1 // Copyright 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef MEDIA_BASE_TEXT_RENDERER_H_ 6 #define MEDIA_BASE_TEXT_RENDERER_H_ 7 8 #include <map> 9 #include <set> 10 11 #include "base/callback.h" 12 #include "base/memory/scoped_ptr.h" 13 #include "base/memory/weak_ptr.h" 14 #include "media/base/demuxer_stream.h" 15 #include "media/base/media_export.h" 16 #include "media/base/pipeline_status.h" 17 #include "media/base/text_ranges.h" 18 #include "media/base/text_track.h" 19 20 namespace base { 21 class SingleThreadTaskRunner; 22 } 23 24 namespace media { 25 26 class TextCue; 27 class TextTrackConfig; 28 29 // Receives decoder buffers from the upstream demuxer, decodes them to text 30 // cues, and then passes them onto the TextTrack object associated with each 31 // demuxer text stream. 32 class MEDIA_EXPORT TextRenderer { 33 public: 34 // |task_runner| is the thread on which TextRenderer will execute. 35 // 36 // |add_text_track_cb] is called when the demuxer requests (via its host) 37 // that a new text track be created. 38 TextRenderer( 39 const scoped_refptr<base::SingleThreadTaskRunner>& task_runner, 40 const AddTextTrackCB& add_text_track_cb); 41 42 // Stops all operations and fires all pending callbacks. 43 ~TextRenderer(); 44 45 // |ended_cb| is executed when all of the text tracks have reached 46 // end of stream, following a play request. 47 void Initialize(const base::Closure& ended_cb); 48 49 // Starts text track cue decoding and rendering. 50 void StartPlaying(); 51 52 // Temporarily suspends decoding and rendering, executing |callback| when 53 // playback has been suspended. 54 void Pause(const base::Closure& callback); 55 56 // Discards any text data, executing |callback| when completed. 57 void Flush(const base::Closure& callback); 58 59 // Adds new |text_stream|, having the indicated |config|, to the text stream 60 // collection managed by this text renderer. 61 void AddTextStream(DemuxerStream* text_stream, 62 const TextTrackConfig& config); 63 64 // Removes |text_stream| from the text stream collection. 65 void RemoveTextStream(DemuxerStream* text_stream); 66 67 // Returns true if there are extant text tracks. 68 bool HasTracks() const; 69 70 private: 71 struct TextTrackState { 72 // To determine read progress. 73 enum ReadState { 74 kReadIdle, 75 kReadPending 76 }; 77 78 explicit TextTrackState(scoped_ptr<TextTrack> text_track); 79 ~TextTrackState(); 80 81 ReadState read_state; 82 scoped_ptr<TextTrack> text_track; 83 TextRanges text_ranges_; 84 }; 85 86 // Callback delivered by the demuxer |text_stream| when 87 // a read from the stream completes. 88 void BufferReady(DemuxerStream* text_stream, 89 DemuxerStream::Status status, 90 const scoped_refptr<DecoderBuffer>& input); 91 92 // Dispatches the decoded cue delivered on the demuxer's |text_stream|. 93 void CueReady(DemuxerStream* text_stream, 94 const scoped_refptr<TextCue>& text_cue); 95 96 // Dispatched when the AddTextTrackCB completes, after having created 97 // the TextTrack object associated with |text_stream|. 98 void OnAddTextTrackDone(DemuxerStream* text_stream, 99 scoped_ptr<TextTrack> text_track); 100 101 // Utility function to post a read request on |text_stream|. 102 void Read(TextTrackState* state, DemuxerStream* text_stream); 103 104 scoped_refptr<base::SingleThreadTaskRunner> task_runner_; 105 const AddTextTrackCB add_text_track_cb_; 106 107 // Callbacks provided during Initialize(). 108 base::Closure ended_cb_; 109 110 // Callback provided to Pause(). 111 base::Closure pause_cb_; 112 113 // Simple state tracking variable. 114 enum State { 115 kUninitialized, 116 kPausePending, 117 kPaused, 118 kPlaying, 119 kEnded 120 }; 121 State state_; 122 123 typedef std::map<DemuxerStream*, TextTrackState*> TextTrackStateMap; 124 TextTrackStateMap text_track_state_map_; 125 126 // Indicates how many read requests are in flight. 127 int pending_read_count_; 128 129 // Indicates which text streams have not delivered end-of-stream yet. 130 typedef std::set<DemuxerStream*> PendingEosSet; 131 PendingEosSet pending_eos_set_; 132 133 // NOTE: Weak pointers must be invalidated before all other member variables. 134 base::WeakPtrFactory<TextRenderer> weak_factory_; 135 136 DISALLOW_IMPLICIT_CONSTRUCTORS(TextRenderer); 137 }; 138 139 } // namespace media 140 141 #endif // MEDIA_BASE_TEXT_RENDERER_H_ 142