Add media::VideoEncodeAccelerator with WebRTC integration

content/renderer/media/rtc_video_encoder.cc

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/renderer/media/rtc_video_encoder.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/memory/scoped_vector.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/synchronization/waitable_event.h"
+#include "content/renderer/media/renderer_gpu_video_accelerator_factories.h"
+#include "media/base/bitstream_buffer.h"
+#include "media/base/video_frame.h"
+#include "media/filters/gpu_video_accelerator_factories.h"
+#include "media/video/video_encode_accelerator.h"
+
+#define NOTIFY_ERROR(x)                             \
+  do {                                              \
+    DLOG(ERROR) << "calling NotifyError(): " << x;  \
+    NotifyError(x);                                 \
+  } while (0)
+
+namespace content {
+
+// This private class of RTCVideoEncoder does the actual work of communicating
+// with a media::VideoEncodeAccelerator for handling video encoding.  It can
+// be created on any thread, but should subsequently be posted to (and Destroy()
+// called on) a single thread.  Callbacks to RTCVideoEncoder are posted to the
+// thread on which the instance was constructed.
+//
+// This class separates state related to the thread that RTCVideoEncoder
+// operates on (presently the libjingle worker thread) from the thread that
+// |gpu_factories_| provides for accelerator operations (presently the media
+// thread).  The RTCVideoEncoder class can be deleted directly by WebRTC, while
+// RTCVideoEncoder::Impl stays around long enough to properly shut down the VEA.
+class RTCVideoEncoder::Impl
+    : public media::VideoEncodeAccelerator::Client,
+      public base::RefCountedThreadSafe<RTCVideoEncoder::Impl> {
+ public:
+  explicit Impl(

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

explicit no longer necessary

[sheu, 2013/08/07 09:25:03]

Done.

+      const base::WeakPtr<RTCVideoEncoder>& weak_encoder,
+      const scoped_refptr<RendererGpuVideoAcceleratorFactories>& gpu_factories);
+
+  // Create the VEA and call Initialize() on it.  Called once per instantiation,
+  // and then the instance is then bound forevermore to whichever thread made

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

s/is then/is/

[sheu, 2013/08/07 09:25:03]

Done.

+  // the call.
+  // WebRTC expects this call to be synchronous.

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

This sentence is out of place here considering this could well be asynchronous
givne the async_* params.
Ditto for the other methods below that say the same thing.

[sheu, 2013/08/07 09:25:03]

Done.

+  void CreateAndInitializeVEA(const gfx::Size& input_visible_size,
+                              int32 bitrate,
+                              media::VideoCodecProfile profile,
+                              base::WaitableEvent* async_waiter,
+                              int32_t* async_retval);
+  // Enqueue a frame from WebRTC for encoding.  WebRTC expects this call to be
+  // synchronous.
+  void Enqueue(const webrtc::I420VideoFrame* input_frame,
+               bool force_keyframe,
+               base::WaitableEvent* async_waiter,
+               int32_t* async_retval);
+  // These can be asynchronous to WebRTC.
+  void UseOutputBitstreamBufferId(int32 bitstream_buffer_id);
+  void RequestEncodingParameterChange(int32 bitrate);
+  void Destroy();

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

No you didn't.

[sheu, 2013/08/07 09:25:03]

I added one more.  I suppose you want more than that.

[Ami GONE FROM CHROMIUM, 2013/08/07 21:07:15]

I wanted the doco to talk about how it deletes this but then realized it didn't
but forgot to update my CR comment.  Your PS#8 doco is great.

