media/engine/internalencoderfactory.cc

/*
 *  Copyright (c) 2016 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 "media/engine/internalencoderfactory.h"

#include <utility>

#include "modules/video_coding/codecs/h264/include/h264.h"
#include "modules/video_coding/codecs/vp8/include/vp8.h"
#include "modules/video_coding/codecs/vp9/include/vp9.h"
#include "rtc_base/logging.h"
#include "system_wrappers/include/field_trial.h"

namespace webrtc {

namespace {

// If this field trial is enabled, the "flexfec-03" codec will be advertised
// as being supported by the InternalEncoderFactory. This means that
// "flexfec-03" will appear in the default SDP offer, and we therefore need to
// be ready to receive FlexFEC packets from the remote. It also means that
// FlexFEC SSRCs will be generated by MediaSession and added as "a=ssrc:" and
// "a=ssrc-group:" lines in the local SDP.
bool IsFlexfecAdvertisedFieldTrialEnabled() {
  return webrtc::field_trial::IsEnabled("WebRTC-FlexFEC-03-Advertised");
}

}  // namespace

std::vector<SdpVideoFormat> InternalEncoderFactory::GetSupportedFormats()
    const {
  std::vector<SdpVideoFormat> supported_codecs;
  supported_codecs.push_back(SdpVideoFormat(cricket::kVp8CodecName));
  if (webrtc::VP9Encoder::IsSupported())
    supported_codecs.push_back(SdpVideoFormat(cricket::kVp9CodecName));

  for (const webrtc::SdpVideoFormat& format : webrtc::SupportedH264Codecs())
    supported_codecs.push_back(format);

  supported_codecs.push_back(SdpVideoFormat(cricket::kRedCodecName));
  supported_codecs.push_back(SdpVideoFormat(cricket::kUlpfecCodecName));

  if (IsFlexfecAdvertisedFieldTrialEnabled()) {
    // This value is currently arbitrarily set to 10 seconds. (The unit
    // is microseconds.) This parameter MUST be present in the SDP, but
    // we never use the actual value anywhere in our code however.
    // TODO(brandtr): Consider honouring this value in the sender and receiver.
    SdpVideoFormat::Parameters params = {
        {cricket::kFlexfecFmtpRepairWindow, "10000000"}};
    supported_codecs.push_back(
        SdpVideoFormat(cricket::kFlexfecCodecName, params));
  }

  return supported_codecs;
}

VideoEncoderFactory::CodecInfo InternalEncoderFactory::QueryVideoEncoder(
    const SdpVideoFormat& format) const {
  CodecInfo info;
  info.is_hardware_accelerated = false;
  info.has_internal_source = false;
  return info;
}

std::unique_ptr<VideoEncoder> InternalEncoderFactory::CreateVideoEncoder(
    const SdpVideoFormat& format) {
  if (cricket::CodecNamesEq(format.name, cricket::kVp8CodecName))
    return VP8Encoder::Create();

  if (cricket::CodecNamesEq(format.name, cricket::kVp9CodecName))
    return VP9Encoder::Create();

  if (cricket::CodecNamesEq(format.name, cricket::kH264CodecName))
    return H264Encoder::Create(cricket::VideoCodec(format));

  RTC_LOG(LS_ERROR) << "Trying to created encoder of unsupported format "
                    << format.name;
  return nullptr;
}

}  // namespace webrtc