Implement org.webrtc.VideoEncoder using the android MediaCodec.

BUG=webrtc:7760

Change-Id: I22134fe616d5c5b77148c80f01f1ea1119ae786c
Reviewed-on: https://chromium-review.googlesource.com/526074
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Reviewed-by: Peter Thatcher <pthatcher@webrtc.org>
Commit-Queue: Bjorn Mellem <mellem@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#18573}

webrtc/sdk/android/src/java/org/webrtc/BaseBitrateAdjuster.java

@@ -0,0 +1,38 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+/** BitrateAdjuster that tracks bitrate and framerate but does not adjust them. */
+class BaseBitrateAdjuster implements BitrateAdjuster {
+  protected int targetBitrateBps = 0;
+  protected int targetFps = 0;
+
+  @Override
+  public void setTargets(int targetBitrateBps, int targetFps) {
+    this.targetBitrateBps = targetBitrateBps;
+    this.targetFps = targetFps;
+  }
+
+  @Override
+  public void reportEncodedFrame(int size) {
+    // No op.
+  }
+
+  @Override
+  public int getAdjustedBitrateBps() {
+    return targetBitrateBps;
+  }
+
+  @Override
+  public int getAdjustedFramerate() {
+    return targetFps;
+  }
+}

webrtc/sdk/android/src/java/org/webrtc/BitrateAdjuster.java

@@ -0,0 +1,31 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+/** Object that adjusts the bitrate of a hardware codec. */
+interface BitrateAdjuster {
+  /**
+   * Sets the target bitrate in bits per second and framerate in frames per second.
+   */
+  void setTargets(int targetBitrateBps, int targetFps);
+
+  /**
+   * Reports that a frame of the given size has been encoded.  Returns true if the bitrate should
+   * be adjusted.
+   */
+  void reportEncodedFrame(int size);
+
+  /** Gets the current bitrate. */
+  int getAdjustedBitrateBps();
+
+  /** Gets the current framerate. */
+  int getAdjustedFramerate();
+}

webrtc/sdk/android/src/java/org/webrtc/DynamicBitrateAdjuster.java

@@ -0,0 +1,95 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+/**
+ * BitrateAdjuster that tracks the bandwidth produced by an encoder and dynamically adjusts the
+ * bitrate.  Used for hardware codecs that pay attention to framerate but still deviate from the
+ * target bitrate by unacceptable margins.
+ */
+class DynamicBitrateAdjuster extends BaseBitrateAdjuster {
+  // Change the bitrate at most once every three seconds.
+  private static final double BITRATE_ADJUSTMENT_SEC = 3.0;
+  // Maximum bitrate adjustment scale - no more than 4 times.
+  private static final double BITRATE_ADJUSTMENT_MAX_SCALE = 4;
+  // Amount of adjustment steps to reach maximum scale.
+  private static final int BITRATE_ADJUSTMENT_STEPS = 20;
+
+  private static final double BITS_PER_BYTE = 8.0;
+
+  // How far the codec has deviated above (or below) the target bitrate (tracked in bytes).
+  private double deviationBytes = 0;
+  private double timeSinceLastAdjustmentMs = 0;
+  private int bitrateAdjustmentScaleExp = 0;
+
+  @Override
+  public void setTargets(int targetBitrateBps, int targetFps) {
+    if (this.targetBitrateBps > 0 && targetBitrateBps < this.targetBitrateBps) {
+      // Rescale the accumulator level if the accumulator max decreases
+      deviationBytes = deviationBytes * targetBitrateBps / this.targetBitrateBps;
+    }
+    super.setTargets(targetBitrateBps, targetFps);
+  }
+
+  @Override
+  public void reportEncodedFrame(int size) {
+    if (targetFps == 0) {
+      return;
+    }
+
+    // Accumulate the difference between actual and expected frame sizes.
