path: root/talk/app/webrtc/java/src/org/webrtc/MediaCodecVideoDecoder.java

/*
 * libjingle
 * Copyright 2014 Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.webrtc;

import android.graphics.SurfaceTexture;
import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaCodecInfo.CodecCapabilities;
import android.media.MediaCodecList;
import android.media.MediaFormat;
import android.os.Build;
import android.os.SystemClock;
import android.view.Surface;

import org.webrtc.Logging;

import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.Queue;
import java.util.concurrent.TimeUnit;

// Java-side of peerconnection_jni.cc:MediaCodecVideoDecoder.
// This class is an implementation detail of the Java PeerConnection API.
@SuppressWarnings("deprecation")
public class MediaCodecVideoDecoder {
  // This class is constructed, operated, and destroyed by its C++ incarnation,
  // so the class and its methods have non-public visibility.  The API this
  // class exposes aims to mimic the webrtc::VideoDecoder API as closely as
  // possibly to minimize the amount of translation work necessary.

  private static final String TAG = "MediaCodecVideoDecoder";

  // Tracks webrtc::VideoCodecType.
  public enum VideoCodecType {
    VIDEO_CODEC_VP8,
    VIDEO_CODEC_VP9,
    VIDEO_CODEC_H264
  }

  private static final int DEQUEUE_INPUT_TIMEOUT = 500000;  // 500 ms timeout.
  private static final int MEDIA_CODEC_RELEASE_TIMEOUT_MS = 5000; // Timeout for codec releasing.
  // Active running decoder instance. Set in initDecode() (called from native code)
  // and reset to null in release() call.
  private static MediaCodecVideoDecoder runningInstance = null;
  private static MediaCodecVideoDecoderErrorCallback errorCallback = null;
  private static int codecErrors = 0;

  private Thread mediaCodecThread;
  private MediaCodec mediaCodec;
  private ByteBuffer[] inputBuffers;
  private ByteBuffer[] outputBuffers;
  private static final String VP8_MIME_TYPE = "video/x-vnd.on2.vp8";
  private static final String VP9_MIME_TYPE = "video/x-vnd.on2.vp9";
  private static final String H264_MIME_TYPE = "video/avc";
  // List of supported HW VP8 decoders.
  private static final String[] supportedVp8HwCodecPrefixes =
    {"OMX.qcom.", "OMX.Nvidia.", "OMX.Exynos.", "OMX.Intel." };
  // List of supported HW VP9 decoders.
  private static final String[] supportedVp9HwCodecPrefixes =
    {"OMX.qcom.", "OMX.Exynos." };
  // List of supported HW H.264 decoders.
  private static final String[] supportedH264HwCodecPrefixes =
    {"OMX.qcom.", "OMX.Intel." };
  // NV12 color format supported by QCOM codec, but not declared in MediaCodec -
  // see /hardware/qcom/media/mm-core/inc/OMX_QCOMExtns.h
  private static final int
    COLOR_QCOM_FORMATYUV420PackedSemiPlanar32m = 0x7FA30C04;
  // Allowable color formats supported by codec - in order of preference.
  private static final List<Integer> supportedColorList = Arrays.asList(
    CodecCapabilities.COLOR_FormatYUV420Planar,
    CodecCapabilities.COLOR_FormatYUV420SemiPlanar,
    CodecCapabilities.COLOR_QCOM_FormatYUV420SemiPlanar,
    COLOR_QCOM_FORMATYUV420PackedSemiPlanar32m);
  private int colorFormat;
  private int width;
  private int height;
  private int stride;
  private int sliceHeight;
  private boolean hasDecodedFirstFrame;
  private final Queue<TimeStamps> decodeStartTimeMs = new LinkedList<TimeStamps>();
  private boolean useSurface;

  // The below variables are only used when decoding to a Surface.
  private TextureListener textureListener;
  // Max number of output buffers queued before starting to drop decoded frames.
  private static final int MAX_QUEUED_OUTPUTBUFFERS = 3;
  private int droppedFrames;
  private Surface surface = null;
  private final Queue<DecodedOutputBuffer>
      dequeuedSurfaceOutputBuffers = new LinkedList<DecodedOutputBuffer>();

  // MediaCodec error handler - invoked when critical error happens which may prevent
  // further use of media codec API. Now it means that one of media codec instances
  // is hanging and can no longer be used in the next call.
  public static interface MediaCodecVideoDecoderErrorCallback {
    void onMediaCodecVideoDecoderCriticalError(int codecErrors);
  }

  public static void setErrorCallback(MediaCodecVideoDecoderErrorCallback errorCallback) {
    Logging.d(TAG, "Set error callback");
    MediaCodecVideoDecoder.errorCallback = errorCallback;
  }

