Split AAC utils out of CodecSpecificDataUtil

PiperOrigin-RevId: 297823929

library/common/src/main/java/com/google/android/exoplayer2/audio/AacUtil.java

@@ -0,0 +1,340 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.audio;
+
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.Log;
+import com.google.android.exoplayer2.util.ParsableBitArray;
+
+/** Utility methods for handling AAC audio streams. */
+public final class AacUtil {
+
+  private static final String TAG = "AacUtil";
+
+  /** Holds sample format information for AAC audio. */
+  public static final class Config {
+
+    /** The sample rate in Hertz. */
+    public final int sampleRateHz;
+    /** The number of channels. */
+    public final int channelCount;
+    /** The RFC 6381 codecs string. */
+    public final String codecs;
+
+    private Config(int sampleRateHz, int channelCount, String codecs) {
+      this.sampleRateHz = sampleRateHz;
+      this.channelCount = channelCount;
+      this.codecs = codecs;
+    }
+  }
+
+  // Audio sample count constants assume the frameLengthFlag in the access unit is 0.
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC LC access unit.
+   */
+  public static final int AAC_LC_AUDIO_SAMPLE_COUNT = 1024;
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC XHE access unit.
+   */
+  public static final int AAC_XHE_AUDIO_SAMPLE_COUNT = AAC_LC_AUDIO_SAMPLE_COUNT;
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC HE access unit.
+   */
+  public static final int AAC_HE_AUDIO_SAMPLE_COUNT = 2048;
+  /**
+   * Number of raw audio samples that are produced per channel when decoding an AAC LD access unit.
+   */
+  public static final int AAC_LD_AUDIO_SAMPLE_COUNT = 512;
+
+  private static final int AUDIO_SPECIFIC_CONFIG_FREQUENCY_INDEX_ARBITRARY = 0xF;
+  private static final int[] AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE =
+      new int[] {
+        96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 7350
+      };
+  private static final int AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID = -1;
+  /**
+   * In the channel configurations below, <A> indicates a single channel element; (A, B)
+   * indicates a channel pair element; and [A] indicates a low-frequency effects element. The
+   * speaker mapping short forms used are:
+   *
+   * <ul>
+   *   <li>FC: front center
+   *   <li>BC: back center
+   *   <li>FL/FR: front left/right
+   *   <li>FCL/FCR: front center left/right
+   *   <li>FTL/FTR: front top left/right
+   *   <li>SL/SR: back surround left/right
+   *   <li>BL/BR: back left/right
+   *   <li>LFE: low frequency effects
+   * </ul>
+   */
+  private static final int[] AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE =
+      new int[] {
+        0,
+        1, /* mono: <FC> */
+        2, /* stereo: (FL, FR) */
+        3, /* 3.0: <FC>, (FL, FR) */
+        4, /* 4.0: <FC>, (FL, FR), <BC> */
+        5, /* 5.0 back: <FC>, (FL, FR), (SL, SR) */
+        6, /* 5.1 back: <FC>, (FL, FR), (SL, SR), <BC>, [LFE] */
+        8, /* 7.1 wide back: <FC>, (FCL, FCR), (FL, FR), (SL, SR), [LFE] */
+        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
+        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
+        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
+        7, /* 6.1: <FC>, (FL, FR), (SL, SR), <RC>, [LFE] */
+        8, /* 7.1: <FC>, (FL, FR), (SL, SR), (BL, BR), [LFE] */
+        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
+        8, /* 7.1 top: <FC>, (FL, FR), (SL, SR), [LFE], (FTL, FTR) */
+        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID
+      };
+
+  /**
+   * Prefix for the RFC 6381 codecs string for AAC formats. To form a full codecs string, suffix the
+   * decimal AudioObjectType.
+   */
+  private static final String CODECS_STRING_PREFIX = "mp4a.40.";
+
+  // Advanced Audio Coding Low-Complexity profile.
+  private static final int AUDIO_OBJECT_TYPE_AAC_LC = 2;
+  // Spectral Band Replication.
+  private static final int AUDIO_OBJECT_TYPE_AAC_SBR = 5;
+  // Error Resilient Bit-Sliced Arithmetic Coding.
+  private static final int AUDIO_OBJECT_TYPE_AAC_ER_BSAC = 22;
+  // Enhanced low delay.
+  private static final int AUDIO_OBJECT_TYPE_AAC_ELD = 23;
+  // Parametric Stereo.
+  private static final int AUDIO_OBJECT_TYPE_AAC_PS = 29;
+  // Escape code for extended audio object types.
+  private static final int AUDIO_OBJECT_TYPE_ESCAPE = 31;
+  // Extended high efficiency.
+  private static final int AUDIO_OBJECT_TYPE_AAC_XHE = 42;
+
+  /**
+   * Parses an AAC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
+   *
+   * @param audioSpecificConfig A byte array containing the AudioSpecificConfig to parse.
+   * @return The parsed configuration.
+   * @throws ParserException If the AudioSpecificConfig cannot be parsed as it's not supported.
+   */
+  public static Config parseAudioSpecificConfig(byte[] audioSpecificConfig) throws ParserException {
+    return parseAudioSpecificConfig(
+        new ParsableBitArray(audioSpecificConfig), /* forceReadToEnd= */ false);
+  }
+
+  /**
+   * Parses an AAC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
+   *
+   * @param bitArray A {@link ParsableBitArray} containing the AudioSpecificConfig to parse. The
+   *     position is advanced to the end of the AudioSpecificConfig.
+   * @param forceReadToEnd Whether the entire AudioSpecificConfig should be read. Required for
+   *     knowing the length of the configuration payload.
+   * @return The parsed configuration.
+   * @throws ParserException If the AudioSpecificConfig cannot be parsed as it's not supported.
+   */
+  public static Config parseAudioSpecificConfig(ParsableBitArray bitArray, boolean forceReadToEnd)
+      throws ParserException {
+    int audioObjectType = getAudioObjectType(bitArray);
+    int sampleRateHz = getSamplingFrequency(bitArray);
+    int channelConfiguration = bitArray.readBits(4);
+    String codecs = CODECS_STRING_PREFIX + audioObjectType;
+    if (audioObjectType == AUDIO_OBJECT_TYPE_AAC_SBR
+        || audioObjectType == AUDIO_OBJECT_TYPE_AAC_PS) {
+      // For an AAC bitstream using spectral band replication (SBR) or parametric stereo (PS) with
+      // explicit signaling, we return the extension sampling frequency as the sample rate of the
+      // content; this is identical to the sample rate of the decoded output but may differ from
+      // the sample rate set above.
+      // Use the extensionSamplingFrequencyIndex.
