gt:         ByteBuffer outputBuffer = outputBuffers[result].duplicate();
context: /*
   * libjingle
   * Copyright 2013, 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.media.MediaCodec;
  import android.media.MediaCodecInfo;
  import android.media.MediaCodecList;
  import android.media.MediaFormat;
  import android.os.Build;
  import android.os.Bundle;
  import android.util.Log;
  
  import java.nio.ByteBuffer;
  
  // Java-side of peerconnection_jni.cc:MediaCodecVideoEncoder.
  // This class is an implementation detail of the Java PeerConnection API.
  // MediaCodec is thread-hostile so this class must be operated on a single
  // thread.
  class MediaCodecVideoEncoder {
    // 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::VideoEncoder API as closely as
    // possibly to minimize the amount of translation work necessary.
  
    private static final String TAG = "MediaCodecVideoEncoder";
  
    private static final int DEQUEUE_TIMEOUT = 0;  // Non-blocking, no wait.
    private MediaCodec mediaCodec;
    private ByteBuffer[] outputBuffers;
    private static final String VP8_MIME_TYPE = "video/x-vnd.on2.vp8";
    private Thread mediaCodecThread;
  
    private MediaCodecVideoEncoder() {}
  
    private static boolean isPlatformSupported() {
      if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT)
        return false; // MediaCodec.setParameters is missing.
  
      if (!Build.MODEL.equals("Nexus 5")) {
        // TODO(fischman): Currently the N5 is the only >=KK device containing a
        // HW VP8 encoder, so don't bother with any others.  When this list grows,
        // update the KEY_COLOR_FORMAT logic below.
        return false;
      }
  
      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(VP8_MIME_TYPE)) {
            name = info.getName();
            break;
          }
        }
        if (name == null)
          continue;  // No VP8 support in this codec; try the next one.
        if (name.startsWith("OMX.google.") || name.startsWith("OMX.SEC.")) {
          // SW encoder is highest priority VP8 codec; unlikely we can get HW.
          // "OMX.google." is known-software, while "OMX.SEC." is sometimes SW &
          // sometimes HW, although not VP8 HW in any known device, so treat as SW
          // here (b/9735008 #20).
          return false;
        }
        return true;  // Yay, passed the gauntlet of pre-requisites!
      }
      return false;  // No VP8 encoder.
    }
  
    private static int bitRate(int kbps) {
      // webrtc "kilo" means 1000, not 1024.  Apparently.
      // (and the price for overshooting is frame-dropping as webrtc enforces its
      // bandwidth estimation, which is unpleasant).
      // Since the HW encoder in the N5 overshoots, we clamp to a bit less than
      // the requested rate.  Sad but true.  Bug 3194.
      return kbps * 950;
    }
  
    private void checkOnMediaCodecThread() {
      if (mediaCodecThread.getId() != Thread.currentThread().getId()) {
        throw new RuntimeException(
            "MediaCodecVideoEncoder previously operated on " + mediaCodecThread +
            " but is now called on " + Thread.currentThread());
      }
    }
  
    // Return the array of input buffers, or null on failure.
    private ByteBuffer[] initEncode(int width, int height, int kbps) {
      if (mediaCodecThread != null) {
        throw new RuntimeException("Forgot to release()?");
      }
      mediaCodecThread = Thread.currentThread();
      try {
        MediaFormat format =
            MediaFormat.createVideoFormat(VP8_MIME_TYPE, width, height);
        format.setInteger(MediaFormat.KEY_BIT_RATE, bitRate(kbps));
        // Arbitrary choices.
        format.setInteger(MediaFormat.KEY_FRAME_RATE, 30);
        format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 450);
        // TODO(fischman): when there is more than just the N5 with a VP8 HW
        // encoder, negotiate input colorformats with the codec.  For now
        // hard-code qcom's supported value.  See isPlatformSupported above.
        format.setInteger(
            MediaFormat.KEY_COLOR_FORMAT,
            MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar);
        mediaCodec = MediaCodec.createEncoderByType(VP8_MIME_TYPE);
        if (mediaCodec == null) {
          return null;
        }
        mediaCodec.configure(
            format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
        mediaCodec.start();
        outputBuffers = mediaCodec.getOutputBuffers();
        return mediaCodec.getInputBuffers();
      } catch (IllegalStateException e) {
        Log.e(TAG, "initEncode failed", e);
        return null;
      }
    }
  
    private boolean encode(
        boolean isKeyframe, int inputBuffer, int size,
        long presentationTimestampUs) {
      checkOnMediaCodecThread();
      try {
        if (isKeyframe) {
          // Ideally MediaCodec would honor BUFFER_FLAG_SYNC_FRAME so we could
          // indicate this in queueInputBuffer() below and guarantee _this_ frame
          // be encoded as a key frame, but sadly that flag is ignored.  Instead,
          // we request a key frame "soon".
          Bundle b = new Bundle();
          b.putInt(MediaCodec.PARAMETER_KEY_REQUEST_SYNC_FRAME, 0);
          mediaCodec.setParameters(b);
        }
        mediaCodec.queueInputBuffer(
            inputBuffer, 0, size, presentationTimestampUs, 0);
        return true;
      }
      catch (IllegalStateException e) {
        Log.e(TAG, "encode failed", e);
        return false;
      }
    }
  
    private void release() {
      checkOnMediaCodecThread();
      try {
        mediaCodec.stop();
        mediaCodec.release();
      } catch (IllegalStateException e) {
        Log.e(TAG, "release failed", e);
      }
      mediaCodec = null;
      mediaCodecThread = null;
    }
  
    private boolean setRates(int kbps, int frameRateIgnored) {
      checkOnMediaCodecThread();
      try {
        Bundle params = new Bundle();
        params.putInt(MediaCodec.PARAMETER_KEY_VIDEO_BITRATE, bitRate(kbps));
        mediaCodec.setParameters(params);
        // Sure would be nice to honor the frameRate argument to this function,
        // but MediaCodec doesn't expose that particular knob.  b/12977358
        return true;
      } catch (IllegalStateException e) {
        Log.e(TAG, "setRates failed", e);
        return false;
      }
    }
  
    // 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_TIMEOUT);
      } catch (IllegalStateException e) {
        Log.e(TAG, "dequeueIntputBuffer failed", e);
        return -2;
      }
    }
  
    // Helper struct for dequeueOutputBuffer() below.
    private static class OutputBufferInfo {
      public OutputBufferInfo(
          int index, ByteBuffer buffer, boolean isKeyFrame,
          long presentationTimestampUs) {
        this.index = index;
        this.buffer = buffer;
        this.isKeyFrame = isKeyFrame;
        this.presentationTimestampUs = presentationTimestampUs;
      }
  
      private final int index;
      private final ByteBuffer buffer;
      private final boolean isKeyFrame;
      private final long presentationTimestampUs;
    }
  
    // Dequeue and return an output buffer, or null if no output is ready.  Return
    // a fake OutputBufferInfo with index -1 if the codec is no longer operable.
    private OutputBufferInfo dequeueOutputBuffer() {
      checkOnMediaCodecThread();
      try {
        MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
        int result = mediaCodec.dequeueOutputBuffer(info, DEQUEUE_TIMEOUT);
        if (result >= 0) {
          // MediaCodec doesn't care about Buffer position/remaining/etc so we can
          // mess with them to get a slice and avoid having to pass extra
          // (BufferInfo-related) parameters back to C++.
  