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/*
* 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 "api/video_codecs/video_encoder_software_fallback_wrapper.h"
#include <stdint.h>
#include <cstdio>
#include <memory>
#include <string>
#include <vector>
#include "absl/strings/match.h"
#include "absl/types/optional.h"
#include "api/fec_controller_override.h"
#include "api/transport/field_trial_based_config.h"
#include "api/video/i420_buffer.h"
#include "api/video/video_bitrate_allocation.h"
#include "api/video/video_frame.h"
#include "api/video_codecs/video_codec.h"
#include "api/video_codecs/video_encoder.h"
#include "media/base/video_common.h"
#include "modules/video_coding/include/video_error_codes.h"
#include "modules/video_coding/utility/simulcast_utility.h"
#include "rtc_base/checks.h"
#include "rtc_base/experiments/field_trial_parser.h"
#include "rtc_base/logging.h"
#include "system_wrappers/include/field_trial.h"
namespace webrtc {
namespace {
// If forced fallback is allowed, either:
//
// 1) The forced fallback is requested if the resolution is less than or equal
// to `max_pixels_`. The resolution is allowed to be scaled down to
// `min_pixels_`.
//
// 2) The forced fallback is requested if temporal support is preferred and the
// SW fallback supports temporal layers while the HW encoder does not.
struct ForcedFallbackParams {
public:
bool SupportsResolutionBasedSwitch(const VideoCodec& codec) const {
if (!enable_resolution_based_switch ||
codec.width * codec.height > max_pixels) {
return false;
}
if (vp8_specific_resolution_switch &&
(codec.codecType != kVideoCodecVP8 ||
codec.numberOfSimulcastStreams > 1)) {
return false;
}
return true;
}
bool SupportsTemporalBasedSwitch(const VideoCodec& codec) const {
return enable_temporal_based_switch &&
SimulcastUtility::NumberOfTemporalLayers(codec, 0) != 1;
}
bool enable_temporal_based_switch = false;
bool enable_resolution_based_switch = false;
bool vp8_specific_resolution_switch = false;
int min_pixels = kDefaultMinPixelsPerFrame;
int max_pixels = 320 * 240;
};
const char kVp8ForceFallbackEncoderFieldTrial[] =
"WebRTC-VP8-Forced-Fallback-Encoder-v2";
absl::optional<ForcedFallbackParams> ParseFallbackParamsFromFieldTrials(
const VideoEncoder& main_encoder) {
// Ignore WebRTC-VP8-Forced-Fallback-Encoder-v2 if
// WebRTC-Video-EncoderFallbackSettings is present.
FieldTrialOptional<int> resolution_threshold_px("resolution_threshold_px");
ParseFieldTrial(
{&resolution_threshold_px},
FieldTrialBasedConfig().Lookup("WebRTC-Video-EncoderFallbackSettings"));
if (resolution_threshold_px) {
ForcedFallbackParams params;
params.enable_resolution_based_switch = true;
params.max_pixels = resolution_threshold_px.Value();
return params;
}
const std::string field_trial =
webrtc::field_trial::FindFullName(kVp8ForceFallbackEncoderFieldTrial);
if (!absl::StartsWith(field_trial, "Enabled")) {
return absl::nullopt;
}
int max_pixels_lower_bound =
main_encoder.GetEncoderInfo().scaling_settings.min_pixels_per_frame - 1;
ForcedFallbackParams params;
params.enable_resolution_based_switch = true;
int min_bps = 0;
if (sscanf(field_trial.c_str(), "Enabled-%d,%d,%d", &params.min_pixels,
&params.max_pixels, &min_bps) != 3) {
RTC_LOG(LS_WARNING)
<< "Invalid number of forced fallback parameters provided.";
return absl::nullopt;
} else if (params.min_pixels <= 0 ||
params.max_pixels < max_pixels_lower_bound ||
params.max_pixels < params.min_pixels || min_bps <= 0) {
RTC_LOG(LS_WARNING) << "Invalid forced fallback parameter value provided.";
return absl::nullopt;
}
params.vp8_specific_resolution_switch = true;
return params;
}