+    double expectedBytesPerFrame = (targetBitrateBps / BITS_PER_BYTE) / targetFps;
+    deviationBytes += (size - expectedBytesPerFrame);
+    timeSinceLastAdjustmentMs += 1000.0 / targetFps;
+
+    // Adjust the bitrate when the encoder accumulates one second's worth of data in excess or
+    // shortfall of the target.
+    double deviationThresholdBytes = targetBitrateBps / BITS_PER_BYTE;
+
+    // Cap the deviation, i.e., don't let it grow beyond some level to avoid using too old data for
+    // bitrate adjustment.  This also prevents taking more than 3 "steps" in a given 3-second cycle.
+    double deviationCap = BITRATE_ADJUSTMENT_SEC * deviationThresholdBytes;
+    deviationBytes = Math.min(deviationBytes, deviationCap);
+    deviationBytes = Math.max(deviationBytes, -deviationCap);
+
+    // Do bitrate adjustment every 3 seconds if actual encoder bitrate deviates too much
+    // from the target value.
+    if (timeSinceLastAdjustmentMs <= 1000 * BITRATE_ADJUSTMENT_SEC) {
+      return;
+    }
+
+    if (deviationBytes > deviationThresholdBytes) {
+      // Encoder generates too high bitrate - need to reduce the scale.
+      int bitrateAdjustmentInc = (int) (deviationBytes / deviationThresholdBytes + 0.5);
+      bitrateAdjustmentScaleExp -= bitrateAdjustmentInc;
+      // Don't let the adjustment scale drop below -BITRATE_ADJUSTMENT_STEPS.
+      // This sets a minimum exponent of -1 (bitrateAdjustmentScaleExp / BITRATE_ADJUSTMENT_STEPS).
+      bitrateAdjustmentScaleExp = Math.max(bitrateAdjustmentScaleExp, -BITRATE_ADJUSTMENT_STEPS);
+      deviationBytes = deviationThresholdBytes;
+    } else if (deviationBytes < -deviationThresholdBytes) {
+      // Encoder generates too low bitrate - need to increase the scale.
+      int bitrateAdjustmentInc = (int) (-deviationBytes / deviationThresholdBytes + 0.5);
+      bitrateAdjustmentScaleExp += bitrateAdjustmentInc;
+      // Don't let the adjustment scale exceed BITRATE_ADJUSTMENT_STEPS.
+      // This sets a maximum exponent of 1 (bitrateAdjustmentScaleExp / BITRATE_ADJUSTMENT_STEPS).
+      bitrateAdjustmentScaleExp = Math.min(bitrateAdjustmentScaleExp, BITRATE_ADJUSTMENT_STEPS);
+      deviationBytes = -deviationThresholdBytes;
+    }
+    timeSinceLastAdjustmentMs = 0;
+  }
+
+  @Override
+  public int getAdjustedBitrateBps() {
+    return (int) (targetBitrateBps
+        * Math.pow(BITRATE_ADJUSTMENT_MAX_SCALE,
+              (double) bitrateAdjustmentScaleExp / BITRATE_ADJUSTMENT_STEPS));
+  }
+}

webrtc/sdk/android/src/java/org/webrtc/FramerateBitrateAdjuster.java

@@ -0,0 +1,30 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+/**
+ * BitrateAdjuster that adjusts the bitrate to compensate for changes in the framerate.  Used with
+ * hardware codecs that assume the framerate never changes.
+ */
+class FramerateBitrateAdjuster extends BaseBitrateAdjuster {
+  private static final int INITIAL_FPS = 30;
+
+  @Override
+  public void setTargets(int targetBitrateBps, int targetFps) {
+    if (this.targetFps == 0) {
+      // Framerate-based bitrate adjustment always initializes to the same framerate.