+      sampleRateHz = getSamplingFrequency(bitArray);
+      audioObjectType = getAudioObjectType(bitArray);
+      if (audioObjectType == AUDIO_OBJECT_TYPE_AAC_ER_BSAC) {
+        // Use the extensionChannelConfiguration.
+        channelConfiguration = bitArray.readBits(4);
+      }
+    }
+
+    if (forceReadToEnd) {
+      switch (audioObjectType) {
+        case 1:
+        case 2:
+        case 3:
+        case 4:
+        case 6:
+        case 7:
+        case 17:
+        case 19:
+        case 20:
+        case 21:
+        case 22:
+        case 23:
+          parseGaSpecificConfig(bitArray, audioObjectType, channelConfiguration);
+          break;
+        default:
+          throw new ParserException("Unsupported audio object type: " + audioObjectType);
+      }
+      switch (audioObjectType) {
+        case 17:
+        case 19:
+        case 20:
+        case 21:
+        case 22:
+        case 23:
+          int epConfig = bitArray.readBits(2);
+          if (epConfig == 2 || epConfig == 3) {
+            throw new ParserException("Unsupported epConfig: " + epConfig);
+          }
+          break;
+        default:
+          break;
+      }
+    }
+    // For supported containers, bits_to_decode() is always 0.
+    int channelCount = AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[channelConfiguration];
+    Assertions.checkArgument(channelCount != AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID);
+    return new Config(sampleRateHz, channelCount, codecs);
+  }
+
+  /**
+   * Builds a simple AAC LC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
+   *
+   * @param sampleRate The sample rate in Hz.
+   * @param channelCount The channel count.
+   * @return The AudioSpecificConfig.
+   */
+  public static byte[] buildAacLcAudioSpecificConfig(int sampleRate, int channelCount) {
+    int sampleRateIndex = C.INDEX_UNSET;
+    for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE.length; ++i) {
+      if (sampleRate == AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE[i]) {
+        sampleRateIndex = i;
+      }
+    }
+    int channelConfig = C.INDEX_UNSET;
+    for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE.length; ++i) {
+      if (channelCount == AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[i]) {
+        channelConfig = i;
+      }
+    }
+    if (sampleRate == C.INDEX_UNSET || channelConfig == C.INDEX_UNSET) {
+      throw new IllegalArgumentException(
+          "Invalid sample rate or number of channels: " + sampleRate + ", " + channelCount);
+    }
+    return buildAudioSpecificConfig(AUDIO_OBJECT_TYPE_AAC_LC, sampleRateIndex, channelConfig);
+  }
+
+  /**
+   * Builds a simple AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
+   *
+   * @param audioObjectType The audio object type.
+   * @param sampleRateIndex The sample rate index.
+   * @param channelConfig The channel configuration.
+   * @return The AudioSpecificConfig.
+   */
+  public static byte[] buildAudioSpecificConfig(
+      int audioObjectType, int sampleRateIndex, int channelConfig) {
+    byte[] specificConfig = new byte[2];
+    specificConfig[0] = (byte) (((audioObjectType << 3) & 0xF8) | ((sampleRateIndex >> 1) & 0x07));
+    specificConfig[1] = (byte) (((sampleRateIndex << 7) & 0x80) | ((channelConfig << 3) & 0x78));
+    return specificConfig;
+  }
+
+  /** Returns the encoding for a given AAC audio object type. */
+  @C.Encoding
+  public static int getEncodingForAudioObjectType(int audioObjectType) {
+    switch (audioObjectType) {
+      case AUDIO_OBJECT_TYPE_AAC_LC:
+        return C.ENCODING_AAC_LC;
+      case AUDIO_OBJECT_TYPE_AAC_SBR:
+        return C.ENCODING_AAC_HE_V1;
+      case AUDIO_OBJECT_TYPE_AAC_PS:
+        return C.ENCODING_AAC_HE_V2;
+      case AUDIO_OBJECT_TYPE_AAC_XHE:
+        return C.ENCODING_AAC_XHE;
+      case AUDIO_OBJECT_TYPE_AAC_ELD:
+        return C.ENCODING_AAC_ELD;
+      default:
+        return C.ENCODING_INVALID;
+    }
+  }
+
+  /**
+   * Returns the AAC audio object type as specified in 14496-3 (2005) Table 1.14.
+   *
+   * @param bitArray The bit array containing the audio specific configuration.
+   * @return The audio object type.
+   */
+  private static int getAudioObjectType(ParsableBitArray bitArray) {
+    int audioObjectType = bitArray.readBits(5);
+    if (audioObjectType == AUDIO_OBJECT_TYPE_ESCAPE) {
+      audioObjectType = 32 + bitArray.readBits(6);
+    }
+    return audioObjectType;
+  }
+
+  /**
+   * Returns the AAC sampling frequency (or extension sampling frequency) as specified in 14496-3
+   * (2005) Table 1.13.
+   *
+   * @param bitArray The bit array containing the audio specific configuration.
+   * @return The sampling frequency.
+   */
+  private static int getSamplingFrequency(ParsableBitArray bitArray) {
+    int samplingFrequency;
+    int frequencyIndex = bitArray.readBits(4);
+    if (frequencyIndex == AUDIO_SPECIFIC_CONFIG_FREQUENCY_INDEX_ARBITRARY) {
+      samplingFrequency = bitArray.readBits(24);
+    } else {
+      Assertions.checkArgument(frequencyIndex < 13);
+      samplingFrequency = AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE[frequencyIndex];
+    }
+    return samplingFrequency;
+  }
+
+  private static void parseGaSpecificConfig(
+      ParsableBitArray bitArray, int audioObjectType, int channelConfiguration) {
+    boolean frameLengthFlag = bitArray.readBit();
+    if (frameLengthFlag) {
+      Log.w(TAG, "Unexpected frameLengthFlag = 1");
+    }
+    boolean dependsOnCoreDecoder = bitArray.readBit();
+    if (dependsOnCoreDecoder) {
+      bitArray.skipBits(14); // coreCoderDelay.
+    }
+    boolean extensionFlag = bitArray.readBit();
+    if (channelConfiguration == 0) {
+      throw new UnsupportedOperationException(); // TODO: Implement programConfigElement();
+    }
+    if (audioObjectType == 6 || audioObjectType == 20) {
+      bitArray.skipBits(3); // layerNr.
+    }
+    if (extensionFlag) {
+      if (audioObjectType == 22) {
+        bitArray.skipBits(16); // numOfSubFrame (5), layer_length(11).
+      }
+      if (audioObjectType == 17
+          || audioObjectType == 19
+          || audioObjectType == 20
+          || audioObjectType == 23) {
+        // aacSectionDataResilienceFlag, aacScalefactorDataResilienceFlag,
+        // aacSpectralDataResilienceFlag.
+        bitArray.skipBits(3);
+      }
+      bitArray.skipBits(1); // extensionFlag3.
+    }
+  }
+
+  private AacUtil() {}
+}

