[cast] Handle frame size changes directly in the VideoToolbox encoder (v2).

media/cast/sender/h264_vt_encoder.cc

 // Copyright 2014 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/h264_vt_encoder.h"
 
 #include <string>
 #include <vector>
 
 #include "base/big_endian.h"
@@ skipping 19 matching lines @@
   const VideoEncoder::FrameEncodedCallback frame_encoded_callback;
 
   InProgressFrameEncode(RtpTimestamp rtp,
                         base::TimeTicks r_time,
                         VideoEncoder::FrameEncodedCallback callback)
       : rtp_timestamp(rtp),
         reference_time(r_time),
         frame_encoded_callback(callback) {}
 };
 
-base::ScopedCFTypeRef<CFDictionaryRef> DictionaryWithKeysAndValues(
-    CFTypeRef* keys,
-    CFTypeRef* values,
-    size_t size) {
+base::ScopedCFTypeRef<CFDictionaryRef>
+DictionaryWithKeysAndValues(CFTypeRef* keys, CFTypeRef* values, size_t size) {
   return base::ScopedCFTypeRef<CFDictionaryRef>(CFDictionaryCreate(
-      kCFAllocatorDefault,
-      keys,
-      values,
-      size,
-      &kCFTypeDictionaryKeyCallBacks,
+      kCFAllocatorDefault, keys, values, size, &kCFTypeDictionaryKeyCallBacks,
       &kCFTypeDictionaryValueCallBacks));
 }
 
 base::ScopedCFTypeRef<CFDictionaryRef> DictionaryWithKeyValue(CFTypeRef key,
                                                               CFTypeRef value) {
   CFTypeRef keys[1] = {key};
   CFTypeRef values[1] = {value};
   return DictionaryWithKeysAndValues(keys, values, 1);
 }
 
@@ skipping 142 matching lines @@
     CopyNalsToAnnexB<uint8_t>(bb_data, bb_size, annexb_buffer);
   } else if (nal_size_field_bytes == 2) {
     CopyNalsToAnnexB<uint16_t>(bb_data, bb_size, annexb_buffer);
   } else if (nal_size_field_bytes == 4) {
     CopyNalsToAnnexB<uint32_t>(bb_data, bb_size, annexb_buffer);
   } else {
     NOTREACHED();
   }
 }
 
-// Implementation of the VideoFrameFactory interface using |CVPixelBufferPool|.
-class VideoFrameFactoryCVPixelBufferPoolImpl : public VideoFrameFactory {
+}  // namespace
+
+class H264VideoToolboxEncoder::VideoFrameFactoryImpl
+    : public base::RefCountedThreadSafe<VideoFrameFactoryImpl>,
+      public VideoFrameFactory {
  public:
-  VideoFrameFactoryCVPixelBufferPoolImpl(
-      const base::ScopedCFTypeRef<CVPixelBufferPoolRef>& pool,
-      const gfx::Size& frame_size)
-      : pool_(pool),
-        frame_size_(frame_size) {}
+  // Type that proxies the VideoFrameFactory interface to this class.
+  class Proxy;
 
-  ~VideoFrameFactoryCVPixelBufferPoolImpl() override {}
+  VideoFrameFactoryImpl(const base::WeakPtr<H264VideoToolboxEncoder>& encoder,
+                        const scoped_refptr<CastEnvironment>& cast_environment)
+      : encoder_(encoder), cast_environment_(cast_environment) {}
 
   scoped_refptr<VideoFrame> MaybeCreateFrame(
-      const gfx::Size& frame_size, base::TimeDelta timestamp) override {
-    if (frame_size != frame_size_)
-      return nullptr;  // Buffer pool is not a match for requested frame size.
+      const gfx::Size& frame_size,
+      base::TimeDelta timestamp) override {
+    if (frame_size.IsEmpty()) {
+      DVLOG(1) << "Rejecting empty video frame.";
+      return nullptr;
+    }
 