+      targetFps = INITIAL_FPS;
+    }
+    super.setTargets(targetBitrateBps, targetFps);
+
+    this.targetBitrateBps *= INITIAL_FPS / this.targetFps;
+  }
+}

webrtc/sdk/android/src/java/org/webrtc/HardwareVideoEncoder.java

@@ -0,0 +1,485 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+import android.annotation.TargetApi;
+import android.media.MediaCodec;
+import android.media.MediaCodecInfo;
+import android.media.MediaFormat;
+import android.os.Bundle;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Deque;
+import java.util.Set;
+import java.util.concurrent.LinkedBlockingDeque;
+
+/** Android hardware video encoder. */
+@TargetApi(19)
+@SuppressWarnings("deprecation") // Cannot support API level 19 without using deprecated methods.
+class HardwareVideoEncoder implements VideoEncoder {
+  private static final String TAG = "HardwareVideoEncoder";
+
+  // Bitrate modes - should be in sync with OMX_VIDEO_CONTROLRATETYPE defined
+  // in OMX_Video.h
+  private static final int VIDEO_ControlRateConstant = 2;
+  // Key associated with the bitrate control mode value (above). Not present as a MediaFormat
+  // constant until API level 21.
+  private static final String KEY_BITRATE_MODE = "bitrate-mode";
+
+  // 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;
+
+  private static final int MAX_VIDEO_FRAMERATE = 30;
+
+  // See MAX_ENCODER_Q_SIZE in androidmediaencoder_jni.cc.
+  private static final int MAX_ENCODER_Q_SIZE = 2;
+
+  private static final int MEDIA_CODEC_RELEASE_TIMEOUT_MS = 5000;
+  private static final int DEQUEUE_OUTPUT_BUFFER_TIMEOUT_US = 100000;
+
+  // TODO(mellem):  Maybe move mime types to the factory or a common location.
+  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";
+  private static final Set<String> SUPPORTED_MIME_TYPES =
+      new HashSet<>(Arrays.asList(VP8_MIME_TYPE, VP9_MIME_TYPE, H264_MIME_TYPE));
+
+  private final String codecName;
+  private final String mimeType;
+  private final int colorFormat;
+  private final ColorFormat inputColorFormat;
+  // Base interval for generating key frames.
+  private final int keyFrameIntervalSec;
+  // Interval at which to force a key frame. Used to reduce color distortions caused by some
+  // Qualcomm video encoders.
+  private final long forcedKeyFrameMs;
+  // Presentation timestamp of the last requested (or forced) key frame.
+  private long lastKeyFrameMs;
+
+  private final BitrateAdjuster bitrateAdjuster;
+  private int adjustedBitrate;
+
+  // A queue of EncodedImage.Builders that correspond to frames in the codec.  These builders are
+  // pre-populated with all the information that can't be sent through MediaCodec.
+  private final Deque<EncodedImage.Builder> outputBuilders;
+
+  // Thread that delivers encoded frames to the user callback.
+  private Thread outputThread;
+
+  // Whether the encoder is running.  Volatile so that the output thread can watch this value and
+  // exit when the encoder stops.
+  private volatile boolean running = false;
+  // Any exception thrown during shutdown.  The output thread releases the MediaCodec and uses this
+  // value to send exceptions thrown during release back to the encoder thread.
+  private volatile Exception shutdownException = null;
+
+  private MediaCodec codec;
+  private Callback callback;
+
+  private int width;
+  private int height;
+
+  // Contents of the last observed config frame output by the MediaCodec. Used by H.264.
+  private ByteBuffer configBuffer = null;
+
+  /**
+   * Creates a new HardwareVideoEncoder with the given codecName, mimeType, colorFormat, key frame
+   * intervals, and bitrateAdjuster.
