96 lines
3.2 KiB
C++
96 lines
3.2 KiB
C++
// Copyright 2017 Google LLC. 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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#ifndef PACKAGER_MEDIA_CHUNKING_CHUNKING_HANDLER_
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#define PACKAGER_MEDIA_CHUNKING_CHUNKING_HANDLER_
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#include <atomic>
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#include <optional>
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#include <queue>
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#include <absl/log/log.h>
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#include <packager/chunking_params.h>
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#include <packager/media/base/media_handler.h>
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namespace shaka {
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namespace media {
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/// ChunkingHandler splits the samples into segments / subsegments based on the
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/// specified chunking params.
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/// This handler is a one-in one-out handler.
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/// There can be multiple chunking handler running in different threads or even
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/// different processes, we use the "consistent chunking algorithm" to make sure
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/// the chunks in different streams are aligned without explicit communcating
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/// with each other - which is not efficient and often difficult.
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///
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/// Consistent Chunking Algorithm:
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/// 1. Find the consistent chunkable boundary
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/// Let the timestamps for video frames be (t1, t2, t3, ...). Then a
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/// consistent chunkable boundary is simply the first chunkable boundary after
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/// (tk / N) != (tk-1 / N), where '/' denotes integer division, and N is the
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/// intended chunk duration.
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/// 2. Chunk only at the consistent chunkable boundary
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///
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/// This algorithm will make sure the chunks from different video streams are
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/// aligned if they have aligned GoPs.
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class ChunkingHandler : public MediaHandler {
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public:
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explicit ChunkingHandler(const ChunkingParams& chunking_params);
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~ChunkingHandler() override = default;
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protected:
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/// @name MediaHandler implementation overrides.
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/// @{
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Status InitializeInternal() override;
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Status Process(std::unique_ptr<StreamData> stream_data) override;
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Status OnFlushRequest(size_t input_stream_index) override;
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/// @}
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private:
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friend class ChunkingHandlerTest;
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ChunkingHandler(const ChunkingHandler&) = delete;
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ChunkingHandler& operator=(const ChunkingHandler&) = delete;
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Status OnStreamInfo(std::shared_ptr<const StreamInfo> info);
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Status OnCueEvent(std::shared_ptr<const CueEvent> event);
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Status OnMediaSample(std::shared_ptr<const MediaSample> sample);
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Status EndSegmentIfStarted() const;
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Status EndSubsegmentIfStarted() const;
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bool IsSubsegmentEnabled() {
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return subsegment_duration_ > 0 &&
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subsegment_duration_ != segment_duration_;
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}
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const ChunkingParams chunking_params_;
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// Segment and subsegment duration in stream's time scale.
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int64_t segment_duration_ = 0;
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int64_t subsegment_duration_ = 0;
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// Current segment index, useful to determine where to do chunking.
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int64_t current_segment_index_ = -1;
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// Current subsegment index, useful to determine where to do chunking.
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int64_t current_subsegment_index_ = -1;
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std::optional<int64_t> segment_start_time_;
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std::optional<int64_t> subsegment_start_time_;
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int64_t max_segment_time_ = 0;
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int32_t time_scale_ = 0;
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// The offset is applied to sample timestamps so a full segment is generated
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// after cue points.
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int64_t cue_offset_ = 0;
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};
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} // namespace media
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} // namespace shaka
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#endif // PACKAGER_MEDIA_CHUNKING_CHUNKING_HANDLER_
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