+    base::AutoLock auto_lock(lock_);
+
+    // If the pool size does not match, speculatively reset the encoder to use
+    // the new size and return null. Cache the new frame size right away and
+    // toss away the pixel buffer pool to avoid spurious tasks until the encoder
+    // is done resetting.
+    if (frame_size != pool_frame_size_) {
+      DVLOG(1) << "MaybeCreateFrame: Detected frame size change.";
+      cast_environment_->PostTask(
+          CastEnvironment::MAIN, FROM_HERE,
+          base::Bind(&H264VideoToolboxEncoder::UpdateFrameSize, encoder_,
+                     frame_size));
+      pool_frame_size_ = frame_size;
+      pool_.reset();
+      return nullptr;
+    }
+
+    if (!pool_) {
+      DVLOG(1) << "MaybeCreateFrame: No pixel buffer pool.";
+      return nullptr;
+    }
+
+    // Allocate a pixel buffer from the pool and return a wrapper VideoFrame.
     base::ScopedCFTypeRef<CVPixelBufferRef> buffer;
-    if (CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pool_,
-                                           buffer.InitializeInto()) !=
-            kCVReturnSuccess)
-      return nullptr;  // Buffer pool has run out of pixel buffers.
+    auto status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pool_,
+                                                     buffer.InitializeInto());
+    if (status != kCVReturnSuccess) {
+      DLOG(ERROR) << "CVPixelBufferPoolCreatePixelBuffer failed: " << status;
+      return nullptr;
+    }
+
     DCHECK(buffer);
-
     return VideoFrame::WrapCVPixelBuffer(buffer, timestamp);
   }
 
+  void Update(const base::ScopedCFTypeRef<CVPixelBufferPoolRef>& pool,
+              const gfx::Size& frame_size) {
+    base::AutoLock auto_lock(lock_);
+    pool_ = pool;
+    pool_frame_size_ = frame_size;
+  }
+
  private:
-  const base::ScopedCFTypeRef<CVPixelBufferPoolRef> pool_;
-  const gfx::Size frame_size_;
+  friend class base::RefCountedThreadSafe<VideoFrameFactoryImpl>;
+  ~VideoFrameFactoryImpl() override {}
 
-  DISALLOW_COPY_AND_ASSIGN(VideoFrameFactoryCVPixelBufferPoolImpl);
+  base::Lock lock_;
+  base::ScopedCFTypeRef<CVPixelBufferPoolRef> pool_;
+  gfx::Size pool_frame_size_;
+
+  // Weak back reference to the encoder and the cast envrionment so we can
+  // message the encoder when the frame size changes.
+  const base::WeakPtr<H264VideoToolboxEncoder> encoder_;
+  const scoped_refptr<CastEnvironment> cast_environment_;
+
+  DISALLOW_COPY_AND_ASSIGN(VideoFrameFactoryImpl);
 };
 
-}  // namespace
+class H264VideoToolboxEncoder::VideoFrameFactoryImpl::Proxy
+    : public VideoFrameFactory {
+ public:
+  explicit Proxy(
+      const scoped_refptr<VideoFrameFactoryImpl>& video_frame_factory)
+      : video_frame_factory_(video_frame_factory) {
+    DCHECK(video_frame_factory_);
+  }
+
+  scoped_refptr<VideoFrame> MaybeCreateFrame(
+      const gfx::Size& frame_size,
+      base::TimeDelta timestamp) override {
+    return video_frame_factory_->MaybeCreateFrame(frame_size, timestamp);
+  }
+
+ private:
+  ~Proxy() override {}
+
+  const scoped_refptr<VideoFrameFactoryImpl> video_frame_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(Proxy);
+};
 
 // static
 bool H264VideoToolboxEncoder::IsSupported(
     const VideoSenderConfig& video_config) {
   return video_config.codec == CODEC_VIDEO_H264 && VideoToolboxGlue::Get();
 }
 
