Support emsg metadata decoding

Note: End to end emsg support is still non-functional.
There's some additional plumbing that still needs to
be done.

Issue: #2176

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=143775147

library/src/androidTest/java/com/google/android/exoplayer2/metadata/emsg/EventMessageDecoderTest.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2017 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.metadata.emsg;
+
+import android.test.MoreAsserts;
+import com.google.android.exoplayer2.metadata.Metadata;
+import junit.framework.TestCase;
+
+/**
+ * Test for {@link EventMessageDecoder}.
+ */
+public final class EventMessageDecoderTest extends TestCase {
+
+  public void testDecodeEventMessage() {
+    byte[] rawEmsgBody = new byte[] {
+        117, 114, 110, 58, 116, 101, 115, 116, 0, // scheme_id_uri = "urn:test"
+        49, 50, 51, 0, // value = "123"
+        0, 0, -69, -128, // timescale = 48000
+        0, 0, 0, 0, // presentation_time_delta (ignored) = 0
+        0, 2, 50, -128, // event_duration = 144000
+        0, 15, 67, -45, // id = 1000403
+        0, 1, 2, 3, 4}; // message_data = {0, 1, 2, 3, 4}
+    EventMessageDecoder decoder = new EventMessageDecoder();
+    Metadata metadata = decoder.decode(rawEmsgBody, rawEmsgBody.length);
+    assertEquals(1, metadata.length());
+    EventMessage eventMessage = (EventMessage) metadata.get(0);
+    assertEquals("urn:test", eventMessage.schemeIdUri);
+    assertEquals("123", eventMessage.value);
+    assertEquals(3000, eventMessage.durationMs);
+    assertEquals(1000403, eventMessage.id);
+    MoreAsserts.assertEquals(new byte[] {0, 1, 2, 3, 4}, eventMessage.messageData);
+  }
+
+}

library/src/androidTest/java/com/google/android/exoplayer2/metadata/emsg/EventMessageTest.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2017 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.metadata.emsg;
+
+import android.os.Parcel;
+import junit.framework.TestCase;
+
+/**
+ * Test for {@link EventMessage}.
+ */
+public final class EventMessageTest extends TestCase {
+
+  public void testEventMessageParcelable() {
+    EventMessage eventMessage = new EventMessage("urn:test", "123", 3000, 1000403,
+        new byte[] {0, 1, 2, 3, 4});
+    // Write to parcel.
+    Parcel parcel = Parcel.obtain();
+    eventMessage.writeToParcel(parcel, 0);
+    // Create from parcel.
+    parcel.setDataPosition(0);
+    EventMessage fromParcelEventMessage = EventMessage.CREATOR.createFromParcel(parcel);
+    // Assert equals.
+    assertEquals(eventMessage, fromParcelEventMessage);
+  }
+
+}

library/src/androidTest/java/com/google/android/exoplayer2/metadata/id3/Id3DecoderTest.java

@@ -21,9 +21,9 @@ import com.google.android.exoplayer2.metadata.MetadataDecoderException;
 import junit.framework.TestCase;
 
 /**
- * Test for {@link Id3Decoder}
+ * Test for {@link Id3Decoder}.
  */
-public class Id3DecoderTest extends TestCase {
+public final class Id3DecoderTest extends TestCase {
 
   public void testDecodeTxxxFrame() throws MetadataDecoderException {
     byte[] rawId3 = new byte[] {73, 68, 51, 4, 0, 0, 0, 0, 0, 41, 84, 88, 88, 88, 0, 0, 0, 31, 0, 0,

library/src/main/java/com/google/android/exoplayer2/metadata/emsg/EventMessage.java

