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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_WEBCODECS_DECODER_SELECTOR_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_WEBCODECS_DECODER_SELECTOR_H_
#include <memory>
#include "base/memory/weak_ptr.h"
#include "base/task/sequenced_task_runner.h"
#include "media/base/demuxer_stream.h"
#include "media/base/media_util.h"
#include "media/filters/decoder_selector.h"
#include "media/filters/decoder_stream_traits.h"
#include "third_party/blink/renderer/modules/modules_export.h"
namespace blink {
template <media::DemuxerStream::Type StreamType>
class NullDemuxerStream;
template <media::DemuxerStream::Type StreamType>
class DecoderSelector {
public:
typedef media::DecoderStreamTraits<StreamType> StreamTraits;
typedef typename StreamTraits::DecoderType Decoder;
typedef typename StreamTraits::DecoderConfigType DecoderConfig;
using DecoderOrError =
typename media::DecoderSelector<StreamType>::DecoderOrError;
// Callback to create a list of decoders to select from.
using CreateDecodersCB =
base::RepeatingCallback<std::vector<std::unique_ptr<Decoder>>()>;
// Emits the result of a single call to SelectDecoder(). Parameter is
// the initialized Decoder. nullptr if selection failed. The caller owns the
// Decoder.
using SelectDecoderCB = base::OnceCallback<void(std::unique_ptr<Decoder>)>;
// Construction can happen on any thread, but all subsequent API calls
// including destruction must use |task_runner| thread.
// Provided callbacks will be called on |task_runner|. |output_cb| will always
// be Post()'ed.
DecoderSelector(scoped_refptr<base::SequencedTaskRunner> task_runner,
CreateDecodersCB create_decoders_cb,
typename Decoder::OutputCB output_cb);
// Aborts any pending decoder selection.
~DecoderSelector();
// Disallow copy and assign.
DecoderSelector(const DecoderSelector&) = delete;
DecoderSelector& operator=(const DecoderSelector&) = delete;
// Selects and initializes a decoder using |config|. Decoder will
// be returned via |select_decoder_cb| posted to |task_runner_|. Subsequent
// calls will again select from the full list of decoders.
void SelectDecoder(const DecoderConfig& config,
bool low_delay,
SelectDecoderCB select_decoder_cb);
private:
// Helper to create |stream_traits_|.
std::unique_ptr<StreamTraits> CreateStreamTraits();
// Proxy SelectDecoderCB from impl_ to our |select_decoder_cb|.
void OnDecoderSelected(SelectDecoderCB select_decoder_cb,
DecoderOrError decoder_or_error,
std::unique_ptr<media::DecryptingDemuxerStream>);
// Implements heavy lifting for decoder selection.
media::DecoderSelector<StreamType> impl_;
// Shim to satisfy dependencies of |impl_|. Provides DecoderConfig to |impl_|.
std::unique_ptr<NullDemuxerStream<StreamType>> demuxer_stream_;
// Helper to unify API for configuring audio/video decoders.
std::unique_ptr<StreamTraits> stream_traits_;
// Repeating callback for decoder outputs.
typename Decoder::OutputCB output_cb_;
// TODO(chcunningham): Route MEDIA_LOG for WebCodecs.
media::NullMediaLog null_media_log_;
base::WeakPtrFactory<DecoderSelector<StreamType>> weak_factory_{this};
};
typedef DecoderSelector<media::DemuxerStream::VIDEO>
WebCodecsVideoDecoderSelector;
typedef DecoderSelector<media::DemuxerStream::AUDIO>
WebCodecsAudioDecoderSelector;
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_MODULES_WEBCODECS_DECODER_SELECTOR_H_
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