

@@ -17,8 +17,11 @@ package com.google.android.exoplayer2;
 
 import android.media.AudioFormat;
 import android.media.MediaCodec;
+import android.support.annotation.IntDef;
 import android.view.Surface;
 import com.google.android.exoplayer2.util.Util;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.UUID;
 
 /**
@@ -70,55 +73,79 @@ public final class C {
    */
   public static final String UTF8_NAME = "UTF-8";
 
+  /**
+   * Crypto modes for a codec.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({CRYPTO_MODE_UNENCRYPTED, CRYPTO_MODE_AES_CTR, CRYPTO_MODE_AES_CBC})
+  public @interface CryptoMode {}
+  /**
+   * @see MediaCodec#CRYPTO_MODE_UNENCRYPTED
+   */
+  @SuppressWarnings("InlinedApi")
+  public static final int CRYPTO_MODE_UNENCRYPTED = MediaCodec.CRYPTO_MODE_UNENCRYPTED;
   /**
    * @see MediaCodec#CRYPTO_MODE_AES_CTR
    */
   @SuppressWarnings("InlinedApi")
   public static final int CRYPTO_MODE_AES_CTR = MediaCodec.CRYPTO_MODE_AES_CTR;
+  /**
+   * @see MediaCodec#CRYPTO_MODE_AES_CBC
+   */
+  @SuppressWarnings("InlinedApi")
+  public static final int CRYPTO_MODE_AES_CBC = MediaCodec.CRYPTO_MODE_AES_CBC;
 
+  /**
+   * Represents an audio encoding, or an invalid or unset value.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({Format.NO_VALUE, ENCODING_INVALID, ENCODING_PCM_8BIT, ENCODING_PCM_16BIT,
+      ENCODING_PCM_24BIT, ENCODING_PCM_32BIT, ENCODING_AC3, ENCODING_E_AC3, ENCODING_DTS,
+      ENCODING_DTS_HD})
+  public @interface Encoding {}
+
+  /**
+   * Represents a PCM audio encoding, or an invalid or unset value.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({Format.NO_VALUE, ENCODING_INVALID, ENCODING_PCM_8BIT, ENCODING_PCM_16BIT,
+      ENCODING_PCM_24BIT, ENCODING_PCM_32BIT})
+  public @interface PcmEncoding {}
   /**
    * @see AudioFormat#ENCODING_INVALID
    */
   public static final int ENCODING_INVALID = AudioFormat.ENCODING_INVALID;
-
   /**
    * @see AudioFormat#ENCODING_PCM_8BIT
    */
   public static final int ENCODING_PCM_8BIT = AudioFormat.ENCODING_PCM_8BIT;
-
   /**
    * @see AudioFormat#ENCODING_PCM_16BIT
    */
   public static final int ENCODING_PCM_16BIT = AudioFormat.ENCODING_PCM_16BIT;
-
   /**
    * PCM encoding with 24 bits per sample.
    */
   public static final int ENCODING_PCM_24BIT = 0x80000000;
-
   /**
    * PCM encoding with 32 bits per sample.
    */
   public static final int ENCODING_PCM_32BIT = 0x40000000;
-
   /**
    * @see AudioFormat#ENCODING_AC3
    */
   @SuppressWarnings("InlinedApi")
   public static final int ENCODING_AC3 = AudioFormat.ENCODING_AC3;
-
   /**
    * @see AudioFormat#ENCODING_E_AC3
    */
   @SuppressWarnings("InlinedApi")
   public static final int ENCODING_E_AC3 = AudioFormat.ENCODING_E_AC3;
-
   /**
    * @see AudioFormat#ENCODING_DTS
    */
   @SuppressWarnings("InlinedApi")
   public static final int ENCODING_DTS = AudioFormat.ENCODING_DTS;
-
   /**
    * @see AudioFormat#ENCODING_DTS_HD
    */
@@ -132,48 +159,93 @@ public final class C {
   public static final int CHANNEL_OUT_7POINT1_SURROUND = Util.SDK_INT < 23
       ? AudioFormat.CHANNEL_OUT_7POINT1 : AudioFormat.CHANNEL_OUT_7POINT1_SURROUND;
 
+  /**
+   * Flags which can apply to a buffer containing a media sample.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {BUFFER_FLAG_KEY_FRAME, BUFFER_FLAG_END_OF_STREAM,
+      BUFFER_FLAG_ENCRYPTED, BUFFER_FLAG_DECODE_ONLY})
+  public @interface BufferFlags {}
   /**
    * Indicates that a buffer holds a synchronization sample.
    */
   @SuppressWarnings("InlinedApi")
   public static final int BUFFER_FLAG_KEY_FRAME = MediaCodec.BUFFER_FLAG_KEY_FRAME;
-
   /**
    * Flag for empty buffers that signal that the end of the stream was reached.
    */
   @SuppressWarnings("InlinedApi")
   public static final int BUFFER_FLAG_END_OF_STREAM = MediaCodec.BUFFER_FLAG_END_OF_STREAM;
-
   /**
    * Indicates that a buffer is (at least partially) encrypted.
    */
   public static final int BUFFER_FLAG_ENCRYPTED = 0x40000000;
-
   /**
    * Indicates that a buffer should be decoded but not rendered.
    */
   public static final int BUFFER_FLAG_DECODE_ONLY = 0x80000000;
 
+  /**
+   * Track selection flags.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {SELECTION_FLAG_DEFAULT, SELECTION_FLAG_FORCED,
+      SELECTION_FLAG_AUTOSELECT})
+  public @interface SelectionFlags {}
+  /**
+   * Indicates that the track should be selected if user preferences do not state otherwise.
+   */
+  public static final int SELECTION_FLAG_DEFAULT = 1;
+  /**
+   * Indicates that the track must be displayed. Only applies to text tracks.
+   */
+  public static final int SELECTION_FLAG_FORCED = 2;
+  /**
+   * Indicates that the player may choose to play the track in absence of an explicit user
+   * preference.
+   */
+  public static final int SELECTION_FLAG_AUTOSELECT = 4;
+
+  /**
+   * Represents a streaming or other media type.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({TYPE_DASH, TYPE_SS, TYPE_HLS, TYPE_OTHER})
+  public @interface ContentType {}
+  /**
+   * Value returned by {@link Util#inferContentType(String)} for DASH manifests.
+   */
+  public static final int TYPE_DASH = 0;
+  /**
+   * Value returned by {@link Util#inferContentType(String)} for Smooth Streaming manifests.
+   */
+  public static final int TYPE_SS = 1;
+  /**
+   * Value returned by {@link Util#inferContentType(String)} for HLS manifests.
+   */
+  public static final int TYPE_HLS = 2;
+  /**
+   * Value returned by {@link Util#inferContentType(String)} for files other than DASH, HLS or
+   * Smooth Streaming manifests.
+   */
+  public static final int TYPE_OTHER = 3;
+
   /**
    * A return value for methods where the end of an input was encountered.
    */
   public static final int RESULT_END_OF_INPUT = -1;
-
   /**
    * A return value for methods where the length of parsed data exceeds the maximum length allowed.
    */
   public static final int RESULT_MAX_LENGTH_EXCEEDED = -2;
-
   /**
    * A return value for methods where nothing was read.
    */
   public static final int RESULT_NOTHING_READ = -3;
-
   /**
    * A return value for methods where a buffer was read.
    */
   public static final int RESULT_BUFFER_READ = -4;
-
   /**
    * A return value for methods where a format was read.
    */
@@ -183,32 +255,26 @@ public final class C {
    * A data type constant for data of unknown or unspecified type.
    */
   public static final int DATA_TYPE_UNKNOWN = 0;
-
   /**
    * A data type constant for media, typically containing media samples.
    */
   public static final int DATA_TYPE_MEDIA = 1;
-
   /**
    * A data type constant for media, typically containing only initialization data.
    */
   public static final int DATA_TYPE_MEDIA_INITIALIZATION = 2;
-
   /**
    * A data type constant for drm or encryption data.
    */
   public static final int DATA_TYPE_DRM = 3;
-
   /**
    * A data type constant for a manifest file.
    */
   public static final int DATA_TYPE_MANIFEST = 4;
-
   /**
    * A data type constant for time synchronization data.
    */
   public static final int DATA_TYPE_TIME_SYNCHRONIZATION = 5;
-
   /**
    * Applications or extensions may define custom {@code DATA_TYPE_*} constants greater than or
    * equal to this value.
@@ -219,32 +285,26 @@ public final class C {
    * A type constant for tracks of unknown type.
    */
   public static final int TRACK_TYPE_UNKNOWN = -1;
-
   /**
    * A type constant for tracks of some default type, where the type itself is unknown.
    */
   public static final int TRACK_TYPE_DEFAULT = 0;
-
   /**
    * A type constant for audio tracks.
    */
   public static final int TRACK_TYPE_AUDIO = 1;
-
   /**
    * A type constant for video tracks.
    */
   public static final int TRACK_TYPE_VIDEO = 2;
-
   /**
    * A type constant for text tracks.
    */
   public static final int TRACK_TYPE_TEXT = 3;
-
   /**
    * A type constant for metadata tracks.
    */
   public static final int TRACK_TYPE_METADATA = 4;
-
   /**
    * Applications or extensions may define custom {@code TRACK_TYPE_*} constants greater than or
    * equal to this value.
@@ -255,27 +315,22 @@ public final class C {
    * A selection reason constant for selections whose reasons are unknown or unspecified.
    */
   public static final int SELECTION_REASON_UNKNOWN = 0;
-
   /**
    * A selection reason constant for an initial track selection.
    */
   public static final int SELECTION_REASON_INITIAL = 1;
-
   /**
    * A selection reason constant for an manual (i.e. user initiated) track selection.
    */
   public static final int SELECTION_REASON_MANUAL = 2;
-
   /**
    * A selection reason constant for an adaptive track selection.
    */
   public static final int SELECTION_REASON_ADAPTIVE = 3;
-
   /**
    * A selection reason constant for a trick play track selection.
    */
   public static final int SELECTION_REASON_TRICK_PLAY = 4;
-
   /**
    * Applications or extensions may define custom {@code SELECTION_REASON_*} constants greater than
    * or equal to this value.
@@ -363,16 +418,20 @@ public final class C {
    */
   public static final int MSG_CUSTOM_BASE = 10000;
 
+  /**
+   * The stereo mode for 360/3D/VR videos.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({Format.NO_VALUE, STEREO_MODE_MONO, STEREO_MODE_TOP_BOTTOM, STEREO_MODE_LEFT_RIGHT})
+  public @interface StereoMode {}
   /**
    * Indicates Monoscopic stereo layout, used with 360/3D/VR videos.
    */
   public static final int STEREO_MODE_MONO = 0;
-
   /**
    * Indicates Top-Bottom stereo layout, used with 360/3D/VR videos.
    */
   public static final int STEREO_MODE_TOP_BOTTOM = 1;
-
   /**
    * Indicates Left-Right stereo layout, used with 360/3D/VR videos.
    */

library/src/main/java/com/google/android/exoplayer2/ExoPlaybackException.java

@@ -15,15 +15,24 @@
  */
 package com.google.android.exoplayer2;
 
