Google Git
Sign in
cobalt / cobalt / 56d7c4e1a836a7ef6e2823bffb8d1567758b82eb / . / media / cast / sender / external_video_encoder.cc
blob: 3644e1dbf5cfd3cbe76176ea56b76e35d080adad [file] [log] [blame]
// 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/external_video_encoder.h"
#include <array>
#include <cmath>
#include <sstream>
#include <utility>
#include "base/bind.h"
#include "base/command_line.h"
#include "base/logging.h"
#include "base/memory/shared_memory_mapping.h"
#include "base/memory/unsafe_shared_memory_region.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "build/build_config.h"
#include "media/base/bind_to_current_loop.h"
#include "media/base/bitrate.h"
#include "media/base/media_switches.h"
#include "media/base/video_frame.h"
#include "media/base/video_types.h"
#include "media/base/video_util.h"
#include "media/cast/cast_config.h"
#include "media/cast/common/rtp_time.h"
#include "media/cast/logging/logging_defines.h"
#include "media/cast/net/cast_transport_config.h"
#include "media/cast/sender/vpx_quantizer_parser.h"
#include "media/video/h264_parser.h"
namespace {
// The percentage of each frame to sample. This value is based on an
// analysis that showed sampling 10% of the rows of a frame generated
// reasonably accurate results.
constexpr int kFrameSamplingPercentage = 10;
// QP for H.264 encoders ranges from [0, 51] (inclusive).
constexpr int kMaxH264Quantizer = 51;
// Number of buffers for encoded bit stream.
constexpr size_t kOutputBufferCount = 3;
// Maximum number of extra input buffers for encoder. The input buffers are only
// used when copy is needed to match the required coded size.
constexpr size_t kExtraInputBufferCount = 2;
// This value is used to calculate the encoder utilization. The encoder is
// assumed to be in full usage when the number of frames in progress reaches it.
constexpr int kBacklogRedlineThreshold = 4;
// The number of histogram buckets for quantization estimation. These
// histograms must encompass the range [-255, 255] (inclusive).
constexpr int kQuantizationHistogramSize = 511;
} // namespace
namespace media {
namespace cast {
// Container for the associated data of a video frame being processed.
struct InProgressExternalVideoFrameEncode {
// The source content to encode.
const scoped_refptr<VideoFrame> video_frame;
// The reference time for this frame.
const base::TimeTicks reference_time;
// The callback to run when the result is ready.
VideoEncoder::FrameEncodedCallback frame_encoded_callback;
// The target encode bit rate.
const int target_bit_rate;
// The real-world encode start time. This is used to compute the encoded
// frame's |encoder_utilization| and so it uses the real-world clock instead
// of the CastEnvironment clock, the latter of which might be simulated.
const base::TimeTicks start_time;
InProgressExternalVideoFrameEncode(
scoped_refptr<VideoFrame> v_frame,
base::TimeTicks r_time,
VideoEncoder::FrameEncodedCallback callback,
int bit_rate)
: video_frame(std::move(v_frame)),
reference_time(r_time),
frame_encoded_callback(std::move(callback)),
target_bit_rate(bit_rate),
start_time(base::TimeTicks::Now()) {}
};
// Owns a VideoEncoderAccelerator instance and provides the necessary adapters
// to encode media::VideoFrames and emit media::cast::EncodedFrames. All
// methods must be called on the thread associated with the given
// SingleThreadTaskRunner, except for the task_runner() accessor.
