[Cast] Size-Adaptable platform video encoders.

media/cast/sender/size_adaptable_video_encoder_base.cc

+// Copyright 2015 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 "media/cast/sender/size_adaptable_video_encoder_base.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "media/base/video_frame.h"
+
+namespace media {
+namespace cast {
+
+SizeAdaptableVideoEncoderBase::SizeAdaptableVideoEncoderBase(
+    const scoped_refptr<CastEnvironment>& cast_environment,
+    const VideoSenderConfig& video_config,
+    const StatusChangeCallback& status_change_cb)
+    : cast_environment_(cast_environment),
+      video_config_(video_config),
+      status_change_cb_(status_change_cb),
+      frames_in_encoder_(0),
+      last_frame_id_(kStartFrameId),
+      weak_factory_(this) {
+  cast_environment_->PostTask(
+      CastEnvironment::MAIN,
+      FROM_HERE,
+      base::Bind(status_change_cb_, STATUS_INITIALIZED));
+}
+
+SizeAdaptableVideoEncoderBase::~SizeAdaptableVideoEncoderBase() {
+  weak_factory_.InvalidateWeakPtrs();

[hubbe, 2015/02/11 00:47:54]

This is kind of weird.
Why invalidate weak pointers before destroying the encoder?
(Add a comment?)

[miu, 2015/02/11 02:14:23]

Done.  Consolidated into DestroyCurrentEncoder(), and there's a comment there to
explain.

+  DestroyCurrentEncoder();
+}
+
+bool SizeAdaptableVideoEncoderBase::EncodeVideoFrame(
+    const scoped_refptr<media::VideoFrame>& video_frame,
+    const base::TimeTicks& reference_time,
+    const FrameEncodedCallback& frame_encoded_callback) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+
+  const gfx::Size frame_size = video_frame->visible_rect().size();
+  if (frame_size.IsEmpty()) {
+    DVLOG(1) << "Rejecting empty video frame.";
+    return false;
+  }
+  if (frame_size != current_encoder_frame_size_ || !current_encoder_) {
+    VLOG(1) << "Dropping frame (of size " << frame_size.ToString()
+            << ") until a replacement encoder is spun-up.  Current encoder "
+               "handles frames of size "
+            << current_encoder_frame_size_.ToString() << '.';
+    MaybeSpawnReplacementEncoder(frame_size);
+    return false;
+  }
+
+  const bool is_frame_accepted = current_encoder_->EncodeVideoFrame(
+      video_frame,
+      reference_time,
+      base::Bind(&SizeAdaptableVideoEncoderBase::OnEncodedVideoFrame,
+                 weak_factory_.GetWeakPtr(),
+                 frame_encoded_callback));
+  if (is_frame_accepted)
+    ++frames_in_encoder_;
+  return is_frame_accepted;
+}
+
+void SizeAdaptableVideoEncoderBase::SetBitRate(int new_bit_rate) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  video_config_.start_bitrate = new_bit_rate;
+  if (current_encoder_)
+    current_encoder_->SetBitRate(new_bit_rate);
+}
+
+void SizeAdaptableVideoEncoderBase::GenerateKeyFrame() {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  if (current_encoder_)
+    current_encoder_->GenerateKeyFrame();
+}
+
+void SizeAdaptableVideoEncoderBase::LatestFrameIdToReference(uint32 frame_id) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  if (current_encoder_)
+    current_encoder_->LatestFrameIdToReference(frame_id);
+}
+
+scoped_ptr<VideoFrameFactory>
+    SizeAdaptableVideoEncoderBase::CreateVideoFrameFactory() {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  return nullptr;
+}
+
+void SizeAdaptableVideoEncoderBase::EmitFrames() {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  if (current_encoder_)
+    current_encoder_->EmitFrames();
+}
+
+StatusChangeCallback
+    SizeAdaptableVideoEncoderBase::CreateEncoderStatusChangeCallback() {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  return base::Bind(&SizeAdaptableVideoEncoderBase::OnEncoderStatusChange,
+                    weak_factory_.GetWeakPtr());
+}
+
+void SizeAdaptableVideoEncoderBase::OnEncoderReplaced(
+    VideoEncoder* replacement_encoder) {}
+
+void SizeAdaptableVideoEncoderBase::DestroyCurrentEncoder() {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  current_encoder_.reset();
+}
+
+void SizeAdaptableVideoEncoderBase::MaybeSpawnReplacementEncoder(

[hubbe, 2015/02/11 00:47:54]

I don't like "Maybe"
I think "Try" or "" would be better.

[miu, 2015/02/11 02:14:23]

Done.

+    const gfx::Size& size_needed) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+
+  // If prior frames are still encoding in the current encoder, let them finish
+  // first.
+  if (frames_in_encoder_ > 0) {
+    current_encoder_->EmitFrames();
+    return;
+  }
+
+  if (next_encoder_.get())
+    return;  // Already spawned.
+
+  // Prevent future callbacks from |current_encoder_| and destroy it.
+  weak_factory_.InvalidateWeakPtrs();
+  DestroyCurrentEncoder();
+
+  OnEncoderStatusChange(STATUS_CODEC_REINIT_PENDING);
+  next_encoder_frame_size_ = size_needed;
+  VLOG(1) << "Creating replacement video encoder (for frame size change from "
+          << current_encoder_frame_size_.ToString() << " to "
+          << next_encoder_frame_size_.ToString() << ").";
+  next_encoder_ = CreateReplacementEncoder().Pass();
+  DCHECK(next_encoder_.get());
+}
+
+void SizeAdaptableVideoEncoderBase::OnEncoderStatusChange(
+    OperationalStatus status) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  if (next_encoder_.get() && status == STATUS_INITIALIZED) {
+    // Begin using the replacement encoder.
+    current_encoder_ = next_encoder_.Pass();
+    current_encoder_frame_size_ = next_encoder_frame_size_;
+    OnEncoderReplaced(current_encoder_.get());
+  }
+  status_change_cb_.Run(status);
+}
+
+void SizeAdaptableVideoEncoderBase::OnEncodedVideoFrame(
+    const FrameEncodedCallback& frame_encoded_callback,
+    scoped_ptr<EncodedFrame> encoded_frame) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
+  --frames_in_encoder_;
+  DCHECK_GE(frames_in_encoder_, 0);
+  last_frame_id_ = encoded_frame->frame_id;
+  frame_encoded_callback.Run(encoded_frame.Pass());
+}
+
+}  // namespace cast
+}  // namespace media