library/common/src/main/java/com/google/android/exoplayer2/util/CodecSpecificDataUtil.java

@@ -18,7 +18,6 @@ package com.google.android.exoplayer2.util;
 import android.util.Pair;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
-import com.google.android.exoplayer2.ParserException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -26,253 +25,8 @@ import java.util.List;
 /** Provides utilities for handling various types of codec-specific data. */
 public final class CodecSpecificDataUtil {
 
-  private static final String TAG = "CodecSpecificDataUtil";
-
-  /** Holds sample format information for AAC audio. */
-  public static final class AacConfig {
-
-    /** The sample rate in Hertz. */
-    public final int sampleRateHz;
-    /** The number of channels. */
-    public final int channelCount;
-    /** The RFC 6381 codecs string. */
-    public final String codecs;
-
-    private AacConfig(int sampleRateHz, int channelCount, String codecs) {
-      this.sampleRateHz = sampleRateHz;
-      this.channelCount = channelCount;
-      this.codecs = codecs;
-    }
-  }
-
-  // AAC audio sample count constants assume the frameLengthFlag in the access unit is 0.
-  /**
-   * Number of raw audio samples that are produced per channel when decoding an AAC LC access unit.
-   */
-  public static final int AAC_LC_AUDIO_SAMPLE_COUNT = 1024;
-  /**
-   * Number of raw audio samples that are produced per channel when decoding an AAC XHE access unit.
-   */
-  public static final int AAC_XHE_AUDIO_SAMPLE_COUNT = AAC_LC_AUDIO_SAMPLE_COUNT;
-  /**
-   * Number of raw audio samples that are produced per channel when decoding an AAC HE access unit.
-   */
-  public static final int AAC_HE_AUDIO_SAMPLE_COUNT = 2048;
-  /**
-   * Number of raw audio samples that are produced per channel when decoding an AAC LD access unit.
-   */
-  public static final int AAC_LD_AUDIO_SAMPLE_COUNT = 512;
-
   private static final byte[] NAL_START_CODE = new byte[] {0, 0, 0, 1};
 