 H264VideoToolboxEncoder::H264VideoToolboxEncoder(
     const scoped_refptr<CastEnvironment>& cast_environment,
     const VideoSenderConfig& video_config,
-    const gfx::Size& frame_size,
-    uint32 first_frame_id,
     const StatusChangeCallback& status_change_cb)
     : cast_environment_(cast_environment),
       videotoolbox_glue_(VideoToolboxGlue::Get()),
-      frame_size_(frame_size),
+      video_config_(video_config),
       status_change_cb_(status_change_cb),
-      next_frame_id_(first_frame_id),
-      encode_next_frame_as_keyframe_(false) {
-  DCHECK(!frame_size_.IsEmpty());
+      last_frame_id_(kStartFrameId),
+      encode_next_frame_as_keyframe_(false),
+      weak_factory_(this) {
+  DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
   DCHECK(!status_change_cb_.is_null());
 
-  OperationalStatus operational_status;
-  if (video_config.codec == CODEC_VIDEO_H264 && videotoolbox_glue_) {
-    operational_status = Initialize(video_config) ?
-        STATUS_INITIALIZED : STATUS_INVALID_CONFIGURATION;
-  } else {
-    operational_status = STATUS_UNSUPPORTED_CODEC;
+  OperationalStatus operational_status =
+      H264VideoToolboxEncoder::IsSupported(video_config)
+          ? STATUS_INITIALIZED
+          : STATUS_UNSUPPORTED_CODEC;
+  cast_environment_->PostTask(
+      CastEnvironment::MAIN, FROM_HERE,
+      base::Bind(status_change_cb_, operational_status));
+
+  if (operational_status == STATUS_INITIALIZED) {
+    video_frame_factory_ =
+        scoped_refptr<VideoFrameFactoryImpl>(new VideoFrameFactoryImpl(
+            weak_factory_.GetWeakPtr(), cast_environment_));
   }
-  cast_environment_->PostTask(
-      CastEnvironment::MAIN,
-      FROM_HERE,
-      base::Bind(status_change_cb_, operational_status));
 }
 
 H264VideoToolboxEncoder::~H264VideoToolboxEncoder() {
-  Teardown();
+  DestroyCompressionSession();
 }
 
-bool H264VideoToolboxEncoder::Initialize(
-    const VideoSenderConfig& video_config) {
+void H264VideoToolboxEncoder::ResetCompressionSession() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(!compression_session_);
 
-  // Note that the encoder object is given to the compression session as the
-  // callback context using a raw pointer. The C API does not allow us to use
-  // a smart pointer, nor is this encoder ref counted. However, this is still
-  // safe, because we 1) we own the compression session and 2) we tear it down
-  // safely. When destructing the encoder, the compression session is flushed
-  // and invalidated. Internally, VideoToolbox will join all of its threads
-  // before returning to the client. Therefore, when control returns to us, we
-  // are guaranteed that the output callback will not execute again.
+  // Notify that we're resetting the encoder.
+  cast_environment_->PostTask(
+      CastEnvironment::MAIN, FROM_HERE,
+      base::Bind(status_change_cb_, STATUS_CODEC_REINIT_PENDING));
+
+  // Destroy the current session, if any.
+  DestroyCompressionSession();
 
   // On OS X, allow the hardware encoder. Don't require it, it does not support
   // all configurations (some of which are used for testing).
   base::ScopedCFTypeRef<CFDictionaryRef> encoder_spec;
 #if !defined(OS_IOS)
   encoder_spec = DictionaryWithKeyValue(
       videotoolbox_glue_
           ->kVTVideoEncoderSpecification_EnableHardwareAcceleratedVideoEncoder(),
       kCFBooleanTrue);
 #endif
 