class ExternalVideoEncoder::VEAClientImpl final
: public VideoEncodeAccelerator::Client,
public base::RefCountedThreadSafe<VEAClientImpl> {
public:
VEAClientImpl(
const scoped_refptr<CastEnvironment>& cast_environment,
const scoped_refptr<base::SingleThreadTaskRunner>& encoder_task_runner,
std::unique_ptr<media::VideoEncodeAccelerator> vea,
double max_frame_rate,
StatusChangeCallback status_change_cb)
: cast_environment_(cast_environment),
task_runner_(encoder_task_runner),
max_frame_rate_(max_frame_rate),
status_change_cb_(std::move(status_change_cb)),
video_encode_accelerator_(std::move(vea)),
encoder_active_(false),
next_frame_id_(FrameId::first()),
key_frame_encountered_(false),
codec_profile_(media::VIDEO_CODEC_PROFILE_UNKNOWN),
key_frame_quantizer_parsable_(false),
requested_bit_rate_(-1),
allocate_input_buffer_in_progress_(false) {}
base::SingleThreadTaskRunner* task_runner() const {
return task_runner_.get();
}
void Initialize(const gfx::Size& frame_size,
VideoCodecProfile codec_profile,
int start_bit_rate,
FrameId first_frame_id) {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
requested_bit_rate_ = start_bit_rate;
const media::VideoEncodeAccelerator::Config config(
media::PIXEL_FORMAT_I420, frame_size, codec_profile,
media::Bitrate::ConstantBitrate(start_bit_rate));
encoder_active_ = video_encode_accelerator_->Initialize(config, this);
next_frame_id_ = first_frame_id;
codec_profile_ = codec_profile;
UMA_HISTOGRAM_BOOLEAN("Cast.Sender.VideoEncodeAcceleratorInitializeSuccess",
encoder_active_);
cast_environment_->PostTask(
CastEnvironment::MAIN, FROM_HERE,
base::BindOnce(status_change_cb_, encoder_active_
? STATUS_INITIALIZED
: STATUS_CODEC_INIT_FAILED));
}
void SetBitRate(int bit_rate) {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
requested_bit_rate_ = bit_rate;
if (encoder_active_) {
video_encode_accelerator_->RequestEncodingParametersChange(
Bitrate::ConstantBitrate(bit_rate),
static_cast<uint32_t>(max_frame_rate_ + 0.5));
}
}
// The destruction call back of the copied video frame to free its use of
// the input buffer.
void ReturnInputBufferToPool(int index) {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
DCHECK_GE(index, 0);
DCHECK_LT(index, static_cast<int>(input_buffers_.size()));
free_input_buffer_index_.push_back(index);
}
void EncodeVideoFrame(
scoped_refptr<media::VideoFrame> video_frame,
base::TimeTicks reference_time,
bool key_frame_requested,
VideoEncoder::FrameEncodedCallback frame_encoded_callback) {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
in_progress_frame_encodes_.push_back(InProgressExternalVideoFrameEncode(
video_frame, reference_time, std::move(frame_encoded_callback),
requested_bit_rate_));
if (!encoder_active_) {
AbortLatestEncodeAttemptDueToErrors();
return;
}
// If there are no free input buffers in the pool, request allocation of
// another one. Since that's an asynchronous process, simply abort encoding
// this frame and hope that the input buffer is ready for the next frame(s).
if (free_input_buffer_index_.empty()) {
if (!allocate_input_buffer_in_progress_ &&
input_buffers_.size() < max_allowed_input_buffers_) {
allocate_input_buffer_in_progress_ = true;
const size_t buffer_size = media::VideoFrame::AllocationSize(
media::PIXEL_FORMAT_I420, frame_coded_size_);
task_runner_->PostTask(
FROM_HERE, base::BindOnce(&VEAClientImpl::AllocateInputBuffer, this,
buffer_size));
}
AbortLatestEncodeAttemptDueToErrors();
return;
}
// Copy the |video_frame| into the input buffer provided by the VEA
// implementation, and with the exact row stride required. Note that, even
// if |video_frame|'s stride matches VEA's requirement, |video_frame|'s
// memory backing (heap, base::UnsafeSharedMemoryRegion, etc.) could be
// something VEA can't handle (as of this writing, it expects an unsafe
// region).
//
// TODO(crbug.com/888829): Revisit whether we can remove this memcpy, if VEA
// can accept other "memory backing" methods.
scoped_refptr<media::VideoFrame> frame = video_frame;
if (video_frame->coded_size() != frame_coded_size_ ||
video_frame->storage_type() !=
media::VideoFrame::StorageType::STORAGE_SHMEM) {
const int index = free_input_buffer_index_.back();
std::pair<base::UnsafeSharedMemoryRegion,
base::WritableSharedMemoryMapping>* input_buffer =
input_buffers_[index].get();
DCHECK(input_buffer->first.IsValid());
DCHECK(input_buffer->second.IsValid());
frame = VideoFrame::WrapExternalData(
video_frame->format(), frame_coded_size_, video_frame->visible_rect(),
video_frame->visible_rect().size(),
input_buffer->second.GetMemoryAsSpan<uint8_t>().data(),
input_buffer->second.size(), video_frame->timestamp());
if (!frame || !media::I420CopyWithPadding(*video_frame, frame.get())) {
LOG(DFATAL) << "Error: ExternalVideoEncoder: copy failed.";
AbortLatestEncodeAttemptDueToErrors();
return;
}
frame->BackWithSharedMemory(&input_buffer->first);
frame->AddDestructionObserver(media::BindToCurrentLoop(base::BindOnce(
&ExternalVideoEncoder::VEAClientImpl::ReturnInputBufferToPool, this,
index)));
free_input_buffer_index_.pop_back();
}
// BitstreamBufferReady will be called once the encoder is done.