+import android.support.annotation.IntDef;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.util.Assertions;
 import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * Thrown when a non-recoverable playback failure occurs.
  */
 public final class ExoPlaybackException extends Exception {
 
+  /**
+   * The type of source that produced the error.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({TYPE_SOURCE, TYPE_RENDERER, TYPE_UNEXPECTED})
+  public @interface Type {}
   /**
    * The error occurred loading data from a {@link MediaSource}.
    * <p>
@@ -47,6 +56,7 @@ public final class ExoPlaybackException extends Exception {
    * The type of the playback failure. One of {@link #TYPE_SOURCE}, {@link #TYPE_RENDERER} and
    * {@link #TYPE_UNEXPECTED}.
    */
+  @Type
   public final int type;
 
   /**
@@ -85,7 +95,8 @@ public final class ExoPlaybackException extends Exception {
     return new ExoPlaybackException(TYPE_UNEXPECTED, null, cause, C.INDEX_UNSET);
   }
 
-  private ExoPlaybackException(int type, String message, Throwable cause, int rendererIndex) {
+  private ExoPlaybackException(@Type int type, String message, Throwable cause,
+      int rendererIndex) {
     super(message, cause);
     this.type = type;
     this.rendererIndex = rendererIndex;

library/src/main/java/com/google/android/exoplayer2/Format.java

@@ -39,20 +39,6 @@ public final class Format implements Parcelable {
    */
   public static final int NO_VALUE = -1;
 
-  /**
-   * Indicates that the track should be selected if user preferences do not state otherwise.
-   */
-  public static final int SELECTION_FLAG_DEFAULT = 1;
-  /**
-   * Indicates that the track must be displayed. Only applies to text tracks.
-   */
-  public static final int SELECTION_FLAG_FORCED = 2;
-  /**
-   * Indicates that the player may choose to play the track in absence of an explicit user
-   * preference.
-   */
-  public static final int SELECTION_FLAG_AUTOSELECT = 4;
-
   /**
    * A value for {@link #subsampleOffsetUs} to indicate that subsample timestamps are relative to
    * the timestamps of their parent samples.
@@ -131,6 +117,7 @@ public final class Format implements Parcelable {
    * modes are {@link C#STEREO_MODE_MONO}, {@link C#STEREO_MODE_TOP_BOTTOM}, {@link
    * C#STEREO_MODE_LEFT_RIGHT}.
    */
+  @C.StereoMode
   public final int stereoMode;
   /**
    * The projection data for 360/VR video, or null if not applicable.
@@ -153,6 +140,7 @@ public final class Format implements Parcelable {
    * {@link C#ENCODING_PCM_24BIT} and {@link C#ENCODING_PCM_32BIT}. Set to {@link #NO_VALUE} for
    * other media types.
    */
+  @C.PcmEncoding
   public final int pcmEncoding;
   /**
    * The number of samples to trim from the start of the decoded audio stream.
@@ -177,6 +165,7 @@ public final class Format implements Parcelable {
   /**
    * Track selection flags.
    */
+  @C.SelectionFlags
   public final int selectionFlags;
 
   /**
@@ -218,7 +207,7 @@ public final class Format implements Parcelable {
   public static Format createVideoSampleFormat(String id, String sampleMimeType, String codecs,
       int bitrate, int maxInputSize, int width, int height, float frameRate,
       List<byte[]> initializationData, int rotationDegrees, float pixelWidthHeightRatio,
-      byte[] projectionData, int stereoMode, DrmInitData drmInitData) {
+      byte[] projectionData, @C.StereoMode int stereoMode, DrmInitData drmInitData) {
     return new Format(id, null, sampleMimeType, codecs, bitrate, maxInputSize, width, height,
         frameRate, rotationDegrees, pixelWidthHeightRatio, projectionData, stereoMode, NO_VALUE,
         NO_VALUE, NO_VALUE, NO_VALUE, NO_VALUE, 0, null, OFFSET_SAMPLE_RELATIVE, initializationData,
@@ -229,7 +218,7 @@ public final class Format implements Parcelable {
 
   public static Format createAudioContainerFormat(String id, String containerMimeType,
       String sampleMimeType, String codecs, int bitrate, int channelCount, int sampleRate,
-      List<byte[]> initializationData, int selectionFlags, String language) {
+      List<byte[]> initializationData, @C.SelectionFlags int selectionFlags, String language) {
     return new Format(id, containerMimeType, sampleMimeType, codecs, bitrate, NO_VALUE, NO_VALUE,
         NO_VALUE, NO_VALUE, NO_VALUE, NO_VALUE, null, NO_VALUE, channelCount, sampleRate, NO_VALUE,
         NO_VALUE, NO_VALUE, selectionFlags, language, OFFSET_SAMPLE_RELATIVE, initializationData,
@@ -238,25 +227,26 @@ public final class Format implements Parcelable {
 
   public static Format createAudioSampleFormat(String id, String sampleMimeType, String codecs,
       int bitrate, int maxInputSize, int channelCount, int sampleRate,
-      List<byte[]> initializationData, DrmInitData drmInitData, int selectionFlags,
+      List<byte[]> initializationData, DrmInitData drmInitData,
-      String language) {
+      @C.SelectionFlags int selectionFlags, String language) {
     return createAudioSampleFormat(id, sampleMimeType, codecs, bitrate, maxInputSize, channelCount,
         sampleRate, NO_VALUE, initializationData, drmInitData, selectionFlags, language);
   }
 
   public static Format createAudioSampleFormat(String id, String sampleMimeType, String codecs,
-      int bitrate, int maxInputSize, int channelCount, int sampleRate, int pcmEncoding,
+      int bitrate, int maxInputSize, int channelCount, int sampleRate,
-      List<byte[]> initializationData, DrmInitData drmInitData, int selectionFlags,
+      @C.PcmEncoding int pcmEncoding, List<byte[]> initializationData, DrmInitData drmInitData,
-      String language) {
+      @C.SelectionFlags int selectionFlags, String language) {
     return createAudioSampleFormat(id, sampleMimeType, codecs, bitrate, maxInputSize, channelCount,
         sampleRate, pcmEncoding, NO_VALUE, NO_VALUE, initializationData, drmInitData,
         selectionFlags, language);
   }
 
   public static Format createAudioSampleFormat(String id, String sampleMimeType, String codecs,
-      int bitrate, int maxInputSize, int channelCount, int sampleRate, int pcmEncoding,
+      int bitrate, int maxInputSize, int channelCount, int sampleRate,
-      int encoderDelay, int encoderPadding, List<byte[]> initializationData,
+      @C.PcmEncoding int pcmEncoding, int encoderDelay, int encoderPadding,
-      DrmInitData drmInitData, int selectionFlags, String language) {
+      List<byte[]> initializationData, DrmInitData drmInitData,
+      @C.SelectionFlags int selectionFlags, String language) {
     return new Format(id, null, sampleMimeType, codecs, bitrate, maxInputSize, NO_VALUE, NO_VALUE,
         NO_VALUE, NO_VALUE, NO_VALUE, null, NO_VALUE, channelCount, sampleRate, pcmEncoding,
         encoderDelay, encoderPadding, selectionFlags, language, OFFSET_SAMPLE_RELATIVE,
@@ -266,20 +256,21 @@ public final class Format implements Parcelable {
   // Text.
 
   public static Format createTextContainerFormat(String id, String containerMimeType,
-      String sampleMimeType, String codecs, int bitrate, int selectionFlags, String language) {
+      String sampleMimeType, String codecs, int bitrate, @C.SelectionFlags int selectionFlags,
+      String language) {
     return new Format(id, containerMimeType, sampleMimeType, codecs, bitrate, NO_VALUE, NO_VALUE,
         NO_VALUE, NO_VALUE, NO_VALUE, NO_VALUE, null, NO_VALUE, NO_VALUE, NO_VALUE, NO_VALUE,
         NO_VALUE, NO_VALUE, selectionFlags, language, OFFSET_SAMPLE_RELATIVE, null, null);
   }
 
   public static Format createTextSampleFormat(String id, String sampleMimeType, String codecs,
-      int bitrate, int selectionFlags, String language, DrmInitData drmInitData) {
+      int bitrate, @C.SelectionFlags int selectionFlags, String language, DrmInitData drmInitData) {
     return createTextSampleFormat(id, sampleMimeType, codecs, bitrate, selectionFlags, language,
         drmInitData, OFFSET_SAMPLE_RELATIVE);
   }
 
   public static Format createTextSampleFormat(String id, String sampleMimeType, String codecs,
-      int bitrate, int selectionFlags, String language, DrmInitData drmInitData,
+      int bitrate, @C.SelectionFlags int selectionFlags, String language, DrmInitData drmInitData,
       long subsampleOffsetUs) {
     return new Format(id, null, sampleMimeType, codecs, bitrate, NO_VALUE, NO_VALUE, NO_VALUE,
         NO_VALUE, NO_VALUE, NO_VALUE, null, NO_VALUE, NO_VALUE, NO_VALUE, NO_VALUE, NO_VALUE,
@@ -313,10 +304,10 @@ public final class Format implements Parcelable {
 
   /* package */ Format(String id, String containerMimeType, String sampleMimeType, String codecs,
       int bitrate, int maxInputSize, int width, int height, float frameRate, int rotationDegrees,
-      float pixelWidthHeightRatio, byte[] projectionData, int stereoMode, int channelCount,
+      float pixelWidthHeightRatio, byte[] projectionData, @C.StereoMode int stereoMode,
-      int sampleRate, int pcmEncoding, int encoderDelay, int encoderPadding, int selectionFlags,
+      int channelCount, int sampleRate, @C.PcmEncoding int pcmEncoding, int encoderDelay,
-      String language, long subsampleOffsetUs, List<byte[]> initializationData,
+      int encoderPadding, @C.SelectionFlags int selectionFlags, String language,
-      DrmInitData drmInitData) {
+      long subsampleOffsetUs, List<byte[]> initializationData, DrmInitData drmInitData) {
     this.id = id;
     this.containerMimeType = containerMimeType;
     this.sampleMimeType = sampleMimeType;
@@ -343,6 +334,7 @@ public final class Format implements Parcelable {
     this.drmInitData = drmInitData;
   }
 
