HttpSampleSource

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.nio.ByteBuffer;

import android.os.AsyncTask;
import android.util.Log;

import com.google.android.exoplayer.FormatHolder;
import com.google.android.exoplayer.SampleHolder;
import com.google.android.exoplayer.SampleSource;
import com.google.android.exoplayer.TrackInfo;
import com.google.android.exoplayer.TrackRenderer;

public class HttpSampleSource extends AsyncTask<Void, Void, Void> implements SampleSource
{
	private final String TAG = "HttpSampleSource";
	private ByteBuffer byteBuffer;
	private int byteBufferSize;
	private URL url;
	private String mimeType;
	private TrackInfo trackInfo;
	private boolean readNeeded = true;

	HttpSampleSource(URL url, String mimeType)
	{
		this.url = url;
		this.mimeType = mimeType;
		trackInfo = new TrackInfo(mimeType, TrackRenderer.MATCH_LONGEST);
	}

	@Override
	public boolean prepare() throws IOException
	{
		if (getStatus() == AsyncTask.Status.PENDING)
		{
			execute();
		}

		return true;
	}

	@Override
	protected Void doInBackground(Void... params)
	{
		try
		{
			URLConnection conn = url.openConnection();
			InputStream inputStream = conn.getInputStream();
			
			ByteArrayOutputStream byteArrayOS = new ByteArrayOutputStream();
			
			byte[] buffer = new byte[1024];
			int len;
			while ((len = inputStream.read(buffer)) != -1 && !isCancelled())
			{
				byteBufferSize += len;
				byteArrayOS.write(buffer, 0, len);
			}
			byteBuffer = ByteBuffer.wrap(byteArrayOS.toByteArray());
		} catch (Exception e)
		{
			Debug.warn(TAG, e.getMessage());
		}
		return null;
	}

	@Override
	public int getTrackCount()
	{
		return 1;
	}

	@Override
	public TrackInfo getTrackInfo(int track)
	{
		return trackInfo;
	}

	@Override
	public void enable(int track, long timeUs)
	{
		readNeeded = true;
	}

	@Override
	public void disable(int track)
	{
		
	}

	@Override
	public void continueBuffering(long playbackPositionUs)
	{
		
	}

	@Override
	public int readData(int track, long playbackPositionUs, FormatHolder formatHolder, SampleHolder sampleHolder, boolean onlyReadDiscontinuity) throws IOException
	{
		if (byteBuffer == null)
		{
			return NOTHING_READ;
		}
		
		if (sampleHolder != null && readNeeded){
			sampleHolder.size = byteBufferSize;
			sampleHolder.data = byteBuffer;
			readNeeded = false;
			return SAMPLE_READ;
		}
		
		return END_OF_STREAM;
	}

	@Override
	public long seekToUs(long timeUs)
	{
		return timeUs;
	}

	@Override
	public long getBufferedPositionUs()
	{
		return TrackRenderer.END_OF_TRACK;
	}

	@Override
	public void release()
	{

	}
}

Can you explain exactly how you use this to make WebVTT closed caption works? I can get the subtitle to bytes array successfully, then:

textRenderer = new TextTrackRenderer(httpSampleSource, player,
                            player.getMainHandler().getLooper(), new WebvttParser());

to create TextTrackRenderer, but when video plays, subtitle didn't display and there's logcat:

W/AudioCapabilities﹕ Unsupported mime audio/x-ms-wma
W/AudioCapabilities﹕ Unsupported mime audio/vnd.rn-realaudio
W/AudioCapabilities﹕ Unsupported mime audio/mpeg-L2
W/AudioCapabilities﹕ Unsupported mime audio/ac3
W/AudioCapabilities﹕ Unsupported mime audio/x-ape
W/AudioCapabilities﹕ Unsupported mime audio/vnd.dts
W/AudioCapabilities﹕ Unsupported mime audio/x-pcm
W/AudioCapabilities﹕ Unsupported mime audio/ffmpeg
W/VideoCapabilities﹕ Unsupported mime video/mpeg2
W/VideoCapabilities﹕ Unsupported mime video/x-ms-wmv
W/VideoCapabilities﹕ Unsupported mime video/vnd.rn-realvideo
W/VideoCapabilities﹕ Unsupported mime video/vc1
W/VideoCapabilities﹕ Unsupported mime video/x-flv
W/VideoCapabilities﹕ Unsupported mime video/divx
W/VideoCapabilities﹕ Unsupported mime video/ffmpeg

Those lines don't show up when I don't add textRenderer to renderers[ Player.TYPE_TEXT) (video and audio still work).

Sorry, just found out that I forgot to turn on CC :D Your code works very well, thanks :) Still don't know what causes these messages in logcat, but they are harmless.