84 lines
3.2 KiB
C
84 lines
3.2 KiB
C
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// Copyright 2018 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#include <list>
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#include "packager/media/base/media_handler.h"
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#include "packager/media/chunking/sync_point_queue.h"
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namespace shaka {
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namespace media {
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/// The cue alignment handler is a N-to-N handler that will inject CueEvents
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/// into all streams. It will align the cues across streams (and handlers)
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/// using a shared SyncPointQueue.
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///
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/// There should be a cue alignment handler per demuxer/thread and not per
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/// stream. A cue alignment handler must be one per thread in order to properly
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/// manage blocking.
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class CueAlignmentHandler : public MediaHandler {
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public:
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explicit CueAlignmentHandler(SyncPointQueue* sync_points);
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~CueAlignmentHandler() = default;
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private:
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CueAlignmentHandler(const CueAlignmentHandler&) = delete;
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CueAlignmentHandler& operator=(const CueAlignmentHandler&) = delete;
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struct StreamState {
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// Information for the stream.
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std::shared_ptr<const StreamInfo> info;
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// Cached samples that cannot be dispatched. All the samples should be at or
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// after |hint|.
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std::list<std::unique_ptr<StreamData>> samples;
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// If set, the stream is pending to be flushed.
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bool to_be_flushed = false;
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// If set, it points to the next cue it has to send downstream. Note that if
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// it is not set, the next cue is not determined.
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// This is set but not really used by video stream.
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std::shared_ptr<const CueEvent> cue;
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// If |cue| is set, this is the hint for the cue after |cue|, i.e. next next
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// cue; otherwise this is the hint for the next cue. This holds the time in
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// seconds of the scheduled (unpromoted) next or next next cue's time. This
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// is essentially the barrier for the sample stream. Non video samples after
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// this barrier must wait until the |cue| is determined and thus the next
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// hint to be determined; video samples will promote the hint to cue when
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// seeing the first key frame after |next_cue_hint|.
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double next_cue_hint = 0;
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};
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// MediaHandler overrides.
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Status InitializeInternal() override;
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Status Process(std::unique_ptr<StreamData> data) override;
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Status OnFlushRequest(size_t stream_index) override;
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// Internal handling functions for different stream data.
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Status OnStreamInfo(std::unique_ptr<StreamData> data);
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Status OnSample(std::unique_ptr<StreamData> sample);
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// Update stream states with new sync point.
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Status UseNewSyncPoint(std::shared_ptr<const CueEvent> new_sync);
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// Check if everyone is waiting for new hint points.
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bool EveryoneWaitingAtHint() const;
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// Dispatch or save incoming sample.
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Status AcceptSample(std::unique_ptr<StreamData> sample,
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StreamState* stream_state);
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// Dispatch the cue if the new sample comes at or after it.
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Status DispatchCueIfNeeded(size_t stream_index,
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double next_sample_time_in_seconds,
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StreamState* stream_state);
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SyncPointQueue* const sync_points_ = nullptr;
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std::vector<StreamState> stream_states_;
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};
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} // namespace media
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} // namespace shaka
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