Implement H264 codec in Objective-C classes.

webrtc/sdk/objc/Framework/Classes/VideoToolbox/encoder.mm

Index: webrtc/sdk/objc/Framework/Classes/VideoToolbox/encoder.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/VideoToolbox/encoder.mm b/webrtc/sdk/objc/Framework/Classes/VideoToolbox/encoder.mm
deleted file mode 100644
index d3f5ef9a93300eb5ad6b722e0e71c54adf95614b..0000000000000000000000000000000000000000
--- a/webrtc/sdk/objc/Framework/Classes/VideoToolbox/encoder.mm
+++ /dev/null
@@ -1,765 +0,0 @@
-/*
- *  Copyright (c) 2015 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.
- *
- */
-
-#include "webrtc/sdk/objc/Framework/Classes/VideoToolbox/encoder.h"
-
-#include <memory>
-#include <string>
-#include <vector>
-
-#if defined(WEBRTC_IOS)
-#import "Common/RTCUIApplicationStatusObserver.h"
-#import "WebRTC/UIDevice+RTCDevice.h"
-#endif
-#import "WebRTC/RTCVideoFrameBuffer.h"
-#include "libyuv/convert_from.h"
-#include "webrtc/common_video/h264/profile_level_id.h"
-#include "webrtc/rtc_base/checks.h"
-#include "webrtc/rtc_base/logging.h"
-#include "webrtc/sdk/objc/Framework/Classes/Video/objc_frame_buffer.h"
-#include "webrtc/sdk/objc/Framework/Classes/VideoToolbox/nalu_rewriter.h"
-#include "webrtc/system_wrappers/include/clock.h"
-
-namespace internal {
-
-// The ratio between kVTCompressionPropertyKey_DataRateLimits and
-// kVTCompressionPropertyKey_AverageBitRate. The data rate limit is set higher
-// than the average bit rate to avoid undershooting the target.
-const float kLimitToAverageBitRateFactor = 1.5f;
-// These thresholds deviate from the default h264 QP thresholds, as they
-// have been found to work better on devices that support VideoToolbox
-const int kLowH264QpThreshold = 28;
-const int kHighH264QpThreshold = 39;
-
-// Convenience function for creating a dictionary.
-inline CFDictionaryRef CreateCFDictionary(CFTypeRef* keys,
-                                          CFTypeRef* values,
-                                          size_t size) {
-  return CFDictionaryCreate(kCFAllocatorDefault, keys, values, size,
-                            &kCFTypeDictionaryKeyCallBacks,
-                            &kCFTypeDictionaryValueCallBacks);
-}
-
-// Copies characters from a CFStringRef into a std::string.
-std::string CFStringToString(const CFStringRef cf_string) {
-  RTC_DCHECK(cf_string);
-  std::string std_string;
-  // Get the size needed for UTF8 plus terminating character.
-  size_t buffer_size =
-      CFStringGetMaximumSizeForEncoding(CFStringGetLength(cf_string),
-                                        kCFStringEncodingUTF8) +
-      1;
-  std::unique_ptr<char[]> buffer(new char[buffer_size]);
-  if (CFStringGetCString(cf_string, buffer.get(), buffer_size,
-                         kCFStringEncodingUTF8)) {
-    // Copy over the characters.
-    std_string.assign(buffer.get());
-  }
-  return std_string;
-}
-
-// Convenience function for setting a VT property.
-void SetVTSessionProperty(VTSessionRef session,
-                          CFStringRef key,
-                          int32_t value) {
-  CFNumberRef cfNum =
-      CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &value);
-  OSStatus status = VTSessionSetProperty(session, key, cfNum);
-  CFRelease(cfNum);
-  if (status != noErr) {
-    std::string key_string = CFStringToString(key);
-    LOG(LS_ERROR) << "VTSessionSetProperty failed to set: " << key_string
-                  << " to " << value << ": " << status;
-  }
-}
-
-// Convenience function for setting a VT property.
-void SetVTSessionProperty(VTSessionRef session,
-                          CFStringRef key,
-                          uint32_t value) {
-  int64_t value_64 = value;
-  CFNumberRef cfNum =
-      CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt64Type, &value_64);
-  OSStatus status = VTSessionSetProperty(session, key, cfNum);
-  CFRelease(cfNum);
-  if (status != noErr) {
-    std::string key_string = CFStringToString(key);
-    LOG(LS_ERROR) << "VTSessionSetProperty failed to set: " << key_string
-                  << " to " << value << ": " << status;
-  }
-}
-
-// Convenience function for setting a VT property.