absl::optional<ForcedFallbackParams> GetForcedFallbackParams(
bool prefer_temporal_support,
const VideoEncoder& main_encoder) {
absl::optional<ForcedFallbackParams> params =
ParseFallbackParamsFromFieldTrials(main_encoder);
if (prefer_temporal_support) {
if (!params.has_value()) {
params.emplace();
}
params->enable_temporal_based_switch = true;
}
return params;
}
class VideoEncoderSoftwareFallbackWrapper final : public VideoEncoder {
public:
VideoEncoderSoftwareFallbackWrapper(
std::unique_ptr<webrtc::VideoEncoder> sw_encoder,
std::unique_ptr<webrtc::VideoEncoder> hw_encoder,
bool prefer_temporal_support);
~VideoEncoderSoftwareFallbackWrapper() override;
void SetFecControllerOverride(
FecControllerOverride* fec_controller_override) override;
int32_t InitEncode(const VideoCodec* codec_settings,
const VideoEncoder::Settings& settings) override;
int32_t RegisterEncodeCompleteCallback(
EncodedImageCallback* callback) override;
int32_t Release() override;
int32_t Encode(const VideoFrame& frame,
const std::vector<VideoFrameType>* frame_types) override;
void OnPacketLossRateUpdate(float packet_loss_rate) override;
void OnRttUpdate(int64_t rtt_ms) override;
void OnLossNotification(const LossNotification& loss_notification) override;
void SetRates(const RateControlParameters& parameters) override;
EncoderInfo GetEncoderInfo() const override;
private:
bool InitFallbackEncoder(bool is_forced);
bool TryInitForcedFallbackEncoder();
bool IsFallbackActive() const;
VideoEncoder* current_encoder() {
switch (encoder_state_) {
case EncoderState::kUninitialized:
RTC_LOG(LS_WARNING)
<< "Trying to access encoder in uninitialized fallback wrapper.";
// Return main encoder to preserve previous behavior.
[[fallthrough]];
case EncoderState::kMainEncoderUsed:
return encoder_.get();
case EncoderState::kFallbackDueToFailure:
case EncoderState::kForcedFallback:
return fallback_encoder_.get();
}
RTC_CHECK_NOTREACHED();
}
// Updates encoder with last observed parameters, such as callbacks, rates,
// etc.
void PrimeEncoder(VideoEncoder* encoder) const;
// Settings used in the last InitEncode call and used if a dynamic fallback to
// software is required.
VideoCodec codec_settings_;
absl::optional<VideoEncoder::Settings> encoder_settings_;
// The last rate control settings, if set.
absl::optional<RateControlParameters> rate_control_parameters_;
// The last channel parameters set.
absl::optional<float> packet_loss_;
absl::optional<int64_t> rtt_;
absl::optional<LossNotification> loss_notification_;
enum class EncoderState {
kUninitialized,
kMainEncoderUsed,
kFallbackDueToFailure,
kForcedFallback
};
EncoderState encoder_state_;
const std::unique_ptr<webrtc::VideoEncoder> encoder_;
const std::unique_ptr<webrtc::VideoEncoder> fallback_encoder_;
EncodedImageCallback* callback_;
const absl::optional<ForcedFallbackParams> fallback_params_;
int32_t EncodeWithMainEncoder(const VideoFrame& frame,
const std::vector<VideoFrameType>* frame_types);
};
VideoEncoderSoftwareFallbackWrapper::VideoEncoderSoftwareFallbackWrapper(
std::unique_ptr<webrtc::VideoEncoder> sw_encoder,
std::unique_ptr<webrtc::VideoEncoder> hw_encoder,
bool prefer_temporal_support)
: encoder_state_(EncoderState::kUninitialized),
encoder_(std::move(hw_encoder)),
fallback_encoder_(std::move(sw_encoder)),
callback_(nullptr),
fallback_params_(
GetForcedFallbackParams(prefer_temporal_support, *encoder_)) {
RTC_DCHECK(fallback_encoder_);
}
VideoEncoderSoftwareFallbackWrapper::~VideoEncoderSoftwareFallbackWrapper() =
default;
void VideoEncoderSoftwareFallbackWrapper::PrimeEncoder(
VideoEncoder* encoder) const {
RTC_DCHECK(encoder);
// Replay callback, rates, and channel parameters.