   // Certain encoders prefer kCVPixelFormatType_422YpCbCr8, which is not
   // supported through VideoFrame. We can force 420 formats to be used instead.
   const int formats[] = {
-    kCVPixelFormatType_420YpCbCr8Planar,
-    CoreVideoGlue::kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange
-  };
+      kCVPixelFormatType_420YpCbCr8Planar,
+      CoreVideoGlue::kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange};
   // Keep these attachment settings in-sync with those in ConfigureSession().
-  CFTypeRef attachments_keys[] = {
-    kCVImageBufferColorPrimariesKey,
-    kCVImageBufferTransferFunctionKey,
-    kCVImageBufferYCbCrMatrixKey
-  };
-  CFTypeRef attachments_values[] = {
-    kCVImageBufferColorPrimaries_ITU_R_709_2,
-    kCVImageBufferTransferFunction_ITU_R_709_2,
-    kCVImageBufferYCbCrMatrix_ITU_R_709_2
-  };
-  CFTypeRef buffer_attributes_keys[] = {
-    kCVPixelBufferPixelFormatTypeKey,
-    kCVBufferPropagatedAttachmentsKey
-  };
+  CFTypeRef attachments_keys[] = {kCVImageBufferColorPrimariesKey,
+                                  kCVImageBufferTransferFunctionKey,
+                                  kCVImageBufferYCbCrMatrixKey};
+  CFTypeRef attachments_values[] = {kCVImageBufferColorPrimaries_ITU_R_709_2,
+                                    kCVImageBufferTransferFunction_ITU_R_709_2,
+                                    kCVImageBufferYCbCrMatrix_ITU_R_709_2};
+  CFTypeRef buffer_attributes_keys[] = {kCVPixelBufferPixelFormatTypeKey,
+                                        kCVBufferPropagatedAttachmentsKey};
   CFTypeRef buffer_attributes_values[] = {
-    ArrayWithIntegers(formats, arraysize(formats)).release(),
-    DictionaryWithKeysAndValues(attachments_keys,
-                                attachments_values,
-                                arraysize(attachments_keys)).release()
-  };
+      ArrayWithIntegers(formats, arraysize(formats)).release(),
+      DictionaryWithKeysAndValues(attachments_keys, attachments_values,
+                                  arraysize(attachments_keys)).release()};
   const base::ScopedCFTypeRef<CFDictionaryRef> buffer_attributes =
       DictionaryWithKeysAndValues(buffer_attributes_keys,
                                   buffer_attributes_values,
                                   arraysize(buffer_attributes_keys));
   for (auto& v : buffer_attributes_values)
     CFRelease(v);
 
-  VTCompressionSessionRef session;
+  // Create the compression session.
+
+  // Note that the encoder object is given to the compression session as the
+  // callback context using a raw pointer. The C API does not allow us to use a
+  // smart pointer, nor is this encoder ref counted. However, this is still
+  // safe, because we 1) we own the compression session and 2) we tear it down
+  // safely. When destructing the encoder, the compression session is flushed
+  // and invalidated. Internally, VideoToolbox will join all of its threads
+  // before returning to the client. Therefore, when control returns to us, we
+  // are guaranteed that the output callback will not execute again.
   OSStatus status = videotoolbox_glue_->VTCompressionSessionCreate(
       kCFAllocatorDefault, frame_size_.width(), frame_size_.height(),
       CoreMediaGlue::kCMVideoCodecType_H264, encoder_spec, buffer_attributes,
       nullptr /* compressedDataAllocator */,
       &H264VideoToolboxEncoder::CompressionCallback,
-      reinterpret_cast<void*>(this), &session);
+      reinterpret_cast<void*>(this), compression_session_.InitializeInto());
   if (status != noErr) {
     DLOG(ERROR) << " VTCompressionSessionCreate failed: " << status;
-    return false;
+    // Notify that reinitialization has failed.
+    cast_environment_->PostTask(
+        CastEnvironment::MAIN, FROM_HERE,
+        base::Bind(status_change_cb_, STATUS_CODEC_INIT_FAILED));
+    return;
   }
-  compression_session_.reset(session);
 
-  ConfigureSession(video_config);
+  // Configure the session (apply session properties based on the current state
+  // of the encoder, experimental tuning and requirements).
+  ConfigureCompressionSession();
 
-  return true;
+  // Update the video frame factory.
+  base::ScopedCFTypeRef<CVPixelBufferPoolRef> pool(
+      videotoolbox_glue_->VTCompressionSessionGetPixelBufferPool(
+          compression_session_),
+      base::scoped_policy::RETAIN);
+  video_frame_factory_->Update(pool, frame_size_);
+
+  // Notify that reinitialization is done.
+  cast_environment_->PostTask(
+      CastEnvironment::MAIN, FROM_HERE,
+      base::Bind(status_change_cb_, STATUS_INITIALIZED));
 }
 