+  @SuppressWarnings("ResourceType")
   /* package */ Format(Parcel in) {
     id = in.readString();
     containerMimeType = in.readString();
@@ -389,7 +381,7 @@ public final class Format implements Parcelable {
   }
 
   public Format copyWithContainerInfo(String id, int bitrate, int width, int height,
-      int selectionFlags, String language) {
+      @C.SelectionFlags int selectionFlags, String language) {
     return new Format(id, containerMimeType, sampleMimeType, codecs, bitrate, maxInputSize,
         width, height, frameRate, rotationDegrees, pixelWidthHeightRatio, projectionData,
         stereoMode, channelCount, sampleRate, pcmEncoding, encoderDelay, encoderPadding,
@@ -402,7 +394,7 @@ public final class Format implements Parcelable {
     String codecs = this.codecs == null ? manifestFormat.codecs : this.codecs;
     int bitrate = this.bitrate == NO_VALUE ? manifestFormat.bitrate : this.bitrate;
     float frameRate = this.frameRate == NO_VALUE ? manifestFormat.frameRate : this.frameRate;
-    int selectionFlags = this.selectionFlags |  manifestFormat.selectionFlags;
+    @C.SelectionFlags int selectionFlags = this.selectionFlags |  manifestFormat.selectionFlags;
     String language = this.language == null ? manifestFormat.language : this.language;
     DrmInitData drmInitData = (preferManifestDrmInitData && manifestFormat.drmInitData != null)
         || this.drmInitData == null ? manifestFormat.drmInitData : this.drmInitData;

library/src/main/java/com/google/android/exoplayer2/audio/AudioTrack.java

@@ -208,7 +208,9 @@ public final class AudioTrack {
   private android.media.AudioTrack audioTrack;
   private int sampleRate;
   private int channelConfig;
+  @C.Encoding
   private int sourceEncoding;
+  @C.Encoding
   private int targetEncoding;
   private boolean passthrough;
   private int pcmFrameSize;
@@ -348,8 +350,8 @@ public final class AudioTrack {
    * @param specifiedBufferSize A specific size for the playback buffer in bytes, or 0 to infer a
    *     suitable buffer size automatically.
    */
-  public void configure(String mimeType, int channelCount, int sampleRate, int pcmEncoding,
+  public void configure(String mimeType, int channelCount, int sampleRate,
-      int specifiedBufferSize) {
+      @C.PcmEncoding int pcmEncoding, int specifiedBufferSize) {
     int channelConfig;
     switch (channelCount) {
       case 1:
@@ -381,7 +383,7 @@ public final class AudioTrack {
     }
 
     boolean passthrough = !MimeTypes.AUDIO_RAW.equals(mimeType);
-    int sourceEncoding;
+    @C.Encoding int sourceEncoding;
     if (passthrough) {
       sourceEncoding = getEncodingForMimeType(mimeType);
     } else if (pcmEncoding == C.ENCODING_PCM_8BIT || pcmEncoding == C.ENCODING_PCM_16BIT
@@ -470,7 +472,7 @@ public final class AudioTrack {
         if (keepSessionIdAudioTrack == null) {
           int sampleRate = 4000; // Equal to private android.media.AudioTrack.MIN_SAMPLE_RATE.
           int channelConfig = AudioFormat.CHANNEL_OUT_MONO;
-          int encoding = C.ENCODING_PCM_16BIT;
+          @C.PcmEncoding int encoding = C.ENCODING_PCM_16BIT;
           int bufferSize = 2; // Use a two byte buffer, as it is not actually used for playback.
           keepSessionIdAudioTrack = new android.media.AudioTrack(streamType, sampleRate,
               channelConfig, encoding, bufferSize, android.media.AudioTrack.MODE_STATIC, sessionId);
@@ -962,7 +964,7 @@ public final class AudioTrack {
    * @return The 16-bit PCM output. Different to the out parameter if null was passed, or if the
    *     capacity was insufficient for the output.
    */
-  private static ByteBuffer resampleTo16BitPcm(ByteBuffer buffer, int sourceEncoding,
+  private static ByteBuffer resampleTo16BitPcm(ByteBuffer buffer, @C.PcmEncoding int sourceEncoding,
       ByteBuffer out) {
     int offset = buffer.position();
     int limit = buffer.limit();
@@ -1023,6 +1025,7 @@ public final class AudioTrack {
     return resampledBuffer;
   }
 
+  @C.Encoding
   private static int getEncodingForMimeType(String mimeType) {
     switch (mimeType) {
       case MimeTypes.AUDIO_AC3:
@@ -1038,7 +1041,7 @@ public final class AudioTrack {
     }
   }
 
-  private static int getFramesPerEncodedSample(int encoding, ByteBuffer buffer) {
+  private static int getFramesPerEncodedSample(@C.Encoding int encoding, ByteBuffer buffer) {
     if (encoding == C.ENCODING_DTS || encoding == C.ENCODING_DTS_HD) {
       return DtsUtil.parseDtsAudioSampleCount(buffer);
     } else if (encoding == C.ENCODING_AC3) {

library/src/main/java/com/google/android/exoplayer2/decoder/Buffer.java

@@ -22,6 +22,7 @@ import com.google.android.exoplayer2.C;
  */
 public abstract class Buffer {
 
+  @C.BufferFlags
   private int flags;
 
   /**
@@ -58,7 +59,7 @@ public abstract class Buffer {
    * @param flags The flags to set, which should be a combination of the {@code C.BUFFER_FLAG_*}
    *     constants.
    */
-  public final void setFlags(int flags) {
+  public final void setFlags(@C.BufferFlags int flags) {
     this.flags = flags;
   }
 
@@ -68,7 +69,7 @@ public abstract class Buffer {
    * @param flag The flag to add to this buffer's flags, which should be one of the
    *     {@code C.BUFFER_FLAG_*} constants.
    */
-  public final void addFlag(int flag) {
+  public final void addFlag(@C.BufferFlags int flag) {
     flags |= flag;
   }
 
@@ -77,7 +78,7 @@ public abstract class Buffer {
    *
    * @param flag The flag to remove.
    */
-  public final void clearFlag(int flag) {
+  public final void clearFlag(@C.BufferFlags int flag) {
     flags &= ~flag;
   }
 
@@ -87,7 +88,7 @@ public abstract class Buffer {
    * @param flag The flag to check.
    * @return Whether the flag is set.
    */
-  protected final boolean getFlag(int flag) {
+  protected final boolean getFlag(@C.BufferFlags int flag) {
     return (flags & flag) == flag;
   }
 

library/src/main/java/com/google/android/exoplayer2/decoder/CryptoInfo.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.decoder;
 
 import android.annotation.TargetApi;
+import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.Util;
 
 /**
@@ -34,6 +35,7 @@ public final class CryptoInfo {
   /**
    * @see android.media.MediaCodec.CryptoInfo#mode
    */
+  @C.CryptoMode
   public int mode;
   /**
    * @see android.media.MediaCodec.CryptoInfo#numBytesOfClearData
@@ -58,7 +60,7 @@ public final class CryptoInfo {
    * @see android.media.MediaCodec.CryptoInfo#set(int, int[], int[], byte[], byte[], int)
    */
   public void set(int numSubSamples, int[] numBytesOfClearData, int[] numBytesOfEncryptedData,
-      byte[] key, byte[] iv, int mode) {
+      byte[] key, byte[] iv, @C.CryptoMode int mode) {
     this.numSubSamples = numSubSamples;
     this.numBytesOfClearData = numBytesOfClearData;
     this.numBytesOfEncryptedData = numBytesOfEncryptedData;

library/src/main/java/com/google/android/exoplayer2/decoder/DecoderInputBuffer.java

@@ -15,7 +15,10 @@
  */
 package com.google.android.exoplayer2.decoder;
 
+import android.support.annotation.IntDef;
 import com.google.android.exoplayer2.C;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.nio.ByteBuffer;
 
 /**
@@ -23,16 +26,21 @@ import java.nio.ByteBuffer;
  */
 public class DecoderInputBuffer extends Buffer {
 
+  /**
+   * The buffer replacement mode, which may disable replacement.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({BUFFER_REPLACEMENT_MODE_DISABLED, BUFFER_REPLACEMENT_MODE_NORMAL,
+      BUFFER_REPLACEMENT_MODE_DIRECT})
+  public @interface BufferReplacementMode {}
   /**
    * Disallows buffer replacement.
    */
   public static final int BUFFER_REPLACEMENT_MODE_DISABLED = 0;
-
   /**
    * Allows buffer replacement using {@link ByteBuffer#allocate(int)}.
    */
   public static final int BUFFER_REPLACEMENT_MODE_NORMAL = 1;
-
   /**
    * Allows buffer replacement using {@link ByteBuffer#allocateDirect(int)}.
    */
@@ -53,6 +61,7 @@ public class DecoderInputBuffer extends Buffer {
    */
   public long timeUs;
 
+  @BufferReplacementMode
   private final int bufferReplacementMode;
 
   /**
@@ -60,7 +69,7 @@ public class DecoderInputBuffer extends Buffer {
    *     of {@link #BUFFER_REPLACEMENT_MODE_DISABLED}, {@link #BUFFER_REPLACEMENT_MODE_NORMAL} and
    *     {@link #BUFFER_REPLACEMENT_MODE_DIRECT}.
    */
-  public DecoderInputBuffer(int bufferReplacementMode) {
+  public DecoderInputBuffer(@BufferReplacementMode int bufferReplacementMode) {
     this.cryptoInfo = new CryptoInfo();
     this.bufferReplacementMode = bufferReplacementMode;
   }

library/src/main/java/com/google/android/exoplayer2/drm/DrmSession.java

@@ -16,6 +16,9 @@
 package com.google.android.exoplayer2.drm;
 
 import android.annotation.TargetApi;
+import android.support.annotation.IntDef;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * A DRM session.
@@ -23,6 +26,12 @@ import android.annotation.TargetApi;
 @TargetApi(16)
 public interface DrmSession<T extends ExoMediaCrypto> {
 
+  /**
+   * The state of the DRM session.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({STATE_ERROR, STATE_CLOSED, STATE_OPENING, STATE_OPENED, STATE_OPENED_WITH_KEYS})
+  @interface State {}
   /**
    * The session has encountered an error. {@link #getError()} can be used to retrieve the cause.
    */
@@ -50,6 +59,7 @@ public interface DrmSession<T extends ExoMediaCrypto> {
    * @return One of {@link #STATE_ERROR}, {@link #STATE_CLOSED}, {@link #STATE_OPENING},
    *     {@link #STATE_OPENED} and {@link #STATE_OPENED_WITH_KEYS}.
    */
+  @State
   int getState();
 
   /**

library/src/main/java/com/google/android/exoplayer2/drm/StreamingDrmSessionManager.java

@@ -87,6 +87,7 @@ public class StreamingDrmSessionManager<T extends ExoMediaCrypto> implements Drm
 
   private int openCount;
   private boolean provisioningInProgress;
+  @DrmSession.State
   private int state;
   private T mediaCrypto;
   private Exception lastException;
@@ -291,6 +292,7 @@ public class StreamingDrmSessionManager<T extends ExoMediaCrypto> implements Drm
   // DrmSession implementation.
 