-void SetVTSessionProperty(VTSessionRef session, CFStringRef key, bool value) {
-  CFBooleanRef cf_bool = (value) ? kCFBooleanTrue : kCFBooleanFalse;
-  OSStatus status = VTSessionSetProperty(session, key, cf_bool);
-  if (status != noErr) {
-    std::string key_string = CFStringToString(key);
-    LOG(LS_ERROR) << "VTSessionSetProperty failed to set: " << key_string
-                  << " to " << value << ": " << status;
-  }
-}
-
-// Convenience function for setting a VT property.
-void SetVTSessionProperty(VTSessionRef session,
-                          CFStringRef key,
-                          CFStringRef value) {
-  OSStatus status = VTSessionSetProperty(session, key, value);
-  if (status != noErr) {
-    std::string key_string = CFStringToString(key);
-    std::string val_string = CFStringToString(value);
-    LOG(LS_ERROR) << "VTSessionSetProperty failed to set: " << key_string
-                  << " to " << val_string << ": " << status;
-  }
-}
-
-// Struct that we pass to the encoder per frame to encode. We receive it again
-// in the encoder callback.
-struct FrameEncodeParams {
-  FrameEncodeParams(webrtc::H264VideoToolboxEncoder* e,
-                    const webrtc::CodecSpecificInfo* csi,
-                    int32_t w,
-                    int32_t h,
-                    int64_t rtms,
-                    uint32_t ts,
-                    webrtc::VideoRotation r)
-      : encoder(e),
-        width(w),
-        height(h),
-        render_time_ms(rtms),
-        timestamp(ts),
-        rotation(r) {
-    if (csi) {
-      codec_specific_info = *csi;
-    } else {
-      codec_specific_info.codecType = webrtc::kVideoCodecH264;
-    }
-  }
-
-  webrtc::H264VideoToolboxEncoder* encoder;
-  webrtc::CodecSpecificInfo codec_specific_info;
-  int32_t width;
-  int32_t height;
-  int64_t render_time_ms;
-  uint32_t timestamp;
-  webrtc::VideoRotation rotation;
-};
-
-// We receive I420Frames as input, but we need to feed CVPixelBuffers into the
-// encoder. This performs the copy and format conversion.
-// TODO(tkchin): See if encoder will accept i420 frames and compare performance.
-bool CopyVideoFrameToPixelBuffer(const rtc::scoped_refptr<webrtc::I420BufferInterface>& frame,
-                                 CVPixelBufferRef pixel_buffer) {
-  RTC_DCHECK(pixel_buffer);
-  RTC_DCHECK_EQ(CVPixelBufferGetPixelFormatType(pixel_buffer),
-                kCVPixelFormatType_420YpCbCr8BiPlanarFullRange);
-  RTC_DCHECK_EQ(CVPixelBufferGetHeightOfPlane(pixel_buffer, 0),
-                static_cast<size_t>(frame->height()));
-  RTC_DCHECK_EQ(CVPixelBufferGetWidthOfPlane(pixel_buffer, 0),
-                static_cast<size_t>(frame->width()));
-
-  CVReturn cvRet = CVPixelBufferLockBaseAddress(pixel_buffer, 0);
-  if (cvRet != kCVReturnSuccess) {
-    LOG(LS_ERROR) << "Failed to lock base address: " << cvRet;
-    return false;
-  }
-  uint8_t* dst_y = reinterpret_cast<uint8_t*>(
-      CVPixelBufferGetBaseAddressOfPlane(pixel_buffer, 0));
-  int dst_stride_y = CVPixelBufferGetBytesPerRowOfPlane(pixel_buffer, 0);
-  uint8_t* dst_uv = reinterpret_cast<uint8_t*>(
-      CVPixelBufferGetBaseAddressOfPlane(pixel_buffer, 1));
-  int dst_stride_uv = CVPixelBufferGetBytesPerRowOfPlane(pixel_buffer, 1);
-  // Convert I420 to NV12.