+   *
+   * @param codecName the hardware codec implementation to use
+   * @param mimeType MIME type of the codec's output; must be one of "video/x-vnd.on2.vp8",
+   *     "video/x-vnd.on2.vp9", or "video/avc"
+   * @param colorFormat color format used by the input buffer
+   * @param keyFrameIntervalSec interval in seconds between key frames; used to initialize the codec
+   * @param forceKeyFrameIntervalMs interval at which to force a key frame if one is not requested;
+   *     used to reduce distortion caused by some codec implementations
+   * @param bitrateAdjuster algorithm used to correct codec implementations that do not produce the
+   *     desired bitrates
+   * @throws IllegalArgumentException if either mimeType or colorFormat is unsupported
+   */
+  public HardwareVideoEncoder(String codecName, String mimeType, int colorFormat,
+      int keyFrameIntervalSec, int forceKeyFrameIntervalMs, BitrateAdjuster bitrateAdjuster) {
+    if (!SUPPORTED_MIME_TYPES.contains(mimeType)) {
+      throw new IllegalArgumentException("Unsupported MIME type: " + mimeType);
+    }
+    this.codecName = codecName;
+    this.mimeType = mimeType;
+    this.colorFormat = colorFormat;
+    this.inputColorFormat = ColorFormat.valueOf(colorFormat);
+    this.keyFrameIntervalSec = keyFrameIntervalSec;
+    this.forcedKeyFrameMs = forceKeyFrameIntervalMs;
+    this.bitrateAdjuster = bitrateAdjuster;
+    this.outputBuilders = new LinkedBlockingDeque<>();
+  }
+
+  @Override
+  public VideoCodecStatus initEncode(Settings settings, Callback callback) {
+    return initEncodeInternal(
+        settings.width, settings.height, settings.startBitrate, settings.maxFramerate, callback);
+  }
+
+  private VideoCodecStatus initEncodeInternal(
+      int width, int height, int bitrateKbps, int fps, Callback callback) {
+    Logging.d(
+        TAG, "initEncode: " + width + " x " + height + ". @ " + bitrateKbps + "kbps. Fps: " + fps);
+    this.width = width;
+    this.height = height;
+    if (bitrateKbps != 0 && fps != 0) {
+      bitrateAdjuster.setTargets(bitrateKbps * 1000, fps);
+    }
+    adjustedBitrate = bitrateAdjuster.getAdjustedBitrateBps();
+
+    this.callback = callback;
+
+    lastKeyFrameMs = -1;
+
+    codec = createCodecByName(codecName);
+    if (codec == null) {
+      Logging.e(TAG, "Cannot create media encoder " + codecName);
+      return VideoCodecStatus.ERROR;
+    }
+    try {
+      MediaFormat format = MediaFormat.createVideoFormat(mimeType, width, height);
+      format.setInteger(MediaFormat.KEY_BIT_RATE, adjustedBitrate);
+      format.setInteger(KEY_BITRATE_MODE, VIDEO_ControlRateConstant);
+      format.setInteger(MediaFormat.KEY_COLOR_FORMAT, colorFormat);
+      format.setInteger(MediaFormat.KEY_FRAME_RATE, bitrateAdjuster.getAdjustedFramerate());
+      format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, keyFrameIntervalSec);
+      Logging.d(TAG, "Format: " + format);
+      codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
+      codec.start();
+    } catch (IllegalStateException e) {
+      Logging.e(TAG, "initEncode failed", e);
+      release();
+      return VideoCodecStatus.ERROR;
+    }
+
+    running = true;
+    outputThread = createOutputThread();
+    outputThread.start();
+
+    return VideoCodecStatus.OK;
+  }
+
+  @Override
+  public VideoCodecStatus release() {
+    try {
+      // The outputThread actually stops and releases the codec once running is false.
+      running = false;
+      if (!ThreadUtils.joinUninterruptibly(outputThread, MEDIA_CODEC_RELEASE_TIMEOUT_MS)) {
+        Logging.e(TAG, "Media encoder release timeout");
+        return VideoCodecStatus.TIMEOUT;
+      }
+      if (shutdownException != null) {
+        // Log the exception and turn it into an error.