  // Helper struct for findVp8Decoder() below.
  private static class DecoderProperties {
    public DecoderProperties(String codecName, int colorFormat) {
      this.codecName = codecName;
      this.colorFormat = colorFormat;
    }
    public final String codecName; // OpenMax component name for VP8 codec.
    public final int colorFormat;  // Color format supported by codec.
  }

  private static DecoderProperties findDecoder(
      String mime, String[] supportedCodecPrefixes) {
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
      return null; // MediaCodec.setParameters is missing.
    }
    Logging.d(TAG, "Trying to find HW decoder for mime " + mime);
    for (int i = 0; i < MediaCodecList.getCodecCount(); ++i) {
      MediaCodecInfo info = MediaCodecList.getCodecInfoAt(i);
      if (info.isEncoder()) {
        continue;
      }
      String name = null;
      for (String mimeType : info.getSupportedTypes()) {
        if (mimeType.equals(mime)) {
          name = info.getName();
          break;
        }
      }
      if (name == null) {
        continue;  // No HW support in this codec; try the next one.
      }
      Logging.d(TAG, "Found candidate decoder " + name);

      // Check if this is supported decoder.
      boolean supportedCodec = false;
      for (String codecPrefix : supportedCodecPrefixes) {
        if (name.startsWith(codecPrefix)) {
          supportedCodec = true;
          break;
        }
      }
      if (!supportedCodec) {
        continue;
      }

      // Check if codec supports either yuv420 or nv12.
      CodecCapabilities capabilities =
          info.getCapabilitiesForType(mime);
      for (int colorFormat : capabilities.colorFormats) {
        Logging.v(TAG, "   Color: 0x" + Integer.toHexString(colorFormat));
      }
      for (int supportedColorFormat : supportedColorList) {
        for (int codecColorFormat : capabilities.colorFormats) {
          if (codecColorFormat == supportedColorFormat) {
            // Found supported HW decoder.
            Logging.d(TAG, "Found target decoder " + name +
                ". Color: 0x" + Integer.toHexString(codecColorFormat));
            return new DecoderProperties(name, codecColorFormat);
          }
        }
      }
    }
    Logging.d(TAG, "No HW decoder found for mime " + mime);
    return null;  // No HW decoder.
  }

  public static boolean isVp8HwSupported() {
    return findDecoder(VP8_MIME_TYPE, supportedVp8HwCodecPrefixes) != null;
  }

  public static boolean isVp9HwSupported() {
    return findDecoder(VP9_MIME_TYPE, supportedVp9HwCodecPrefixes) != null;
  }

  public static boolean isH264HwSupported() {
    return findDecoder(H264_MIME_TYPE, supportedH264HwCodecPrefixes) != null;
  }

  public static void printStackTrace() {
    if (runningInstance != null && runningInstance.mediaCodecThread != null) {
      StackTraceElement[] mediaCodecStackTraces = runningInstance.mediaCodecThread.getStackTrace();
      if (mediaCodecStackTraces.length > 0) {
        Logging.d(TAG, "MediaCodecVideoDecoder stacks trace:");
        for (StackTraceElement stackTrace : mediaCodecStackTraces) {
          Logging.d(TAG, stackTrace.toString());
        }
      }
    }
  }

  private void checkOnMediaCodecThread() throws IllegalStateException {
    if (mediaCodecThread.getId() != Thread.currentThread().getId()) {
      throw new IllegalStateException(
          "MediaCodecVideoDecoder previously operated on " + mediaCodecThread +
          " but is now called on " + Thread.currentThread());
    }
  }

