Make AudioSinkAudioTrackImpl compatible to pre-M devices

Change-Id: I2d6d9628f752860afcc8bf13caecc36e2c10fc5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1640788Reviewed-by: Simeon Anfinrud <sanfin@chromium.org>
Commit-Queue: Erik Wolsheimer <ewol@google.com>
Cr-Commit-Position: refs/heads/master@{#665955}

chromecast/media/cma/backend/android/java/src/org/chromium/chromecast/cma/backend/android/AudioSinkAudioTrackImpl.java

@@ -76,6 +76,16 @@ class AudioSinkAudioTrackImpl {
         }
     };
 
+    /** See VolumeControl for this mapping. */
+    private static final SparseIntArray CAST_TYPE_TO_ANDROID_STREAM_TYPE = new SparseIntArray(4) {
+        {
+            append(AudioContentType.MEDIA, AudioManager.STREAM_MUSIC);
+            append(AudioContentType.ALARM, AudioManager.STREAM_ALARM);
+            append(AudioContentType.COMMUNICATION, AudioManager.STREAM_SYSTEM);
+            append(AudioContentType.OTHER, AudioManager.STREAM_VOICE_CALL);
+        }
+    };
+
     // Hardcoded AudioTrack config parameters.
     private static final int CHANNEL_CONFIG = AudioFormat.CHANNEL_OUT_STEREO;
     private static final int AUDIO_FORMAT = AudioFormat.ENCODING_PCM_FLOAT;
@@ -331,6 +341,7 @@ class AudioSinkAudioTrackImpl {
                         + "ms) usageType=" + usageType + " contentType=" + contentType
                         + " with session-id=" + sessionId);
 
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             AudioTrack.Builder builder = new AudioTrack.Builder();
             builder.setBufferSizeInBytes(bufferSizeInBytes)
                     .setTransferMode(AUDIO_MODE)
@@ -344,8 +355,19 @@ class AudioSinkAudioTrackImpl {
                                             .setChannelMask(CHANNEL_CONFIG)
                                             .build());
             if (sessionId != AudioManager.ERROR) builder.setSessionId(sessionId);
-
             mAudioTrack = builder.build();
+        } else {
+            // Using pre-M API.
+            if (sessionId == AudioManager.ERROR) {
+                mAudioTrack = new AudioTrack(CAST_TYPE_TO_ANDROID_STREAM_TYPE.get(castContentType),
+                        mSampleRateInHz, CHANNEL_CONFIG, AUDIO_FORMAT, bufferSizeInBytes,
+                        AudioTrack.MODE_STREAM);
+            } else {
+                mAudioTrack = new AudioTrack(CAST_TYPE_TO_ANDROID_STREAM_TYPE.get(castContentType),
+                        mSampleRateInHz, CHANNEL_CONFIG, AudioFormat.AUDIO_FORMAT,
+                        bufferSizeInBytes, AudioTrack.MODE_STREAM, sessionId);
+            }
+        }
 
         // Allocated shared buffers.
         mPcmBuffer = ByteBuffer.allocateDirect(bytesPerBuffer);
@@ -414,9 +436,14 @@ class AudioSinkAudioTrackImpl {
             playtimeLeftNsecs = lastPlayoutTimeNsecs - now;
         } else {
             // We have no timestamp to estimate how much is left to play, so assume the worst case.
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                 long most_frames_left =
                         Math.min(mTotalFramesWritten, mAudioTrack.getBufferSizeInFrames());
                 playtimeLeftNsecs = convertFramesToNanoTime(most_frames_left);
+            } else {
+                // Using pre-M API. Don't know how many frames there are, so assume the worst case.
+                playtimeLeftNsecs = 0;
+            }
         }
         return (playtimeLeftNsecs < 0) ? 0 : playtimeLeftNsecs / 1000; // return usecs
     }
@@ -449,8 +476,12 @@ class AudioSinkAudioTrackImpl {
     }
 
     int getUnderrunCount() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             return mAudioTrack.getUnderrunCount();
         }
+        // Using pre-M API.
+        return 0;
+    }
 
     /** Writes the PCM data of the given size into the AudioTrack object. The
      * PCM data is provided through the memory-mapped ByteBuffer.