-  private static final int AUDIO_SPECIFIC_CONFIG_FREQUENCY_INDEX_ARBITRARY = 0xF;
-
-  private static final int[] AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE = new int[] {
-    96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 7350
-  };
-
-  private static final int AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID = -1;
-  /**
-   * In the channel configurations below, <A> indicates a single channel element; (A, B) indicates a
-   * channel pair element; and [A] indicates a low-frequency effects element.
-   * The speaker mapping short forms used are:
-   * - FC: front center
-   * - BC: back center
-   * - FL/FR: front left/right
-   * - FCL/FCR: front center left/right
-   * - FTL/FTR: front top left/right
-   * - SL/SR: back surround left/right
-   * - BL/BR: back left/right
-   * - LFE: low frequency effects
-   */
-  private static final int[] AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE =
-      new int[] {
-        0,
-        1, /* mono: <FC> */
-        2, /* stereo: (FL, FR) */
-        3, /* 3.0: <FC>, (FL, FR) */
-        4, /* 4.0: <FC>, (FL, FR), <BC> */
-        5, /* 5.0 back: <FC>, (FL, FR), (SL, SR) */
-        6, /* 5.1 back: <FC>, (FL, FR), (SL, SR), <BC>, [LFE] */
-        8, /* 7.1 wide back: <FC>, (FCL, FCR), (FL, FR), (SL, SR), [LFE] */
-        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
-        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
-        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
-        7, /* 6.1: <FC>, (FL, FR), (SL, SR), <RC>, [LFE] */
-        8, /* 7.1: <FC>, (FL, FR), (SL, SR), (BL, BR), [LFE] */
-        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID,
-        8, /* 7.1 top: <FC>, (FL, FR), (SL, SR), [LFE], (FTL, FTR) */
-        AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID
-      };
-
-  /**
-   * Prefix for the RFC 6381 codecs string for AAC formats. To form a full codecs string, suffix the
-   * decimal AudioObjectType.
-   */
-  private static final String AAC_CODECS_STRING_PREFIX = "mp4a.40.";
-
-  // Advanced Audio Coding Low-Complexity profile.
-  private static final int AUDIO_OBJECT_TYPE_AAC_LC = 2;
-  // Spectral Band Replication.
-  private static final int AUDIO_OBJECT_TYPE_AAC_SBR = 5;
-  // Error Resilient Bit-Sliced Arithmetic Coding.
-  private static final int AUDIO_OBJECT_TYPE_AAC_ER_BSAC = 22;
-  // Enhanced low delay.
-  private static final int AUDIO_OBJECT_TYPE_AAC_ELD = 23;
-  // Parametric Stereo.
-  private static final int AUDIO_OBJECT_TYPE_AAC_PS = 29;
-  // Escape code for extended audio object types.
-  private static final int AUDIO_OBJECT_TYPE_ESCAPE = 31;
-  // Extended high efficiency.
-  private static final int AUDIO_OBJECT_TYPE_AAC_XHE = 42;
-
-  private CodecSpecificDataUtil() {}
-
-  /**
-   * Parses an AAC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
-   *
-   * @param audioSpecificConfig A byte array containing the AudioSpecificConfig to parse.
-   * @return The parsed configuration.
-   * @throws ParserException If the AudioSpecificConfig cannot be parsed as it's not supported.
-   */
-  public static AacConfig parseAacAudioSpecificConfig(byte[] audioSpecificConfig)
-      throws ParserException {
-    return parseAacAudioSpecificConfig(
-        new ParsableBitArray(audioSpecificConfig), /* forceReadToEnd= */ false);
-  }
-
-  /**
-   * Parses an AAC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
-   *
-   * @param bitArray A {@link ParsableBitArray} containing the AudioSpecificConfig to parse. The
-   *     position is advanced to the end of the AudioSpecificConfig.
-   * @param forceReadToEnd Whether the entire AudioSpecificConfig should be read. Required for
-   *     knowing the length of the configuration payload.
-   * @return The parsed configuration.
-   * @throws ParserException If the AudioSpecificConfig cannot be parsed as it's not supported.
-   */
-  public static AacConfig parseAacAudioSpecificConfig(
-      ParsableBitArray bitArray, boolean forceReadToEnd) throws ParserException {
-    int audioObjectType = getAacAudioObjectType(bitArray);
-    int sampleRateHz = getAacSamplingFrequency(bitArray);
-    int channelConfiguration = bitArray.readBits(4);
-    String codecs = AAC_CODECS_STRING_PREFIX + audioObjectType;
-    if (audioObjectType == AUDIO_OBJECT_TYPE_AAC_SBR
-        || audioObjectType == AUDIO_OBJECT_TYPE_AAC_PS) {
-      // For an AAC bitstream using spectral band replication (SBR) or parametric stereo (PS) with