-  int ret = libyuv::I420ToNV12(
-      frame->DataY(), frame->StrideY(),
-      frame->DataU(), frame->StrideU(),
-      frame->DataV(), frame->StrideV(),
-      dst_y, dst_stride_y, dst_uv, dst_stride_uv,
-      frame->width(), frame->height());
-  CVPixelBufferUnlockBaseAddress(pixel_buffer, 0);
-  if (ret) {
-    LOG(LS_ERROR) << "Error converting I420 VideoFrame to NV12 :" << ret;
-    return false;
-  }
-  return true;
-}
-
-CVPixelBufferRef CreatePixelBuffer(CVPixelBufferPoolRef pixel_buffer_pool) {
-  if (!pixel_buffer_pool) {
-    LOG(LS_ERROR) << "Failed to get pixel buffer pool.";
-    return nullptr;
-  }
-  CVPixelBufferRef pixel_buffer;
-  CVReturn ret = CVPixelBufferPoolCreatePixelBuffer(nullptr, pixel_buffer_pool,
-                                                    &pixel_buffer);
-  if (ret != kCVReturnSuccess) {
-    LOG(LS_ERROR) << "Failed to create pixel buffer: " << ret;
-    // We probably want to drop frames here, since failure probably means
-    // that the pool is empty.
-    return nullptr;
-  }
-  return pixel_buffer;
-}
-
-// This is the callback function that VideoToolbox calls when encode is
-// complete. From inspection this happens on its own queue.
-void VTCompressionOutputCallback(void* encoder,
-                                 void* params,
-                                 OSStatus status,
-                                 VTEncodeInfoFlags info_flags,
-                                 CMSampleBufferRef sample_buffer) {
-  std::unique_ptr<FrameEncodeParams> encode_params(
-      reinterpret_cast<FrameEncodeParams*>(params));
-  encode_params->encoder->OnEncodedFrame(
-      status, info_flags, sample_buffer, encode_params->codec_specific_info,
-      encode_params->width, encode_params->height,
-      encode_params->render_time_ms, encode_params->timestamp,
-      encode_params->rotation);
-}
-
-// Extract VideoToolbox profile out of the cricket::VideoCodec. If there is no
-// specific VideoToolbox profile for the specified level, AutoLevel will be
-// returned. The user must initialize the encoder with a resolution and
-// framerate conforming to the selected H264 level regardless.
-CFStringRef ExtractProfile(const cricket::VideoCodec& codec) {
-  const rtc::Optional<webrtc::H264::ProfileLevelId> profile_level_id =
-      webrtc::H264::ParseSdpProfileLevelId(codec.params);
-  RTC_DCHECK(profile_level_id);
-  switch (profile_level_id->profile) {
-    case webrtc::H264::kProfileConstrainedBaseline:
-    case webrtc::H264::kProfileBaseline:
-      switch (profile_level_id->level) {
-        case webrtc::H264::kLevel3:
-          return kVTProfileLevel_H264_Baseline_3_0;
-        case webrtc::H264::kLevel3_1:
-          return kVTProfileLevel_H264_Baseline_3_1;
-        case webrtc::H264::kLevel3_2:
-          return kVTProfileLevel_H264_Baseline_3_2;
-        case webrtc::H264::kLevel4:
-          return kVTProfileLevel_H264_Baseline_4_0;
-        case webrtc::H264::kLevel4_1:
-          return kVTProfileLevel_H264_Baseline_4_1;
-        case webrtc::H264::kLevel4_2:
-          return kVTProfileLevel_H264_Baseline_4_2;
-        case webrtc::H264::kLevel5:
-          return kVTProfileLevel_H264_Baseline_5_0;
-        case webrtc::H264::kLevel5_1:
-          return kVTProfileLevel_H264_Baseline_5_1;
-        case webrtc::H264::kLevel5_2:
-          return kVTProfileLevel_H264_Baseline_5_2;
-        case webrtc::H264::kLevel1:
-        case webrtc::H264::kLevel1_b:
-        case webrtc::H264::kLevel1_1:
-        case webrtc::H264::kLevel1_2:
-        case webrtc::H264::kLevel1_3:
-        case webrtc::H264::kLevel2:
-        case webrtc::H264::kLevel2_1:
-        case webrtc::H264::kLevel2_2:
-          return kVTProfileLevel_H264_Baseline_AutoLevel;
-      }
-
-    case webrtc::H264::kProfileMain:
-      switch (profile_level_id->level) {
-        case webrtc::H264::kLevel3:
-          return kVTProfileLevel_H264_Main_3_0;