video_encode_accelerator_->Encode(std::move(frame), key_frame_requested);
}
protected:
void NotifyError(VideoEncodeAccelerator::Error error) final {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
DCHECK(error != VideoEncodeAccelerator::kInvalidArgumentError &&
error != VideoEncodeAccelerator::kIllegalStateError);
encoder_active_ = false;
cast_environment_->PostTask(
CastEnvironment::MAIN, FROM_HERE,
base::BindOnce(status_change_cb_, STATUS_CODEC_RUNTIME_ERROR));
// TODO(crbug.com/1199930): Force-flush all |in_progress_frame_encodes_|
// immediately so pending frames do not become stuck, freezing VideoSender.
}
void AllocateInputBuffer(size_t size) {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
auto memory = base::UnsafeSharedMemoryRegion::Create(size);
if (memory.IsValid()) {
base::WritableSharedMemoryMapping mapping = memory.Map();
DCHECK(mapping.IsValid());
input_buffers_.push_back(
std::make_unique<std::pair<base::UnsafeSharedMemoryRegion,
base::WritableSharedMemoryMapping>>(
std::move(memory), std::move(mapping)));
free_input_buffer_index_.push_back(input_buffers_.size() - 1);
}
allocate_input_buffer_in_progress_ = false;
}
void AllocateOutputBuffers(size_t size) {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
for (size_t i = 0; i < kOutputBufferCount; ++i) {
auto memory = base::UnsafeSharedMemoryRegion::Create(size);
base::WritableSharedMemoryMapping mapping = memory.Map();
DCHECK(mapping.IsValid());
output_buffers_.push_back(
std::make_pair(std::move(memory), std::move(mapping)));
video_encode_accelerator_->UseOutputBitstreamBuffer(
media::BitstreamBuffer(static_cast<int32_t>(i),
output_buffers_[i].first.Duplicate(),
output_buffers_[i].first.GetSize()));
}
}
// Called by the VEA to indicate its buffer requirements.
void RequireBitstreamBuffers(unsigned int input_count,
const gfx::Size& input_coded_size,
size_t output_buffer_size) final {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
frame_coded_size_ = input_coded_size;
max_allowed_input_buffers_ = input_count + kExtraInputBufferCount;
task_runner_->PostTask(
FROM_HERE, base::BindOnce(&VEAClientImpl::AllocateOutputBuffers, this,
output_buffer_size));
}
// Encoder has encoded a frame and it's available in one of the output
// buffers. Package the result in a media::cast::EncodedFrame and post it
// to the Cast MAIN thread via the supplied callback.
void BitstreamBufferReady(int32_t bitstream_buffer_id,
const BitstreamBufferMetadata& metadata) final {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
if (bitstream_buffer_id < 0 ||
bitstream_buffer_id >= static_cast<int32_t>(output_buffers_.size())) {
NOTREACHED();
VLOG(1) << "BitstreamBufferReady(): invalid bitstream_buffer_id="
<< bitstream_buffer_id;
NotifyError(media::VideoEncodeAccelerator::kPlatformFailureError);
return;
}
const char* output_buffer_memory = output_buffers_[bitstream_buffer_id]
.second.GetMemoryAsSpan<char>()
.data();
if (metadata.payload_size_bytes >
output_buffers_[bitstream_buffer_id].second.size()) {
NOTREACHED();
VLOG(1) << "BitstreamBufferReady(): invalid payload_size = "
<< metadata.payload_size_bytes;
NotifyError(media::VideoEncodeAccelerator::kPlatformFailureError);
return;
}
if (metadata.key_frame) {
key_frame_encountered_ = true;
}
if (!key_frame_encountered_) {
// Do not send video until we have encountered the first key frame.