+
+  // media::VideoEncodeAccelerator::Client implementation.
+  virtual void NotifyInitializeDone() OVERRIDE;
+  virtual void RequireBitstreamBuffers(int input_count,
+                                       const gfx::Size& input_coded_size,
+                                       size_t output_buffer_size) OVERRIDE;
+  virtual void BitstreamBufferReady(int32 bitstream_buffer_id,
+                                    size_t payload_size,
+                                    bool key_frame) OVERRIDE;
+  virtual void NotifyError(media::VideoEncodeAccelerator::Error error) OVERRIDE;
+
+ private:
+  friend class base::RefCountedThreadSafe<Impl>;
+
+  enum {
+    kInputBufferExtraCount = 1,  // The number of input buffers allocated, more
+                                 // than what is requested by
+                                 // VEA::RequireBitstreamBuffers().
+    kOutputBufferCount = 3,
+  };
+
+  virtual ~Impl();
+
+  // Perform encoding on an input frame from the input queue.
+  void EncodeOneFrame();
+
+  // Notify that an input frame is finished for encoding.  |index| is the index
+  // of the completed frame in |input_buffers_|.
+  void EncodeFrameFinished(int index);
+
+  // Set up/signal |async_waiter_| and |async_retval_|; see declarations below.
+  void RegisterAsyncWaiter(base::WaitableEvent* waiter, int32_t* retval);
+  void SignalAsyncWaiter(int32_t retval);
+
+  base::ThreadChecker thread_checker_;
+
+  // Weak pointer to the parent RTCVideoEncoder, for posting back VEA::Client
+  // notifications.
+  const base::WeakPtr<RTCVideoEncoder> weak_encoder_;
+
+  // The message loop on which to post callbacks to |weak_encoder_|.
+  const scoped_refptr<base::MessageLoopProxy> encoder_message_loop_proxy_;
+
+  // Factory for creating VEAs, shared memory buffers, etc.
+  const scoped_refptr<RendererGpuVideoAcceleratorFactories> gpu_factories_;
+
+  // webrtc::VideoEncoder expects InitEncode() and Encode() to be synchronous.
+  // Do this by waiting on the |async_waiter_| and returning the return value in
+  // |async_retval_| when initialization completes, encoding completes, or
+  // an error occurs.
+  base::WaitableEvent* async_waiter_;
+  int32_t* async_retval_;
+
+  // The underlying VEA to perform encoding on.
+  scoped_ptr<media::VideoEncodeAccelerator> video_encoder_;
+
+  // Next input frame.  Since there is at most one next frame, a single-element
+  // queue is sufficient.
+  const webrtc::I420VideoFrame* input_next_frame_;
+
+  // Whether to encode a keyframe next.
+  bool input_next_frame_keyframe_;
+
+  // Frame sizes.
+  gfx::Size input_frame_coded_size_;
+  gfx::Size input_visible_size_;
+
+  // Shared memory buffers for input/output with the VEA.
+  ScopedVector<base::SharedMemory> input_buffers_;
+  ScopedVector<base::SharedMemory> output_buffers_;
+
+  // Input buffers ready to be filled with input from Encode().  As a LIFO since
+  // we don't care about ordering.
+  std::vector<int> input_buffers_free_;
+
+  DISALLOW_COPY_AND_ASSIGN(Impl);
+};
+
+RTCVideoEncoder::Impl::Impl(
+    const base::WeakPtr<RTCVideoEncoder>& weak_encoder,
+    const scoped_refptr<RendererGpuVideoAcceleratorFactories>& gpu_factories)
+    : weak_encoder_(weak_encoder),
+      encoder_message_loop_proxy_(base::MessageLoopProxy::current()),
+      gpu_factories_(gpu_factories),
+      async_waiter_(NULL),
+      async_retval_(NULL),
+      input_next_frame_(NULL),
+      input_next_frame_keyframe_(false) {
+  thread_checker_.DetachFromThread();
+}
+
+void RTCVideoEncoder::Impl::CreateAndInitializeVEA(
+    const gfx::Size& input_visible_size,
+    int32 bitrate,
+    media::VideoCodecProfile profile,
+    base::WaitableEvent* async_waiter,
+    int32_t* async_retval) {
+  DVLOG(3) << "Impl::CreateAndInitializeVEA()";
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  RegisterAsyncWaiter(async_waiter, async_retval);
+
+  // Check for overflow converting codecSettings.startBitrate (kilobits/sec) to
+  // bits/sec.
+  if (bitrate > kint32max / 1000) {
+    NOTIFY_ERROR(media::VideoEncodeAccelerator::kInvalidArgumentError);
+    return;
+  }
+
+  video_encoder_ = gpu_factories_->CreateVideoEncodeAccelerator(this).Pass();
+  if (!video_encoder_) {
+    NOTIFY_ERROR(media::VideoEncodeAccelerator::kPlatformFailureError);
+    return;
+  }
+  input_visible_size_ = input_visible_size;
+  video_encoder_->Initialize(media::VideoFrame::I420,