if (callback_) {
encoder->RegisterEncodeCompleteCallback(callback_);
}
if (rate_control_parameters_) {
encoder->SetRates(*rate_control_parameters_);
}
if (rtt_.has_value()) {
encoder->OnRttUpdate(rtt_.value());
}
if (packet_loss_.has_value()) {
encoder->OnPacketLossRateUpdate(packet_loss_.value());
}
if (loss_notification_.has_value()) {
encoder->OnLossNotification(loss_notification_.value());
}
}
bool VideoEncoderSoftwareFallbackWrapper::InitFallbackEncoder(bool is_forced) {
RTC_LOG(LS_WARNING) << "Encoder falling back to software encoding.";
RTC_DCHECK(encoder_settings_.has_value());
const int ret = fallback_encoder_->InitEncode(&codec_settings_,
encoder_settings_.value());
if (ret != WEBRTC_VIDEO_CODEC_OK) {
RTC_LOG(LS_ERROR) << "Failed to initialize software-encoder fallback.";
fallback_encoder_->Release();
return false;
}
if (encoder_state_ == EncoderState::kMainEncoderUsed) {
// Since we're switching to the fallback encoder, Release the real encoder.
// It may be re-initialized via InitEncode later, and it will continue to
// get Set calls for rates and channel parameters in the meantime.
encoder_->Release();
}
if (is_forced) {
encoder_state_ = EncoderState::kForcedFallback;
} else {
encoder_state_ = EncoderState::kFallbackDueToFailure;
}
return true;
}
void VideoEncoderSoftwareFallbackWrapper::SetFecControllerOverride(
FecControllerOverride* fec_controller_override) {
// It is important that only one of those would ever interact with the
// `fec_controller_override` at a given time. This is the responsibility
// of `this` to maintain.
encoder_->SetFecControllerOverride(fec_controller_override);
fallback_encoder_->SetFecControllerOverride(fec_controller_override);
}
int32_t VideoEncoderSoftwareFallbackWrapper::InitEncode(
const VideoCodec* codec_settings,
const VideoEncoder::Settings& settings) {
// Store settings, in case we need to dynamically switch to the fallback
// encoder after a failed Encode call.
codec_settings_ = *codec_settings;
encoder_settings_ = settings;
// Clear stored rate/channel parameters.
rate_control_parameters_ = absl::nullopt;
RTC_DCHECK_EQ(encoder_state_, EncoderState::kUninitialized)
<< "InitEncode() should never be called on an active instance!";
// Try to init forced software codec if it should be used.
if (TryInitForcedFallbackEncoder()) {
PrimeEncoder(current_encoder());
return WEBRTC_VIDEO_CODEC_OK;
}
int32_t ret = encoder_->InitEncode(codec_settings, settings);
if (ret == WEBRTC_VIDEO_CODEC_OK) {
encoder_state_ = EncoderState::kMainEncoderUsed;
PrimeEncoder(current_encoder());
return ret;
}
// Try to instantiate software codec.
if (InitFallbackEncoder(/*is_forced=*/false)) {
PrimeEncoder(current_encoder());
return WEBRTC_VIDEO_CODEC_OK;
}
// Software encoder failed too, use original return code.