-        case webrtc::H264::kLevel3_1:
-          return kVTProfileLevel_H264_Main_3_1;
-        case webrtc::H264::kLevel3_2:
-          return kVTProfileLevel_H264_Main_3_2;
-        case webrtc::H264::kLevel4:
-          return kVTProfileLevel_H264_Main_4_0;
-        case webrtc::H264::kLevel4_1:
-          return kVTProfileLevel_H264_Main_4_1;
-        case webrtc::H264::kLevel4_2:
-          return kVTProfileLevel_H264_Main_4_2;
-        case webrtc::H264::kLevel5:
-          return kVTProfileLevel_H264_Main_5_0;
-        case webrtc::H264::kLevel5_1:
-          return kVTProfileLevel_H264_Main_5_1;
-        case webrtc::H264::kLevel5_2:
-          return kVTProfileLevel_H264_Main_5_2;
-        case webrtc::H264::kLevel1:
-        case webrtc::H264::kLevel1_b:
-        case webrtc::H264::kLevel1_1:
-        case webrtc::H264::kLevel1_2:
-        case webrtc::H264::kLevel1_3:
-        case webrtc::H264::kLevel2:
-        case webrtc::H264::kLevel2_1:
-        case webrtc::H264::kLevel2_2:
-          return kVTProfileLevel_H264_Main_AutoLevel;
-      }
-
-    case webrtc::H264::kProfileConstrainedHigh:
-    case webrtc::H264::kProfileHigh:
-      switch (profile_level_id->level) {
-        case webrtc::H264::kLevel3:
-          return kVTProfileLevel_H264_High_3_0;
-        case webrtc::H264::kLevel3_1:
-          return kVTProfileLevel_H264_High_3_1;
-        case webrtc::H264::kLevel3_2:
-          return kVTProfileLevel_H264_High_3_2;
-        case webrtc::H264::kLevel4:
-          return kVTProfileLevel_H264_High_4_0;
-        case webrtc::H264::kLevel4_1:
-          return kVTProfileLevel_H264_High_4_1;
-        case webrtc::H264::kLevel4_2:
-          return kVTProfileLevel_H264_High_4_2;
-        case webrtc::H264::kLevel5:
-          return kVTProfileLevel_H264_High_5_0;
-        case webrtc::H264::kLevel5_1:
-          return kVTProfileLevel_H264_High_5_1;
-        case webrtc::H264::kLevel5_2:
-          return kVTProfileLevel_H264_High_5_2;
-        case webrtc::H264::kLevel1:
-        case webrtc::H264::kLevel1_b:
-        case webrtc::H264::kLevel1_1:
-        case webrtc::H264::kLevel1_2:
-        case webrtc::H264::kLevel1_3:
-        case webrtc::H264::kLevel2:
-        case webrtc::H264::kLevel2_1:
-        case webrtc::H264::kLevel2_2:
-          return kVTProfileLevel_H264_High_AutoLevel;
-      }
-  }
-}
-
-}  // namespace internal
-
-namespace webrtc {
-
-// .5 is set as a mininum to prevent overcompensating for large temporary
-// overshoots. We don't want to degrade video quality too badly.
-// .95 is set to prevent oscillations. When a lower bitrate is set on the
-// encoder than previously set, its output seems to have a brief period of
-// drastically reduced bitrate, so we want to avoid that. In steady state
-// conditions, 0.95 seems to give us better overall bitrate over long periods
-// of time.
-H264VideoToolboxEncoder::H264VideoToolboxEncoder(const cricket::VideoCodec& codec)
-    : callback_(nullptr),
-      compression_session_(nullptr),
-      bitrate_adjuster_(Clock::GetRealTimeClock(), .5, .95),
-      packetization_mode_(H264PacketizationMode::NonInterleaved),
-      profile_(internal::ExtractProfile(codec)) {
-  LOG(LS_INFO) << "Using profile " << internal::CFStringToString(profile_);
-  RTC_CHECK(cricket::CodecNamesEq(codec.name, cricket::kH264CodecName));
-}
-
-H264VideoToolboxEncoder::~H264VideoToolboxEncoder() {
-  DestroyCompressionSession();
-}
-
-int H264VideoToolboxEncoder::InitEncode(const VideoCodec* codec_settings,
-                                        int number_of_cores,
-                                        size_t max_payload_size) {
-  RTC_DCHECK(codec_settings);
-  RTC_DCHECK_EQ(codec_settings->codecType, kVideoCodecH264);
-
-  width_ = codec_settings->width;
-  height_ = codec_settings->height;
-  mode_ = codec_settings->mode;
-  // We can only set average bitrate on the HW encoder.