  // Pass null in |surfaceTextureHelper| to configure the codec for ByteBuffer output.
  private boolean initDecode(
      VideoCodecType type, int width, int height, SurfaceTextureHelper surfaceTextureHelper) {
    if (mediaCodecThread != null) {
      throw new RuntimeException("Forgot to release()?");
    }
    useSurface = (surfaceTextureHelper != null);
    String mime = null;
    String[] supportedCodecPrefixes = null;
    if (type == VideoCodecType.VIDEO_CODEC_VP8) {
      mime = VP8_MIME_TYPE;
      supportedCodecPrefixes = supportedVp8HwCodecPrefixes;
    } else if (type == VideoCodecType.VIDEO_CODEC_VP9) {
      mime = VP9_MIME_TYPE;
      supportedCodecPrefixes = supportedVp9HwCodecPrefixes;
    } else if (type == VideoCodecType.VIDEO_CODEC_H264) {
      mime = H264_MIME_TYPE;
      supportedCodecPrefixes = supportedH264HwCodecPrefixes;
    } else {
      throw new RuntimeException("Non supported codec " + type);
    }
    DecoderProperties properties = findDecoder(mime, supportedCodecPrefixes);
    if (properties == null) {
      throw new RuntimeException("Cannot find HW decoder for " + type);
    }
    Logging.d(TAG, "Java initDecode: " + type + " : "+ width + " x " + height +
        ". Color: 0x" + Integer.toHexString(properties.colorFormat) +
        ". Use Surface: " + useSurface);
    runningInstance = this; // Decoder is now running and can be queried for stack traces.
    mediaCodecThread = Thread.currentThread();
    try {
      this.width = width;
      this.height = height;
      stride = width;
      sliceHeight = height;

      if (useSurface) {
        textureListener = new TextureListener(surfaceTextureHelper);
        surface = new Surface(surfaceTextureHelper.getSurfaceTexture());
      }

      MediaFormat format = MediaFormat.createVideoFormat(mime, width, height);
      if (!useSurface) {
        format.setInteger(MediaFormat.KEY_COLOR_FORMAT, properties.colorFormat);
      }
      Logging.d(TAG, "  Format: " + format);
      mediaCodec =
          MediaCodecVideoEncoder.createByCodecName(properties.codecName);
      if (mediaCodec == null) {
        Logging.e(TAG, "Can not create media decoder");
        return false;
      }
      mediaCodec.configure(format, surface, null, 0);
      mediaCodec.start();
      colorFormat = properties.colorFormat;
      outputBuffers = mediaCodec.getOutputBuffers();
      inputBuffers = mediaCodec.getInputBuffers();
      decodeStartTimeMs.clear();
      hasDecodedFirstFrame = false;
      dequeuedSurfaceOutputBuffers.clear();
      droppedFrames = 0;
      Logging.d(TAG, "Input buffers: " + inputBuffers.length +
          ". Output buffers: " + outputBuffers.length);
      return true;
    } catch (IllegalStateException e) {
      Logging.e(TAG, "initDecode failed", e);
      return false;
    }
  }

  private void release() {
    Logging.d(TAG, "Java releaseDecoder. Total number of dropped frames: " + droppedFrames);
    checkOnMediaCodecThread();

    // Run Mediacodec stop() and release() on separate thread since sometime
    // Mediacodec.stop() may hang.
    final CountDownLatch releaseDone = new CountDownLatch(1);

    Runnable runMediaCodecRelease = new Runnable() {
      @Override
      public void run() {
        try {
          Logging.d(TAG, "Java releaseDecoder on release thread");
          mediaCodec.stop();
          mediaCodec.release();
          Logging.d(TAG, "Java releaseDecoder on release thread done");
        } catch (Exception e) {
          Logging.e(TAG, "Media decoder release failed", e);
        }
        releaseDone.countDown();
      }
    };
    new Thread(runMediaCodecRelease).start();

    if (!ThreadUtils.awaitUninterruptibly(releaseDone, MEDIA_CODEC_RELEASE_TIMEOUT_MS)) {
      Logging.e(TAG, "Media decoder release timeout");
      codecErrors++;
      if (errorCallback != null) {
        Logging.e(TAG, "Invoke codec error callback. Errors: " + codecErrors);
        errorCallback.onMediaCodecVideoDecoderCriticalError(codecErrors);
      }
    }

    mediaCodec = null;
    mediaCodecThread = null;
    runningInstance = null;
    if (useSurface) {
      surface.release();
      surface = null;
      textureListener.release();
    }
    Logging.d(TAG, "Java releaseDecoder done");
  }