-      // explicit signaling, we return the extension sampling frequency as the sample rate of the
-      // content; this is identical to the sample rate of the decoded output but may differ from
-      // the sample rate set above.
-      // Use the extensionSamplingFrequencyIndex.
-      sampleRateHz = getAacSamplingFrequency(bitArray);
-      audioObjectType = getAacAudioObjectType(bitArray);
-      if (audioObjectType == AUDIO_OBJECT_TYPE_AAC_ER_BSAC) {
-        // Use the extensionChannelConfiguration.
-        channelConfiguration = bitArray.readBits(4);
-      }
-    }
-
-    if (forceReadToEnd) {
-      switch (audioObjectType) {
-        case 1:
-        case 2:
-        case 3:
-        case 4:
-        case 6:
-        case 7:
-        case 17:
-        case 19:
-        case 20:
-        case 21:
-        case 22:
-        case 23:
-          parseGaSpecificConfig(bitArray, audioObjectType, channelConfiguration);
-          break;
-        default:
-          throw new ParserException("Unsupported audio object type: " + audioObjectType);
-      }
-      switch (audioObjectType) {
-        case 17:
-        case 19:
-        case 20:
-        case 21:
-        case 22:
-        case 23:
-          int epConfig = bitArray.readBits(2);
-          if (epConfig == 2 || epConfig == 3) {
-            throw new ParserException("Unsupported epConfig: " + epConfig);
-          }
-          break;
-      }
-    }
-    // For supported containers, bits_to_decode() is always 0.
-    int channelCount = AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[channelConfiguration];
-    Assertions.checkArgument(channelCount != AUDIO_SPECIFIC_CONFIG_CHANNEL_CONFIGURATION_INVALID);
-    return new AacConfig(sampleRateHz, channelCount, codecs);
-  }
-
-  /**
-   * Builds a simple HE-AAC LC AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
-   *
-   * @param sampleRate The sample rate in Hz.
-   * @param channelCount The channel count.
-   * @return The AudioSpecificConfig.
-   */
-  public static byte[] buildAacLcAudioSpecificConfig(int sampleRate, int channelCount) {
-    int sampleRateIndex = C.INDEX_UNSET;
-    for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE.length; ++i) {
-      if (sampleRate == AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE[i]) {
-        sampleRateIndex = i;
-      }
-    }
-    int channelConfig = C.INDEX_UNSET;
-    for (int i = 0; i < AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE.length; ++i) {
-      if (channelCount == AUDIO_SPECIFIC_CONFIG_CHANNEL_COUNT_TABLE[i]) {
-        channelConfig = i;
-      }
-    }
-    if (sampleRate == C.INDEX_UNSET || channelConfig == C.INDEX_UNSET) {
-      throw new IllegalArgumentException(
-          "Invalid sample rate or number of channels: " + sampleRate + ", " + channelCount);
-    }
-    return buildAacAudioSpecificConfig(AUDIO_OBJECT_TYPE_AAC_LC, sampleRateIndex, channelConfig);
-  }
-
-  /**
-   * Builds a simple AudioSpecificConfig, as defined in ISO 14496-3 1.6.2.1
-   *
-   * @param audioObjectType The audio object type.
-   * @param sampleRateIndex The sample rate index.
-   * @param channelConfig The channel configuration.
-   * @return The AudioSpecificConfig.
-   */
-  public static byte[] buildAacAudioSpecificConfig(int audioObjectType, int sampleRateIndex,
-      int channelConfig) {
-    byte[] specificConfig = new byte[2];
-    specificConfig[0] = (byte) (((audioObjectType << 3) & 0xF8) | ((sampleRateIndex >> 1) & 0x07));
-    specificConfig[1] = (byte) (((sampleRateIndex << 7) & 0x80) | ((channelConfig << 3) & 0x78));
-    return specificConfig;
-  }
-
-  /** Returns the encoding for a given AAC audio object type. */
-  @C.Encoding
-  public static int getEncodingForAacAudioObjectType(int audioObjectType) {
-    switch (audioObjectType) {
-      case AUDIO_OBJECT_TYPE_AAC_LC:
-        return C.ENCODING_AAC_LC;
-      case AUDIO_OBJECT_TYPE_AAC_SBR:
-        return C.ENCODING_AAC_HE_V1;
-      case AUDIO_OBJECT_TYPE_AAC_PS:
-        return C.ENCODING_AAC_HE_V2;
-      case AUDIO_OBJECT_TYPE_AAC_XHE:
-        return C.ENCODING_AAC_XHE;
-      case AUDIO_OBJECT_TYPE_AAC_ELD:
-        return C.ENCODING_AAC_ELD;
-      default:
-        return C.ENCODING_INVALID;
-    }
-  }
-
   /**
    * Parses an ALAC AudioSpecificConfig (i.e. an <a
    * href="https://github.com/macosforge/alac/blob/master/ALACMagicCookieDescription.txt">ALACSpecificConfig</a>).
@@ -414,67 +168,5 @@ public final class CodecSpecificDataUtil {
     return true;
   }
 