   @Override
+  @DrmSession.State
   public final int getState() {
     return state;
   }

library/src/main/java/com/google/android/exoplayer2/drm/UnsupportedDrmException.java

@@ -15,11 +15,21 @@
  */
 package com.google.android.exoplayer2.drm;
 
+import android.support.annotation.IntDef;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
 /**
  * Thrown when the requested DRM scheme is not supported.
  */
 public final class UnsupportedDrmException extends Exception {
 
+  /**
+   * The reason for the exception.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({REASON_UNSUPPORTED_SCHEME, REASON_INSTANTIATION_ERROR})
+  public @interface Reason {}
   /**
    * The requested DRM scheme is unsupported by the device.
    */
@@ -33,12 +43,13 @@ public final class UnsupportedDrmException extends Exception {
   /**
    * Either {@link #REASON_UNSUPPORTED_SCHEME} or {@link #REASON_INSTANTIATION_ERROR}.
    */
+  @Reason
   public final int reason;
 
   /**
    * @param reason {@link #REASON_UNSUPPORTED_SCHEME} or {@link #REASON_INSTANTIATION_ERROR}.
    */
-  public UnsupportedDrmException(int reason) {
+  public UnsupportedDrmException(@Reason int reason) {
     this.reason = reason;
   }
 
@@ -46,7 +57,7 @@ public final class UnsupportedDrmException extends Exception {
    * @param reason {@link #REASON_UNSUPPORTED_SCHEME} or {@link #REASON_INSTANTIATION_ERROR}.
    * @param cause The cause of this exception.
    */
-  public UnsupportedDrmException(int reason, Exception cause) {
+  public UnsupportedDrmException(@Reason int reason, Exception cause) {
     super(cause);
     this.reason = reason;
   }

library/src/main/java/com/google/android/exoplayer2/extractor/DefaultTrackOutput.java

@@ -496,7 +496,8 @@ public final class DefaultTrackOutput implements TrackOutput {
   }
 
   @Override
-  public void sampleMetadata(long timeUs, int flags, int size, int offset, byte[] encryptionKey) {
+  public void sampleMetadata(long timeUs, @C.BufferFlags int flags, int size, int offset,
+      byte[] encryptionKey) {
     if (!startWriteOperation()) {
       infoQueue.commitSampleTimestamp(timeUs);
       return;
@@ -836,8 +837,8 @@ public final class DefaultTrackOutput implements TrackOutput {
       }
     }
 
-    public synchronized void commitSample(long timeUs, int sampleFlags, long offset, int size,
+    public synchronized void commitSample(long timeUs, @C.BufferFlags int sampleFlags, long offset,
-        byte[] encryptionKey) {
+        int size, byte[] encryptionKey) {
       Assertions.checkState(!upstreamFormatRequired);
       commitSampleTimestamp(timeUs);
       timesUs[relativeWriteIndex] = timeUs;

library/src/main/java/com/google/android/exoplayer2/extractor/DummyTrackOutput.java

@@ -50,7 +50,8 @@ public final class DummyTrackOutput implements TrackOutput {
   }
 
   @Override
-  public void sampleMetadata(long timeUs, int flags, int size, int offset, byte[] encryptionKey) {
+  public void sampleMetadata(long timeUs, @C.BufferFlags int flags, int size, int offset,
+      byte[] encryptionKey) {
     // Do nothing.
   }
 

library/src/main/java/com/google/android/exoplayer2/extractor/TrackOutput.java

@@ -72,6 +72,7 @@ public interface TrackOutput {
    *     whose metadata is being passed.
    * @param encryptionKey The encryption key associated with the sample. May be null.
    */
-  void sampleMetadata(long timeUs, int flags, int size, int offset, byte[] encryptionKey);
+  void sampleMetadata(long timeUs, @C.BufferFlags int flags, int size, int offset,
+      byte[] encryptionKey);
 
 }

library/src/main/java/com/google/android/exoplayer2/extractor/mkv/MatroskaExtractor.java

@@ -264,6 +264,7 @@ public final class MatroskaExtractor implements Extractor {
   private int[] blockLacingSampleSizes;
   private int blockTrackNumber;
   private int blockTrackNumberLength;
+  @C.BufferFlags
   private int blockFlags;
 
   // Sample reading state.
@@ -1314,7 +1315,7 @@ public final class MatroskaExtractor implements Extractor {
     public void initializeOutput(ExtractorOutput output, int trackId) throws ParserException {
       String mimeType;
       int maxInputSize = Format.NO_VALUE;
-      int pcmEncoding = Format.NO_VALUE;
+      @C.PcmEncoding int pcmEncoding = Format.NO_VALUE;
       List<byte[]> initializationData = null;
       switch (codecId) {
         case CODEC_ID_VP8:
@@ -1429,9 +1430,9 @@ public final class MatroskaExtractor implements Extractor {
       }
 
       Format format;
-      int selectionFlags = 0;
+      @C.SelectionFlags int selectionFlags = 0;
-      selectionFlags |= flagDefault ? Format.SELECTION_FLAG_DEFAULT : 0;
+      selectionFlags |= flagDefault ? C.SELECTION_FLAG_DEFAULT : 0;
-      selectionFlags |= flagForced ? Format.SELECTION_FLAG_FORCED : 0;
+      selectionFlags |= flagForced ? C.SELECTION_FLAG_FORCED : 0;
       // TODO: Consider reading the name elements of the tracks and, if present, incorporating them
       // into the trackId passed when creating the formats.
       if (MimeTypes.isAudio(mimeType)) {

library/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

@@ -665,6 +665,7 @@ import java.util.List;
     List<byte[]> initializationData = null;
     String mimeType = null;
     byte[] projectionData = null;
+    @C.StereoMode
     int stereoMode = Format.NO_VALUE;
     while (childPosition - position < size) {
       parent.setPosition(childPosition);
@@ -889,7 +890,7 @@ import java.util.List;
 
     if (out.format == null && mimeType != null) {
       // TODO: Determine the correct PCM encoding.
-      int pcmEncoding =
+      @C.PcmEncoding int pcmEncoding =
           MimeTypes.AUDIO_RAW.equals(mimeType) ? C.ENCODING_PCM_16BIT : Format.NO_VALUE;
       out.format = Format.createAudioSampleFormat(Integer.toString(trackId), mimeType, null,
           Format.NO_VALUE, Format.NO_VALUE, channelCount, sampleRate, pcmEncoding,
@@ -1169,6 +1170,7 @@ import java.util.List;
 
     public Format format;
     public int nalUnitLengthFieldLength;
+    @Track.Transformation
     public int requiredSampleTransformation;
 
     public StsdData(int numberOfEntries) {

library/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.extractor.mp4;
 
+import android.support.annotation.IntDef;
 import android.util.Log;
 import android.util.Pair;
 import android.util.SparseArray;
@@ -38,6 +39,8 @@ import com.google.android.exoplayer2.util.NalUnitUtil;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -64,6 +67,13 @@ public final class FragmentedMp4Extractor implements Extractor {
   private static final String TAG = "FragmentedMp4Extractor";
   private static final int SAMPLE_GROUP_TYPE_seig = Util.getIntegerCodeForString("seig");
 
+  /**
+   * Flags controlling the behavior of the extractor.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {FLAG_WORKAROUND_EVERY_VIDEO_FRAME_IS_SYNC_FRAME,
+      FLAG_WORKAROUND_IGNORE_TFDT_BOX, FLAG_SIDELOADED})
+  public @interface Flags {}
   /**
    * Flag to work around an issue in some video streams where every frame is marked as a sync frame.
    * The workaround overrides the sync frame flags in the stream, forcing them to false except for
@@ -72,12 +82,10 @@ public final class FragmentedMp4Extractor implements Extractor {
    * This flag does nothing if the stream is not a video stream.
    */
   public static final int FLAG_WORKAROUND_EVERY_VIDEO_FRAME_IS_SYNC_FRAME = 1;
-
   /**
    * Flag to ignore any tfdt boxes in the stream.
    */
   public static final int FLAG_WORKAROUND_IGNORE_TFDT_BOX = 2;
-
   /**
    * Flag to indicate that the {@link Track} was sideloaded, instead of being declared by the MP4
    * container.
@@ -95,6 +103,7 @@ public final class FragmentedMp4Extractor implements Extractor {
   private static final int STATE_READING_SAMPLE_CONTINUE = 4;
 
   // Workarounds.
+  @Flags
   private final int flags;
   private final Track sideloadedTrack;
 
@@ -135,18 +144,18 @@ public final class FragmentedMp4Extractor implements Extractor {
   }
 
   /**
-   * @param flags Flags to allow parsing of faulty streams.
+   * @param flags Flags that control the extractor's behavior.
    */
-  public FragmentedMp4Extractor(int flags) {
+  public FragmentedMp4Extractor(@Flags int flags) {
     this(flags, null);
   }
 
   /**
-   * @param flags Flags to allow parsing of faulty streams.
+   * @param flags Flags that control the extractor's behavior.
    * @param sideloadedTrack Sideloaded track information, in the case that the extractor
    *     will not receive a moov box in the input data.
    */
-  public FragmentedMp4Extractor(int flags, Track sideloadedTrack) {
+  public FragmentedMp4Extractor(@Flags int flags, Track sideloadedTrack) {
     this.sideloadedTrack = sideloadedTrack;
     this.flags = flags | (sideloadedTrack != null ? FLAG_SIDELOADED : 0);
     atomHeader = new ParsableByteArray(Atom.LONG_HEADER_SIZE);
@@ -422,7 +431,7 @@ public final class FragmentedMp4Extractor implements Extractor {
   }
 
   private static void parseMoof(ContainerAtom moof, SparseArray<TrackBundle> trackBundleArray,
-      int flags, byte[] extendedTypeScratch) throws ParserException {
+      @Flags int flags, byte[] extendedTypeScratch) throws ParserException {
     int moofContainerChildrenSize = moof.containerChildren.size();
     for (int i = 0; i < moofContainerChildrenSize; i++) {
       Atom.ContainerAtom child = moof.containerChildren.get(i);
@@ -437,7 +446,7 @@ public final class FragmentedMp4Extractor implements Extractor {
    * Parses a traf atom (defined in 14496-12).
    */
   private static void parseTraf(ContainerAtom traf, SparseArray<TrackBundle> trackBundleArray,
-      int flags, byte[] extendedTypeScratch) throws ParserException {
+      @Flags int flags, byte[] extendedTypeScratch) throws ParserException {
     LeafAtom tfhd = traf.getLeafAtomOfType(Atom.TYPE_tfhd);
     TrackBundle trackBundle = parseTfhd(tfhd.data, trackBundleArray, flags);
     if (trackBundle == null) {
@@ -488,7 +497,7 @@ public final class FragmentedMp4Extractor implements Extractor {
   }
 
   private static void parseTruns(ContainerAtom traf, TrackBundle trackBundle, long decodeTime,
-      int flags) {
+      @Flags int flags) {
     int trunCount = 0;
     int totalSampleCount = 0;
     List<LeafAtom> leafChildren = traf.leafChildren;
@@ -643,8 +652,8 @@ public final class FragmentedMp4Extractor implements Extractor {
    * @param trun The trun atom to decode.
    * @return The starting position of samples for the next run.
    */
-  private static int parseTrun(TrackBundle trackBundle, int index, long decodeTime, int flags,
+  private static int parseTrun(TrackBundle trackBundle, int index, long decodeTime,
-      ParsableByteArray trun, int trackRunStart) {
+      @Flags int flags, ParsableByteArray trun, int trackRunStart) {
     trun.setPosition(Atom.HEADER_SIZE);
     int fullAtom = trun.readInt();
     int atomFlags = Atom.parseFullAtomFlags(fullAtom);
@@ -994,7 +1003,7 @@ public final class FragmentedMp4Extractor implements Extractor {
     }
 
     long sampleTimeUs = fragment.getSamplePresentationTime(sampleIndex) * 1000L;
-    int sampleFlags = (fragment.definesEncryptionData ? C.BUFFER_FLAG_ENCRYPTED : 0)
+    @C.BufferFlags int sampleFlags = (fragment.definesEncryptionData ? C.BUFFER_FLAG_ENCRYPTED : 0)
         | (fragment.sampleIsSyncFrameTable[sampleIndex] ? C.BUFFER_FLAG_KEY_FRAME : 0);
     int sampleDescriptionIndex = fragment.header.sampleDescriptionIndex;
     byte[] encryptionKey = null;

library/src/main/java/com/google/android/exoplayer2/extractor/mp4/Track.java

@@ -15,14 +15,23 @@
  */
 package com.google.android.exoplayer2.extractor.mp4;
 