-void H264VideoToolboxEncoder::ConfigureSession(
-    const VideoSenderConfig& video_config) {
+void H264VideoToolboxEncoder::ConfigureCompressionSession() {
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_ProfileLevel(),
       videotoolbox_glue_->kVTProfileLevel_H264_Main_AutoLevel());
   SetSessionProperty(videotoolbox_glue_->kVTCompressionPropertyKey_RealTime(),
                      true);
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_AllowFrameReordering(),
       false);
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_MaxKeyFrameInterval(), 240);
   SetSessionProperty(
       videotoolbox_glue_
           ->kVTCompressionPropertyKey_MaxKeyFrameIntervalDuration(),
       240);
   // TODO(jfroy): implement better bitrate control
   //              https://crbug.com/425352
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_AverageBitRate(),
-      (video_config.min_bitrate + video_config.max_bitrate) / 2);
+      (video_config_.min_bitrate + video_config_.max_bitrate) / 2);
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_ExpectedFrameRate(),
-      video_config.max_frame_rate);
+      video_config_.max_frame_rate);
   // Keep these attachment settings in-sync with those in Initialize().
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_ColorPrimaries(),
       kCVImageBufferColorPrimaries_ITU_R_709_2);
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_TransferFunction(),
       kCVImageBufferTransferFunction_ITU_R_709_2);
   SetSessionProperty(
       videotoolbox_glue_->kVTCompressionPropertyKey_YCbCrMatrix(),
       kCVImageBufferYCbCrMatrix_ITU_R_709_2);
-  if (video_config.max_number_of_video_buffers_used > 0) {
+  if (video_config_.max_number_of_video_buffers_used > 0) {
     SetSessionProperty(
         videotoolbox_glue_->kVTCompressionPropertyKey_MaxFrameDelayCount(),
-        video_config.max_number_of_video_buffers_used);
+        video_config_.max_number_of_video_buffers_used);
   }
 }
 
-void H264VideoToolboxEncoder::Teardown() {
+void H264VideoToolboxEncoder::DestroyCompressionSession() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // If the compression session exists, invalidate it. This blocks until all
   // pending output callbacks have returned and any internal threads have
   // joined, ensuring no output callback ever sees a dangling encoder pointer.
+  //
+  // Before destroying the compression session, the video frame factory's pool
+  // is updated to null so that no thread will produce new video frames via the
+  // factory until a new compression session is created. The current frame size
+  // is passed to prevent the video frame factory from posting |UpdateFrameSize|
+  // tasks. Indeed, |DestroyCompressionSession| is either called from
+  // |ResetCompressionSession|, in which case a new pool and frame size will be
+  // set, or from callsites that require that there be no compression session
+  // (ex: the dtor).
   if (compression_session_) {
+    video_frame_factory_->Update(
+        base::ScopedCFTypeRef<CVPixelBufferPoolRef>(nullptr), frame_size_);
     videotoolbox_glue_->VTCompressionSessionInvalidate(compression_session_);
     compression_session_.reset();
   }
 }
 
 bool H264VideoToolboxEncoder::EncodeVideoFrame(
     const scoped_refptr<media::VideoFrame>& video_frame,
     const base::TimeTicks& reference_time,
     const FrameEncodedCallback& frame_encoded_callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!frame_encoded_callback.is_null());
 
-  if (!compression_session_) {
-    DLOG(ERROR) << " compression session is null";
+  // Reject empty video frames.
+  const gfx::Size frame_size = video_frame->visible_rect().size();
+  if (frame_size.IsEmpty()) {
+    DVLOG(1) << "Rejecting empty video frame.";
     return false;
   }
 
-  if (video_frame->visible_rect().size() != frame_size_)
+  // Handle frame size changes. This will reset the compression session.
+  if (frame_size != frame_size_) {
+    DVLOG(1) << "EncodeVideoFrame: Detected frame size change.";
+    UpdateFrameSize(frame_size);
+  }
+
+  // Need a compression session to continue.
+  if (!compression_session_) {
+    DLOG(ERROR) << "No compression session.";
     return false;
+  }
 