  // Dequeue an input buffer and return its index, -1 if no input buffer is
  // available, or -2 if the codec is no longer operative.
  private int dequeueInputBuffer() {
    checkOnMediaCodecThread();
    try {
      return mediaCodec.dequeueInputBuffer(DEQUEUE_INPUT_TIMEOUT);
    } catch (IllegalStateException e) {
      Logging.e(TAG, "dequeueIntputBuffer failed", e);
      return -2;
    }
  }

  private boolean queueInputBuffer(int inputBufferIndex, int size, long presentationTimeStamUs,
      long timeStampMs, long ntpTimeStamp) {
    checkOnMediaCodecThread();
    try {
      inputBuffers[inputBufferIndex].position(0);
      inputBuffers[inputBufferIndex].limit(size);
      decodeStartTimeMs.add(new TimeStamps(SystemClock.elapsedRealtime(), timeStampMs,
          ntpTimeStamp));
      mediaCodec.queueInputBuffer(inputBufferIndex, 0, size, presentationTimeStamUs, 0);
      return true;
    }
    catch (IllegalStateException e) {
      Logging.e(TAG, "decode failed", e);
      return false;
    }
  }

  private static class TimeStamps {
    public TimeStamps(long decodeStartTimeMs, long timeStampMs, long ntpTimeStampMs) {
      this.decodeStartTimeMs = decodeStartTimeMs;
      this.timeStampMs = timeStampMs;
      this.ntpTimeStampMs = ntpTimeStampMs;
    }
    private final long decodeStartTimeMs; // Time when this frame was queued for decoding.
    private final long timeStampMs; // Only used for bookkeeping in Java. Used in C++;
    private final long ntpTimeStampMs; // Only used for bookkeeping in Java. Used in C++;
  }

  // Helper struct for dequeueOutputBuffer() below.
  private static class DecodedOutputBuffer {
    public DecodedOutputBuffer(int index, int offset, int size, long timeStampMs,
        long ntpTimeStampMs, long decodeTime, long endDecodeTime) {
      this.index = index;
      this.offset = offset;
      this.size = size;
      this.timeStampMs = timeStampMs;
      this.ntpTimeStampMs = ntpTimeStampMs;
      this.decodeTimeMs = decodeTime;
      this.endDecodeTimeMs = endDecodeTime;
    }

    private final int index;
    private final int offset;
    private final int size;
    private final long timeStampMs;
    private final long ntpTimeStampMs;
    // Number of ms it took to decode this frame.
    private final long decodeTimeMs;
    // System time when this frame finished decoding.
    private final long endDecodeTimeMs;
  }

  // Helper struct for dequeueTextureBuffer() below.
  private static class DecodedTextureBuffer {
    private final int textureID;
    private final float[] transformMatrix;
    private final long timeStampMs;
    private final long ntpTimeStampMs;
    private final long decodeTimeMs;
    // Interval from when the frame finished decoding until this buffer has been created.
    // Since there is only one texture, this interval depend on the time from when
    // a frame is decoded and provided to C++ and until that frame is returned to the MediaCodec
    // so that the texture can be updated with the next decoded frame.
    private final long frameDelayMs;

    // A DecodedTextureBuffer with zero |textureID| has special meaning and represents a frame
    // that was dropped.
    public DecodedTextureBuffer(int textureID, float[] transformMatrix, long timeStampMs,
        long ntpTimeStampMs, long decodeTimeMs, long frameDelay) {
      this.textureID = textureID;
      this.transformMatrix = transformMatrix;
      this.timeStampMs = timeStampMs;
      this.ntpTimeStampMs = ntpTimeStampMs;
      this.decodeTimeMs = decodeTimeMs;
      this.frameDelayMs = frameDelay;
    }
  }

  // Poll based texture listener.
  private static class TextureListener
      implements SurfaceTextureHelper.OnTextureFrameAvailableListener {
    private final SurfaceTextureHelper surfaceTextureHelper;
    // |newFrameLock| is used to synchronize arrival of new frames with wait()/notifyAll().
    private final Object newFrameLock = new Object();
    // |bufferToRender| is non-null when waiting for transition between addBufferToRender() to
    // onTextureFrameAvailable().
    private DecodedOutputBuffer bufferToRender;
    private DecodedTextureBuffer renderedBuffer;

    public TextureListener(SurfaceTextureHelper surfaceTextureHelper) {
      this.surfaceTextureHelper = surfaceTextureHelper;
      surfaceTextureHelper.setListener(this);
    }

    public void addBufferToRender(DecodedOutputBuffer buffer) {
      if (bufferToRender != null) {
        Logging.e(TAG,
            "Unexpected addBufferToRender() called while waiting for a texture.");
        throw new IllegalStateException("Waiting for a texture.");
      }
      bufferToRender = buffer;
    }

    public boolean isWaitingForTexture() {
      synchronized (newFrameLock) {
        return bufferToRender != null;
      }
    }

