120 lines
4.0 KiB
C++
120 lines
4.0 KiB
C++
// Copyright 2015 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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#ifndef PACKAGER_MEDIA_FORMATS_WEBVTT_WEBVTT_SAMPLE_CONVERTER_H_
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#define PACKAGER_MEDIA_FORMATS_WEBVTT_WEBVTT_SAMPLE_CONVERTER_H_
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#include <stdint.h>
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#include <list>
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#include "packager/media/formats/mp4/box.h"
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#include "packager/media/formats/mp4/box_definitions.h"
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#include "packager/media/formats/webvtt/cue.h"
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#include "packager/status.h"
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namespace shaka {
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namespace media {
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/// Appends box to vector.
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/// @param box is the box to be serialized.
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/// @param output_vector is where the data is appended.
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void AppendBoxToVector(mp4::Box* box, std::vector<uint8_t>* output_vector);
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/// According to the spec, when cues overlap, samples must be created.\n
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/// The example below has 2 WebVTT cues:\n
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/// 00:01:00.000 --> 00:02:00.000\n
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/// hello\n
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///\n
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/// 00:01:15.000 --> 00:02:15.000\n
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/// how are you?\n
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///\n
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/// These are added (AddSample()) as 2 samples but must be split into 3 samples
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/// and 4 cues ('vttc' boxes).\n
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/// First sample:\n
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/// start_time: 00:01:00.000\n
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/// duration: 15 seconds\n
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/// cue payload: hello\n
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///\n
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/// Second sample:\n
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/// start_time: 00:01:15.000\n
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/// duration: 45 seconds\n
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/// cue payload: hello\n
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/// cue payload: how are you?\n
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///\n
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/// Third sample:\n
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/// start_time: 00:02:00.000\n
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/// duration: 15 seconds\n
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/// cue payload: how are you?\n
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///\n
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/// This class buffers the samples that are passed to AddSample() and creates
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/// more samples as necessary.
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/// Methods are virtual only for mocking, not intended for inheritance.
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class WebVttSampleConverter {
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public:
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WebVttSampleConverter();
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virtual ~WebVttSampleConverter();
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/// Add a webvtt cue.
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/// @param cue is a webvtt cue.
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virtual void PushCue(const Cue& cue);
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/// Process all the buffered samples.
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/// This finalizes the object and further calls to PushSample() may result in
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/// an undefined behavior.
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virtual void Flush();
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/// @return The number of samples that are processed and ready to be popped.
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virtual size_t ReadySamplesSize();
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/// Returns a MediaSample that is non-overlapping with the previous samples
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/// that it has output. The data in the sample is one or more ISO-BMFF boxes
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/// for the duration of the sample.
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/// @return The first sample that is ready to be processed.
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virtual std::shared_ptr<MediaSample> PopSample();
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private:
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// Handle |cues_| except the last item, and create samples from them.
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// All cues that overlap with the latest cue are not processed.
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// Usually the last cue (and cues that overlap with it) should not be
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// processed right away because the following cues may overlap with the latest
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// cue or the existing cues.
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// If a cue has been proceessed, then this returns true.
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bool HandleAllCuesButLatest();
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// Same as HandleAllCuesButLatest() but it also includes the latest cue.
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// If a cue has been processed, then this returns true.
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bool HandleAllCues();
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// Sweep line algorithm that handles the cues in |cues_|.
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// This does not erase |cues_|.
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// If a cue has been processed, this returns true.
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// |sweep_line| is the start time and |sweep_stop_time| is when the sweep
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// should stop.
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bool SweepCues(uint64_t sweep_line, uint64_t sweep_stop_time);
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// This is going to be in 'mdat' box. Keep this around until a sample is
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// ready.
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std::list<Cue> cues_;
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// For comment samples.
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std::list<mp4::VTTAdditionalTextBox> additional_texts_;
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// Samples that are ready to be processed.
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std::list<std::shared_ptr<MediaSample>> ready_samples_;
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// This keeps track of the max end time of the processed cues which is the
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// start time of the next cue. Used to check if cue_current_time has to be set
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// or an empty cue (gap) has to be added.
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uint64_t next_cue_start_time_;
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DISALLOW_COPY_AND_ASSIGN(WebVttSampleConverter);
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};
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} // namespace media
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} // namespace shaka
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#endif // PACKAGER_MEDIA_FORMATS_WEBVTT_WEBVTT_SAMPLE_CONVERTER_H_
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