+                             input_visible_size_,
+                             profile,
+                             bitrate * 1000);
+}
+
+void RTCVideoEncoder::Impl::Enqueue(const webrtc::I420VideoFrame* input_frame,
+                                    bool force_keyframe,
+                                    base::WaitableEvent* async_waiter,
+                                    int32_t* async_retval) {
+  DVLOG(3) << "Impl::Enqueue()";
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!input_next_frame_);
+
+  RegisterAsyncWaiter(async_waiter, async_retval);
+  input_next_frame_ = input_frame;
+  input_next_frame_keyframe_ = force_keyframe;
+
+  if (!input_buffers_free_.empty())
+    EncodeOneFrame();
+}
+
+void RTCVideoEncoder::Impl::UseOutputBitstreamBufferId(
+    int32 bitstream_buffer_id) {
+  DVLOG(3) << "Impl::UseOutputBitstreamBufferIndex(): "
+              "bitstream_buffer_id=" << bitstream_buffer_id;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (video_encoder_) {
+    video_encoder_->UseOutputBitstreamBuffer(media::BitstreamBuffer(
+        bitstream_buffer_id,
+        output_buffers_[bitstream_buffer_id]->handle(),
+        output_buffers_[bitstream_buffer_id]->mapped_size()));
+  }
+}
+
+void RTCVideoEncoder::Impl::RequestEncodingParameterChange(int32 bitrate) {
+  DVLOG(3) << "Impl::RequestEncodingParameterChange(): bitrate=" << bitrate;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (video_encoder_)
+    video_encoder_->RequestEncodingParameterChange(bitrate);
+}
+
+void RTCVideoEncoder::Impl::Destroy() {
+  DVLOG(3) << "Impl::Destroy()";
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (video_encoder_)
+    video_encoder_.release()->Destroy();
+}
+
+void RTCVideoEncoder::Impl::NotifyInitializeDone() {
+  DVLOG(3) << "Impl::NotifyInitializeDone()";
+  DCHECK(thread_checker_.CalledOnValidThread());
+  SignalAsyncWaiter(WEBRTC_VIDEO_CODEC_OK);
+}
+
+void RTCVideoEncoder::Impl::RequireBitstreamBuffers(
+    int input_count,
+    const gfx::Size& input_coded_size,
+    size_t output_buffer_size) {
+  DVLOG(3) << "Impl::RequireBitstreamBuffers(): input_count=" << input_count
+           << ", input_coded_size=" << input_coded_size.ToString()
+           << ", output_buffer_size=" << output_buffer_size;
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (!video_encoder_)
+    return;
+
+  input_frame_coded_size_ = input_coded_size;
+
+  for (int i = 0; i < input_count + kInputBufferExtraCount; ++i) {
+    base::SharedMemory* shm =
+        gpu_factories_->CreateSharedMemory(input_coded_size.GetArea() * 3 / 2);
+    if (!shm) {
+      DLOG(ERROR) << "Impl::RequireBitstreamBuffers(): "
+                     "failed to create input buffer " << i;
+      NOTIFY_ERROR(media::VideoEncodeAccelerator::kPlatformFailureError);
+      return;
+    }
+    input_buffers_.push_back(shm);
+    input_buffers_free_.push_back(i);
+  }
+
+  for (int i = 0; i < kOutputBufferCount; ++i) {
+    base::SharedMemory* shm =
+        gpu_factories_->CreateSharedMemory(output_buffer_size);
+    if (!shm) {
+      DLOG(ERROR) << "Impl::RequireBitstreamBuffers(): "
+                     "failed to create output buffer " << i;
+      NOTIFY_ERROR(media::VideoEncodeAccelerator::kPlatformFailureError);
+      return;
+    }
+    output_buffers_.push_back(shm);
+  }
+
+  // Immediately provide all output buffers to the VEA.
+  for (size_t i = 0; i < output_buffers_.size(); ++i) {
+    video_encoder_->UseOutputBitstreamBuffer(media::BitstreamBuffer(
+        i, output_buffers_[i]->handle(), output_buffers_[i]->mapped_size()));
+  }
+}
+
+void RTCVideoEncoder::Impl::BitstreamBufferReady(int32 bitstream_buffer_id,
+                                                 size_t payload_size,
+                                                 bool key_frame) {
+  DVLOG(3) << "Impl::BitstreamBufferReady(): "
+              "bitstream_buffer_id=" << bitstream_buffer_id
+           << ", payload_size=" << payload_size
+           << ", key_frame=" << key_frame;
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (bitstream_buffer_id < 0 ||
+      bitstream_buffer_id >= static_cast<int>(output_buffers_.size())) {
+    DLOG(ERROR) << "Impl::BitstreamBufferReady(): invalid bitstream_buffer_id="
+                << bitstream_buffer_id;
+    NOTIFY_ERROR(media::VideoEncodeAccelerator::kInvalidArgumentError);

