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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/modules/mediacapturefromelement/html_video_element_capturer_source.h"
#include "base/functional/bind.h"
#include "base/location.h"
#include "base/memory/ptr_util.h"
#include "base/task/single_thread_task_runner.h"
#include "base/trace_event/trace_event.h"
#include "media/base/limits.h"
#include "third_party/blink/public/platform/web_media_player.h"
#include "third_party/blink/public/web/modules/mediastream/media_stream_video_source.h"
#include "third_party/blink/renderer/platform/mediastream/webrtc_uma_histograms.h"
#include "third_party/blink/renderer/platform/scheduler/public/post_cross_thread_task.h"
#include "third_party/blink/renderer/platform/scheduler/public/thread.h"
#include "third_party/blink/renderer/platform/wtf/cross_thread_copier_media.h"
#include "third_party/blink/renderer/platform/wtf/cross_thread_functional.h"
namespace {
constexpr float kMinFramesPerSecond = 1.0;
BASE_FEATURE(kUseVideoFrameRateForCaptureRate,
"UseVideoFrameRateForCaptureRate",
base::FEATURE_ENABLED_BY_DEFAULT);
} // anonymous namespace
namespace blink {
// static
std::unique_ptr<HtmlVideoElementCapturerSource>
HtmlVideoElementCapturerSource::CreateFromWebMediaPlayerImpl(
blink::WebMediaPlayer* player,
const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
// Save histogram data so we can see how much HTML Video capture is used.
// The histogram counts the number of calls to the JS API.
UpdateWebRTCMethodCount(RTCAPIName::kVideoCaptureStream);
// TODO(crbug.com/963651): Remove the need for AsWeakPtr altogether.
return base::WrapUnique(new HtmlVideoElementCapturerSource(
player->AsWeakPtr(), io_task_runner, task_runner));
}
HtmlVideoElementCapturerSource::HtmlVideoElementCapturerSource(
const base::WeakPtr<blink::WebMediaPlayer>& player,
const scoped_refptr<base::SingleThreadTaskRunner>& io_task_runner,
scoped_refptr<base::SingleThreadTaskRunner> task_runner)
: web_media_player_(player),
io_task_runner_(io_task_runner),
task_runner_(task_runner),
capture_frame_rate_(0.0) {
DCHECK(web_media_player_);
}
HtmlVideoElementCapturerSource::~HtmlVideoElementCapturerSource() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
}
media::VideoCaptureFormats
HtmlVideoElementCapturerSource::GetPreferredFormats() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
double capture_rate = blink::MediaStreamVideoSource::kDefaultFrameRate;
if (base::FeatureList::IsEnabled(kUseVideoFrameRateForCaptureRate)) {
if (auto metadata =
web_media_player_->GetVideoFramePresentationMetadata()) {
if (metadata->average_frame_duration.is_positive()) {
capture_rate = 1.0 / metadata->average_frame_duration.InSecondsF();
}
}
}
// WebMediaPlayer has a setRate() but can't be read back.
// TODO(mcasas): Add getRate() to WMPlayer and/or fix the spec to allow users
// to specify it.
return {media::VideoCaptureFormat(gfx::Size(web_media_player_->NaturalSize()),
capture_rate, media::PIXEL_FORMAT_I420)};
}
void HtmlVideoElementCapturerSource::StartCapture(
const media::VideoCaptureParams& params,
VideoCaptureCallbacks video_capture_callbacks,
VideoCaptureRunningCallbackCB running_callback) {
DVLOG(2) << __func__ << " requested "
<< media::VideoCaptureFormat::ToString(params.requested_format);
DCHECK(params.requested_format.IsValid());
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
running_callback_ = std::move(running_callback);
if (!web_media_player_ || !web_media_player_->HasVideo()) {
running_callback_.Run(VideoCaptureRunState::kStopped);
return;
}
new_frame_callback_ = std::move(video_capture_callbacks.deliver_frame_cb);
// Force |capture_frame_rate_| to be in between k{Min,Max}FramesPerSecond.
capture_frame_rate_ =
std::max(kMinFramesPerSecond,
std::min(static_cast<float>(media::limits::kMaxFramesPerSecond),
params.requested_format.frame_rate));
running_callback_.Run(VideoCaptureRunState::kRunning);
task_runner_->PostTask(
FROM_HERE, WTF::BindOnce(&HtmlVideoElementCapturerSource::sendNewFrame,
weak_factory_.GetWeakPtr()));
}
void HtmlVideoElementCapturerSource::StopCapture() {
DVLOG(2) << __func__;
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
running_callback_.Reset();
new_frame_callback_.Reset();
next_capture_time_ = base::TimeTicks();
}
void HtmlVideoElementCapturerSource::sendNewFrame() {
DVLOG(3) << __func__;
TRACE_EVENT0("media", "HtmlVideoElementCapturerSource::sendNewFrame");
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
if (!web_media_player_ || new_frame_callback_.is_null() ||
web_media_player_->WouldTaintOrigin()) {
return;
}
const base::TimeTicks current_time = base::TimeTicks::Now();
if (start_capture_time_.is_null())
start_capture_time_ = current_time;
if (auto frame = web_media_player_->GetCurrentFrameThenUpdate()) {
auto new_frame = media::VideoFrame::WrapVideoFrame(
frame, frame->format(), frame->visible_rect(), frame->natural_size());
new_frame->set_timestamp(current_time - start_capture_time_);
// Post with CrossThreadBind here, instead of CrossThreadBindOnce,
// otherwise the |new_frame_callback_| ivar can be nulled out
// unintentionally.
PostCrossThreadTask(
*io_task_runner_, FROM_HERE,
CrossThreadBindOnce(new_frame_callback_, std::move(new_frame),
current_time));
}
// Calculate the time in the future where the next frame should be created.
const base::TimeDelta frame_interval =
base::Microseconds(1E6 / capture_frame_rate_);
if (next_capture_time_.is_null()) {
next_capture_time_ = current_time + frame_interval;
} else {
next_capture_time_ += frame_interval;
// Don't accumulate any debt if we are lagging behind - just post next frame
// immediately and continue as normal.
if (next_capture_time_ < current_time)
next_capture_time_ = current_time;
}
// Schedule next capture.
PostDelayedCrossThreadTask(
*task_runner_, FROM_HERE,
CrossThreadBindOnce(&HtmlVideoElementCapturerSource::sendNewFrame,
weak_factory_.GetWeakPtr()),
next_capture_time_ - current_time);
}
} // namespace blink
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