feat: support multiple audio tracks (base on ExoPlayer version 2.17.1)

多音轨支持的一般思路： 1. 自定义 AudioRenderer 和 RendererFactory，创建多个 audio renderer 2. 自定义 TrackSelector，建立 track 和 renderer 之间的映射关系 3. build ExoPlayer 时设置自定义的 RendererFactory 和 TrackSelector 参考 google#6589 此外，ExoPlayer 音频播放使用系统 media 的 AudioTrack，在版本 2.13.0 时， ExoPlayer 变更了 audioSessionId 的生成方式和时机，导致多个音轨 renderer 对应了同一个 audioSessionId 的 AudioTrack，从而播放异常。所以，此版本 ExoPlayer 的多音轨支持基于上述思路又额外重构了 audioSessionId 的生成方式。 ExoPlayer audioSessionId 相关变动参考： google@a95b2eb note for dev: ```kotlin val renderersFactory = MultiAudioRenderersFactory( context, audioRenderersCount = 2, mediaClockRendererIndex = 0 ) val exoPlayer = ExoPlayer.Builder(context) .setRenderersFactory(renderersFactory) .build() ```
y4n9b0 · Jun 2, 2022 · 773ea06 · 773ea06
1 parent 8129675
commit 773ea06
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Showing 12 changed files with 329 additions and 21 deletions.
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java b/library/core/src/main/java/com/google/android/exoplayer2/BaseRenderer.java
@@ -20,6 +20,7 @@
 
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.analytics.PlayerId;
+import com.google.android.exoplayer2.audio.AudioSink;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.decoder.DecoderInputBuffer.InsufficientCapacityException;
 import com.google.android.exoplayer2.source.SampleStream;
@@ -80,6 +81,12 @@ public MediaClock getMediaClock() {
     return null;
   }
 
+  @Override
+  @Nullable
+  public AudioSink getAudioSink() {
+    return null;
+  }
+
   @Override
   public final int getState() {
     return state;

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/DefaultRenderersFactory.java b/library/core/src/main/java/com/google/android/exoplayer2/DefaultRenderersFactory.java
@@ -627,6 +627,11 @@ protected AudioSink buildAudioSink(
         .build();
   }
 
+  @Nullable
+  protected AudioSink buildAudioSink(){
+    return buildAudioSink(context, enableFloatOutput, enableAudioTrackPlaybackParams, enableOffload);
+  }
+
   /**
    * Returns the {@link MediaCodecAdapter.Factory} that will be used when creating {@link
    * com.google.android.exoplayer2.mediacodec.MediaCodecRenderer} instances.

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java b/library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java
@@ -332,11 +332,7 @@ public ExoPlayerImpl(ExoPlayer.Builder builder, @Nullable Player wrappingPlayer)
       playlistMetadata = MediaMetadata.EMPTY;
       staticAndDynamicMediaMetadata = MediaMetadata.EMPTY;
       maskingWindowIndex = C.INDEX_UNSET;
-      if (Util.SDK_INT < 21) {
-        audioSessionId = initializeKeepSessionIdAudioTrack(C.AUDIO_SESSION_ID_UNSET);
-      } else {
-        audioSessionId = Util.generateAudioSessionIdV21(applicationContext);
-      }
+      audioSessionId = findAudioSessionIdByMediaClock();
       currentCues = ImmutableList.of();
       throwsWhenUsingWrongThread = true;
 
@@ -362,8 +358,7 @@ public ExoPlayerImpl(ExoPlayer.Builder builder, @Nullable Player wrappingPlayer)
       deviceInfo = createDeviceInfo(streamVolumeManager);
       videoSize = VideoSize.UNKNOWN;
 
-      sendRendererMessage(TRACK_TYPE_AUDIO, MSG_SET_AUDIO_SESSION_ID, audioSessionId);
-      sendRendererMessage(TRACK_TYPE_VIDEO, MSG_SET_AUDIO_SESSION_ID, audioSessionId);
+      sendAudioSessionIdToRenderers();
       sendRendererMessage(TRACK_TYPE_AUDIO, MSG_SET_AUDIO_ATTRIBUTES, audioAttributes);
       sendRendererMessage(TRACK_TYPE_VIDEO, MSG_SET_SCALING_MODE, videoScalingMode);
       sendRendererMessage(
@@ -378,6 +373,43 @@ public ExoPlayerImpl(ExoPlayer.Builder builder, @Nullable Player wrappingPlayer)
     }
   }
 