+import android.support.annotation.IntDef;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * Encapsulates information describing an MP4 track.
  */
 public final class Track {
 
+  /**
+   * The transformation to apply to samples in the track, if any.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({TRANSFORMATION_NONE, TRANSFORMATION_CEA608_CDAT})
+  public @interface Transformation {}
   /**
    * A no-op sample transformation.
    */
@@ -66,6 +75,7 @@ public final class Track {
    * One of {@code TRANSFORMATION_*}. Defines the transformation to apply before outputting each
    * sample.
    */
+  @Transformation
   public final int sampleTransformation;
 
   /**
@@ -90,7 +100,7 @@ public final class Track {
   public final int nalUnitLengthFieldLength;
 
   public Track(int id, int type, long timescale, long movieTimescale, long durationUs,
-      Format format, int sampleTransformation,
+      Format format, @Transformation int sampleTransformation,
       TrackEncryptionBox[] sampleDescriptionEncryptionBoxes, int nalUnitLengthFieldLength,
       long[] editListDurations, long[] editListMediaTimes) {
     this.id = id;

library/src/main/java/com/google/android/exoplayer2/extractor/mp4/TrackSampleTable.java

@@ -49,7 +49,8 @@ import com.google.android.exoplayer2.util.Util;
    */
   public final int[] flags;
 
-  TrackSampleTable(long[] offsets, int[] sizes, int maximumSize, long[] timestampsUs, int[] flags) {
+  public TrackSampleTable(long[] offsets, int[] sizes, int maximumSize, long[] timestampsUs,
+      int[] flags) {
     Assertions.checkArgument(sizes.length == timestampsUs.length);
     Assertions.checkArgument(offsets.length == timestampsUs.length);
     Assertions.checkArgument(flags.length == timestampsUs.length);

library/src/main/java/com/google/android/exoplayer2/extractor/ts/H262Reader.java

@@ -128,7 +128,7 @@ import java.util.Collections;
       if (hasOutputFormat && (startCodeValue == START_GROUP || startCodeValue == START_PICTURE)) {
         int bytesWrittenPastStartCode = limit - startCodeOffset;
         if (foundFirstFrameInGroup) {
-          int flags = isKeyframe ? C.BUFFER_FLAG_KEY_FRAME : 0;
+          @C.BufferFlags int flags = isKeyframe ? C.BUFFER_FLAG_KEY_FRAME : 0;
           int size = (int) (totalBytesWritten - framePosition) - bytesWrittenPastStartCode;
           output.sampleMetadata(frameTimeUs, flags, size, bytesWrittenPastStartCode, null);
           isKeyframe = false;

library/src/main/java/com/google/android/exoplayer2/extractor/ts/H264Reader.java

@@ -420,7 +420,7 @@ import java.util.List;
     }
 
     private void outputSample(int offset) {
-      int flags = sampleIsKeyframe ? C.BUFFER_FLAG_KEY_FRAME : 0;
+      @C.BufferFlags int flags = sampleIsKeyframe ? C.BUFFER_FLAG_KEY_FRAME : 0;
       int size = (int) (nalUnitStartPosition - samplePosition);
       output.sampleMetadata(sampleTimeUs, flags, size, offset, null);
     }

library/src/main/java/com/google/android/exoplayer2/extractor/ts/H265Reader.java

@@ -471,7 +471,7 @@ import java.util.Collections;
     }
 
     private void outputSample(int offset) {
-      int flags = sampleIsKeyframe ? C.BUFFER_FLAG_KEY_FRAME : 0;
+      @C.BufferFlags int flags = sampleIsKeyframe ? C.BUFFER_FLAG_KEY_FRAME : 0;
       int size = (int) (nalUnitStartPosition - samplePosition);
       output.sampleMetadata(sampleTimeUs, flags, size, offset, null);
     }

library/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.extractor.ts;
 
+import android.support.annotation.IntDef;
 import android.util.Log;
 import android.util.SparseArray;
 import android.util.SparseBooleanArray;
@@ -32,6 +33,8 @@ import com.google.android.exoplayer2.util.ParsableBitArray;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * Facilitates the extraction of data from the MPEG-2 TS container format.
@@ -50,6 +53,13 @@ public final class TsExtractor implements Extractor {
 
   };
 
+  /**
+   * Flags controlling what workarounds are enabled for the extractor.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {WORKAROUND_ALLOW_NON_IDR_KEYFRAMES, WORKAROUND_IGNORE_AAC_STREAM,
+      WORKAROUND_IGNORE_H264_STREAM, WORKAROUND_DETECT_ACCESS_UNITS, WORKAROUND_MAP_BY_TYPE})
+  public @interface WorkaroundFlags {}
   public static final int WORKAROUND_ALLOW_NON_IDR_KEYFRAMES = 1;
   public static final int WORKAROUND_IGNORE_AAC_STREAM = 2;
   public static final int WORKAROUND_IGNORE_H264_STREAM = 4;
@@ -83,6 +93,7 @@ public final class TsExtractor implements Extractor {
   private static final int BUFFER_SIZE = TS_PACKET_SIZE * BUFFER_PACKET_COUNT;
 
   private final TimestampAdjuster timestampAdjuster;
+  @WorkaroundFlags
   private final int workaroundFlags;
   private final ParsableByteArray tsPacketBuffer;
   private final ParsableBitArray tsScratch;
@@ -103,7 +114,7 @@ public final class TsExtractor implements Extractor {
     this(timestampAdjuster, 0);
   }
 
-  public TsExtractor(TimestampAdjuster timestampAdjuster, int workaroundFlags) {
+  public TsExtractor(TimestampAdjuster timestampAdjuster, @WorkaroundFlags int workaroundFlags) {
     this.timestampAdjuster = timestampAdjuster;
     this.workaroundFlags = workaroundFlags;
     tsPacketBuffer = new ParsableByteArray(BUFFER_SIZE);

library/src/main/java/com/google/android/exoplayer2/extractor/wav/WavHeader.java

@@ -31,6 +31,7 @@ import com.google.android.exoplayer2.C;
   /** Bits per sample for the audio data. */
   private final int bitsPerSample;
   /** The PCM encoding */
+  @C.PcmEncoding
   private final int encoding;
 
   /** Offset to the start of sample data. */
@@ -39,7 +40,7 @@ import com.google.android.exoplayer2.C;
   private long dataSize;
 
   public WavHeader(int numChannels, int sampleRateHz, int averageBytesPerSecond, int blockAlignment,
-      int bitsPerSample, int encoding) {
+      int bitsPerSample, @C.PcmEncoding int encoding) {
     this.numChannels = numChannels;
     this.sampleRateHz = sampleRateHz;
     this.averageBytesPerSecond = averageBytesPerSecond;
@@ -99,6 +100,7 @@ import com.google.android.exoplayer2.C;
   }
 
   /** Returns the PCM encoding. **/
+  @C.PcmEncoding
   public int getEncoding() {
     return encoding;
   }

library/src/main/java/com/google/android/exoplayer2/extractor/wav/WavHeaderReader.java

@@ -87,7 +87,7 @@ import java.io.IOException;
           + blockAlignment);
     }
 
-    int encoding = Util.getPcmEncoding(bitsPerSample);
+    @C.PcmEncoding int encoding = Util.getPcmEncoding(bitsPerSample);
     if (encoding == C.ENCODING_INVALID) {
       Log.e(TAG, "Unsupported WAV bit depth: " + bitsPerSample);
       return null;

library/src/main/java/com/google/android/exoplayer2/mediacodec/MediaCodecRenderer.java

@@ -293,7 +293,7 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
     MediaCrypto mediaCrypto = null;
     boolean drmSessionRequiresSecureDecoder = false;
     if (drmSession != null) {
-      int drmSessionState = drmSession.getState();
+      @DrmSession.State int drmSessionState = drmSession.getState();
       if (drmSessionState == DrmSession.STATE_ERROR) {
         throw ExoPlaybackException.createForRenderer(drmSession.getError(), getIndex());
       } else if (drmSessionState == DrmSession.STATE_OPENED
@@ -682,7 +682,7 @@ public abstract class MediaCodecRenderer extends BaseRenderer {
     if (drmSession == null) {
       return false;
     }
-    int drmSessionState = drmSession.getState();
+    @DrmSession.State int drmSessionState = drmSession.getState();
     if (drmSessionState == DrmSession.STATE_ERROR) {
       throw ExoPlaybackException.createForRenderer(drmSession.getError(), getIndex());
     }

library/src/main/java/com/google/android/exoplayer2/source/MergingMediaSource.java

@@ -15,11 +15,14 @@
  */
 package com.google.android.exoplayer2.source;
 
+import android.support.annotation.IntDef;
 import com.google.android.exoplayer2.Timeline;
 import com.google.android.exoplayer2.source.MediaPeriod.Callback;
 import com.google.android.exoplayer2.upstream.Allocator;
 import com.google.android.exoplayer2.util.Assertions;
 import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.ArrayList;
 import java.util.Arrays;
 
@@ -36,11 +39,16 @@ public final class MergingMediaSource implements MediaSource {
    */
   public static final class IllegalMergeException extends IOException {
 
+    /**
+     * The reason the merge failed.
+     */
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef({REASON_WINDOWS_ARE_DYNAMIC, REASON_PERIOD_COUNT_MISMATCH})
+    public @interface Reason {}
     /**
      * The merge failed because one of the sources being merged has a dynamic window.
      */
     public static final int REASON_WINDOWS_ARE_DYNAMIC = 0;
-
     /**
      * The merge failed because the sources have different period counts.
      */
@@ -50,13 +58,14 @@ public final class MergingMediaSource implements MediaSource {
      * The reason the merge failed. One of {@link #REASON_WINDOWS_ARE_DYNAMIC} and
      * {@link #REASON_PERIOD_COUNT_MISMATCH}.
      */
+    @Reason
     public final int reason;
 
     /**
      * @param reason The reason the merge failed. One of {@link #REASON_WINDOWS_ARE_DYNAMIC} and
      *     {@link #REASON_PERIOD_COUNT_MISMATCH}.
      */
-    public IllegalMergeException(int reason) {
+    public IllegalMergeException(@Reason int reason) {
       this.reason = reason;
     }
 

library/src/main/java/com/google/android/exoplayer2/source/chunk/ChunkExtractorWrapper.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source.chunk;
 
+import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.extractor.Extractor;
@@ -150,7 +151,8 @@ public final class ChunkExtractorWrapper implements ExtractorOutput, TrackOutput
   }
 