-  target_bitrate_bps_ = codec_settings->startBitrate;
-  bitrate_adjuster_.SetTargetBitrateBps(target_bitrate_bps_);
-
-  // TODO(tkchin): Try setting payload size via
-  // kVTCompressionPropertyKey_MaxH264SliceBytes.
-
-  return ResetCompressionSession();
-}
-
-int H264VideoToolboxEncoder::Encode(
-    const VideoFrame& frame,
-    const CodecSpecificInfo* codec_specific_info,
-    const std::vector<FrameType>* frame_types) {
-  // |input_frame| size should always match codec settings.
-  RTC_DCHECK_EQ(frame.width(), width_);
-  RTC_DCHECK_EQ(frame.height(), height_);
-  if (!callback_ || !compression_session_) {
-    return WEBRTC_VIDEO_CODEC_UNINITIALIZED;
-  }
-#if defined(WEBRTC_IOS)
-  if (![[RTCUIApplicationStatusObserver sharedInstance] isApplicationActive]) {
-    // Ignore all encode requests when app isn't active. In this state, the
-    // hardware encoder has been invalidated by the OS.
-    return WEBRTC_VIDEO_CODEC_OK;
-  }
-#endif
-  bool is_keyframe_required = false;
-
-  // Get a pixel buffer from the pool and copy frame data over.
-  CVPixelBufferPoolRef pixel_buffer_pool =
-      VTCompressionSessionGetPixelBufferPool(compression_session_);
-#if defined(WEBRTC_IOS)
-  if (!pixel_buffer_pool) {
-    // Kind of a hack. On backgrounding, the compression session seems to get
-    // invalidated, which causes this pool call to fail when the application
-    // is foregrounded and frames are being sent for encoding again.
-    // Resetting the session when this happens fixes the issue.
-    // In addition we request a keyframe so video can recover quickly.
-    ResetCompressionSession();
-    pixel_buffer_pool =
-        VTCompressionSessionGetPixelBufferPool(compression_session_);
-    is_keyframe_required = true;
-    LOG(LS_INFO) << "Resetting compression session due to invalid pool.";
-  }
-#endif
-
-  CVPixelBufferRef pixel_buffer = nullptr;
-  if (frame.video_frame_buffer()->type() == VideoFrameBuffer::Type::kNative) {
-    // Native frame.
-    rtc::scoped_refptr<ObjCFrameBuffer> objc_frame_buffer(
-        static_cast<ObjCFrameBuffer*>(frame.video_frame_buffer().get()));
-    id<RTCVideoFrameBuffer> wrapped_frame_buffer =
-        (id<RTCVideoFrameBuffer>)objc_frame_buffer->wrapped_frame_buffer();
-
-    if ([wrapped_frame_buffer isKindOfClass:[RTCCVPixelBuffer class]]) {
-      RTCCVPixelBuffer* rtc_pixel_buffer = (RTCCVPixelBuffer*)wrapped_frame_buffer;
-      if (![rtc_pixel_buffer requiresCropping]) {
-        // This pixel buffer might have a higher resolution than what the
-        // compression session is configured to. The compression session can
-        // handle that and will output encoded frames in the configured
-        // resolution regardless of the input pixel buffer resolution.
-        pixel_buffer = rtc_pixel_buffer.pixelBuffer;
-        CVBufferRetain(pixel_buffer);
-      } else {
-        // Cropping required, we need to crop and scale to a new pixel buffer.
-        pixel_buffer = internal::CreatePixelBuffer(pixel_buffer_pool);
-        if (!pixel_buffer) {
-          return WEBRTC_VIDEO_CODEC_ERROR;
-        }
-        int dst_width = CVPixelBufferGetWidth(pixel_buffer);
-        int dst_height = CVPixelBufferGetHeight(pixel_buffer);
-        if ([rtc_pixel_buffer requiresScalingToWidth:dst_width height:dst_height]) {
-          int size =
-              [rtc_pixel_buffer bufferSizeForCroppingAndScalingToWidth:dst_width height:dst_height];
-          nv12_scale_buffer_.resize(size);
-        } else {
-          nv12_scale_buffer_.clear();
-        }
-        nv12_scale_buffer_.shrink_to_fit();
-        if (![rtc_pixel_buffer cropAndScaleTo:pixel_buffer
-                               withTempBuffer:nv12_scale_buffer_.data()]) {
-          return WEBRTC_VIDEO_CODEC_ERROR;
-        }
-      }
-    }
-  }
-
-  if (!pixel_buffer) {
-    // We did not have a native frame, or the ObjCVideoFrame wrapped a non-native frame
-    pixel_buffer = internal::CreatePixelBuffer(pixel_buffer_pool);
-    if (!pixel_buffer) {
-      return WEBRTC_VIDEO_CODEC_ERROR;
-    }
-    RTC_DCHECK(pixel_buffer);
-    if (!internal::CopyVideoFrameToPixelBuffer(frame.video_frame_buffer()->ToI420(),
-                                               pixel_buffer)) {
-      LOG(LS_ERROR) << "Failed to copy frame data.";
-      CVBufferRelease(pixel_buffer);
-      return WEBRTC_VIDEO_CODEC_ERROR;
-    }
-  }
-
-  // Check if we need a keyframe.