+  private int findAudioSessionIdByMediaClock() {
+    int audioSessionId = C.AUDIO_SESSION_ID_UNSET;
+    if (renderers.length > 0) {
+      int firstAudioTrackSessionId = C.AUDIO_SESSION_ID_UNSET;
+      boolean foundMediaClockAudioTrackSessionId = false;
+      for (Renderer renderer : renderers) {
+        if (renderer.getTrackType() == TRACK_TYPE_AUDIO
+            && renderer.getAudioSink() != null) {
+          int currentSessionId = renderer.getAudioSink().getAudioSessionId();
+          if (renderer.getMediaClock() != null) {
+            // 寻找基准时钟所在音轨的 audioSessionId
+            audioSessionId = currentSessionId;
+            foundMediaClockAudioTrackSessionId = true;
+            break;
+          }
+          if (firstAudioTrackSessionId == C.AUDIO_SESSION_ID_UNSET) {
+            // 记录第一个音轨的 audioSessionId
+            firstAudioTrackSessionId = currentSessionId;
+          }
+        }
+      }
+      if (!foundMediaClockAudioTrackSessionId) {
+        // 没找着作为基准时钟的音轨，则使用第一个音轨的 audioSessionId
+        audioSessionId = firstAudioTrackSessionId;
+      }
+    }
+    if (audioSessionId == C.AUDIO_SESSION_ID_UNSET) {
+      // 所有 renderers 均未设置 audioSessionId
+      if (Util.SDK_INT < 21) {
+        audioSessionId = initializeKeepSessionIdAudioTrack(C.AUDIO_SESSION_ID_UNSET);
+      } else {
+        audioSessionId = Util.generateAudioSessionIdV21(applicationContext);
+      }
+    }
+    return audioSessionId;
+  }
+
   @SuppressWarnings("deprecation") // Returning deprecated class.
   @Override
   @Deprecated
@@ -1388,8 +1420,7 @@ public void setAudioSessionId(int audioSessionId) {
       initializeKeepSessionIdAudioTrack(audioSessionId);
     }
     this.audioSessionId = audioSessionId;
-    sendRendererMessage(TRACK_TYPE_AUDIO, MSG_SET_AUDIO_SESSION_ID, audioSessionId);
-    sendRendererMessage(TRACK_TYPE_VIDEO, MSG_SET_AUDIO_SESSION_ID, audioSessionId);
+    sendAudioSessionIdToRenderers();
     int finalAudioSessionId = audioSessionId;
     listeners.sendEvent(
         EVENT_AUDIO_SESSION_ID, listener -> listener.onAudioSessionIdChanged(finalAudioSessionId));
@@ -2608,6 +2639,16 @@ private void sendRendererMessage(
     }
   }
 
+  private void sendAudioSessionIdToRenderers() {
+    for (Renderer renderer : renderers) {
+      int trackType = renderer.getTrackType();
+      if (trackType == TRACK_TYPE_VIDEO ||
+          (trackType == TRACK_TYPE_AUDIO && renderer.getMediaClock() != null)) {
+        createMessageInternal(renderer).setType(MSG_SET_AUDIO_SESSION_ID).setPayload(audioSessionId).send();
+      }
+    }
+  }
+
   /**
    * Initializes {@link #keepSessionIdAudioTrack} to keep an audio session ID alive. If the audio
    * session ID is {@link C#AUDIO_SESSION_ID_UNSET} then a new audio session ID is generated.