+        Logging.e(TAG, "Media encoder release exception", shutdownException);
+        return VideoCodecStatus.ERROR;
+      }
+    } finally {
+      codec = null;
+      outputThread = null;
+      outputBuilders.clear();
+    }
+    return VideoCodecStatus.OK;
+  }
+
+  @Override
+  public VideoCodecStatus encode(VideoFrame videoFrame, EncodeInfo encodeInfo) {
+    if (codec == null) {
+      return VideoCodecStatus.UNINITIALIZED;
+    }
+
+    // If input resolution changed, restart the codec with the new resolution.
+    int frameWidth = videoFrame.getWidth();
+    int frameHeight = videoFrame.getHeight();
+    if (frameWidth != width || frameHeight != height) {
+      VideoCodecStatus status = resetCodec(frameWidth, frameHeight);
+      if (status != VideoCodecStatus.OK) {
+        return status;
+      }
+    }
+
+    // No timeout.  Don't block for an input buffer, drop frames if the encoder falls behind.
+    int index;
+    try {
+      index = codec.dequeueInputBuffer(0 /* timeout */);
+    } catch (IllegalStateException e) {
+      Logging.e(TAG, "dequeueInputBuffer failed", e);
+      return VideoCodecStatus.FALLBACK_SOFTWARE;
+    }
+
+    if (index == -1) {
+      // Encoder is falling behind.  No input buffers available.  Drop the frame.
+      Logging.e(TAG, "Dropped frame, no input buffers available");
+      return VideoCodecStatus.OK; // See webrtc bug 2887.
+    }
+    if (outputBuilders.size() > MAX_ENCODER_Q_SIZE) {
+      // Too many frames in the encoder.  Drop this frame.
+      Logging.e(TAG, "Dropped frame, encoder queue full");
+      return VideoCodecStatus.OK; // See webrtc bug 2887.
+    }
+
+    // TODO(mellem):  Add support for input surfaces and textures.
+    ByteBuffer buffer;
+    try {
+      buffer = codec.getInputBuffers()[index];
+    } catch (IllegalStateException e) {
+      Logging.e(TAG, "getInputBuffers failed", e);
+      return VideoCodecStatus.FALLBACK_SOFTWARE;
+    }
+    VideoFrame.I420Buffer i420 = videoFrame.getBuffer().toI420();
+    inputColorFormat.fillBufferFromI420(buffer, i420);
+
+    boolean requestedKeyFrame = false;
+    for (EncodedImage.FrameType frameType : encodeInfo.frameTypes) {
+      if (frameType == EncodedImage.FrameType.VideoFrameKey) {
+        requestedKeyFrame = true;
+      }
+    }
+
+    // Frame timestamp rounded to the nearest microsecond and millisecond.
+    long presentationTimestampUs = (videoFrame.getTimestampNs() + 500) / 1000;
+    long presentationTimestampMs = (presentationTimestampUs + 500) / 1000;
+    if (requestedKeyFrame || shouldForceKeyFrame(presentationTimestampMs)) {
+      requestKeyFrame(presentationTimestampMs);
+    }
+
+    // Number of bytes in the video buffer. Y channel is sampled at one byte per pixel; U and V are
+    // subsampled at one byte per four pixels.
+    int bufferSize = videoFrame.getBuffer().getHeight() * videoFrame.getBuffer().getWidth() * 3 / 2;
+    EncodedImage.Builder builder = EncodedImage.builder()
+                                       .setTimeStampMs(presentationTimestampMs)
+                                       .setCaptureTimeMs(presentationTimestampMs)
+                                       .setCompleteFrame(true)
+                                       .setEncodedWidth(videoFrame.getWidth())
+                                       .setEncodedHeight(videoFrame.getHeight())
+                                       .setRotation(videoFrame.getRotation());
+    outputBuilders.offer(builder);
+    try {
+      codec.queueInputBuffer(
+          index, 0 /* offset */, bufferSize, presentationTimestampUs, 0 /* flags */);
+    } catch (IllegalStateException e) {
+      Logging.e(TAG, "queueInputBuffer failed", e);
+      // Keep the output builders in sync with buffers in the codec.
+      outputBuilders.pollLast();
+      // IllegalStateException thrown when the codec is in the wrong state.