// Save the bitstream buffer in |stream_header_| to be sent later along
// with the first key frame.
stream_header_.write(output_buffer_memory, metadata.payload_size_bytes);
} else if (!in_progress_frame_encodes_.empty()) {
InProgressExternalVideoFrameEncode& request =
in_progress_frame_encodes_.front();
std::unique_ptr<SenderEncodedFrame> encoded_frame(
new SenderEncodedFrame());
encoded_frame->dependency =
metadata.key_frame ? EncodedFrame::KEY : EncodedFrame::DEPENDENT;
encoded_frame->frame_id = next_frame_id_++;
if (metadata.key_frame) {
encoded_frame->referenced_frame_id = encoded_frame->frame_id;
} else {
encoded_frame->referenced_frame_id = encoded_frame->frame_id - 1;
}
encoded_frame->rtp_timestamp = RtpTimeTicks::FromTimeDelta(
request.video_frame->timestamp(), kVideoFrequency);
encoded_frame->reference_time = request.reference_time;
std::string header = stream_header_.str();
if (!header.empty()) {
encoded_frame->data = std::move(header);
std::ostringstream().swap(stream_header_);
}
encoded_frame->data.append(output_buffer_memory,
metadata.payload_size_bytes);
DCHECK(!encoded_frame->data.empty()) << "BUG: Encoder must provide data.";
// If FRAME_DURATION metadata was provided in the source VideoFrame,
// compute the utilization metrics.
base::TimeDelta frame_duration =
request.video_frame->metadata().frame_duration.value_or(
base::TimeDelta());
if (frame_duration > base::TimeDelta()) {
// Compute encoder utilization in terms of the number of frames in
// backlog, including the current frame encode that is finishing
// here. This "backlog" model works as follows: First, assume that all
// frames utilize the encoder by the same amount. This is actually a
// false assumption, but it still works well because any frame that
// takes longer to encode will naturally cause the backlog to
// increase, and this will result in a higher computed utilization for
// the offending frame. If the backlog continues to increase, because
// the following frames are also taking too long to encode, the
// computed utilization for each successive frame will be higher. At
// some point, upstream control logic will decide that the data volume
// must be reduced.
encoded_frame->encoder_utilization =
static_cast<double>(in_progress_frame_encodes_.size()) /
kBacklogRedlineThreshold;
const double actual_bit_rate =
encoded_frame->data.size() * 8.0 / frame_duration.InSecondsF();
DCHECK_GT(request.target_bit_rate, 0);
const double bitrate_utilization =
actual_bit_rate / request.target_bit_rate;
double quantizer = QuantizerEstimator::NO_RESULT;
// If the quantizer can be parsed from the key frame, try to parse
// the following delta frames as well.
// Otherwise, switch back to entropy estimation for the key frame
// and all the following delta frames.
if (metadata.key_frame || key_frame_quantizer_parsable_) {
if (codec_profile_ == media::VP8PROFILE_ANY) {
quantizer = ParseVpxHeaderQuantizer(
reinterpret_cast<const uint8_t*>(encoded_frame->data.data()),
encoded_frame->data.size());
} else if (codec_profile_ == media::H264PROFILE_MAIN) {
quantizer = GetH264FrameQuantizer(
reinterpret_cast<const uint8_t*>(encoded_frame->data.data()),
encoded_frame->data.size());
} else {
NOTIMPLEMENTED();
}
if (quantizer < 0) {
LOG(ERROR) << "Unable to parse quantizer from encoded "
<< (metadata.key_frame ? "key" : "delta")
<< " frame, id=" << encoded_frame->frame_id;
if (metadata.key_frame) {
key_frame_quantizer_parsable_ = false;
quantizer = quantizer_estimator_.EstimateForKeyFrame(
*request.video_frame);
}
} else {
if (metadata.key_frame) {
key_frame_quantizer_parsable_ = true;
}
}
} else {
quantizer =
quantizer_estimator_.EstimateForDeltaFrame(*request.video_frame);
}
if (quantizer >= 0) {
const double max_quantizer =
codec_profile_ == media::VP8PROFILE_ANY
? static_cast<int>(QuantizerEstimator::MAX_VP8_QUANTIZER)
: static_cast<int>(kMaxH264Quantizer);
encoded_frame->lossy_utilization =
bitrate_utilization * (quantizer / max_quantizer);
}
} else {
quantizer_estimator_.Reset();
}
encoded_frame->encode_completion_time =
cast_environment_->Clock()->NowTicks();
cast_environment_->PostTask(
CastEnvironment::MAIN, FROM_HERE,
base::BindOnce(std::move(request.frame_encoded_callback),
std::move(encoded_frame)));
in_progress_frame_encodes_.pop_front();
} else {
VLOG(1) << "BitstreamBufferReady(): no encoded frame data available";
}
// We need to re-add the output buffer to the encoder after we are done
// with it.