   // Wrap the VideoFrame in a CVPixelBuffer. In all cases, no data will be
   // copied. If the VideoFrame was created by this encoder's video frame
   // factory, then the returned CVPixelBuffer will have been obtained from the
   // compression session's pixel buffer pool. This will eliminate a copy of the
   // frame into memory visible by the hardware encoder. The VideoFrame's
   // lifetime is extended for the lifetime of the returned CVPixelBuffer.
   auto pixel_buffer = media::WrapVideoFrameInCVPixelBuffer(*video_frame);
   if (!pixel_buffer) {
+    DLOG(ERROR) << "WrapVideoFrameInCVPixelBuffer failed.";
     return false;
   }
 
+  // Convert the frame timestamp to CMTime.
   auto timestamp_cm = CoreMediaGlue::CMTimeMake(
       (reference_time - base::TimeTicks()).InMicroseconds(), USEC_PER_SEC);
 
+  // Wrap information we'll need after the frame is encoded in a heap object.
+  // We'll get the pointer back from the VideoToolbox completion callback.
   scoped_ptr<InProgressFrameEncode> request(new InProgressFrameEncode(
       TimeDeltaToRtpDelta(video_frame->timestamp(), kVideoFrequency),
       reference_time, frame_encoded_callback));
 
+  // Build a suitable frame properties dictionary for keyframes.
   base::ScopedCFTypeRef<CFDictionaryRef> frame_props;
   if (encode_next_frame_as_keyframe_) {
     frame_props = DictionaryWithKeyValue(
         videotoolbox_glue_->kVTEncodeFrameOptionKey_ForceKeyFrame(),
         kCFBooleanTrue);
     encode_next_frame_as_keyframe_ = false;
   }
 
-  VTEncodeInfoFlags info;
+  // Submit the frame to the compression session. The function returns as soon
+  // as the frame has been enqueued.
   OSStatus status = videotoolbox_glue_->VTCompressionSessionEncodeFrame(
       compression_session_, pixel_buffer, timestamp_cm,
       CoreMediaGlue::CMTime{0, 0, 0, 0}, frame_props,
-      reinterpret_cast<void*>(request.release()), &info);
+      reinterpret_cast<void*>(request.release()), nullptr);
   if (status != noErr) {
     DLOG(ERROR) << " VTCompressionSessionEncodeFrame failed: " << status;
     return false;
   }
-  if ((info & VideoToolboxGlue::kVTEncodeInfo_FrameDropped)) {
-    DLOG(ERROR) << " frame dropped";
-    return false;
-  }
 
   return true;
 }
 
-void H264VideoToolboxEncoder::SetBitRate(int new_bit_rate) {
+void H264VideoToolboxEncoder::UpdateFrameSize(const gfx::Size& size_needed) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  // Our video frame factory posts a task to update the frame size when its
+  // cache of the frame size differs from what the client requested. To avoid
+  // spurious encoder resets, check again here.
+  if (size_needed == frame_size_) {
+    DCHECK(compression_session_);
+    return;
+  }
+
+  VLOG(1) << "Resetting compression session (for frame size change from "
+          << frame_size_.ToString() << " to " << size_needed.ToString() << ").";
+
+  // If there is an existing session, finish every pending frame.
+  if (compression_session_) {
+    EmitFrames();
+  }
+
+  // Store the new frame size.
+  frame_size_ = size_needed;
+
+  // Reset the compression session.
+  ResetCompressionSession();
+}
+
+void H264VideoToolboxEncoder::SetBitRate(int /*new_bit_rate*/) {
   DCHECK(thread_checker_.CalledOnValidThread());
   // VideoToolbox does not seem to support bitrate reconfiguration.
 }
 
 void H264VideoToolboxEncoder::GenerateKeyFrame() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(compression_session_);
-
   encode_next_frame_as_keyframe_ = true;
 }
 
 void H264VideoToolboxEncoder::LatestFrameIdToReference(uint32 /*frame_id*/) {
   // Not supported by VideoToolbox in any meaningful manner.
 }
 