+      return VideoCodecStatus.FALLBACK_SOFTWARE;
+    }
+    return VideoCodecStatus.OK;
+  }
+
+  @Override
+  public VideoCodecStatus setChannelParameters(short packetLoss, long roundTripTimeMs) {
+    // No op.
+    return VideoCodecStatus.OK;
+  }
+
+  @Override
+  public VideoCodecStatus setRateAllocation(BitrateAllocation bitrateAllocation, int framerate) {
+    if (framerate > MAX_VIDEO_FRAMERATE) {
+      framerate = MAX_VIDEO_FRAMERATE;
+    }
+    bitrateAdjuster.setTargets(bitrateAllocation.getSum(), framerate);
+    return updateBitrate();
+  }
+
+  @Override
+  public ScalingSettings getScalingSettings() {
+    // TODO(mellem):  Implement scaling settings.
+    return null;
+  }
+
+  @Override
+  public String getImplementationName() {
+    return "HardwareVideoEncoder: " + codecName;
+  }
+
+  private VideoCodecStatus resetCodec(int newWidth, int newHeight) {
+    VideoCodecStatus status = release();
+    if (status != VideoCodecStatus.OK) {
+      return status;
+    }
+    // Zero bitrate and framerate indicate not to change the targets.
+    return initEncodeInternal(newWidth, newHeight, 0, 0, callback);
+  }
+
+  private boolean shouldForceKeyFrame(long presentationTimestampMs) {
+    return forcedKeyFrameMs > 0 && presentationTimestampMs > lastKeyFrameMs + forcedKeyFrameMs;
+  }
+
+  private void requestKeyFrame(long presentationTimestampMs) {
+    // 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".
+    try {
+      Bundle b = new Bundle();
+      b.putInt(MediaCodec.PARAMETER_KEY_REQUEST_SYNC_FRAME, 0);
+      codec.setParameters(b);
+    } catch (IllegalStateException e) {
+      Logging.e(TAG, "requestKeyFrame failed", e);
+      return;
+    }
+    lastKeyFrameMs = presentationTimestampMs;
+  }
+
+  private Thread createOutputThread() {
+    return new Thread() {
+      @Override
+      public void run() {
+        while (running) {
+          deliverEncodedImage();
+        }
+        releaseCodecOnOutputThread();
+      }
+    };
+  }
+
+  private void deliverEncodedImage() {
+    try {
+      MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
+      int index = codec.dequeueOutputBuffer(info, DEQUEUE_OUTPUT_BUFFER_TIMEOUT_US);
+      if (index < 0) {
+        return;
+      }
+
+      ByteBuffer codecOutputBuffer = codec.getOutputBuffers()[index];
+      codecOutputBuffer.position(info.offset);
+      codecOutputBuffer.limit(info.offset + info.size);
+
+      if ((info.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
+        Logging.d(TAG, "Config frame generated. Offset: " + info.offset + ". Size: " + info.size);
+        configBuffer = ByteBuffer.allocateDirect(info.size);
+        configBuffer.put(codecOutputBuffer);
+      } else {
+        bitrateAdjuster.reportEncodedFrame(info.size);
+        if (adjustedBitrate != bitrateAdjuster.getAdjustedBitrateBps()) {
+          updateBitrate();
+        }
+
+        ByteBuffer frameBuffer;
+        boolean isKeyFrame = (info.flags & MediaCodec.BUFFER_FLAG_SYNC_FRAME) != 0;
+        if (isKeyFrame && mimeType.equals(H264_MIME_TYPE)) {
+          Logging.d(TAG,
+              "Prepending config frame of size " + configBuffer.capacity()
+                  + " to output buffer with offset " + info.offset + ", size " + info.size);
+          // For H.264 key frame prepend SPS and PPS NALs at the start.