if (encoder_active_) {
video_encode_accelerator_->UseOutputBitstreamBuffer(
media::BitstreamBuffer(
bitstream_buffer_id,
output_buffers_[bitstream_buffer_id].first.Duplicate(),
output_buffers_[bitstream_buffer_id].first.GetSize()));
}
}
private:
friend class base::RefCountedThreadSafe<VEAClientImpl>;
~VEAClientImpl() final {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
while (!in_progress_frame_encodes_.empty())
AbortLatestEncodeAttemptDueToErrors();
// According to the media::VideoEncodeAccelerator interface, Destroy()
// should be called instead of invoking its private destructor.
if (video_encode_accelerator_) {
video_encode_accelerator_.release()->Destroy();
}
}
// This is called when an error occurs while preparing a VideoFrame for
// encode, or to abort a frame encode when shutting down.
void AbortLatestEncodeAttemptDueToErrors() {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
std::unique_ptr<SenderEncodedFrame> no_result(nullptr);
cast_environment_->PostTask(
CastEnvironment::MAIN, FROM_HERE,
base::BindOnce(
std::move(in_progress_frame_encodes_.back().frame_encoded_callback),
std::move(no_result)));
in_progress_frame_encodes_.pop_back();
}
// Parse H264 SPS, PPS, and Slice header, and return the averaged frame
// quantizer in the range of [0, 51], or -1 on parse error.
double GetH264FrameQuantizer(const uint8_t* encoded_data, off_t size) {
DCHECK(task_runner_->RunsTasksInCurrentSequence());
DCHECK(encoded_data);
if (!size) {
return -1;
}
h264_parser_.SetStream(encoded_data, size);
double total_quantizer = 0;
int num_slices = 0;
while (true) {
H264NALU nalu;
H264Parser::Result res = h264_parser_.AdvanceToNextNALU(&nalu);
if (res == H264Parser::kEOStream) {
break;
}
if (res != H264Parser::kOk) {
return -1;
}
switch (nalu.nal_unit_type) {
case H264NALU::kIDRSlice:
case H264NALU::kNonIDRSlice: {
H264SliceHeader slice_header;
if (h264_parser_.ParseSliceHeader(nalu, &slice_header) !=
H264Parser::kOk)
return -1;
const H264PPS* pps =
h264_parser_.GetPPS(slice_header.pic_parameter_set_id);
if (!pps) {
return -1;
}
++num_slices;
int slice_quantizer =
26 +
((slice_header.IsSPSlice() || slice_header.IsSISlice())
? pps->pic_init_qs_minus26 + slice_header.slice_qs_delta
: pps->pic_init_qp_minus26 + slice_header.slice_qp_delta);
DCHECK_GE(slice_quantizer, 0);
DCHECK_LE(slice_quantizer, kMaxH264Quantizer);
total_quantizer += slice_quantizer;
break;
}
case H264NALU::kSPS: {
int id;
if (h264_parser_.ParseSPS(&id) != H264Parser::kOk) {
return -1;
}
break;
}
case H264NALU::kPPS: {
int id;
if (h264_parser_.ParsePPS(&id) != H264Parser::kOk) {
return -1;
}
break;
}
default:
// Skip other NALUs.
break;
}
}
return (num_slices == 0) ? -1 : (total_quantizer / num_slices);
}
const scoped_refptr<CastEnvironment> cast_environment_;
const scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
const double max_frame_rate_;
const StatusChangeCallback status_change_cb_; // Must be run on MAIN thread.
std::unique_ptr<media::VideoEncodeAccelerator> video_encode_accelerator_;
bool encoder_active_;
FrameId next_frame_id_;
bool key_frame_encountered_;
std::ostringstream stream_header_;
VideoCodecProfile codec_profile_;
bool key_frame_quantizer_parsable_;
H264Parser h264_parser_;
// Shared memory buffers for output with the VideoAccelerator.
std::vector<std::pair<base::UnsafeSharedMemoryRegion,
base::WritableSharedMemoryMapping>>
output_buffers_;
// Shared memory buffers for input video frames with the VideoAccelerator.
// These buffers will be allocated only when copy is needed to match the
// required coded size for encoder. They are allocated on-demand, up to
// |max_allowed_input_buffers_|. A VideoFrame wrapping the region will point
// to it, so std::unique_ptr is used to ensure the region has a stable address
// even if the vector grows or shrinks.
std::vector<std::unique_ptr<std::pair<base::UnsafeSharedMemoryRegion,
base::WritableSharedMemoryMapping>>>
input_buffers_;
// Available input buffer index. These buffers are used in FILO order.
std::vector<int> free_input_buffer_index_;
// FIFO list.
std::list<InProgressExternalVideoFrameEncode> in_progress_frame_encodes_;
// The requested encode bit rate for the next frame.
int requested_bit_rate_;
// Used to compute utilization metrics for each frame.
