Using Exoplayer Effie Barak (@CodingChick) 

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What is Exoplayer ...and why is everyone talking about it 

Udemy's Story 

Media Player Simple integration, no extensibility mediaPlayer.setDataSource(url); mediaPlayer.prepare(); mediaPlayer.start(); 

@Override public boolean onError(MediaPlayer mp, int what, int extra) { mediaPlayerError = true; if(what == -38) { //This exception just Happens for varios unexplainable reasons UdemyMediaPlayer.this.prepareAsync(); } return false; } 

This beautiful state machine is a lie 

Exoplayer Very extensible, but steeper implementation curve 

Solves these problems • Open source, written in Java • Built on top of Media Codec • Handles HLS correctly 

Extensible and/ or supports • Background playing • Subtitles • Variable playing speed • Variable resolutions 

Exoplayer basics 

Tips to get started: • ExoPlayer is written in Java. • The sample app is a good place to start. • The default implementaions are Good Implementaions. 

1st part The player player = ExoPlayer.Factory.newInstance( PlayerConstants.RENDERER_COUNT, MIN_BUFFER_MS, MIN_REBUFFER_MS); playerControl = new PlayerControl(player); 

Adding state listeners public abstract class UdemyBaseExoplayer implements ExoPlayer.Listener, ChunkSampleSource.EventListener, HlsSampleSource.EventListener, DefaultBandwidthMeter.EventListener, MediaCodecVideoTrackRenderer.EventListener, MediaCodecAudioTrackRenderer.EventListener player.addListener(this); 

2nd part The Core 

The journey of a Stream 

Allocator allocator = new DefaultAllocator(BUFFER_SEGMENT_SIZE); Handler mainHandler = player.getMainHandler(); DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter(mainHandler, null); DataSource dataSource = new DefaultUriDataSource( context, bandwidthMeter, Util.getUserAgent(mContext, Constants.UDEMY_NAME)); ExtractorSampleSource sampleSource = new ExtractorSampleSource(uri, dataSource, allocator, BUFFER_SEGMENT_COUNT * BUFFER_SEGMENT_SIZE, mainHandler, player, 0); MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(context, sampleSource, MediaCodecSelector.DEFAULT, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT, 5000, mainHandler, player, 50); MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(sampleSource, MediaCodecSelector.DEFAULT, null, true, mainHandler, player, AudioCapabilities.getCapabilities(context), AudioManager.STREAM_MUSIC); TrackRenderer[] renderers = new TrackRenderer[PlayerConstants.RENDERER_COUNT]; renderers[PlayerConstants.TYPE_VIDEO] = videoRenderer; renderers[PlayerConstants.TYPE_AUDIO] = audioRenderer; player.onRenderers(renderers, bandwidthMeter); 

// Allocator allocator = new DefaultAllocator(BUFFER_SEGMENT_SIZE); // Handler mainHandler = player.getMainHandler(); // DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter(mainHandler, null); // DataSource dataSource = new DefaultUriDataSource(context, bandwidthMeter, // Util.getUserAgent(mContext, Constants.UDEMY_NAME)); ExtractorSampleSource sampleSource = new ExtractorSampleSource(uri, dataSource, allocator, BUFFER_SEGMENT_COUNT * BUFFER_SEGMENT_SIZE, mainHandler, player, 0); MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(context, sampleSource, MediaCodecSelector.DEFAULT, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT, 5000, mainHandler, player, 50); MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(sampleSource, MediaCodecSelector.DEFAULT, null, true, mainHandler, player, AudioCapabilities.getCapabilities(context), AudioManager.STREAM_MUSIC); TrackRenderer[] renderers = new TrackRenderer[PlayerConstants.RENDERER_COUNT]; renderers[PlayerConstants.TYPE_VIDEO] = videoRenderer; renderers[PlayerConstants.TYPE_AUDIO] = audioRenderer; player.onRenderers(renderers, bandwidthMeter); 

Build extractors DefaultUriDataSource uriDataSource = new DefaultUriDataSource (context, bandwidthMeter, userAgent); ExtractorSampleSource sampleSource = new ExtractorSampleSource (uri, uriDataSource, allocator, PlayerConstants.BUFFER_SEGMENT_COUNT * PlayerConstants.BUFFER_SEGMENT_SIZE); 

Build renderers TrackRenderer[] renderers = new TrackRenderer[PlayerConstants.RENDERER_COUNT]; MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer( sampleSource, MediaCodecSelector.DEFAULT, null, true, player.getMainHandler(), player, AudioCapabilities.getCapabilities(context), AudioManager.STREAM_MUSIC); renderers[PlayerConstants.TYPE_AUDIO] = audioRenderer; 

Connect renderers to the player player.prepare(renderers); 