-  if (!is_keyframe_required && frame_types) {
-    for (auto frame_type : *frame_types) {
-      if (frame_type == kVideoFrameKey) {
-        is_keyframe_required = true;
-        break;
-      }
-    }
-  }
-
-  CMTime presentation_time_stamp =
-      CMTimeMake(frame.render_time_ms(), 1000);
-  CFDictionaryRef frame_properties = nullptr;
-  if (is_keyframe_required) {
-    CFTypeRef keys[] = {kVTEncodeFrameOptionKey_ForceKeyFrame};
-    CFTypeRef values[] = {kCFBooleanTrue};
-    frame_properties = internal::CreateCFDictionary(keys, values, 1);
-  }
-  std::unique_ptr<internal::FrameEncodeParams> encode_params;
-  encode_params.reset(new internal::FrameEncodeParams(
-      this, codec_specific_info, width_, height_, frame.render_time_ms(),
-      frame.timestamp(), frame.rotation()));
-
-  encode_params->codec_specific_info.codecSpecific.H264.packetization_mode =
-      packetization_mode_;
-
-  // Update the bitrate if needed.
-  SetBitrateBps(bitrate_adjuster_.GetAdjustedBitrateBps());
-
-  OSStatus status = VTCompressionSessionEncodeFrame(
-      compression_session_, pixel_buffer, presentation_time_stamp,
-      kCMTimeInvalid, frame_properties, encode_params.release(), nullptr);
-  if (frame_properties) {
-    CFRelease(frame_properties);
-  }
-  if (pixel_buffer) {
-    CVBufferRelease(pixel_buffer);
-  }
-  if (status != noErr) {
-    LOG(LS_ERROR) << "Failed to encode frame with code: " << status;
-    return WEBRTC_VIDEO_CODEC_ERROR;
-  }
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-int H264VideoToolboxEncoder::RegisterEncodeCompleteCallback(
-    EncodedImageCallback* callback) {
-  callback_ = callback;
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-int H264VideoToolboxEncoder::SetChannelParameters(uint32_t packet_loss,
-                                                  int64_t rtt) {
-  // Encoder doesn't know anything about packet loss or rtt so just return.
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-int H264VideoToolboxEncoder::SetRates(uint32_t new_bitrate_kbit,
-                                      uint32_t frame_rate) {
-  target_bitrate_bps_ = 1000 * new_bitrate_kbit;
-  bitrate_adjuster_.SetTargetBitrateBps(target_bitrate_bps_);
-  SetBitrateBps(bitrate_adjuster_.GetAdjustedBitrateBps());
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-int H264VideoToolboxEncoder::Release() {
-  // Need to reset so that the session is invalidated and won't use the
-  // callback anymore. Do not remove callback until the session is invalidated
-  // since async encoder callbacks can occur until invalidation.
-  int ret = ResetCompressionSession();
-  callback_ = nullptr;
-  return ret;
-}
-
-int H264VideoToolboxEncoder::ResetCompressionSession() {
-  DestroyCompressionSession();
-
-  // Set source image buffer attributes. These attributes will be present on
-  // buffers retrieved from the encoder's pixel buffer pool.