QuantizerEstimator quantizer_estimator_;
// The coded size of the video frame required by Encoder. This size is
// obtained from VEA through |RequireBitstreamBuffers()|.
gfx::Size frame_coded_size_;
// The maximum number of input buffers. These buffers are used to copy
// VideoFrames in order to match the required coded size for encoder.
size_t max_allowed_input_buffers_;
// Set to true when the allocation of an input buffer is in progress, and
// reset to false after the allocated buffer is received.
bool allocate_input_buffer_in_progress_;
DISALLOW_COPY_AND_ASSIGN(VEAClientImpl);
};
// static
bool ExternalVideoEncoder::IsSupported(const FrameSenderConfig& video_config) {
if (video_config.codec != CODEC_VIDEO_VP8 &&
video_config.codec != CODEC_VIDEO_H264)
return false;
// We assume that the system provides a hardware encoder at this point.
return video_config.use_external_encoder;
}
ExternalVideoEncoder::ExternalVideoEncoder(
const scoped_refptr<CastEnvironment>& cast_environment,
const FrameSenderConfig& video_config,
const gfx::Size& frame_size,
FrameId first_frame_id,
StatusChangeCallback status_change_cb,
const CreateVideoEncodeAcceleratorCallback& create_vea_cb)
: cast_environment_(cast_environment),
frame_size_(frame_size),
bit_rate_(video_config.start_bitrate) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
DCHECK_GT(video_config.max_frame_rate, 0);
DCHECK(!frame_size_.IsEmpty());
DCHECK(status_change_cb);
DCHECK(create_vea_cb);
DCHECK_GT(bit_rate_, 0);
create_vea_cb.Run(
base::BindOnce(&ExternalVideoEncoder::OnCreateVideoEncodeAccelerator,
weak_factory_.GetWeakPtr(), video_config, first_frame_id,
std::move(status_change_cb)));
}
ExternalVideoEncoder::~ExternalVideoEncoder() {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
DestroyClientSoon();
}
void ExternalVideoEncoder::DestroyClientSoon() {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
// Ensure |client_| is destroyed from the encoder task runner by dropping the
// reference to it within an encoder task.
if (client_) {
client_->task_runner()->PostTask(
FROM_HERE, base::BindOnce([](scoped_refptr<VEAClientImpl> client) {},
std::move(client_)));
}
}
bool ExternalVideoEncoder::EncodeVideoFrame(
scoped_refptr<media::VideoFrame> video_frame,
base::TimeTicks reference_time,
FrameEncodedCallback frame_encoded_callback) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
DCHECK(!frame_encoded_callback.is_null());
if (!client_ || video_frame->visible_rect().size() != frame_size_) {
return false;
}
client_->task_runner()->PostTask(
FROM_HERE,
base::BindOnce(&VEAClientImpl::EncodeVideoFrame, client_,
std::move(video_frame), reference_time,
key_frame_requested_, std::move(frame_encoded_callback)));
key_frame_requested_ = false;
return true;
}
void ExternalVideoEncoder::SetBitRate(int new_bit_rate) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
DCHECK_GT(new_bit_rate, 0);
bit_rate_ = new_bit_rate;
if (!client_) {
return;
}
client_->task_runner()->PostTask(
FROM_HERE,
base::BindOnce(&VEAClientImpl::SetBitRate, client_, bit_rate_));
}
void ExternalVideoEncoder::GenerateKeyFrame() {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
key_frame_requested_ = true;
}
void ExternalVideoEncoder::OnCreateVideoEncodeAccelerator(
const FrameSenderConfig& video_config,
FrameId first_frame_id,
const StatusChangeCallback& status_change_cb,
scoped_refptr<base::SingleThreadTaskRunner> encoder_task_runner,
std::unique_ptr<media::VideoEncodeAccelerator> vea) {
DCHECK(cast_environment_->CurrentlyOn(CastEnvironment::MAIN));
// The callback will be invoked with null pointers in the case where the
// system does not support or lacks the resources to provide GPU-accelerated
// video encoding.