 scoped_ptr<VideoFrameFactory>
 H264VideoToolboxEncoder::CreateVideoFrameFactory() {
-  if (!videotoolbox_glue_ || !compression_session_)
-    return nullptr;
-  base::ScopedCFTypeRef<CVPixelBufferPoolRef> pool(
-      videotoolbox_glue_->VTCompressionSessionGetPixelBufferPool(
-          compression_session_),
-      base::scoped_policy::RETAIN);
+  DCHECK(thread_checker_.CalledOnValidThread());
   return scoped_ptr<VideoFrameFactory>(
-      new VideoFrameFactoryCVPixelBufferPoolImpl(pool, frame_size_));
+      new VideoFrameFactoryImpl::Proxy(video_frame_factory_));
 }
 
 void H264VideoToolboxEncoder::EmitFrames() {
   DCHECK(thread_checker_.CalledOnValidThread());
-
-  if (!compression_session_) {
-    DLOG(ERROR) << " compression session is null";
+  if (!compression_session_)
     return;
-  }
 
   OSStatus status = videotoolbox_glue_->VTCompressionSessionCompleteFrames(
       compression_session_, CoreMediaGlue::CMTime{0, 0, 0, 0});
   if (status != noErr) {
     DLOG(ERROR) << " VTCompressionSessionCompleteFrames failed: " << status;
   }
 }
 
 bool H264VideoToolboxEncoder::SetSessionProperty(CFStringRef key,
                                                  int32_t value) {
@@ skipping 22 matching lines @@
                                                   CMSampleBufferRef sbuf) {
   auto encoder = reinterpret_cast<H264VideoToolboxEncoder*>(encoder_opaque);
   const scoped_ptr<InProgressFrameEncode> request(
       reinterpret_cast<InProgressFrameEncode*>(request_opaque));
   bool keyframe = false;
   bool has_frame_data = false;
 
   if (status != noErr) {
     DLOG(ERROR) << " encoding failed: " << status;
     encoder->cast_environment_->PostTask(
-        CastEnvironment::MAIN,
-        FROM_HERE,
+        CastEnvironment::MAIN, FROM_HERE,
         base::Bind(encoder->status_change_cb_, STATUS_CODEC_RUNTIME_ERROR));
   } else if ((info & VideoToolboxGlue::kVTEncodeInfo_FrameDropped)) {
     DVLOG(2) << " frame dropped";
   } else {
-    auto sample_attachments = static_cast<CFDictionaryRef>(
-        CFArrayGetValueAtIndex(
+    auto sample_attachments =
+        static_cast<CFDictionaryRef>(CFArrayGetValueAtIndex(
             CoreMediaGlue::CMSampleBufferGetSampleAttachmentsArray(sbuf, true),
             0));
 
     // If the NotSync key is not present, it implies Sync, which indicates a
     // keyframe (at least I think, VT documentation is, erm, sparse). Could
     // alternatively use kCMSampleAttachmentKey_DependsOnOthers == false.
     keyframe = !CFDictionaryContainsKey(
-        sample_attachments,
-        CoreMediaGlue::kCMSampleAttachmentKey_NotSync());
+                   sample_attachments,
+                   CoreMediaGlue::kCMSampleAttachmentKey_NotSync());
     has_frame_data = true;
   }
 
   // Increment the encoder-scoped frame id and assign the new value to this
   // frame. VideoToolbox calls the output callback serially, so this is safe.
-  const uint32 frame_id = encoder->next_frame_id_++;
+  const uint32 frame_id = ++encoder->last_frame_id_;
 
   scoped_ptr<EncodedFrame> encoded_frame(new EncodedFrame());
   encoded_frame->frame_id = frame_id;
   encoded_frame->reference_time = request->reference_time;
   encoded_frame->rtp_timestamp = request->rtp_timestamp;
   if (keyframe) {
     encoded_frame->dependency = EncodedFrame::KEY;
     encoded_frame->referenced_frame_id = frame_id;
   } else {
     encoded_frame->dependency = EncodedFrame::DEPENDENT;
@@ skipping 11 matching lines @@
 
   if (has_frame_data)
     CopySampleBufferToAnnexBBuffer(sbuf, &encoded_frame->data, keyframe);
 
   encoder->cast_environment_->PostTask(
       CastEnvironment::MAIN, FROM_HERE,
       base::Bind(request->frame_encoded_callback,
                  base::Passed(&encoded_frame)));
 }
 