   @Override
-  public void sampleMetadata(long timeUs, int flags, int size, int offset, byte[] encryptionKey) {
+  public void sampleMetadata(long timeUs, @C.BufferFlags int flags, int size, int offset,
+      byte[] encryptionKey) {
     trackOutput.sampleMetadata(timeUs, flags, size, offset, encryptionKey);
   }
 

library/src/main/java/com/google/android/exoplayer2/source/chunk/InitializationChunk.java

@@ -111,7 +111,8 @@ public final class InitializationChunk extends Chunk implements SingleTrackMetad
   }
 
   @Override
-  public void sampleMetadata(long timeUs, int flags, int size, int offset, byte[] encryptionKey) {
+  public void sampleMetadata(long timeUs, @C.BufferFlags int flags, int size, int offset,
+      byte[] encryptionKey) {
     throw new IllegalStateException("Unexpected sample data in initialization chunk");
   }
 

library/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java

@@ -355,7 +355,7 @@ import java.util.Locale;
       timestampAdjuster = timestampAdjusterProvider.getAdjuster(segment.discontinuitySequenceNumber,
           startTimeUs);
       // This flag ensures the change of pid between streams does not affect the sample queues.
-      int workaroundFlags = TsExtractor.WORKAROUND_MAP_BY_TYPE;
+      @TsExtractor.WorkaroundFlags int workaroundFlags = TsExtractor.WORKAROUND_MAP_BY_TYPE;
       String codecs = variants[newVariantIndex].format.codecs;
       if (!TextUtils.isEmpty(codecs)) {
         // Sometimes AAC and H264 streams are declared in TS chunks even though they don't really

library/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylist.java

@@ -15,18 +15,29 @@
  */
 package com.google.android.exoplayer2.source.hls.playlist;
 
+import android.support.annotation.IntDef;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
 /**
  * Represents an HLS playlist.
  */
 public abstract class HlsPlaylist {
 
+  /**
+   * The type of playlist.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({TYPE_MASTER, TYPE_MEDIA})
+  public @interface Type {}
   public static final int TYPE_MASTER = 0;
   public static final int TYPE_MEDIA = 1;
 
   public final String baseUri;
+  @Type
   public final int type;
 
-  protected HlsPlaylist(String baseUri, int type) {
+  protected HlsPlaylist(String baseUri, @Type int type) {
     this.baseUri = baseUri;
     this.type = type;
   }

library/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistParser.java

@@ -62,7 +62,6 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
   private static final String BOOLEAN_TRUE = "YES";
   private static final String BOOLEAN_FALSE = "NO";
 
-
   private static final Pattern REGEX_GROUP_ID = Pattern.compile("GROUP-ID=\"(.+?)\"");
   private static final Pattern REGEX_VIDEO = Pattern.compile("VIDEO=\"(.+?)\"");
   private static final Pattern REGEX_AUDIO = Pattern.compile("AUDIO=\"(.+?)\"");
@@ -138,7 +137,7 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
     while (iterator.hasNext()) {
       line = iterator.next();
       if (line.startsWith(TAG_MEDIA)) {
-        int selectionFlags = parseSelectionFlags(line);
+        @C.SelectionFlags int selectionFlags = parseSelectionFlags(line);
         String uri = parseOptionalStringAttr(line, REGEX_URI);
         String name = parseStringAttr(line, REGEX_NAME);
         String language = parseOptionalStringAttr(line, REGEX_LANGUAGE);
@@ -200,11 +199,11 @@ public final class HlsPlaylistParser implements ParsingLoadable.Parser<HlsPlayli
         muxedCaptionFormat);
   }
 
+  @C.SelectionFlags
   private static int parseSelectionFlags(String line) {
-    return (parseBooleanAttribute(line, REGEX_DEFAULT, false) ? Format.SELECTION_FLAG_DEFAULT : 0)
+    return (parseBooleanAttribute(line, REGEX_DEFAULT, false) ? C.SELECTION_FLAG_DEFAULT : 0)
-        | (parseBooleanAttribute(line, REGEX_FORCED, false) ? Format.SELECTION_FLAG_FORCED : 0)
+        | (parseBooleanAttribute(line, REGEX_FORCED, false) ? C.SELECTION_FLAG_FORCED : 0)
-        | (parseBooleanAttribute(line, REGEX_AUTOSELECT, false) ? Format.SELECTION_FLAG_AUTOSELECT
+        | (parseBooleanAttribute(line, REGEX_AUTOSELECT, false) ? C.SELECTION_FLAG_AUTOSELECT : 0);
-        : 0);
   }
 
   private static HlsMediaPlaylist parseMediaPlaylist(LineIterator iterator, String baseUri)

library/src/main/java/com/google/android/exoplayer2/text/CaptionStyleCompat.java

@@ -18,35 +18,41 @@ package com.google.android.exoplayer2.text;
 import android.annotation.TargetApi;
 import android.graphics.Color;
 import android.graphics.Typeface;
+import android.support.annotation.IntDef;
 import android.view.accessibility.CaptioningManager;
 import android.view.accessibility.CaptioningManager.CaptionStyle;
 import com.google.android.exoplayer2.util.Util;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * A compatibility wrapper for {@link CaptionStyle}.
  */
 public final class CaptionStyleCompat {
 
+  /**
+   * The type of edge, which may be none.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({EDGE_TYPE_NONE, EDGE_TYPE_OUTLINE, EDGE_TYPE_DROP_SHADOW, EDGE_TYPE_RAISED,
+      EDGE_TYPE_DEPRESSED})
+  public @interface EdgeType {}
   /**
    * Edge type value specifying no character edges.
    */
   public static final int EDGE_TYPE_NONE = 0;
-
   /**
    * Edge type value specifying uniformly outlined character edges.
    */
   public static final int EDGE_TYPE_OUTLINE = 1;
-
   /**
    * Edge type value specifying drop-shadowed character edges.
    */
   public static final int EDGE_TYPE_DROP_SHADOW = 2;
-
   /**
    * Edge type value specifying raised bevel character edges.
    */
   public static final int EDGE_TYPE_RAISED = 3;
-
   /**
    * Edge type value specifying depressed bevel character edges.
    */
@@ -88,6 +94,7 @@ public final class CaptionStyleCompat {
    * <li>{@link #EDGE_TYPE_DEPRESSED}
    * </ul>
    */
+  @EdgeType
   public final int edgeType;
 
   /**
@@ -126,8 +133,8 @@ public final class CaptionStyleCompat {
    * @param edgeColor See {@link #edgeColor}.
    * @param typeface See {@link #typeface}.
    */
-  public CaptionStyleCompat(int foregroundColor, int backgroundColor, int windowColor, int edgeType,
+  public CaptionStyleCompat(int foregroundColor, int backgroundColor, int windowColor,
-      int edgeColor, Typeface typeface) {
+      @EdgeType int edgeType, int edgeColor, Typeface typeface) {
     this.foregroundColor = foregroundColor;
     this.backgroundColor = backgroundColor;
     this.windowColor = windowColor;
@@ -137,6 +144,7 @@ public final class CaptionStyleCompat {
   }
 
   @TargetApi(19)
+  @SuppressWarnings("ResourceType")
   private static CaptionStyleCompat createFromCaptionStyleV19(
       CaptioningManager.CaptionStyle captionStyle) {
     return new CaptionStyleCompat(
@@ -145,6 +153,7 @@ public final class CaptionStyleCompat {
   }
 
   @TargetApi(21)
+  @SuppressWarnings("ResourceType")
   private static CaptionStyleCompat createFromCaptionStyleV21(
       CaptioningManager.CaptionStyle captionStyle) {
     return new CaptionStyleCompat(

library/src/main/java/com/google/android/exoplayer2/text/Cue.java

@@ -15,7 +15,10 @@
  */
 package com.google.android.exoplayer2.text;
 
+import android.support.annotation.IntDef;
 import android.text.Layout.Alignment;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * Contains information about a specific cue, including textual content and formatting data.
@@ -26,6 +29,13 @@ public class Cue {
    * An unset position or width.
    */
   public static final float DIMEN_UNSET = Float.MIN_VALUE;
+
+  /**
+   * The type of anchor, which may be unset.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({TYPE_UNSET, ANCHOR_TYPE_START, ANCHOR_TYPE_MIDDLE, ANCHOR_TYPE_END})
+  public @interface AnchorType {}
   /**
    * An unset anchor or line type value.
    */
@@ -44,6 +54,13 @@ public class Cue {
    * box.
    */
   public static final int ANCHOR_TYPE_END = 2;
+
+  /**
+   * The type of line, which may be unset.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({TYPE_UNSET, LINE_TYPE_FRACTION, LINE_TYPE_NUMBER})
+  public @interface LineType {}
   /**
    * Value for {@link #lineType} when {@link #line} is a fractional position.
    */
@@ -83,6 +100,7 @@ public class Cue {
    * -1). For horizontal text the size of the first line of the cue is its height, and the start
    * and end of the viewport are the top and bottom respectively.
    */
+  @LineType
   public final int lineType;
   /**
    * The cue box anchor positioned by {@link #line}. One of {@link #ANCHOR_TYPE_START},
@@ -92,6 +110,7 @@ public class Cue {
    * and {@link #ANCHOR_TYPE_END} correspond to the top, middle and bottom of the cue box
    * respectively.
    */
+  @AnchorType
   public final int lineAnchor;
   /**
    * The fractional position of the {@link #positionAnchor} of the cue box within the viewport in
@@ -110,6 +129,7 @@ public class Cue {
    * and {@link #ANCHOR_TYPE_END} correspond to the left, middle and right of the cue box
    * respectively.
    */
+  @AnchorType
   public final int positionAnchor;
   /**
    * The size of the cue box in the writing direction specified as a fraction of the viewport size
@@ -137,8 +157,8 @@ public class Cue {
    * @param positionAnchor See {@link #positionAnchor}.
    * @param size See {@link #size}.
    */
-  public Cue(CharSequence text, Alignment textAlignment, float line, int lineType, int lineAnchor,
+  public Cue(CharSequence text, Alignment textAlignment, float line, @LineType int lineType,
-      float position, int positionAnchor, float size) {
+      @AnchorType int lineAnchor, float position, @AnchorType int positionAnchor, float size) {
     this.text = text;
     this.textAlignment = textAlignment;
     this.line = line;

library/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlRegion.java

@@ -24,6 +24,7 @@ import com.google.android.exoplayer2.text.Cue;
 
   public final float position;
   public final float line;
+  @Cue.LineType
   public final int lineType;
   public final float width;
 
@@ -31,7 +32,7 @@ import com.google.android.exoplayer2.text.Cue;
     this(Cue.DIMEN_UNSET, Cue.DIMEN_UNSET, Cue.TYPE_UNSET, Cue.DIMEN_UNSET);
   }
 
-  public TtmlRegion(float position, float line, int lineType, float width) {
+  public TtmlRegion(float position, float line, @Cue.LineType int lineType, float width) {
     this.position = position;
     this.line = line;
     this.lineType = lineType;

library/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlStyle.java

@@ -16,8 +16,11 @@
 package com.google.android.exoplayer2.text.ttml;
 
 import android.graphics.Typeface;
+import android.support.annotation.IntDef;
 import android.text.Layout;
 import com.google.android.exoplayer2.util.Assertions;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * Style object of a <code>TtmlNode</code>
@@ -26,15 +29,25 @@ import com.google.android.exoplayer2.util.Assertions;
 
   public static final int UNSPECIFIED = -1;
 