encoder_state_ = EncoderState::kUninitialized;
return ret;
}
int32_t VideoEncoderSoftwareFallbackWrapper::RegisterEncodeCompleteCallback(
EncodedImageCallback* callback) {
callback_ = callback;
return current_encoder()->RegisterEncodeCompleteCallback(callback);
}
int32_t VideoEncoderSoftwareFallbackWrapper::Release() {
if (encoder_state_ == EncoderState::kUninitialized) {
return WEBRTC_VIDEO_CODEC_OK;
}
int32_t ret = current_encoder()->Release();
encoder_state_ = EncoderState::kUninitialized;
return ret;
}
int32_t VideoEncoderSoftwareFallbackWrapper::Encode(
const VideoFrame& frame,
const std::vector<VideoFrameType>* frame_types) {
switch (encoder_state_) {
case EncoderState::kUninitialized:
return WEBRTC_VIDEO_CODEC_ERROR;
case EncoderState::kMainEncoderUsed: {
return EncodeWithMainEncoder(frame, frame_types);
}
case EncoderState::kFallbackDueToFailure:
case EncoderState::kForcedFallback:
return fallback_encoder_->Encode(frame, frame_types);
}
RTC_CHECK_NOTREACHED();
}
int32_t VideoEncoderSoftwareFallbackWrapper::EncodeWithMainEncoder(
const VideoFrame& frame,
const std::vector<VideoFrameType>* frame_types) {
int32_t ret = encoder_->Encode(frame, frame_types);
// If requested, try a software fallback.
bool fallback_requested = (ret == WEBRTC_VIDEO_CODEC_FALLBACK_SOFTWARE);
if (fallback_requested && InitFallbackEncoder(/*is_forced=*/false)) {
// Start using the fallback with this frame.
PrimeEncoder(current_encoder());
if (frame.video_frame_buffer()->type() == VideoFrameBuffer::Type::kNative &&
fallback_encoder_->GetEncoderInfo().supports_native_handle) {
return fallback_encoder_->Encode(frame, frame_types);
} else {
RTC_LOG(LS_INFO) << "Fallback encoder does not support native handle - "
"converting frame to I420";
rtc::scoped_refptr<I420BufferInterface> src_buffer =
frame.video_frame_buffer()->ToI420();
if (!src_buffer) {
RTC_LOG(LS_ERROR) << "Failed to convert from to I420";
return WEBRTC_VIDEO_CODEC_ENCODER_FAILURE;
}
rtc::scoped_refptr<VideoFrameBuffer> dst_buffer =
src_buffer->Scale(codec_settings_.width, codec_settings_.height);
if (!dst_buffer) {
RTC_LOG(LS_ERROR) << "Failed to scale video frame.";
return WEBRTC_VIDEO_CODEC_ENCODER_FAILURE;
}
VideoFrame scaled_frame = frame;
scaled_frame.set_video_frame_buffer(dst_buffer);
scaled_frame.set_update_rect(VideoFrame::UpdateRect{
0, 0, scaled_frame.width(), scaled_frame.height()});
return fallback_encoder_->Encode(scaled_frame, frame_types);
}
}
// Fallback encoder failed too, return original error code.