if (!encoder_task_runner || !vea) {
cast_environment_->PostTask(
CastEnvironment::MAIN, FROM_HERE,
base::BindOnce(status_change_cb, STATUS_CODEC_INIT_FAILED));
return;
}
VideoCodecProfile codec_profile;
switch (video_config.codec) {
case CODEC_VIDEO_VP8:
codec_profile = media::VP8PROFILE_ANY;
break;
case CODEC_VIDEO_H264:
codec_profile = media::H264PROFILE_MAIN;
break;
case CODEC_VIDEO_FAKE:
NOTREACHED() << "Fake software video encoder cannot be external";
FALLTHROUGH;
default:
cast_environment_->PostTask(
CastEnvironment::MAIN, FROM_HERE,
base::BindOnce(status_change_cb, STATUS_UNSUPPORTED_CODEC));
return;
}
// Create a callback that wraps the StatusChangeCallback. It monitors when a
// fatal error occurs and schedules destruction of the VEAClientImpl.
StatusChangeCallback wrapped_status_change_cb = base::BindRepeating(
[](base::WeakPtr<ExternalVideoEncoder> self,
const StatusChangeCallback& status_change_cb,
OperationalStatus status) {
if (self.get()) {
switch (status) {
case STATUS_UNINITIALIZED:
case STATUS_INITIALIZED:
case STATUS_CODEC_REINIT_PENDING:
break;
case STATUS_INVALID_CONFIGURATION:
case STATUS_UNSUPPORTED_CODEC:
case STATUS_CODEC_INIT_FAILED:
case STATUS_CODEC_RUNTIME_ERROR:
// Something bad happened. Destroy the client to: 1) fail-out any
// currently in-progress frame encodes; and 2) prevent future
// EncodeVideoFrame() calls from queuing frames indefinitely.
self->DestroyClientSoon();
break;
}
}
status_change_cb.Run(status);
},
weak_factory_.GetWeakPtr(), status_change_cb);
DCHECK(!client_);
client_ = new VEAClientImpl(cast_environment_, encoder_task_runner,
std::move(vea), video_config.max_frame_rate,
std::move(wrapped_status_change_cb));
client_->task_runner()->PostTask(
FROM_HERE,
base::BindOnce(&VEAClientImpl::Initialize, client_, frame_size_,
codec_profile, bit_rate_, first_frame_id));
}
SizeAdaptableExternalVideoEncoder::SizeAdaptableExternalVideoEncoder(
const scoped_refptr<CastEnvironment>& cast_environment,
const FrameSenderConfig& video_config,
StatusChangeCallback status_change_cb,
const CreateVideoEncodeAcceleratorCallback& create_vea_cb)
: SizeAdaptableVideoEncoderBase(cast_environment,
video_config,
std::move(status_change_cb)),
create_vea_cb_(create_vea_cb) {}
SizeAdaptableExternalVideoEncoder::~SizeAdaptableExternalVideoEncoder() =
default;
std::unique_ptr<VideoEncoder>
SizeAdaptableExternalVideoEncoder::CreateEncoder() {
return std::make_unique<ExternalVideoEncoder>(
cast_environment(), video_config(), frame_size(), next_frame_id(),
CreateEncoderStatusChangeCallback(), create_vea_cb_);
}
QuantizerEstimator::QuantizerEstimator() = default;
QuantizerEstimator::~QuantizerEstimator() = default;
void QuantizerEstimator::Reset() {
last_frame_pixel_buffer_.reset();
}
double QuantizerEstimator::EstimateForKeyFrame(const VideoFrame& frame) {
if (!CanExamineFrame(frame)) {
return NO_RESULT;
}
// If the size of the frame is different from the last frame, allocate a new
// buffer. The buffer only needs to be a fraction of the size of the entire
// frame, since the entropy analysis only examines a subset of each frame.
const gfx::Size size = frame.visible_rect().size();
const int rows_in_subset =
std::max(1, size.height() * kFrameSamplingPercentage / 100);
if (last_frame_size_ != size || !last_frame_pixel_buffer_) {
last_frame_pixel_buffer_.reset(new uint8_t[size.width() * rows_in_subset]);
last_frame_size_ = size;
}
// Compute a histogram where each bucket represents the number of times two
// neighboring pixels were different by a specific amount.
std::array<int, kQuantizationHistogramSize> histogram{};
const int row_skip = size.height() / rows_in_subset;
int y = 0;
for (int i = 0; i < rows_in_subset; ++i, y += row_skip) {
const uint8_t* const row_begin = frame.visible_data(VideoFrame::kYPlane) +
y * frame.stride(VideoFrame::kYPlane);
const uint8_t* const row_end = row_begin + size.width();
int left_hand_pixel_value = static_cast<int>(*row_begin);
for (const uint8_t* p = row_begin + 1; p < row_end; ++p) {
const int right_hand_pixel_value = static_cast<int>(*p);
const int difference = right_hand_pixel_value - left_hand_pixel_value;
const int histogram_index = difference + 255;
++histogram[histogram_index];
left_hand_pixel_value = right_hand_pixel_value; // For next iteration.