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {UNSPECIFIED, STYLE_NORMAL, STYLE_BOLD, STYLE_ITALIC,
+      STYLE_BOLD_ITALIC})
+  public @interface StyleFlags {}
   public static final int STYLE_NORMAL = Typeface.NORMAL;
   public static final int STYLE_BOLD = Typeface.BOLD;
   public static final int STYLE_ITALIC = Typeface.ITALIC;
   public static final int STYLE_BOLD_ITALIC = Typeface.BOLD_ITALIC;
 
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({UNSPECIFIED, FONT_SIZE_UNIT_PIXEL, FONT_SIZE_UNIT_EM, FONT_SIZE_UNIT_PERCENT})
+  public @interface FontSizeUnit {}
   public static final int FONT_SIZE_UNIT_PIXEL = 1;
   public static final int FONT_SIZE_UNIT_EM = 2;
   public static final int FONT_SIZE_UNIT_PERCENT = 3;
 
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({UNSPECIFIED, OFF, ON})
+  private @interface OptionalBoolean {}
   private static final int OFF = 0;
   private static final int ON = 1;
 
@@ -43,10 +56,15 @@ import com.google.android.exoplayer2.util.Assertions;
   private boolean hasFontColor;
   private int backgroundColor;
   private boolean hasBackgroundColor;
+  @OptionalBoolean
   private int linethrough;
+  @OptionalBoolean
   private int underline;
+  @OptionalBoolean
   private int bold;
+  @OptionalBoolean
   private int italic;
+  @FontSizeUnit
   private int fontSizeUnit;
   private float fontSize;
   private String id;
@@ -67,12 +85,13 @@ import com.google.android.exoplayer2.util.Assertions;
    * @return {@link #UNSPECIFIED}, {@link #STYLE_NORMAL}, {@link #STYLE_BOLD}, {@link #STYLE_BOLD}
    *     or {@link #STYLE_BOLD_ITALIC}.
    */
+  @StyleFlags
   public int getStyle() {
     if (bold == UNSPECIFIED && italic == UNSPECIFIED) {
       return UNSPECIFIED;
     }
-    return (bold != UNSPECIFIED ? bold : STYLE_NORMAL)
+    return (bold == ON ? STYLE_BOLD : STYLE_NORMAL)
-        | (italic != UNSPECIFIED ? italic : STYLE_NORMAL);
+        | (italic == ON ? STYLE_ITALIC : STYLE_NORMAL);
   }
 
   public boolean isLinethrough() {
@@ -95,6 +114,18 @@ import com.google.android.exoplayer2.util.Assertions;
     return this;
   }
 
+  public TtmlStyle setBold(boolean bold) {
+    Assertions.checkState(inheritableStyle == null);
+    this.bold = bold ? ON : OFF;
+    return this;
+  }
+
+  public TtmlStyle setItalic(boolean italic) {
+    Assertions.checkState(inheritableStyle == null);
+    this.italic = italic ? ON : OFF;
+    return this;
+  }
+
   public String getFontFamily() {
     return fontFamily;
   }
@@ -140,18 +171,6 @@ import com.google.android.exoplayer2.util.Assertions;
     return hasBackgroundColor;
   }
 
-  public TtmlStyle setBold(boolean isBold) {
-    Assertions.checkState(inheritableStyle == null);
-    bold = isBold ? STYLE_BOLD : STYLE_NORMAL;
-    return this;
-  }
-
-  public TtmlStyle setItalic(boolean isItalic) {
-    Assertions.checkState(inheritableStyle == null);
-    italic = isItalic ? STYLE_ITALIC : STYLE_NORMAL;
-    return this;
-  }
-
   /**
    * Inherits from an ancestor style. Properties like <i>tts:backgroundColor</i> which
    * are not inheritable are not inherited as well as properties which are already set locally
@@ -236,6 +255,7 @@ import com.google.android.exoplayer2.util.Assertions;
     return this;
   }
 
+  @FontSizeUnit
   public int getFontSizeUnit() {
     return fontSizeUnit;
   }

library/src/main/java/com/google/android/exoplayer2/text/webvtt/WebvttCssStyle.java

@@ -16,8 +16,11 @@
 package com.google.android.exoplayer2.text.webvtt;
 
 import android.graphics.Typeface;
+import android.support.annotation.IntDef;
 import android.text.Layout;
 import com.google.android.exoplayer2.util.Util;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -32,15 +35,25 @@ import java.util.List;
 
   public static final int UNSPECIFIED = -1;
 
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {UNSPECIFIED, STYLE_NORMAL, STYLE_BOLD, STYLE_ITALIC,
+      STYLE_BOLD_ITALIC})
+  public @interface StyleFlags {}
   public static final int STYLE_NORMAL = Typeface.NORMAL;
   public static final int STYLE_BOLD = Typeface.BOLD;
   public static final int STYLE_ITALIC = Typeface.ITALIC;
   public static final int STYLE_BOLD_ITALIC = Typeface.BOLD_ITALIC;
 
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({UNSPECIFIED, FONT_SIZE_UNIT_PIXEL, FONT_SIZE_UNIT_EM, FONT_SIZE_UNIT_PERCENT})
+  public @interface FontSizeUnit {}
   public static final int FONT_SIZE_UNIT_PIXEL = 1;
   public static final int FONT_SIZE_UNIT_EM = 2;
   public static final int FONT_SIZE_UNIT_PERCENT = 3;
 
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({UNSPECIFIED, OFF, ON})
+  private @interface OptionalBoolean {}
   private static final int OFF = 0;
   private static final int ON = 1;
 
@@ -56,10 +69,15 @@ import java.util.List;
   private boolean hasFontColor;
   private int backgroundColor;
   private boolean hasBackgroundColor;
+  @OptionalBoolean
   private int linethrough;
+  @OptionalBoolean
   private int underline;
+  @OptionalBoolean
   private int bold;
+  @OptionalBoolean
   private int italic;
+  @FontSizeUnit
   private int fontSizeUnit;
   private float fontSize;
   private Layout.Alignment textAlign;
@@ -144,12 +162,13 @@ import java.util.List;
    * @return {@link #UNSPECIFIED}, {@link #STYLE_NORMAL}, {@link #STYLE_BOLD}, {@link #STYLE_BOLD}
    *     or {@link #STYLE_BOLD_ITALIC}.
    */
+  @StyleFlags
   public int getStyle() {
     if (bold == UNSPECIFIED && italic == UNSPECIFIED) {
       return UNSPECIFIED;
     }
-    return (bold != UNSPECIFIED ? bold : STYLE_NORMAL)
+    return (bold == ON ? STYLE_BOLD : STYLE_NORMAL)
-        | (italic != UNSPECIFIED ? italic : STYLE_NORMAL);
+        | (italic == ON ? STYLE_ITALIC : STYLE_NORMAL);
   }
 
   public boolean isLinethrough() {
@@ -169,6 +188,15 @@ import java.util.List;
     this.underline = underline ? ON : OFF;
     return this;
   }
+  public WebvttCssStyle setBold(boolean bold) {
+    this.bold = bold ? ON : OFF;
+    return this;
+  }
+
+  public WebvttCssStyle setItalic(boolean italic) {
+    this.italic = italic ? ON : OFF;
+    return this;
+  }
 
   public String getFontFamily() {
     return fontFamily;
@@ -213,16 +241,6 @@ import java.util.List;
     return hasBackgroundColor;
   }
 
-  public WebvttCssStyle setBold(boolean isBold) {
-    bold = isBold ? STYLE_BOLD : STYLE_NORMAL;
-    return this;
-  }
-
-  public WebvttCssStyle setItalic(boolean isItalic) {
-    italic = isItalic ? STYLE_ITALIC : STYLE_NORMAL;
-    return this;
-  }
-
   public Layout.Alignment getTextAlign() {
     return textAlign;
   }
@@ -242,6 +260,7 @@ import java.util.List;
     return this;
   }
 
+  @FontSizeUnit
   public int getFontSizeUnit() {
     return fontSizeUnit;
   }

library/src/main/java/com/google/android/exoplayer2/text/webvtt/WebvttCue.java

@@ -37,8 +37,9 @@ import com.google.android.exoplayer2.text.Cue;
         Cue.DIMEN_UNSET, Cue.TYPE_UNSET, Cue.DIMEN_UNSET);
   }
 
-  public WebvttCue(long startTime, long endTime, CharSequence text, Alignment textAlignment, 
+  public WebvttCue(long startTime, long endTime, CharSequence text, Alignment textAlignment,
-      float line, int lineType, int lineAnchor, float position, int positionAnchor, float width) {
+      float line, @Cue.LineType int lineType, @Cue.AnchorType int lineAnchor, float position,
+      @Cue.AnchorType int positionAnchor, float width) {
     super(text, textAlignment, line, lineType, lineAnchor, position, positionAnchor, width);
     this.startTime = startTime;
     this.endTime = endTime;

library/src/main/java/com/google/android/exoplayer2/trackselection/DefaultTrackSelector.java

@@ -442,7 +442,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
       for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
         if (isSupported(trackFormatSupport[trackIndex])) {
           Format format = trackGroup.getFormat(trackIndex);
-          boolean isDefault = (format.selectionFlags & Format.SELECTION_FLAG_DEFAULT) != 0;
+          boolean isDefault = (format.selectionFlags & C.SELECTION_FLAG_DEFAULT) != 0;
           int trackScore;
           if (formatHasLanguage(format, preferredAudioLanguage)) {
             if (isDefault) {
@@ -480,8 +480,8 @@ public class DefaultTrackSelector extends MappingTrackSelector {
       for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
         if (isSupported(trackFormatSupport[trackIndex])) {
           Format format = trackGroup.getFormat(trackIndex);
-          boolean isDefault = (format.selectionFlags & Format.SELECTION_FLAG_DEFAULT) != 0;
+          boolean isDefault = (format.selectionFlags & C.SELECTION_FLAG_DEFAULT) != 0;
-          boolean isForced = (format.selectionFlags & Format.SELECTION_FLAG_FORCED) != 0;
+          boolean isForced = (format.selectionFlags & C.SELECTION_FLAG_FORCED) != 0;
           int trackScore;
           if (formatHasLanguage(format, preferredTextLanguage)) {
             if (isDefault) {
@@ -530,7 +530,7 @@ public class DefaultTrackSelector extends MappingTrackSelector {
       for (int trackIndex = 0; trackIndex < trackGroup.length; trackIndex++) {
         if (isSupported(trackFormatSupport[trackIndex])) {
           Format format = trackGroup.getFormat(trackIndex);
-          boolean isDefault = (format.selectionFlags & Format.SELECTION_FLAG_DEFAULT) != 0;
+          boolean isDefault = (format.selectionFlags & C.SELECTION_FLAG_DEFAULT) != 0;
           int trackScore = isDefault ? 2 : 1;
           if (trackScore > selectedTrackScore) {
             selectedGroup = trackGroup;

library/src/main/java/com/google/android/exoplayer2/ui/SubtitlePainter.java

@@ -66,9 +66,12 @@ import com.google.android.exoplayer2.util.Util;
   private CharSequence cueText;
   private Alignment cueTextAlignment;
   private float cueLine;
+  @Cue.LineType
   private int cueLineType;
+  @Cue.AnchorType
   private int cueLineAnchor;
   private float cuePosition;
+  @Cue.AnchorType
   private int cuePositionAnchor;
   private float cueSize;
   private boolean applyEmbeddedStyles;
@@ -76,6 +79,7 @@ import com.google.android.exoplayer2.util.Util;
   private int backgroundColor;
   private int windowColor;
   private int edgeColor;
+  @CaptionStyleCompat.EdgeType
   private int edgeType;
   private float textSizePx;
   private float bottomPaddingFraction;

library/src/main/java/com/google/android/exoplayer2/upstream/DataSpec.java

@@ -16,8 +16,11 @@
 package com.google.android.exoplayer2.upstream;
 
 import android.net.Uri;
+import android.support.annotation.IntDef;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.Assertions;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.Arrays;
 