Udemy customizations to basic structure • We decreased the buffer size after getting OOM exceptions on low end devices. public static final int BUFFER_SEGMENT_SIZE = 16 * 1024; // Original value was 64 * 1024 public static final int VIDEO_BUFFER_SEGMENTS = 50; // Original value was 200 public static final int AUDIO_BUFFER_SEGMENTS = 20; // Original value was 54 public static final int BUFFER_SEGMENT_COUNT = 64; // Original value was 256 

Udemy customizations to basic structure • We decreased the buffer size after getting OOM exceptions on low end devices. • The ExtractorSampleSource gets a list of possible extractors to work with (mp3 and mp4 only) mp4Extractor = new Mp4Extractor(); mp3Extractor = new Mp3Extractor(); sampleSource = new ExtractorSampleSource(..., mp4Extractor, mp3Extractor); 

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HLS 

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HLS File 

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DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter(); PtsTimestampAdjusterProvider timestampAdjusterProvider = new PtsTimestampAdjusterProvider(); HlsChunkSource chunkSource = new HlsChunkSource(..., uriDataSource, url,..., bandwidthMeter, timestampAdjusterProvider, HlsChunkSource.ADAPTIVE_MODE_SPLICE); 

sampleSource = new HlsSampleSource(chunkSource, ...); 

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The good news HlsChunkSource chunkSource = new HlsChunkSource(..., HlsChunkSource.ADAPTIVE_MODE_NONE); 

The bad news // The index in variants of the currently selected variant. private int selectedVariantIndex; public void getChunkOperation(...) { int nextVariantIndex; ... if (adaptiveMode == ADAPTIVE_MODE_NONE) { nextVariantIndex = selectedVariantIndex; switchingVariantSpliced = false; } else { ... } ... 

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Background Media Playing 

Clear the surface by sending a message to ExoPlayer that sets the surface to null player.blockingSendMessage( videoRenderer, MediaCodecVideoTrackRenderer.MSG_SET_SURFACE, null); 

Create a service to keep the app alive. Both the view and the service control the same instance of the player, stored globally. 

When the app resumes set the surface again setPlayerSurface(surfaceView.getHolder().getSurface()); And in the player public void setSurface(Surface surface) { this.surface = surface; pushSurface(false); } 

Subtitles • Support .srt • Don't crash the video in case of error • Support multiple formats such as UTF-8 

Feed subtitles manually :( 

public void displayExoplayerSubtitles( File file, final MediaController.MediaPlayerControl playerControl, final ViewGroup subtitleLayout, final Context context) { convertFileCaptionList(file, context); runnableCode = new Runnable() { @Override public void run() { displayForPosition(playerControl.getCurrentPosition(), subtitleLayout, context); handler.postDelayed(runnableCode, 200); } }; handler.post(runnableCode); } 

Subtitles conversion https://github.com/JDaren/subtitleConverter 

Variable playback speeds 

Video always follows Audio 

Sonic library (The Java edition) https://github.com/waywardgeek/sonic/blob/master/ Sonic.java 

Implementation 

public class VariableSpeedAudioRenderer extends MediaCodecAudioTrackRenderer 

Method to override private byte[] sonicInputBuffer; private byte[] sonicOutputBuffer; @Override protected void onOutputFormatChanged(final MediaFormat format) { 

Method body // Two samples per frame * 2 to support audio speeds down to 0.5 final int bufferSizeBytes = SAMPLES_PER_CODEC_FRAME * 2 * 2 * channelCount; this.sonicInputBuffer = new byte[bufferSizeBytes]; this.sonicOutputBuffer = new byte[bufferSizeBytes]; this.sonic = new Sonic( format.getInteger(MediaFormat.KEY_SAMPLE_RATE), format.getInteger(MediaFormat.KEY_CHANNEL_COUNT)); this.lastInternalBuffer = ByteBuffer.wrap(sonicOutputBuffer, 0, 0); sonic.flushStream(); sonic.setSpeed(audioSpeed); 

@Override protected boolean processOutputBuffer(..., final ByteBuffer buffer,...) 

private ByteBuffer lastInternalBuffer; buffer.get(sonicInputBuffer, 0, bytesToRead); sonic.writeBytesToStream(sonicInputBuffer, bytesToRead); sonic.readBytesFromStream(sonicOutputBuffer, sonicOutputBuffer.length); return super.processOutputBuffer(..., lastInternalBuffer, ...); 

Some optimization if (bufferIndex == lastSeenBufferIndex) { return super.processOutputBuffer(..., lastInternalBuffer, ..., bufferIndex, ...); } else { lastSeenBufferIndex = bufferIndex; } 

To change the speed in the middle of consuming a buffer if (wasSpeedChanged) { sonic.flushStream(); sonic.setSpeed(audioSpeed); } 

Thank you!