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

No, it's an invalid argument coming from the VEA impl, not IPC, and is thus part
of the "platform".

[sheu, 2013/08/07 09:25:03]

BitstreamBufferReady is part of the VEA::Client interface; this one in
particular gets called by GpuVEAHost, which passes it on directly from IPC.  So
it is coming from IPC.

+    return;
+  }
+  base::SharedMemory* output_buffer = output_buffers_[bitstream_buffer_id];
+  if (payload_size > output_buffer->mapped_size()) {
+    DLOG(ERROR) << "Impl::BitstreamBufferReady(): invalid payload_size="
+                << payload_size;
+    NOTIFY_ERROR(media::VideoEncodeAccelerator::kInvalidArgumentError);
+    return;
+  }
+
+  scoped_ptr<webrtc::EncodedImage> image(new webrtc::EncodedImage(
+      reinterpret_cast<uint8_t*>(output_buffer->memory()),
+      payload_size,
+      output_buffer->mapped_size()));
+  image->_encodedWidth = input_visible_size_.width();
+  image->_encodedHeight = input_visible_size_.height();
+  image->_frameType = (key_frame ? webrtc::kKeyFrame : webrtc::kDeltaFrame);
+  image->_completeFrame = true;
+
+  encoder_message_loop_proxy_->PostTask(
+      FROM_HERE,
+      base::Bind(&RTCVideoEncoder::ReturnEncodedImage,
+                 weak_encoder_,
+                 make_scoped_refptr(this),
+                 base::Passed(&image),
+                 bitstream_buffer_id));
+}
+
+void RTCVideoEncoder::Impl::NotifyError(
+    media::VideoEncodeAccelerator::Error error) {
+  DVLOG(3) << "Impl::NotifyError(): error=" << error;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  int32_t retval;
+  switch (error) {
+    case media::VideoEncodeAccelerator::kInvalidArgumentError:
+      retval = WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
+      break;
+    case media::VideoEncodeAccelerator::kPlatformFailureError:
+      retval = WEBRTC_VIDEO_CODEC_MEMORY;

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

I guess s/MEMORY/ERROR/  (better to be vague than incorrectly precise)

[sheu, 2013/08/07 09:25:03]

Most kPlatformFailureErrors are memory-related I think -- more useful to be able
to distinguish failure classes methinks.

I don't feel strongly either way, so let me know if you concur.

[Ami GONE FROM CHROMIUM, 2013/08/07 21:07:15]

I worry that MEMORY is specific enough that it'll mislead webrtc ppl.
Let's switch to ERROR, which is at least vague enough that debuggers will have
to look.