-  const size_t attributes_size = 3;
-  CFTypeRef keys[attributes_size] = {
-#if defined(WEBRTC_IOS)
-    kCVPixelBufferOpenGLESCompatibilityKey,
-#elif defined(WEBRTC_MAC)
-    kCVPixelBufferOpenGLCompatibilityKey,
-#endif
-    kCVPixelBufferIOSurfacePropertiesKey,
-    kCVPixelBufferPixelFormatTypeKey
-  };
-  CFDictionaryRef io_surface_value =
-      internal::CreateCFDictionary(nullptr, nullptr, 0);
-  int64_t nv12type = kCVPixelFormatType_420YpCbCr8BiPlanarFullRange;
-  CFNumberRef pixel_format =
-      CFNumberCreate(nullptr, kCFNumberLongType, &nv12type);
-  CFTypeRef values[attributes_size] = {kCFBooleanTrue, io_surface_value,
-                                       pixel_format};
-  CFDictionaryRef source_attributes =
-      internal::CreateCFDictionary(keys, values, attributes_size);
-  if (io_surface_value) {
-    CFRelease(io_surface_value);
-    io_surface_value = nullptr;
-  }
-  if (pixel_format) {
-    CFRelease(pixel_format);
-    pixel_format = nullptr;
-  }
-  OSStatus status = VTCompressionSessionCreate(
-      nullptr,  // use default allocator
-      width_, height_, kCMVideoCodecType_H264,
-      nullptr,  // use default encoder
-      source_attributes,
-      nullptr,  // use default compressed data allocator
-      internal::VTCompressionOutputCallback, this, &compression_session_);
-  if (source_attributes) {
-    CFRelease(source_attributes);
-    source_attributes = nullptr;
-  }
-  if (status != noErr) {
-    LOG(LS_ERROR) << "Failed to create compression session: " << status;
-    return WEBRTC_VIDEO_CODEC_ERROR;
-  }
-  ConfigureCompressionSession();
-  return WEBRTC_VIDEO_CODEC_OK;
-}
-
-void H264VideoToolboxEncoder::ConfigureCompressionSession() {
-  RTC_DCHECK(compression_session_);
-  internal::SetVTSessionProperty(compression_session_,
-                                 kVTCompressionPropertyKey_RealTime, true);
-  internal::SetVTSessionProperty(compression_session_,
-                                 kVTCompressionPropertyKey_ProfileLevel,
-                                 profile_);
-  internal::SetVTSessionProperty(compression_session_,
-                                 kVTCompressionPropertyKey_AllowFrameReordering,
-                                 false);
-  SetEncoderBitrateBps(target_bitrate_bps_);
-  // TODO(tkchin): Look at entropy mode and colorspace matrices.
-  // TODO(tkchin): Investigate to see if there's any way to make this work.
-  // May need it to interop with Android. Currently this call just fails.
-  // On inspecting encoder output on iOS8, this value is set to 6.
-  // internal::SetVTSessionProperty(compression_session_,
-  //     kVTCompressionPropertyKey_MaxFrameDelayCount,
-  //     1);
-
-  // Set a relatively large value for keyframe emission (7200 frames or
-  // 4 minutes).
-  internal::SetVTSessionProperty(
-      compression_session_,
-      kVTCompressionPropertyKey_MaxKeyFrameInterval, 7200);
-  internal::SetVTSessionProperty(
-      compression_session_,
-      kVTCompressionPropertyKey_MaxKeyFrameIntervalDuration, 240);
-}
-
-void H264VideoToolboxEncoder::DestroyCompressionSession() {
-  if (compression_session_) {
-    VTCompressionSessionInvalidate(compression_session_);
-    CFRelease(compression_session_);
-    compression_session_ = nullptr;
-  }
-}
-
-const char* H264VideoToolboxEncoder::ImplementationName() const {
-  return "VideoToolbox";
-}
-
-bool H264VideoToolboxEncoder::SupportsNativeHandle() const {
-  return true;
-}
-
-void H264VideoToolboxEncoder::SetBitrateBps(uint32_t bitrate_bps) {
-  if (encoder_bitrate_bps_ != bitrate_bps) {
-    SetEncoderBitrateBps(bitrate_bps);
-  }
-}
-
-void H264VideoToolboxEncoder::SetEncoderBitrateBps(uint32_t bitrate_bps) {
-  if (compression_session_) {
-    internal::SetVTSessionProperty(compression_session_,
-                                   kVTCompressionPropertyKey_AverageBitRate,
-                                   bitrate_bps);
-
-    // TODO(tkchin): Add a helper method to set array value.