return ret;
}
void VideoEncoderSoftwareFallbackWrapper::SetRates(
const RateControlParameters& parameters) {
rate_control_parameters_ = parameters;
return current_encoder()->SetRates(parameters);
}
void VideoEncoderSoftwareFallbackWrapper::OnPacketLossRateUpdate(
float packet_loss_rate) {
packet_loss_ = packet_loss_rate;
current_encoder()->OnPacketLossRateUpdate(packet_loss_rate);
}
void VideoEncoderSoftwareFallbackWrapper::OnRttUpdate(int64_t rtt_ms) {
rtt_ = rtt_ms;
current_encoder()->OnRttUpdate(rtt_ms);
}
void VideoEncoderSoftwareFallbackWrapper::OnLossNotification(
const LossNotification& loss_notification) {
loss_notification_ = loss_notification;
current_encoder()->OnLossNotification(loss_notification);
}
VideoEncoder::EncoderInfo VideoEncoderSoftwareFallbackWrapper::GetEncoderInfo()
const {
EncoderInfo fallback_encoder_info = fallback_encoder_->GetEncoderInfo();
EncoderInfo default_encoder_info = encoder_->GetEncoderInfo();
EncoderInfo info =
IsFallbackActive() ? fallback_encoder_info : default_encoder_info;
info.requested_resolution_alignment = cricket::LeastCommonMultiple(
fallback_encoder_info.requested_resolution_alignment,
default_encoder_info.requested_resolution_alignment);
info.apply_alignment_to_all_simulcast_layers =
fallback_encoder_info.apply_alignment_to_all_simulcast_layers ||
default_encoder_info.apply_alignment_to_all_simulcast_layers;
if (fallback_params_ && fallback_params_->vp8_specific_resolution_switch) {
info.scaling_settings.min_pixels_per_frame = fallback_params_->min_pixels;
}
return info;
}
bool VideoEncoderSoftwareFallbackWrapper::IsFallbackActive() const {
return encoder_state_ == EncoderState::kForcedFallback ||
encoder_state_ == EncoderState::kFallbackDueToFailure;
}
bool VideoEncoderSoftwareFallbackWrapper::TryInitForcedFallbackEncoder() {
if (!fallback_params_) {
return false;
}
RTC_DCHECK_EQ(encoder_state_, EncoderState::kUninitialized);
if (fallback_params_->SupportsResolutionBasedSwitch(codec_settings_)) {
// Settings valid, try to instantiate software codec.
RTC_LOG(LS_INFO) << "Request forced SW encoder fallback: "
<< codec_settings_.width << "x" << codec_settings_.height;
return InitFallbackEncoder(/*is_forced=*/true);
}
if (fallback_params_->SupportsTemporalBasedSwitch(codec_settings_)) {
// First init main encoder to see if that supports temporal layers.
if (encoder_->InitEncode(&codec_settings_, encoder_settings_.value()) ==
WEBRTC_VIDEO_CODEC_OK) {
encoder_state_ = EncoderState::kMainEncoderUsed;
}
if (encoder_state_ == EncoderState::kMainEncoderUsed &&
encoder_->GetEncoderInfo().fps_allocation[0].size() != 1) {
// Primary encoder already supports temporal layers, use that instead.
return true;
}
// Try to initialize fallback and check if it supports temporal layers.
if (fallback_encoder_->InitEncode(&codec_settings_,
encoder_settings_.value()) ==
WEBRTC_VIDEO_CODEC_OK) {
if (fallback_encoder_->GetEncoderInfo().fps_allocation[0].size() != 1) {
// Fallback encoder available and supports temporal layers, use it!
if (encoder_state_ == EncoderState::kMainEncoderUsed) {
// Main encoder initialized but does not support temporal layers,
// release it again.
encoder_->Release();
}
encoder_state_ = EncoderState::kForcedFallback;
RTC_LOG(LS_INFO)
<< "Forced switch to SW encoder due to temporal support.";
return true;
} else {
// Fallback encoder intialization succeeded, but it does not support
// temporal layers either - release it.
fallback_encoder_->Release();
}
}
if (encoder_state_ == EncoderState::kMainEncoderUsed) {
// Main encoder already initialized - make use of it.
RTC_LOG(LS_INFO)
<< "Cannot fall back for temporal support since fallback that "
"supports is not available. Using main encoder instead.";
return true;
}
}
// Neither forced fallback mode supported.
return false;
}
} // namespace
std::unique_ptr<VideoEncoder> CreateVideoEncoderSoftwareFallbackWrapper(
std::unique_ptr<VideoEncoder> sw_fallback_encoder,
std::unique_ptr<VideoEncoder> hw_encoder,
bool prefer_temporal_support) {
return std::make_unique<VideoEncoderSoftwareFallbackWrapper>(
std::move(sw_fallback_encoder), std::move(hw_encoder),
prefer_temporal_support);
}
} // namespace webrtc