    // Callback from |surfaceTextureHelper|. May be called on an arbitrary thread.
    @Override
    public void onTextureFrameAvailable(
        int oesTextureId, float[] transformMatrix, long timestampNs) {
      synchronized (newFrameLock) {
        if (renderedBuffer != null) {
          Logging.e(TAG,
              "Unexpected onTextureFrameAvailable() called while already holding a texture.");
          throw new IllegalStateException("Already holding a texture.");
        }
        // |timestampNs| is always zero on some Android versions.
        renderedBuffer = new DecodedTextureBuffer(oesTextureId, transformMatrix,
            bufferToRender.timeStampMs, bufferToRender.ntpTimeStampMs, bufferToRender.decodeTimeMs,
            SystemClock.elapsedRealtime() - bufferToRender.endDecodeTimeMs);
        bufferToRender = null;
        newFrameLock.notifyAll();
      }
    }

    // Dequeues and returns a DecodedTextureBuffer if available, or null otherwise.
    public DecodedTextureBuffer dequeueTextureBuffer(int timeoutMs) {
      synchronized (newFrameLock) {
        if (renderedBuffer == null && timeoutMs > 0 && isWaitingForTexture()) {
          try {
            newFrameLock.wait(timeoutMs);
          } catch(InterruptedException e) {
            // Restore the interrupted status by reinterrupting the thread.
            Thread.currentThread().interrupt();
          }
        }
        DecodedTextureBuffer returnedBuffer = renderedBuffer;
        renderedBuffer = null;
        return returnedBuffer;
      }
    }

    public void release() {
      // SurfaceTextureHelper.disconnect() will block until any onTextureFrameAvailable() in
      // progress is done. Therefore, the call to disconnect() must be outside any synchronized
      // statement that is also used in the onTextureFrameAvailable() above to avoid deadlocks.
      surfaceTextureHelper.disconnect();
      synchronized (newFrameLock) {
        if (renderedBuffer != null) {
          surfaceTextureHelper.returnTextureFrame();
          renderedBuffer = null;
        }
      }
    }
  }

  // Returns null if no decoded buffer is available, and otherwise a DecodedByteBuffer.
  // Throws IllegalStateException if call is made on the wrong thread, if color format changes to an
  // unsupported format, or if |mediaCodec| is not in the Executing state. Throws CodecException
  // upon codec error.
  private DecodedOutputBuffer dequeueOutputBuffer(int dequeueTimeoutMs) {
    checkOnMediaCodecThread();
    if (decodeStartTimeMs.isEmpty()) {
      return null;
    }
    // Drain the decoder until receiving a decoded buffer or hitting
    // MediaCodec.INFO_TRY_AGAIN_LATER.
    final MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
    while (true) {
      final int result = mediaCodec.dequeueOutputBuffer(
          info, TimeUnit.MILLISECONDS.toMicros(dequeueTimeoutMs));
      switch (result) {
        case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:
          outputBuffers = mediaCodec.getOutputBuffers();
          Logging.d(TAG, "Decoder output buffers changed: " + outputBuffers.length);
          if (hasDecodedFirstFrame) {
            throw new RuntimeException("Unexpected output buffer change event.");
          }
          break;
        case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:
          MediaFormat format = mediaCodec.getOutputFormat();
          Logging.d(TAG, "Decoder format changed: " + format.toString());
          int new_width = format.getInteger(MediaFormat.KEY_WIDTH);
          int new_height = format.getInteger(MediaFormat.KEY_HEIGHT);
          if (hasDecodedFirstFrame && (new_width != width || new_height != height)) {
            throw new RuntimeException("Unexpected size change. Configured " + width + "*" +
                height + ". New " + new_width + "*" + new_height);
          }
          width = format.getInteger(MediaFormat.KEY_WIDTH);
          height = format.getInteger(MediaFormat.KEY_HEIGHT);

          if (!useSurface && format.containsKey(MediaFormat.KEY_COLOR_FORMAT)) {
            colorFormat = format.getInteger(MediaFormat.KEY_COLOR_FORMAT);
            Logging.d(TAG, "Color: 0x" + Integer.toHexString(colorFormat));
            if (!supportedColorList.contains(colorFormat)) {
              throw new IllegalStateException("Non supported color format: " + colorFormat);
            }
          }
          if (format.containsKey("stride")) {
            stride = format.getInteger("stride");
          }
          if (format.containsKey("slice-height")) {
            sliceHeight = format.getInteger("slice-height");
          }
          Logging.d(TAG, "Frame stride and slice height: " + stride + " x " + sliceHeight);
          stride = Math.max(width, stride);
          sliceHeight = Math.max(height, sliceHeight);
          break;
        case MediaCodec.INFO_TRY_AGAIN_LATER:
          return null;
        default:
          hasDecodedFirstFrame = true;
          TimeStamps timeStamps = decodeStartTimeMs.remove();
          return new DecodedOutputBuffer(result, info.offset, info.size, timeStamps.timeStampMs,
              timeStamps.ntpTimeStampMs,
              SystemClock.elapsedRealtime() - timeStamps.decodeStartTimeMs,
              SystemClock.elapsedRealtime());
        }
    }
  }