-    int64_t data_limit_bytes_per_second_value = static_cast<int64_t>(
-        bitrate_bps * internal::kLimitToAverageBitRateFactor / 8);
-    CFNumberRef bytes_per_second =
-        CFNumberCreate(kCFAllocatorDefault,
-                       kCFNumberSInt64Type,
-                       &data_limit_bytes_per_second_value);
-    int64_t one_second_value = 1;
-    CFNumberRef one_second =
-        CFNumberCreate(kCFAllocatorDefault,
-                       kCFNumberSInt64Type,
-                       &one_second_value);
-    const void* nums[2] = { bytes_per_second, one_second };
-    CFArrayRef data_rate_limits =
-        CFArrayCreate(nullptr, nums, 2, &kCFTypeArrayCallBacks);
-    OSStatus status =
-        VTSessionSetProperty(compression_session_,
-                             kVTCompressionPropertyKey_DataRateLimits,
-                             data_rate_limits);
-    if (bytes_per_second) {
-      CFRelease(bytes_per_second);
-    }
-    if (one_second) {
-      CFRelease(one_second);
-    }
-    if (data_rate_limits) {
-      CFRelease(data_rate_limits);
-    }
-    if (status != noErr) {
-      LOG(LS_ERROR) << "Failed to set data rate limit";
-    }
-
-    encoder_bitrate_bps_ = bitrate_bps;
-  }
-}
-
-void H264VideoToolboxEncoder::OnEncodedFrame(
-    OSStatus status,
-    VTEncodeInfoFlags info_flags,
-    CMSampleBufferRef sample_buffer,
-    CodecSpecificInfo codec_specific_info,
-    int32_t width,
-    int32_t height,
-    int64_t render_time_ms,
-    uint32_t timestamp,
-    VideoRotation rotation) {
-  if (status != noErr) {
-    LOG(LS_ERROR) << "H264 encode failed.";
-    return;
-  }
-  if (info_flags & kVTEncodeInfo_FrameDropped) {
-    LOG(LS_INFO) << "H264 encode dropped frame.";
-    return;
-  }
-
-  bool is_keyframe = false;
-  CFArrayRef attachments =
-      CMSampleBufferGetSampleAttachmentsArray(sample_buffer, 0);
-  if (attachments != nullptr && CFArrayGetCount(attachments)) {
-    CFDictionaryRef attachment =
-        static_cast<CFDictionaryRef>(CFArrayGetValueAtIndex(attachments, 0));
-    is_keyframe =
-        !CFDictionaryContainsKey(attachment, kCMSampleAttachmentKey_NotSync);
-  }
-
-  if (is_keyframe) {
-    LOG(LS_INFO) << "Generated keyframe";
-  }
-
-  // Convert the sample buffer into a buffer suitable for RTP packetization.
-  // TODO(tkchin): Allocate buffers through a pool.
-  std::unique_ptr<rtc::Buffer> buffer(new rtc::Buffer());
-  std::unique_ptr<webrtc::RTPFragmentationHeader> header;
-  {
-    webrtc::RTPFragmentationHeader* header_raw;
-    bool result = H264CMSampleBufferToAnnexBBuffer(sample_buffer, is_keyframe,
-                                                   buffer.get(), &header_raw);
-    header.reset(header_raw);
-    if (!result) {
-      return;
-    }
-  }
-  webrtc::EncodedImage frame(buffer->data(), buffer->size(), buffer->size());
-  frame._encodedWidth = width;
-  frame._encodedHeight = height;
-  frame._completeFrame = true;
-  frame._frameType =
-      is_keyframe ? webrtc::kVideoFrameKey : webrtc::kVideoFrameDelta;
-  frame.capture_time_ms_ = render_time_ms;
-  frame._timeStamp = timestamp;
-  frame.rotation_ = rotation;
-  frame.content_type_ =
-      (mode_ == kScreensharing) ? VideoContentType::SCREENSHARE : VideoContentType::UNSPECIFIED;
-  frame.timing_.is_timing_frame = false;
-
-  h264_bitstream_parser_.ParseBitstream(buffer->data(), buffer->size());
-  h264_bitstream_parser_.GetLastSliceQp(&frame.qp_);
-
-  EncodedImageCallback::Result res =
-      callback_->OnEncodedImage(frame, &codec_specific_info, header.get());
-  if (res.error != EncodedImageCallback::Result::OK) {
-    LOG(LS_ERROR) << "Encode callback failed: " << res.error;
-    return;
-  }
-  bitrate_adjuster_.Update(frame._length);
-}
-
-VideoEncoder::ScalingSettings H264VideoToolboxEncoder::GetScalingSettings()
-    const {
-  return VideoEncoder::ScalingSettings(true, internal::kLowH264QpThreshold,
-                                       internal::kHighH264QpThreshold);
-}
-}  // namespace webrtc