-// A ref-counted structure that is shared to provide concurrent access to the
-// VideoFrameFactory instance for the current encoder.  OnEncoderReplaced() can
-// change |factory| whenever an encoder instance has been replaced, while users
-// of CreateVideoFrameFactory() may attempt to read/use |factory| by any thread
-// at any time.
-struct SizeAdaptableH264VideoToolboxVideoEncoder::FactoryHolder
-    : public base::RefCountedThreadSafe<FactoryHolder> {
-  base::Lock lock;
-  scoped_ptr<VideoFrameFactory> factory;
-
- private:
-  friend class base::RefCountedThreadSafe<FactoryHolder>;
-  ~FactoryHolder() {}
-};
-
-SizeAdaptableH264VideoToolboxVideoEncoder::
-    SizeAdaptableH264VideoToolboxVideoEncoder(
-        const scoped_refptr<CastEnvironment>& cast_environment,
-        const VideoSenderConfig& video_config,
-        const StatusChangeCallback& status_change_cb)
-        : SizeAdaptableVideoEncoderBase(cast_environment,
-                                        video_config,
-                                        status_change_cb),
-          holder_(new FactoryHolder()) {}
-
-SizeAdaptableH264VideoToolboxVideoEncoder::
-    ~SizeAdaptableH264VideoToolboxVideoEncoder() {}
-
-// A proxy allowing SizeAdaptableH264VideoToolboxVideoEncoder to swap out the
-// VideoFrameFactory instance to match one appropriate for the current encoder
-// instance.
-class SizeAdaptableH264VideoToolboxVideoEncoder::VideoFrameFactoryProxy
-    : public VideoFrameFactory {
- public:
-  explicit VideoFrameFactoryProxy(const scoped_refptr<FactoryHolder>& holder)
-      : holder_(holder) {}
-
-  ~VideoFrameFactoryProxy() override {}
-
-  scoped_refptr<VideoFrame> MaybeCreateFrame(
-      const gfx::Size& frame_size, base::TimeDelta timestamp) override {
-    base::AutoLock auto_lock(holder_->lock);
-    return holder_->factory ?
-        holder_->factory->MaybeCreateFrame(frame_size, timestamp) : nullptr;
-  }
-
- private:
-  const scoped_refptr<FactoryHolder> holder_;
-
-  DISALLOW_COPY_AND_ASSIGN(VideoFrameFactoryProxy);
-};
-
-scoped_ptr<VideoFrameFactory>
-    SizeAdaptableH264VideoToolboxVideoEncoder::CreateVideoFrameFactory() {
-  return scoped_ptr<VideoFrameFactory>(new VideoFrameFactoryProxy(holder_));
-}
-
-scoped_ptr<VideoEncoder>
-    SizeAdaptableH264VideoToolboxVideoEncoder::CreateEncoder() {
-  return scoped_ptr<VideoEncoder>(new H264VideoToolboxEncoder(
-      cast_environment(),
-      video_config(),
-      frame_size(),
-      last_frame_id() + 1,
-      CreateEncoderStatusChangeCallback()));
-}
-
-void SizeAdaptableH264VideoToolboxVideoEncoder::OnEncoderReplaced(
-    VideoEncoder* replacement_encoder) {
-  scoped_ptr<VideoFrameFactory> current_factory(
-      replacement_encoder->CreateVideoFrameFactory());
-  base::AutoLock auto_lock(holder_->lock);
-  holder_->factory = current_factory.Pass();
-  SizeAdaptableVideoEncoderBase::OnEncoderReplaced(replacement_encoder);
-}
-
-void SizeAdaptableH264VideoToolboxVideoEncoder::DestroyEncoder() {
-  {
-    base::AutoLock auto_lock(holder_->lock);
-    holder_->factory.reset();
-  }
-  SizeAdaptableVideoEncoderBase::DestroyEncoder();
-}
-
 }  // namespace cast
 }  // namespace media