 /**
@@ -25,6 +28,12 @@ import java.util.Arrays;
  */
 public final class DataSpec {
 
+  /**
+   * The flags that apply to any request for data.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {FLAG_ALLOW_GZIP})
+  public @interface Flags {}
   /**
    * Permits an underlying network stack to request that the server use gzip compression.
    * <p>
@@ -69,6 +78,7 @@ public final class DataSpec {
   /**
    * Request flags. Currently {@link #FLAG_ALLOW_GZIP} is the only supported flag.
    */
+  @Flags
   public final int flags;
 
   /**
@@ -86,7 +96,7 @@ public final class DataSpec {
    * @param uri {@link #uri}.
    * @param flags {@link #flags}.
    */
-  public DataSpec(Uri uri, int flags) {
+  public DataSpec(Uri uri, @Flags int flags) {
     this(uri, 0, C.LENGTH_UNSET, null, flags);
   }
 
@@ -111,7 +121,7 @@ public final class DataSpec {
    * @param key {@link #key}.
    * @param flags {@link #flags}.
    */
-  public DataSpec(Uri uri, long absoluteStreamPosition, long length, String key, int flags) {
+  public DataSpec(Uri uri, long absoluteStreamPosition, long length, String key, @Flags int flags) {
     this(uri, absoluteStreamPosition, absoluteStreamPosition, length, key, flags);
   }
 
@@ -127,7 +137,7 @@ public final class DataSpec {
    * @param flags {@link #flags}.
    */
   public DataSpec(Uri uri, long absoluteStreamPosition, long position, long length, String key,
-      int flags) {
+      @Flags int flags) {
     this(uri, null, absoluteStreamPosition, position, length, key, flags);
   }
 
@@ -144,7 +154,7 @@ public final class DataSpec {
    * @param flags {@link #flags}.
    */
   public DataSpec(Uri uri, byte[] postBody, long absoluteStreamPosition, long position, long length,
-      String key, int flags) {
+      String key, @Flags int flags) {
     Assertions.checkArgument(absoluteStreamPosition >= 0);
     Assertions.checkArgument(position >= 0);
     Assertions.checkArgument(length > 0 || length == C.LENGTH_UNSET);

library/src/main/java/com/google/android/exoplayer2/upstream/HttpDataSource.java

@@ -15,10 +15,13 @@
  */
 package com.google.android.exoplayer2.upstream;
 
+import android.support.annotation.IntDef;
 import android.text.TextUtils;
 import com.google.android.exoplayer2.util.Predicate;
 import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.List;
 import java.util.Map;
 
@@ -57,10 +60,14 @@ public interface HttpDataSource extends DataSource {
    */
   class HttpDataSourceException extends IOException {
 
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef({TYPE_OPEN, TYPE_READ, TYPE_CLOSE})
+    public @interface Type {}
     public static final int TYPE_OPEN = 1;
     public static final int TYPE_READ = 2;
     public static final int TYPE_CLOSE = 3;
 
+    @Type
     public final int type;
 
     /**
@@ -68,25 +75,26 @@ public interface HttpDataSource extends DataSource {
      */
     public final DataSpec dataSpec;
 
-    public HttpDataSourceException(DataSpec dataSpec, int type) {
+    public HttpDataSourceException(DataSpec dataSpec, @Type int type) {
       super();
       this.dataSpec = dataSpec;
       this.type = type;
     }
 
-    public HttpDataSourceException(String message, DataSpec dataSpec, int type) {
+    public HttpDataSourceException(String message, DataSpec dataSpec, @Type int type) {
       super(message);
       this.dataSpec = dataSpec;
       this.type = type;
     }
 
-    public HttpDataSourceException(IOException cause, DataSpec dataSpec, int type) {
+    public HttpDataSourceException(IOException cause, DataSpec dataSpec, @Type int type) {
       super(cause);
       this.dataSpec = dataSpec;
       this.type = type;
     }
 
-    public HttpDataSourceException(String message, IOException cause, DataSpec dataSpec, int type) {
+    public HttpDataSourceException(String message, IOException cause, DataSpec dataSpec,
+        @Type int type) {
       super(message, cause);
       this.dataSpec = dataSpec;
       this.type = type;

library/src/main/java/com/google/android/exoplayer2/upstream/cache/CacheDataSource.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.upstream.cache;
 
 import android.net.Uri;
+import android.support.annotation.IntDef;
 import android.util.Log;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.upstream.DataSink;
@@ -27,6 +28,8 @@ import com.google.android.exoplayer2.upstream.TeeDataSource;
 import com.google.android.exoplayer2.upstream.cache.CacheDataSink.CacheDataSinkException;
 import java.io.IOException;
 import java.io.InterruptedIOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 
 /**
  * A {@link DataSource} that reads and writes a {@link Cache}. Requests are fulfilled from the cache
@@ -43,6 +46,13 @@ public final class CacheDataSource implements DataSource {
    */
   public static final long DEFAULT_MAX_CACHE_FILE_SIZE = 2 * 1024 * 1024;
 
+  /**
+   * Flags controlling the cache's behavior.
+   */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef(flag = true, value = {FLAG_BLOCK_ON_CACHE, FLAG_IGNORE_CACHE_ON_ERROR,
+      FLAG_CACHE_UNBOUNDED_REQUESTS})
+  public @interface Flags {}
   /**
    * A flag indicating whether we will block reads if the cache key is locked. If this flag is
    * set, then we will read from upstream if the cache key is locked.
@@ -106,7 +116,7 @@ public final class CacheDataSource implements DataSource {
    * Constructs an instance with default {@link DataSource} and {@link DataSink} instances for
    * reading and writing the cache and with {@link #DEFAULT_MAX_CACHE_FILE_SIZE}.
    */
-  public CacheDataSource(Cache cache, DataSource upstream, int flags) {
+  public CacheDataSource(Cache cache, DataSource upstream, @Flags int flags) {
     this(cache, upstream, flags, DEFAULT_MAX_CACHE_FILE_SIZE);
   }
 
@@ -123,7 +133,8 @@ public final class CacheDataSource implements DataSource {
    *     exceeds this value, then the data will be fragmented into multiple cache files. The
    *     finer-grained this is the finer-grained the eviction policy can be.
    */
-  public CacheDataSource(Cache cache, DataSource upstream, int flags, long maxCacheFileSize) {
+  public CacheDataSource(Cache cache, DataSource upstream, @Flags int flags,
+      long maxCacheFileSize) {
     this(cache, upstream, new FileDataSource(), new CacheDataSink(cache, maxCacheFileSize),
         flags, null);
   }
@@ -142,7 +153,7 @@ public final class CacheDataSource implements DataSource {
    * @param eventListener An optional {@link EventListener} to receive events.
    */
   public CacheDataSource(Cache cache, DataSource upstream, DataSource cacheReadDataSource,
-      DataSink cacheWriteDataSink, int flags, EventListener eventListener) {
+      DataSink cacheWriteDataSink, @Flags int flags, EventListener eventListener) {
     this.cache = cache;
     this.cacheReadDataSource = cacheReadDataSource;
     this.blockOnCache = (flags & FLAG_BLOCK_ON_CACHE) != 0;

library/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -88,27 +88,6 @@ public final class Util {
    */
   public static final String MODEL = Build.MODEL;
 
-  /**
-   * Value returned by {@link #inferContentType(String)} for DASH manifests.
-   */
-  public static final int TYPE_DASH = 0;
-
-  /**
-   * Value returned by {@link #inferContentType(String)} for Smooth Streaming manifests.
-   */
-  public static final int TYPE_SS = 1;
-
-  /**
-   * Value returned by {@link #inferContentType(String)} for HLS manifests.
-   */
-  public static final int TYPE_HLS = 2;
-
-  /**
-   * Value returned by {@link #inferContentType(String)} for files other than DASH, HLS or Smooth
-   * Streaming manifests.
-   */
-  public static final int TYPE_OTHER = 3;
-
   private static final String TAG = "Util";
   private static final Pattern XS_DATE_TIME_PATTERN = Pattern.compile(
       "(\\d\\d\\d\\d)\\-(\\d\\d)\\-(\\d\\d)[Tt]"
@@ -712,6 +691,7 @@ public final class Util {
    *     {@link C#ENCODING_PCM_32BIT}. If the bit depth is unsupported then
    *     {@link C#ENCODING_INVALID} is returned.
    */
+  @C.PcmEncoding
   public static int getPcmEncoding(int bitDepth) {
     switch (bitDepth) {
       case 8:
@@ -731,19 +711,20 @@ public final class Util {
    * Makes a best guess to infer the type from a file name.
    *
    * @param fileName Name of the file. It can include the path of the file.
-   * @return One of {@link #TYPE_DASH}, {@link #TYPE_SS}, {@link #TYPE_HLS} or {@link #TYPE_OTHER}.
+   * @return The content type.
    */
+  @C.ContentType
   public static int inferContentType(String fileName) {
     if (fileName == null) {
-      return TYPE_OTHER;
+      return C.TYPE_OTHER;
     } else if (fileName.endsWith(".mpd")) {
-      return TYPE_DASH;
+      return C.TYPE_DASH;
     } else if (fileName.endsWith(".ism") || fileName.endsWith(".isml")) {
-      return TYPE_SS;
+      return C.TYPE_SS;
     } else if (fileName.endsWith(".m3u8")) {
-      return TYPE_HLS;
+      return C.TYPE_HLS;
     } else {
-      return TYPE_OTHER;
+      return C.TYPE_OTHER;
     }
   }
 

testutils/src/main/java/com/google/android/exoplayer2/testutil/FakeTrackOutput.java

@@ -88,7 +88,8 @@ public final class FakeTrackOutput implements TrackOutput, Dumper.Dumpable {
   }
 
   @Override
-  public void sampleMetadata(long timeUs, int flags, int size, int offset, byte[] encryptionKey) {
+  public void sampleMetadata(long timeUs, @C.BufferFlags int flags, int size, int offset,
+      byte[] encryptionKey) {
     sampleTimesUs.add(timeUs);
     sampleFlags.add(flags);
     sampleStartOffsets.add(sampleData.length - offset - size);