+          frameBuffer = ByteBuffer.allocateDirect(info.size + configBuffer.capacity());
+          configBuffer.rewind();
+          frameBuffer.put(configBuffer);
+        } else {
+          frameBuffer = ByteBuffer.allocateDirect(info.size);
+        }
+        frameBuffer.put(codecOutputBuffer);
+        frameBuffer.rewind();
+
+        EncodedImage.FrameType frameType = EncodedImage.FrameType.VideoFrameDelta;
+        if (isKeyFrame) {
+          Logging.d(TAG, "Sync frame generated");
+          frameType = EncodedImage.FrameType.VideoFrameKey;
+        }
+        EncodedImage.Builder builder = outputBuilders.poll();
+        builder.setBuffer(frameBuffer).setFrameType(frameType);
+        // TODO(mellem):  Set codec-specific info.
+        callback.onEncodedFrame(builder.createEncodedImage(), new CodecSpecificInfo());
+      }
+      codec.releaseOutputBuffer(index, false);
+    } catch (IllegalStateException e) {
+      Logging.e(TAG, "deliverOutput failed", e);
+    }
+  }
+
+  private void releaseCodecOnOutputThread() {
+    Logging.d(TAG, "Releasing MediaCodec on output thread");
+    try {
+      codec.stop();
+    } catch (Exception e) {
+      Logging.e(TAG, "Media encoder stop failed", e);
+    }
+    try {
+      codec.release();
+    } catch (Exception e) {
+      Logging.e(TAG, "Media encoder release failed", e);
+      // Propagate exceptions caught during release back to the main thread.
+      shutdownException = e;
+    }
+    Logging.d(TAG, "Release on output thread done");
+  }
+
+  private VideoCodecStatus updateBitrate() {
+    adjustedBitrate = bitrateAdjuster.getAdjustedBitrateBps();
+    try {
+      Bundle params = new Bundle();
+      params.putInt(MediaCodec.PARAMETER_KEY_VIDEO_BITRATE, adjustedBitrate);
+      codec.setParameters(params);
+      return VideoCodecStatus.OK;
+    } catch (IllegalStateException e) {
+      Logging.e(TAG, "updateBitrate failed", e);
+      return VideoCodecStatus.ERROR;
+    }
+  }
+
+  private static MediaCodec createCodecByName(String codecName) {
+    try {
+      return MediaCodec.createByCodecName(codecName);
+    } catch (IOException | IllegalArgumentException e) {
+      Logging.e(TAG, "createCodecByName failed", e);
+      return null;
+    }
+  }
+
+  /**
+   * Enumeration of supported color formats used for MediaCodec's input.
+   */
+  private static enum ColorFormat {
+    I420 {
+      @Override
+      void fillBufferFromI420(ByteBuffer buffer, VideoFrame.I420Buffer i420) {
+        buffer.put(i420.getDataY());
+        buffer.put(i420.getDataU());
+        buffer.put(i420.getDataV());
+      }
+    },
+    NV12 {
+      @Override
+      void fillBufferFromI420(ByteBuffer buffer, VideoFrame.I420Buffer i420) {
+        buffer.put(i420.getDataY());
+
+        // Interleave the bytes from the U and V portions, starting with U.
+        ByteBuffer u = i420.getDataU();
+        ByteBuffer v = i420.getDataV();
+        int i = 0;
+        while (u.hasRemaining() && v.hasRemaining()) {
+          buffer.put(u.get());
+          buffer.put(v.get());
+        }
+      }
+    };
+
+    abstract void fillBufferFromI420(ByteBuffer buffer, VideoFrame.I420Buffer i420);
+
+    static ColorFormat valueOf(int colorFormat) {
+      switch (colorFormat) {
+        case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
+          return I420;
+        case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
+        case MediaCodecInfo.CodecCapabilities.COLOR_QCOM_FormatYUV420SemiPlanar:
+        case COLOR_QCOM_FORMATYUV420PackedSemiPlanar32m:
+          return NV12;
+        default:
+          throw new IllegalArgumentException("Unsupported colorFormat: " + colorFormat);
+      }
+    }
+  }
+}