-  /**
+  private CodecSpecificDataUtil() {}
-   * Returns the AAC audio object type as specified in 14496-3 (2005) Table 1.14.
-   *
-   * @param bitArray The bit array containing the audio specific configuration.
-   * @return The audio object type.
-   */
-  private static int getAacAudioObjectType(ParsableBitArray bitArray) {
-    int audioObjectType = bitArray.readBits(5);
-    if (audioObjectType == AUDIO_OBJECT_TYPE_ESCAPE) {
-      audioObjectType = 32 + bitArray.readBits(6);
-    }
-    return audioObjectType;
-  }
-
-  /**
-   * Returns the AAC sampling frequency (or extension sampling frequency) as specified in 14496-3
-   * (2005) Table 1.13.
-   *
-   * @param bitArray The bit array containing the audio specific configuration.
-   * @return The sampling frequency.
-   */
-  private static int getAacSamplingFrequency(ParsableBitArray bitArray) {
-    int samplingFrequency;
-    int frequencyIndex = bitArray.readBits(4);
-    if (frequencyIndex == AUDIO_SPECIFIC_CONFIG_FREQUENCY_INDEX_ARBITRARY) {
-      samplingFrequency = bitArray.readBits(24);
-    } else {
-      Assertions.checkArgument(frequencyIndex < 13);
-      samplingFrequency = AUDIO_SPECIFIC_CONFIG_SAMPLING_RATE_TABLE[frequencyIndex];
-    }
-    return samplingFrequency;
-  }
-
-  private static void parseGaSpecificConfig(ParsableBitArray bitArray, int audioObjectType,
-      int channelConfiguration) {
-    boolean frameLengthFlag = bitArray.readBit();
-    if (frameLengthFlag) {
-      Log.w(TAG, "Unexpected AAC frameLengthFlag = 1");
-    }
-    boolean dependsOnCoreDecoder = bitArray.readBit();
-    if (dependsOnCoreDecoder) {
-      bitArray.skipBits(14); // coreCoderDelay.
-    }
-    boolean extensionFlag = bitArray.readBit();
-    if (channelConfiguration == 0) {
-      throw new UnsupportedOperationException(); // TODO: Implement programConfigElement();
-    }
-    if (audioObjectType == 6 || audioObjectType == 20) {
-      bitArray.skipBits(3); // layerNr.
-    }
-    if (extensionFlag) {
-      if (audioObjectType == 22) {
-        bitArray.skipBits(16); // numOfSubFrame (5), layer_length(11).
-      }
-      if (audioObjectType == 17 || audioObjectType == 19 || audioObjectType == 20
-          || audioObjectType == 23) {
-        // aacSectionDataResilienceFlag, aacScalefactorDataResilienceFlag,
-        // aacSpectralDataResilienceFlag.
-        bitArray.skipBits(3);
-      }
-      bitArray.skipBits(1); // extensionFlag3.
-    }
-  }
 }