+      break;
+    default:
+      retval = WEBRTC_VIDEO_CODEC_ERROR;
+  }
+
+  if (video_encoder_)
+    video_encoder_.release()->Destroy();
+
+  if (async_waiter_) {
+    SignalAsyncWaiter(retval);
+  } else {
+    encoder_message_loop_proxy_->PostTask(
+        FROM_HERE,
+        base::Bind(&RTCVideoEncoder::NotifyError,
+                   weak_encoder_,
+                   make_scoped_refptr(this),
+                   retval));
+  }
+}
+
+RTCVideoEncoder::Impl::~Impl() { DCHECK(!video_encoder_); }
+
+void RTCVideoEncoder::Impl::EncodeOneFrame() {
+  DVLOG(3) << "Impl::EncodeOneFrame()";
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(input_next_frame_);
+  DCHECK(!input_buffers_free_.empty());
+
+  const int index = input_buffers_free_.back();
+  base::SharedMemory* input_buffer = input_buffers_[index];

[sheu, 2013/08/07 09:25:03]

Actually now that I think of it, I should move these into the conditional.

+
+  if (video_encoder_) {

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

Isn't the negation an error condition?

[sheu, 2013/08/07 09:25:03]

It is, but I'd still like to leave the Impl in a self-consistent state even if
an error occurs.

+    // Do a strided copy of the input frame to match the input requirements for
+    // the encoder.

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

Please add a TODO pointing to a crbug for the remaining work.

[sheu, 2013/08/07 09:25:03]

Done.

+    const uint8_t* src = input_next_frame_->buffer(webrtc::kYPlane);
+    uint8* dst = reinterpret_cast<uint8*>(input_buffer->memory());
+    uint8* const y_dst = dst;
+    int width = input_frame_coded_size_.width();
+    int stride = input_next_frame_->stride(webrtc::kYPlane);
+    for (int i = 0; i < input_next_frame_->height(); ++i) {
+      memcpy(dst, src, width);
+      src += stride;
+      dst += width;

[sheu, 2013/08/06 06:16:36]

Teehee

The benefits of not testing

+    }
+    src = input_next_frame_->buffer(webrtc::kUPlane);
+    width = input_frame_coded_size_.width() / 2;
+    stride = input_next_frame_->stride(webrtc::kUPlane);
+    uint8* const u_dst = dst;
+    for (int i = 0; i < input_next_frame_->height() / 2; ++i) {
+      memcpy(dst, src, width);
+      src += stride;
+      dst += width;
+    }
+    src = input_next_frame_->buffer(webrtc::kVPlane);
+    width = input_frame_coded_size_.width() / 2;
+    stride = input_next_frame_->stride(webrtc::kVPlane);
+    uint8* const v_dst = dst;
+    for (int i = 0; i < input_next_frame_->height() / 2; ++i) {
+      memcpy(dst, src, width);
+      src += stride;
+      dst += width;
+    }
+
+    scoped_refptr<media::VideoFrame> frame =
+        media::VideoFrame::WrapExternalYuvData(
+            media::VideoFrame::I420,
+            input_frame_coded_size_,
+            gfx::Rect(input_visible_size_),
+            input_visible_size_,
+            input_frame_coded_size_.width(),
+            input_frame_coded_size_.width() / 2,
+            input_frame_coded_size_.width() / 2,
+            y_dst,
+            u_dst,
+            v_dst,
+            base::TimeDelta(),
+            input_buffer->handle(),
+            base::Bind(
+                &RTCVideoEncoder::Impl::EncodeFrameFinished, this, index));
+    video_encoder_->Encode(frame, input_next_frame_keyframe_);
+  }
+
+  input_next_frame_ = NULL;
+  input_next_frame_keyframe_ = false;
+  input_buffers_free_.pop_back();
+
+  SignalAsyncWaiter(WEBRTC_VIDEO_CODEC_OK);
+}
+
+void RTCVideoEncoder::Impl::EncodeFrameFinished(int index) {
+  DVLOG(3) << "Impl::EncodeFrameFinished(): index=" << index;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_GE(index, 0);
+  DCHECK_LT(index, static_cast<int>(input_buffers_.size()));
+  input_buffers_free_.push_back(index);
+  if (input_next_frame_)
+    EncodeOneFrame();
+}
+
+void RTCVideoEncoder::Impl::RegisterAsyncWaiter(base::WaitableEvent* waiter,
+                                                int32_t* retval) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!async_waiter_);
+  DCHECK(!async_retval_);
+  async_waiter_ = waiter;
+  async_retval_ = retval;
+}
+
+void RTCVideoEncoder::Impl::SignalAsyncWaiter(int32_t retval) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  *async_retval_ = retval;
+  async_waiter_->Signal();
+  async_retval_ = NULL;
+  async_waiter_ = NULL;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//
+// RTCVideoEncoder
+//
+////////////////////////////////////////////////////////////////////////////////
+
+#undef NOTIFY_ERROR

