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* Copyright (c) 2022 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 <memory>
#include "absl/types/optional.h"
#include "api/test/video/video_frame_writer.h"
#include "api/video/video_sink_interface.h"
#include "system_wrappers/include/clock.h"
#include "test/testsupport/video_frame_writer.h"
namespace webrtc {
namespace test {
// Writes video to the specified video writer with specified fixed frame rate.
// If at the point in time X no new frames are passed to the writer, the
// previous frame is used to fill the gap and preserve frame rate.
// This adaptor uses next algorithm:
// There are output "slots" at a fixed frame rate (starting at the time of the
// first received frame). Each incoming frame is assigned to the closest output
// slot. Then empty slots are filled by repeating the closest filled slot before
// empty one. If there are multiple frames closest to the same slot, the latest
// received one is used.
// The frames are outputted for the whole duration of the class life after the
// first frame was written or until it will be closed.
// For example if frames from A to F were received, then next output sequence
// will be generated:
// Received frames: A B C D EF Destructor called
// | | | | || |
// v v v v vv v
// X----X----X----X----X----X----X----X----X----+----+--
// | | | | | | | | |
// Produced frames: A A A B C C F F F
// This class is not thread safe.
class FixedFpsVideoFrameWriterAdapter : public VideoFrameWriter {
FixedFpsVideoFrameWriterAdapter(int fps,
Clock* clock,
std::unique_ptr<VideoFrameWriter> delegate);
~FixedFpsVideoFrameWriterAdapter() override;
bool WriteFrame(const webrtc::VideoFrame& frame) override;
// Closes adapter and underlying delegate. User mustn't call to the WriteFrame
// after calling this method.
void Close() override;
// Writes `last_frame_` for each "slot" from `last_frame_time_` up to now
// excluding the last one.
// Updates `last_frame_time_` to the position of the last NOT WRITTEN frame.
// Returns true if all writes were successful, otherwise retuns false. In such
// case it is not guranteed how many frames were actually written.
bool WriteMissedSlotsExceptLast(Timestamp now);
Timestamp Now() const;
// Because `TimeDelta` stores time with microseconds precision
// `last_frame_time_` may have a small drift and for very long streams it
// must be updated to use double for time.
const TimeDelta inter_frame_interval_;
Clock* const clock_;
std::unique_ptr<VideoFrameWriter> delegate_;
bool is_closed_ = false;
// Expected time slot for the last frame.
Timestamp last_frame_time_ = Timestamp::MinusInfinity();
absl::optional<VideoFrame> last_frame_ = absl::nullopt;
} // namespace test
} // namespace webrtc