  // Returns null if no decoded buffer is available, and otherwise a DecodedTextureBuffer.
  // Throws IllegalStateException if call is made on the wrong thread, if color format changes to an
  // unsupported format, or if |mediaCodec| is not in the Executing state. Throws CodecException
  // upon codec error. If |dequeueTimeoutMs| > 0, the oldest decoded frame will be dropped if
  // a frame can't be returned.
  private DecodedTextureBuffer dequeueTextureBuffer(int dequeueTimeoutMs) {
    checkOnMediaCodecThread();
    if (!useSurface) {
      throw new IllegalStateException("dequeueTexture() called for byte buffer decoding.");
    }
    DecodedOutputBuffer outputBuffer = dequeueOutputBuffer(dequeueTimeoutMs);
    if (outputBuffer != null) {
      dequeuedSurfaceOutputBuffers.add(outputBuffer);
    }

    MaybeRenderDecodedTextureBuffer();
    // Check if there is texture ready now by waiting max |dequeueTimeoutMs|.
    DecodedTextureBuffer renderedBuffer = textureListener.dequeueTextureBuffer(dequeueTimeoutMs);
    if (renderedBuffer != null) {
      MaybeRenderDecodedTextureBuffer();
      return renderedBuffer;
    }

    if ((dequeuedSurfaceOutputBuffers.size()
         >= Math.min(MAX_QUEUED_OUTPUTBUFFERS, outputBuffers.length)
         || (dequeueTimeoutMs > 0 && !dequeuedSurfaceOutputBuffers.isEmpty()))) {
      ++droppedFrames;
      // Drop the oldest frame still in dequeuedSurfaceOutputBuffers.
      // The oldest frame is owned by |textureListener| and can't be dropped since
      // mediaCodec.releaseOutputBuffer has already been called.
      final DecodedOutputBuffer droppedFrame = dequeuedSurfaceOutputBuffers.remove();
      if (dequeueTimeoutMs > 0) {
        // TODO(perkj): Re-add the below log when VideoRenderGUI has been removed or fixed to
        // return the one and only texture even if it does not render.
        // Logging.w(TAG, "Draining decoder. Dropping frame with TS: "
        //    + droppedFrame.timeStampMs + ". Total number of dropped frames: " + droppedFrames);
      } else {
        Logging.w(TAG, "Too many output buffers. Dropping frame with TS: "
            + droppedFrame.timeStampMs + ". Total number of dropped frames: " + droppedFrames);
      }

      mediaCodec.releaseOutputBuffer(droppedFrame.index, false /* render */);
      return new DecodedTextureBuffer(0, null, droppedFrame.timeStampMs,
          droppedFrame.ntpTimeStampMs, droppedFrame.decodeTimeMs,
          SystemClock.elapsedRealtime() - droppedFrame.endDecodeTimeMs);
    }
    return null;
  }

  private void MaybeRenderDecodedTextureBuffer() {
    if (dequeuedSurfaceOutputBuffers.isEmpty() || textureListener.isWaitingForTexture()) {
      return;
    }
    // Get the first frame in the queue and render to the decoder output surface.
    final DecodedOutputBuffer buffer = dequeuedSurfaceOutputBuffers.remove();
    textureListener.addBufferToRender(buffer);
    mediaCodec.releaseOutputBuffer(buffer.index, true /* render */);
  }

  // Release a dequeued output byte buffer back to the codec for re-use. Should only be called for
  // non-surface decoding.
  // Throws IllegalStateException if the call is made on the wrong thread, if codec is configured
  // for surface decoding, or if |mediaCodec| is not in the Executing state. Throws
  // MediaCodec.CodecException upon codec error.
  private void returnDecodedOutputBuffer(int index)
      throws IllegalStateException, MediaCodec.CodecException {
    checkOnMediaCodecThread();
    if (useSurface) {
      throw new IllegalStateException("returnDecodedOutputBuffer() called for surface decoding.");
    }
    mediaCodec.releaseOutputBuffer(index, false /* render */);
  }
}