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

go above separator

[sheu, 2013/08/07 09:25:03]

Done.

+
+RTCVideoEncoder::RTCVideoEncoder(
+    media::VideoCodecProfile profile,
+    const scoped_refptr<RendererGpuVideoAcceleratorFactories>& gpu_factories)
+    : video_codec_profile_(profile),
+      gpu_factories_(gpu_factories),
+      weak_this_factory_(this),
+      weak_this_(weak_this_factory_.GetWeakPtr()),
+      encoded_image_callback_(NULL),
+      impl_status_(WEBRTC_VIDEO_CODEC_UNINITIALIZED) {
+  DVLOG(1) << "RTCVideoEncoder(): profile=" << profile;
+}
+
+RTCVideoEncoder::~RTCVideoEncoder() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  Release();
+  DCHECK(!impl_);
+}
+
+int32_t RTCVideoEncoder::InitEncode(const webrtc::VideoCodec* codec_settings,
+                                    int32_t number_of_cores,
+                                    uint32_t max_payload_size) {
+  DVLOG(1) << "InitEncode(): codecType=" << codec_settings->codecType
+           << ", width=" << codec_settings->width
+           << ", height=" << codec_settings->height
+           << ", startBitrate=" << codec_settings->startBitrate;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!impl_);
+
+  impl_ = new Impl(weak_this_, gpu_factories_);
+  base::WaitableEvent initialization_waiter(true, false);
+  int32_t initialization_retval = WEBRTC_VIDEO_CODEC_UNINITIALIZED;

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

What does that mean?

[sheu, 2013/08/07 09:25:03]

Yeah ok that made no sense.

Anyways I was thinking that impl_ and impl_status_ are tied together implicitly
and I would like to avoid mucking with it where I don't also set impl_ to NULL.

+  gpu_factories_->GetMessageLoop()->PostTask(
+      FROM_HERE,
+      base::Bind(&RTCVideoEncoder::Impl::CreateAndInitializeVEA,
+                 impl_,
+                 gfx::Size(codec_settings->width, codec_settings->height),
+                 codec_settings->startBitrate,
+                 video_codec_profile_,
+                 &initialization_waiter,
+                 &initialization_retval));
+
+  // webrtc::VideoEncoder expects this call to be synchronous.
+  initialization_waiter.Wait();
+  return initialization_retval;
+}
+
+int32_t RTCVideoEncoder::Encode(
+    const webrtc::I420VideoFrame& input_image,
+    const webrtc::CodecSpecificInfo* codec_specific_info,
+    const std::vector<webrtc::VideoFrameType>* frame_types) {
+  DVLOG(3) << "Encode()";
+  // DCHECK(thread_checker_.CalledOnValidThread());

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

Big-ass TODO please, then.

[sheu, 2013/08/07 09:25:03]

Done.