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/MultiAudioRenderersFactory.java b/library/core/src/main/java/com/google/android/exoplayer2/MultiAudioRenderersFactory.java
@@ -0,0 +1,124 @@
+package com.google.android.exoplayer2;
+
+import android.content.Context;
+import android.os.Handler;
+import com.google.android.exoplayer2.audio.AudioRendererEventListener;
+import com.google.android.exoplayer2.audio.AudioSink;
+import com.google.android.exoplayer2.audio.MultiAudioRenderer;
+import com.google.android.exoplayer2.mediacodec.MediaCodecSelector;
+import com.google.android.exoplayer2.util.Util;
+import java.lang.reflect.Constructor;
+import java.util.ArrayList;
+
+public class MultiAudioRenderersFactory extends DefaultRenderersFactory {
+
+  private final int audioRenderersCount;
+  private final int mediaClockRendererIndex;
+
+  /**
+   * @param context A {@link Context}.
+   */
+  public MultiAudioRenderersFactory(
+      Context context,
+      int audioRenderersCount,
+      int mediaClockRendererIndex) {
+    super(context);
+    this.audioRenderersCount = Math.max(audioRenderersCount, 1);
+    this.mediaClockRendererIndex = mediaClockRendererIndex;
+  }
+
+  @Override
+  protected void buildAudioRenderers(
+      Context context,
+      @ExtensionRendererMode int extensionRendererMode,
+      MediaCodecSelector mediaCodecSelector,
+      boolean enableDecoderFallback,
+      AudioSink audioSink,
+      Handler eventHandler,
+      AudioRendererEventListener eventListener,
+      ArrayList<Renderer> out) {
+    for (int i = 0; i < audioRenderersCount; i++) {
+      AudioSink uniqueAudioSink = buildAudioSink();
+      if (Util.SDK_INT >= 21) {
+        int audioSessionId = Util.generateAudioSessionIdV21(context);
+        uniqueAudioSink.setAudioSessionId(audioSessionId);
+      } else {
+        // fixme
+      }
+      boolean provideMediaClock = mediaClockRendererIndex == i;
+      MultiAudioRenderer renderer = new MultiAudioRenderer(
+          context,
+          mediaCodecSelector,
+          enableDecoderFallback,
+          eventHandler,
+          eventListener,
+          uniqueAudioSink,
+          provideMediaClock
+      );
+      out.add(renderer);
+    }
+
+    if (extensionRendererMode == EXTENSION_RENDERER_MODE_OFF) {
+      return;
+    }
+    int extensionRendererIndex = out.size();
+    if (extensionRendererMode == EXTENSION_RENDERER_MODE_PREFER) {
+      extensionRendererIndex--;
+    }
+
+    try {
+      // Full class names used for constructor args so the LINT rule triggers if any of them move.
+      Class<?> clazz = Class.forName("com.google.android.exoplayer2.ext.opus.LibopusAudioRenderer");
+      Constructor<?> constructor =
+          clazz.getConstructor(
+              android.os.Handler.class,
+              com.google.android.exoplayer2.audio.AudioRendererEventListener.class,
+              com.google.android.exoplayer2.audio.AudioSink.class);
+      Renderer renderer =
+          (Renderer) constructor.newInstance(eventHandler, eventListener, audioSink);
+      out.add(extensionRendererIndex++, renderer);
+    } catch (ClassNotFoundException e) {
+      // Expected if the app was built without the extension.
+    } catch (Exception e) {
+      // The extension is present, but instantiation failed.
+      throw new RuntimeException("Error instantiating Opus extension", e);
+    }
+
+    try {
+      // Full class names used for constructor args so the LINT rule triggers if any of them move.
+      Class<?> clazz = Class.forName("com.google.android.exoplayer2.ext.flac.LibflacAudioRenderer");
+      Constructor<?> constructor =
+          clazz.getConstructor(
+              android.os.Handler.class,
+              com.google.android.exoplayer2.audio.AudioRendererEventListener.class,
+              com.google.android.exoplayer2.audio.AudioSink.class);
+      Renderer renderer =
+          (Renderer) constructor.newInstance(eventHandler, eventListener, audioSink);
+      out.add(extensionRendererIndex++, renderer);
+    } catch (ClassNotFoundException e) {
+      // Expected if the app was built without the extension.
+    } catch (Exception e) {
+      // The extension is present, but instantiation failed.
+      throw new RuntimeException("Error instantiating FLAC extension", e);
+    }
+
+    try {
+      // Full class names used for constructor args so the LINT rule triggers if any of them move.
+      Class<?> clazz =
+          Class.forName("com.google.android.exoplayer2.ext.ffmpeg.FfmpegAudioRenderer");
+      Constructor<?> constructor =
+          clazz.getConstructor(
+              android.os.Handler.class,
+              com.google.android.exoplayer2.audio.AudioRendererEventListener.class,
+              com.google.android.exoplayer2.audio.AudioSink.class);
+      Renderer renderer =
+          (Renderer) constructor.newInstance(eventHandler, eventListener, audioSink);
+      out.add(extensionRendererIndex++, renderer);
+    } catch (ClassNotFoundException e) {
+      // Expected if the app was built without the extension.
+    } catch (Exception e) {
+      // The extension is present, but instantiation failed.
+      throw new RuntimeException("Error instantiating FFmpeg extension", e);
+    }
+  }
+}
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/Renderer.java b/library/core/src/main/java/com/google/android/exoplayer2/Renderer.java
@@ -23,6 +23,7 @@
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.analytics.PlayerId;
 import com.google.android.exoplayer2.audio.AudioAttributes;
+import com.google.android.exoplayer2.audio.AudioSink;
 import com.google.android.exoplayer2.audio.AuxEffectInfo;
 import com.google.android.exoplayer2.source.SampleStream;
 import com.google.android.exoplayer2.util.MediaClock;
@@ -273,6 +274,9 @@ interface WakeupListener {
   @Nullable
   MediaClock getMediaClock();
 