@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2017 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.metadata.emsg;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+import com.google.android.exoplayer2.metadata.Metadata;
+import com.google.android.exoplayer2.util.Util;
+import java.util.Arrays;
+
+/**
+ * An Event Message (emsg) as defined in ISO 23009-1.
+ */
+public final class EventMessage implements Metadata.Entry {
+
+  /**
+   * The message scheme.
+   */
+  public final String schemeIdUri;
+
+  /**
+   * The value for the event.
+   */
+  public final String value;
+
+  /**
+   * The duration of the event in milliseconds.
+   */
+  public final long durationMs;
+
+  /**
+   * The instance identifier.
+   */
+  public final long id;
+
+  /**
+   * The body of the message.
+   */
+  public final byte[] messageData;
+
+  // Lazily initialized hashcode.
+  private int hashCode;
+
+  /**
+   *
+   * @param schemeIdUri The message scheme.
+   * @param value The value for the event.
+   * @param durationMs The duration of the event in milliseconds.
+   * @param id The instance identifier.
+   * @param messageData The body of the message.
+   */
+  public EventMessage(String schemeIdUri, String value, long durationMs, long id,
+      byte[] messageData) {
+    this.schemeIdUri = schemeIdUri;
+    this.value = value;
+    this.durationMs = durationMs;
+    this.id = id;
+    this.messageData = messageData;
+  }
+
+  /* package */ EventMessage(Parcel in) {
+    schemeIdUri = in.readString();
+    value = in.readString();
+    durationMs = in.readLong();
+    id = in.readLong();
+    messageData = in.createByteArray();
+  }
+
+  @Override
+  public int hashCode() {
+    if (hashCode == 0) {
+      int result = 17;
+      result = 31 * result + (schemeIdUri != null ? schemeIdUri.hashCode() : 0);
+      result = 31 * result + (value != null ? value.hashCode() : 0);
+      result = 31 * result + (int) (durationMs ^ (durationMs >>> 32));
+      result = 31 * result + (int) (id ^ (id >>> 32));
+      result = 31 * result + Arrays.hashCode(messageData);
+      hashCode = result;
+    }
+    return hashCode;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null || getClass() != obj.getClass()) {
+      return false;
+    }
+    EventMessage other = (EventMessage) obj;
+    return durationMs == other.durationMs && id == other.id
+        && Util.areEqual(schemeIdUri, other.schemeIdUri) && Util.areEqual(value, other.value)
+        && Arrays.equals(messageData, other.messageData);
+  }
+
+  // Parcelable implementation.
+
+  @Override
+  public int describeContents() {
+    return 0;
+  }
+
+  @Override
+  public void writeToParcel(Parcel dest, int flags) {
+    dest.writeString(schemeIdUri);
+    dest.writeString(value);
+    dest.writeLong(durationMs);
+    dest.writeLong(id);
+    dest.writeByteArray(messageData);
+  }
+
+  public static final Parcelable.Creator<EventMessage> CREATOR =
+      new Parcelable.Creator<EventMessage>() {
+
+    @Override
+    public EventMessage createFromParcel(Parcel in) {
+      return new EventMessage(in);
+    }
+
+    @Override
+    public EventMessage[] newArray(int size) {
+      return new EventMessage[size];
+    }
+
+  };
+
+}

library/src/main/java/com/google/android/exoplayer2/metadata/emsg/EventMessageDecoder.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2017 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.metadata.emsg;
+
+import com.google.android.exoplayer2.metadata.Metadata;
+import com.google.android.exoplayer2.metadata.MetadataDecoder;
+import com.google.android.exoplayer2.util.MimeTypes;
+import com.google.android.exoplayer2.util.ParsableByteArray;
+import java.util.Arrays;
+
+/**
+ * Decodes Event Message (emsg) atoms, as defined in ISO 23009-1.
+ * <p>
+ * Atom data should be provided to the decoder without the full atom header (i.e. starting from the
+ * first byte of the scheme_id_uri field).
+ */
+public final class EventMessageDecoder implements MetadataDecoder {
+
+  @Override
+  public boolean canDecode(String mimeType) {
+    return MimeTypes.APPLICATION_EMSG.equals(mimeType);
+  }
+
+  @Override
+  public Metadata decode(byte[] data, int size) {
+    ParsableByteArray emsgData = new ParsableByteArray(data, size);
+    String schemeIdUri = emsgData.readNullTerminatedString();
+    String value = emsgData.readNullTerminatedString();
+    long timescale = emsgData.readUnsignedInt();
+    emsgData.skipBytes(4); // presentation_time_delta
+    long durationMs = (emsgData.readUnsignedInt() * 1000) / timescale;
+    long id = emsgData.readUnsignedInt();
+    byte[] messageData = Arrays.copyOfRange(data, emsgData.getPosition(), size);
+    return new Metadata(new EventMessage(schemeIdUri, value, durationMs, id, messageData));
+  }
+
+}

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

@@ -79,6 +79,7 @@ public final class MimeTypes {
   public static final String APPLICATION_PGS = BASE_TYPE_APPLICATION + "/pgs";
   public static final String APPLICATION_SCTE35 = BASE_TYPE_APPLICATION + "/x-scte35";
   public static final String APPLICATION_CAMERA_MOTION = BASE_TYPE_APPLICATION + "/x-camera-motion";
+  public static final String APPLICATION_EMSG = BASE_TYPE_APPLICATION + "/x-emsg";
 
   private MimeTypes() {}