+  if (!impl_) {
+    DVLOG(3) << "Encode(): returning impl_status_=" << impl_status_;
+    return impl_status_;
+  }
+
+  base::WaitableEvent encode_waiter(true, false);
+  int32_t encode_retval = WEBRTC_VIDEO_CODEC_UNINITIALIZED;
+  gpu_factories_->GetMessageLoop()->PostTask(
+      FROM_HERE,
+      base::Bind(&RTCVideoEncoder::Impl::Enqueue,
+                 impl_,
+                 &input_image,
+                 (frame_types->front() == webrtc::kKeyFrame),
+                 &encode_waiter,
+                 &encode_retval));
+
+  // webrtc::VideoEncoder expects this call to be synchronous.
+  encode_waiter.Wait();
+  DVLOG(3) << "Encode(): returning encode_retval=" << encode_retval;
+  return encode_retval;
+}
+
+int32_t RTCVideoEncoder::RegisterEncodeCompleteCallback(
+    webrtc::EncodedImageCallback* callback) {
+  DVLOG(3) << "RegisterEncodeCompleteCallback()";
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!impl_) {
+    DVLOG(3) << "RegisterEncodeCompleteCallback(): returning " << impl_status_;
+    return impl_status_;
+  }
+
+  encoded_image_callback_ = callback;
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+int32_t RTCVideoEncoder::Release() {
+  DVLOG(3) << "Release()";
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  // Reset the gpu_factory_, in case we reuse this encoder.
+  gpu_factories_->Abort();
+  gpu_factories_ = gpu_factories_->Clone();
+  if (impl_) {
+    gpu_factories_->GetMessageLoop()->PostTask(
+        FROM_HERE, base::Bind(&RTCVideoEncoder::Impl::Destroy, impl_));
+    impl_ = NULL;
+    impl_status_ = WEBRTC_VIDEO_CODEC_UNINITIALIZED;
+  }
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+int32_t RTCVideoEncoder::SetChannelParameters(uint32_t packet_loss, int rtt) {
+  DVLOG(3) << "SetChannelParameters(): packet_loss=" << packet_loss
+           << ", rtt=" << rtt;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  // Ignored.
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+int32_t RTCVideoEncoder::SetRates(uint32_t new_bit_rate,
+                                  uint32_t /* ignored_frame_rate */) {
+  DVLOG(3) << "SetRates(): new_bit_rate=" << new_bit_rate;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!impl_) {
+    DVLOG(3) << "SetRates(): returning " << impl_status_;
+    return impl_status_;
+  }
+
+  gpu_factories_->GetMessageLoop()->PostTask(
+      FROM_HERE,
+      base::Bind(&RTCVideoEncoder::Impl::RequestEncodingParameterChange,
+                 impl_,
+                 new_bit_rate));
+  return WEBRTC_VIDEO_CODEC_OK;
+}
+
+void RTCVideoEncoder::ReturnEncodedImage(const scoped_refptr<Impl>& impl,
+                                         scoped_ptr<webrtc::EncodedImage> image,
+                                         int32 bitstream_buffer_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (impl != impl_)
+    return;
+
+  DVLOG(3) << "ReturnEncodedImage(): "
+              "bitstream_buffer_id=" << bitstream_buffer_id;
+
+  if (!encoded_image_callback_)
+    return;
+
+  int32_t retval = encoded_image_callback_->Encoded(*image, NULL, NULL);
+  if (retval < 0) {
+    DLOG(ERROR) << "ReturnEncodedImage(): encoded_image_callback_ returned "
+                << retval;
+    NotifyError(impl_, retval);
+    return;
+  }
+
+  // The call through webrtc::EncodedImageCallback is synchronous, so we can
+  // immediately recycle the output buffer back to the Impl.
+  gpu_factories_->GetMessageLoop()->PostTask(
+      FROM_HERE,
+      base::Bind(&RTCVideoEncoder::Impl::UseOutputBitstreamBufferId,
+                 impl_,
+                 bitstream_buffer_id));
+}
+
+void RTCVideoEncoder::NotifyError(const scoped_refptr<Impl>& impl,
+                                  int32_t error) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (!impl_)

[Ami GONE FROM CHROMIUM, 2013/08/06 20:41:13]

impossible given l.623 (and the fact that the only caller of this function
passes it a |this| for |impl|.

[sheu, 2013/08/07 09:25:03]

Done.

+    return;
+  if (impl != impl_)
+    return;
+
+  DVLOG(1) << "NotifyError(): error=" << error;
+
+  impl_status_ = error;
+  gpu_factories_->GetMessageLoop()->PostTask(
+      FROM_HERE, base::Bind(&RTCVideoEncoder::Impl::Destroy, impl_));
+  impl_ = NULL;
+}
+
+}  // namespace content