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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_BASE_MEDIA_TRACK_H_
#define MEDIA_BASE_MEDIA_TRACK_H_
#include <string>
#include "base/types/strong_alias.h"
#include "media/base/media_export.h"
#include "media/base/stream_parser.h"
namespace media {
class MEDIA_EXPORT MediaTrack {
public:
enum Type { Text, Audio, Video };
using Id = base::StrongAlias<class IdTag, std::string>;
using Kind = base::StrongAlias<class KindTag, std::string>;
using Label = base::StrongAlias<class LabelTag, std::string>;
using Language = base::StrongAlias<class LanguageTag, std::string>;
MediaTrack(Type type,
StreamParser::TrackId bytestream_track_id,
const Kind& kind,
const Label& label,
const Language& lang);
~MediaTrack();
Type type() const { return type_; }
StreamParser::TrackId bytestream_track_id() const {
return bytestream_track_id_;
}
const Kind& kind() const { return kind_; }
const Label& label() const { return label_; }
const Language& language() const { return language_; }
Id id() const { return id_; }
void set_id(Id id) {
DCHECK(id_.value().empty());
DCHECK(!id.value().empty());
id_ = id;
}
private:
Type type_;
// |bytestream_track_id_| is read from the bytestream and is guaranteed to be
// unique only within the scope of single bytestream's initialization segment.
// But we might have multiple bytestreams (MediaSource might have multiple
// SourceBuffers attached to it, which translates into ChunkDemuxer having
// multiple SourceBufferStates and multiple bytestreams) or subsequent init
// segments may redefine the bytestream ids. Thus bytestream track ids are not
// guaranteed to be unique at the Demuxer and HTMLMediaElement level. So we
// generate truly unique media track |id_| on the Demuxer level.
StreamParser::TrackId bytestream_track_id_;
Id id_;
// These properties are read from input streams by stream parsers as specified
// in https://dev.w3.org/html5/html-sourcing-inband-tracks/.
Kind kind_;
Label label_;
Language language_;
};
// Helper for logging.
MEDIA_EXPORT const char* TrackTypeToStr(MediaTrack::Type type);
} // namespace media
#endif // MEDIA_BASE_MEDIA_TRACK_H_
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