library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java

@@ -28,7 +28,6 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.PlaybackParameters;
 import com.google.android.exoplayer2.audio.AudioProcessor.UnhandledAudioFormatException;
 import com.google.android.exoplayer2.util.Assertions;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.Util;
 import java.nio.ByteBuffer;
@@ -1258,14 +1257,14 @@ public final class DefaultAudioSink implements AudioSink {
       case C.ENCODING_MP3:
         return MpegAudioUtil.parseMpegAudioFrameSampleCount(buffer.get(buffer.position()));
       case C.ENCODING_AAC_LC:
-        return CodecSpecificDataUtil.AAC_LC_AUDIO_SAMPLE_COUNT;
+        return AacUtil.AAC_LC_AUDIO_SAMPLE_COUNT;
       case C.ENCODING_AAC_HE_V1:
       case C.ENCODING_AAC_HE_V2:
-        return CodecSpecificDataUtil.AAC_HE_AUDIO_SAMPLE_COUNT;
+        return AacUtil.AAC_HE_AUDIO_SAMPLE_COUNT;
       case C.ENCODING_AAC_XHE:
-        return CodecSpecificDataUtil.AAC_XHE_AUDIO_SAMPLE_COUNT;
+        return AacUtil.AAC_XHE_AUDIO_SAMPLE_COUNT;
       case C.ENCODING_AAC_ELD:
-        return CodecSpecificDataUtil.AAC_LD_AUDIO_SAMPLE_COUNT;
+        return AacUtil.AAC_LD_AUDIO_SAMPLE_COUNT;
       case C.ENCODING_DTS:
       case C.ENCODING_DTS_HD:
         return DtsUtil.parseDtsAudioSampleCount(buffer);

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/flv/AudioTagPayloadReader.java

@@ -18,9 +18,8 @@ package com.google.android.exoplayer2.extractor.flv;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.extractor.TrackOutput;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil.AacConfig;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import java.util.Collections;
@@ -109,8 +108,7 @@ import java.util.Collections;
         // Parse the sequence header.
         byte[] audioSpecificConfig = new byte[data.bytesLeft()];
         data.readBytes(audioSpecificConfig, 0, audioSpecificConfig.length);
-        AacConfig aacConfig =
+        AacUtil.Config aacConfig = AacUtil.parseAudioSpecificConfig(audioSpecificConfig);
-            CodecSpecificDataUtil.parseAacAudioSpecificConfig(audioSpecificConfig);
         Format format =
             new Format.Builder()
                 .setSampleMimeType(MimeTypes.AUDIO_AAC)