}
// Copy the row of pixels into the buffer. This will be used when
// generating histograms for future delta frames.
memcpy(last_frame_pixel_buffer_.get() + i * size.width(),
row_begin,
size.width());
}
// Estimate a quantizer value depending on the difference data in the
// histogram and return it.
const int num_samples = (size.width() - 1) * rows_in_subset;
return ToQuantizerEstimate(ComputeEntropyFromHistogram(
histogram.data(), histogram.size(), num_samples));
}
double QuantizerEstimator::EstimateForDeltaFrame(const VideoFrame& frame) {
if (!CanExamineFrame(frame)) {
return NO_RESULT;
}
// If the size of the |frame| has changed, no difference can be examined.
// In this case, process this frame as if it were a key frame.
const gfx::Size& size = frame.visible_rect().size();
if (last_frame_size_ != size || !last_frame_pixel_buffer_) {
return EstimateForKeyFrame(frame);
}
const int rows_in_subset =
std::max(1, size.height() * (kFrameSamplingPercentage / 100));
// Compute a histogram where each bucket represents the number of times the
// same pixel in this frame versus the last frame was different by a specific
// amount.
std::array<int, kQuantizationHistogramSize> histogram{};
const int row_skip = size.height() / rows_in_subset;
int y = 0;
for (int i = 0; i < rows_in_subset; ++i, y += row_skip) {
const uint8_t* const row_begin = frame.visible_data(VideoFrame::kYPlane) +
y * frame.stride(VideoFrame::kYPlane);
const uint8_t* const row_end = row_begin + size.width();
uint8_t* const last_frame_row_begin =
last_frame_pixel_buffer_.get() + i * size.width();
for (const uint8_t *p = row_begin, *q = last_frame_row_begin; p < row_end;
++p, ++q) {
const int difference = static_cast<int>(*p) - static_cast<int>(*q);
const int histogram_index = difference + 255;
++histogram[histogram_index];
}
// Copy the row of pixels into the buffer. This will be used when
// generating histograms for future delta frames.
memcpy(last_frame_row_begin, row_begin, size.width());
}
// Estimate a quantizer value depending on the difference data in the
// histogram and return it.
const int num_samples = size.width() * rows_in_subset;
return ToQuantizerEstimate(ComputeEntropyFromHistogram(
histogram.data(), histogram.size(), num_samples));
}
// static
bool QuantizerEstimator::CanExamineFrame(const VideoFrame& frame) {
DCHECK_EQ(8, VideoFrame::PlaneHorizontalBitsPerPixel(frame.format(),
VideoFrame::kYPlane));
return media::IsYuvPlanar(frame.format()) &&
!frame.visible_rect().IsEmpty();
}
// static
double QuantizerEstimator::ComputeEntropyFromHistogram(const int* histogram,
size_t histogram_size,
int num_samples) {
DCHECK_LT(0, num_samples);
double entropy = 0.0;
for (size_t i = 0; i < histogram_size; ++i) {
const double probability = static_cast<double>(histogram[i]) / num_samples;
if (probability > 0.0) {
entropy = entropy - probability * std::log2(probability);
}
}
return entropy;
}
// static
double QuantizerEstimator::ToQuantizerEstimate(double shannon_entropy) {
DCHECK_GE(shannon_entropy, 0.0);
// This math is based on an analysis of data produced by running a wide range
// of mirroring content in a Cast streaming session on a Chromebook Pixel
// (2013 edition). The output from the Pixel's built-in hardware encoder was
// compared to an identically-configured software implementation (libvpx)
// running alongside. Based on an analysis of the data, the following linear
// mapping seems to produce reasonable VP8 quantizer values from the
// |shannon_entropy| values.
constexpr double kEntropyAtMaxQuantizer = 7.5;
constexpr double kSlope =
(MAX_VP8_QUANTIZER - MIN_VP8_QUANTIZER) / kEntropyAtMaxQuantizer;
const double quantizer = std::min<double>(
MAX_VP8_QUANTIZER, MIN_VP8_QUANTIZER + kSlope * shannon_entropy);
return quantizer;
}
} // namespace cast
} // namespace media