+  @Nullable
+  AudioSink getAudioSink();
+
   /**
    * Returns the current state of the renderer.
    *

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioSink.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioSink.java
@@ -418,6 +418,9 @@ boolean handleBuffer(ByteBuffer buffer, long presentationTimeUs, int encodedAcce
   /** Sets the audio session id. */
   void setAudioSessionId(int audioSessionId);
 
+  /** Gets the audio session id. */
+  int getAudioSessionId();
+
   /** Sets the auxiliary effect. */
   void setAuxEffectInfo(AuxEffectInfo auxEffectInfo);
 
@@ -443,6 +446,8 @@ boolean handleBuffer(ByteBuffer buffer, long presentationTimeUs, int encodedAcce
    */
   void setVolume(float volume);
 
+  float getVolume();
+
   /** Pauses playback. */
   void pause();
 

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
@@ -1327,6 +1327,11 @@ public void setAudioSessionId(int audioSessionId) {
     }
   }
 
+  @Override
+  public int getAudioSessionId() {
+    return audioSessionId;
+  }
+
   @Override
   public void setAuxEffectInfo(AuxEffectInfo auxEffectInfo) {
     if (this.auxEffectInfo.equals(auxEffectInfo)) {
@@ -1381,6 +1386,11 @@ private void setVolumeInternal() {
     }
   }
 
+  @Override
+  public float getVolume(){
+    return volume;
+  }
+
   @Override
   public void pause() {
     playing = false;

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/ForwardingAudioSink.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/ForwardingAudioSink.java
@@ -129,6 +129,11 @@ public void setAudioSessionId(int audioSessionId) {
     sink.setAudioSessionId(audioSessionId);
   }
 
+  @Override
+  public int getAudioSessionId() {
+    return sink.getAudioSessionId();
+  }
+
   @Override
   public void setAuxEffectInfo(AuxEffectInfo auxEffectInfo) {
     sink.setAuxEffectInfo(auxEffectInfo);
@@ -149,6 +154,11 @@ public void setVolume(float volume) {
     sink.setVolume(volume);
   }
 
+  @Override
+  public float getVolume() {
+    return sink.getVolume();
+  }
+
   @Override
   public void pause() {
     sink.pause();

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java
@@ -453,6 +453,11 @@ public MediaClock getMediaClock() {
     return this;
   }
 
+  @Override
+  public AudioSink getAudioSink(){
+    return audioSink;
+  }
+
   @Override
   protected float getCodecOperatingRateV23(
       float targetPlaybackSpeed, Format format, Format[] streamFormats) {

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/MultiAudioRenderer.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/MultiAudioRenderer.java
@@ -0,0 +1,36 @@
+package com.google.android.exoplayer2.audio;
+
+import android.content.Context;
+import android.os.Handler;
+import androidx.annotation.Nullable;
+import com.google.android.exoplayer2.mediacodec.MediaCodecSelector;
+import com.google.android.exoplayer2.util.MediaClock;
+
+public class MultiAudioRenderer extends MediaCodecAudioRenderer {
+
+  private final boolean provideMediaClock;
+
+  public MultiAudioRenderer(
+      Context context,
+      MediaCodecSelector mediaCodecSelector,
+      boolean enableDecoderFallback,
+      @Nullable Handler eventHandler,
+      @Nullable AudioRendererEventListener eventListener,
+      AudioSink audioSink,
+      boolean provideMediaClock) {
+    super(
+        context,
+        mediaCodecSelector,
+        enableDecoderFallback,
+        eventHandler,
+        eventListener,
+        audioSink);
+    this.provideMediaClock = provideMediaClock;
+  }
+
+  @Nullable
+  @Override
+  public MediaClock getMediaClock() {
+    return provideMediaClock ? this : null;
+  }
+}