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

@@ -22,6 +22,7 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.audio.Ac3Util;
 import com.google.android.exoplayer2.audio.Ac4Util;
 import com.google.android.exoplayer2.drm.DrmInitData;
@@ -29,7 +30,6 @@ import com.google.android.exoplayer2.extractor.GaplessInfoHolder;
 import com.google.android.exoplayer2.metadata.Metadata;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.CodecSpecificDataUtil;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil.AacConfig;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.ParsableByteArray;
@@ -1184,8 +1184,7 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
           if (MimeTypes.AUDIO_AAC.equals(mimeType) && initializationData != null) {
             // Update sampleRate and channelCount from the AudioSpecificConfig initialization data,
             // which is more reliable. See [Internal: b/10903778].
-            AacConfig aacConfig =
+            AacUtil.Config aacConfig = AacUtil.parseAudioSpecificConfig(initializationData);
-                CodecSpecificDataUtil.parseAacAudioSpecificConfig(initializationData);
             sampleRate = aacConfig.sampleRateHz;
             channelCount = aacConfig.channelCount;
             codecs = aacConfig.codecs;

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

@@ -19,13 +19,12 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.extractor.DummyTrackOutput;
 import com.google.android.exoplayer2.extractor.ExtractorOutput;
 import com.google.android.exoplayer2.extractor.TrackOutput;
 import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
 import com.google.android.exoplayer2.util.Assertions;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil.AacConfig;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.ParsableBitArray;
@@ -467,9 +466,9 @@ public final class AdtsReader implements ElementaryStreamReader {
       int channelConfig = adtsScratch.readBits(3);
 
       byte[] audioSpecificConfig =
-          CodecSpecificDataUtil.buildAacAudioSpecificConfig(
+          AacUtil.buildAudioSpecificConfig(
               audioObjectType, firstFrameSampleRateIndex, channelConfig);
-      AacConfig aacConfig = CodecSpecificDataUtil.parseAacAudioSpecificConfig(audioSpecificConfig);
+      AacUtil.Config aacConfig = AacUtil.parseAudioSpecificConfig(audioSpecificConfig);
       Format format =
           new Format.Builder()
               .setId(formatId)

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

@@ -19,12 +19,11 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.extractor.ExtractorOutput;
 import com.google.android.exoplayer2.extractor.TrackOutput;
 import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
 import com.google.android.exoplayer2.util.Assertions;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil;
-import com.google.android.exoplayer2.util.CodecSpecificDataUtil.AacConfig;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.ParsableBitArray;
 import com.google.android.exoplayer2.util.ParsableByteArray;
@@ -273,8 +272,7 @@ public final class LatmReader implements ElementaryStreamReader {
 
   private int parseAudioSpecificConfig(ParsableBitArray data) throws ParserException {
     int bitsLeft = data.bitsLeft();
-    AacConfig config =
+    AacUtil.Config config = AacUtil.parseAudioSpecificConfig(data, /* forceReadToEnd= */ true);
-        CodecSpecificDataUtil.parseAacAudioSpecificConfig(data, /* forceReadToEnd= */ true);
     sampleRateHz = config.sampleRateHz;
     channelCount = config.channelCount;
     return bitsLeft - data.bitsLeft();

library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/manifest/SsManifestParser.java

@@ -23,6 +23,7 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.drm.DrmInitData.SchemeData;
 import com.google.android.exoplayer2.extractor.mp4.PsshAtomUtil;
@@ -687,7 +688,7 @@ public class SsManifestParser implements ParsingLoadable.Parser<SsManifest> {
         if (codecSpecificData.isEmpty() && MimeTypes.AUDIO_AAC.equals(sampleMimeType)) {
           codecSpecificData =
               Collections.singletonList(
-                  CodecSpecificDataUtil.buildAacLcAudioSpecificConfig(sampleRate, channelCount));
+                  AacUtil.buildAacLcAudioSpecificConfig(sampleRate, channelCount));
         }
         formatBuilder
             .setContainerMimeType(MimeTypes.AUDIO_MP4)