75 lines
2.8 KiB
C++
75 lines
2.8 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_BASE_TRICK_PLAY_HANDLER_H_
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#define PACKAGER_MEDIA_BASE_TRICK_PLAY_HANDLER_H_
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#include <list>
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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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class VideoStreamInfo;
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/// TrickPlayHandler is a single-input single-output media handler. It takes
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/// the input stream and converts it to a trick play stream by limiting which
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/// samples get passed downstream.
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// The stream data in trick play streams are not simple duplicates. Some
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// information get changed (e.g. VideoStreamInfo.trick_play_factor).
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class TrickPlayHandler : public MediaHandler {
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public:
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explicit TrickPlayHandler(uint32_t factor);
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private:
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TrickPlayHandler(const TrickPlayHandler&) = delete;
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TrickPlayHandler& operator=(const TrickPlayHandler&) = delete;
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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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Status OnStreamInfo(const StreamInfo& info);
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Status OnSegmentInfo(std::shared_ptr<const SegmentInfo> info);
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Status OnMediaSample(const MediaSample& sample);
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Status OnTrickFrame(const MediaSample& sample);
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const uint32_t factor_;
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uint64_t total_frames_ = 0;
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uint64_t total_key_frames_ = 0;
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uint64_t total_trick_frames_ = 0;
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// We cannot just send video info through as we need to calculate the play
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// rate using the first two trick play frames. This reference should only be
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// used to update the play back rate before video info is sent downstream.
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// After getting sent downstream, this should never be used.
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std::shared_ptr<VideoStreamInfo> video_info_;
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// We need to track the segment that most recently finished so that we can
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// extend its duration if there are empty segments.
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std::shared_ptr<SegmentInfo> previous_segment_;
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// Since we are dropping frames, the time that those frames would have been
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// on screen need to be added to the frame before them. Keep a reference to
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// the most recent trick play frame so that we can grow its duration as we
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// drop other frames.
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std::shared_ptr<MediaSample> previous_trick_frame_;
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// Since we cannot send messages downstream right away, keep a queue of
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// messages that need to be sent down. At the start, we use this to queue
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// messages until we can send out |video_info_|. To ensure messages are
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// kept in order, messages are only dispatched through this queue and never
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// directly.
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std::list<std::unique_ptr<StreamData>> delayed_messages_;
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};
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} // namespace media
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} // namespace shaka
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#endif // PACKAGER_MEDIA_BASE_TRICK_PLAY_HANDLER_H_
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