1 // Copyright (c) 2012 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 // SourceBufferStream is a data structure that stores media Buffers in ranges. 6 // Buffers can be appended out of presentation order. Buffers are retrieved by 7 // seeking to the desired start point and calling GetNextBuffer(). Buffers are 8 // returned in sequential presentation order. 9 10 #ifndef MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_ 11 #define MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_ 12 13 #include <deque> 14 #include <list> 15 #include <string> 16 #include <utility> 17 #include <vector> 18 19 #include "base/memory/ref_counted.h" 20 #include "media/base/audio_decoder_config.h" 21 #include "media/base/media_export.h" 22 #include "media/base/media_log.h" 23 #include "media/base/ranges.h" 24 #include "media/base/stream_parser_buffer.h" 25 #include "media/base/text_track_config.h" 26 #include "media/base/video_decoder_config.h" 27 28 namespace media { 29 30 class SourceBufferRange; 31 32 // See file-level comment for complete description. 33 class MEDIA_EXPORT SourceBufferStream { 34 public: 35 typedef StreamParser::BufferQueue BufferQueue; 36 37 // Status returned by GetNextBuffer(). 38 // kSuccess: Indicates that the next buffer was returned. 39 // kNeedBuffer: Indicates that we need more data before a buffer can be 40 // returned. 41 // kConfigChange: Indicates that the next buffer requires a config change. 42 enum Status { 43 kSuccess, 44 kNeedBuffer, 45 kConfigChange, 46 kEndOfStream 47 }; 48 49 enum Type { 50 kAudio, 51 kVideo, 52 kText 53 }; 54 55 SourceBufferStream(const AudioDecoderConfig& audio_config, 56 const LogCB& log_cb, 57 bool splice_frames_enabled); 58 SourceBufferStream(const VideoDecoderConfig& video_config, 59 const LogCB& log_cb, 60 bool splice_frames_enabled); 61 SourceBufferStream(const TextTrackConfig& text_config, 62 const LogCB& log_cb, 63 bool splice_frames_enabled); 64 65 ~SourceBufferStream(); 66 67 // Signals that the next buffers appended are part of a new media segment 68 // starting at |media_segment_start_time|. 69 // TODO(acolwell/wolenetz): This should be changed to a presentation 70 // timestamp. See http://crbug.com/402502 71 void OnNewMediaSegment(DecodeTimestamp media_segment_start_time); 72 73 // Add the |buffers| to the SourceBufferStream. Buffers within the queue are 74 // expected to be in order, but multiple calls to Append() may add buffers out 75 // of order or overlapping. Assumes all buffers within |buffers| are in 76 // presentation order and are non-overlapping. 77 // Returns true if Append() was successful, false if |buffers| are not added. 78 // TODO(vrk): Implement garbage collection. (crbug.com/125070) 79 bool Append(const BufferQueue& buffers); 80 81 // Removes buffers between |start| and |end| according to the steps 82 // in the "Coded Frame Removal Algorithm" in the Media Source 83 // Extensions Spec. 84 // https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html#sourcebuffer-coded-frame-removal 85 // 86 // |duration| is the current duration of the presentation. It is 87 // required by the computation outlined in the spec. 88 void Remove(base::TimeDelta start, base::TimeDelta end, 89 base::TimeDelta duration); 90 91 // Changes the SourceBufferStream's state so that it will start returning 92 // buffers starting from the closest keyframe before |timestamp|. 93 void Seek(base::TimeDelta timestamp); 94 95 // Returns true if the SourceBufferStream has seeked to a time without 96 // buffered data and is waiting for more data to be appended. 97 bool IsSeekPending() const; 98 99 // Notifies the SourceBufferStream that the media duration has been changed to 100 // |duration| so it should drop any data past that point. 101 void OnSetDuration(base::TimeDelta duration); 102 103 // Fills |out_buffer| with a new buffer. Buffers are presented in order from 104 // the last call to Seek(), or starting with the first buffer appended if 105 // Seek() has not been called yet. 106 // |out_buffer|'s timestamp may be earlier than the |timestamp| passed to 107 // the last Seek() call. 108 // Returns kSuccess if |out_buffer| is filled with a valid buffer, kNeedBuffer 109 // if there is not enough data buffered to fulfill the request, and 110 // kConfigChange if the next buffer requires a config change. 111 Status GetNextBuffer(scoped_refptr<StreamParserBuffer>* out_buffer); 112 113 // Returns a list of the buffered time ranges. 114 Ranges<base::TimeDelta> GetBufferedTime() const; 115 116 // Returns the duration of the buffered ranges, which is equivalent 117 // to the end timestamp of the last buffered range. If no data is buffered 118 // then base::TimeDelta() is returned. 119 base::TimeDelta GetBufferedDuration() const; 120 121 // Notifies this object that end of stream has been signalled. 122 void MarkEndOfStream(); 123 124 // Clear the end of stream state set by MarkEndOfStream(). 125 void UnmarkEndOfStream(); 126 127 const AudioDecoderConfig& GetCurrentAudioDecoderConfig(); 128 const VideoDecoderConfig& GetCurrentVideoDecoderConfig(); 129 const TextTrackConfig& GetCurrentTextTrackConfig(); 130 131 // Notifies this object that the audio config has changed and buffers in 132 // future Append() calls should be associated with this new config. 133 bool UpdateAudioConfig(const AudioDecoderConfig& config); 134 135 // Notifies this object that the video config has changed and buffers in 136 // future Append() calls should be associated with this new config. 137 bool UpdateVideoConfig(const VideoDecoderConfig& config); 138 139 // Returns the largest distance between two adjacent buffers in this stream, 140 // or an estimate if no two adjacent buffers have been appended to the stream 141 // yet. 142 base::TimeDelta GetMaxInterbufferDistance() const; 143 144 void set_memory_limit(int memory_limit) { 145 memory_limit_ = memory_limit; 146 } 147 148 private: 149 friend class SourceBufferStreamTest; 150 151 typedef std::list<SourceBufferRange*> RangeList; 152 153 // Frees up space if the SourceBufferStream is taking up too much memory. 154 void GarbageCollectIfNeeded(); 155 156 // Attempts to delete approximately |total_bytes_to_free| amount of data 157 // |ranges_|, starting at the front of |ranges_| and moving linearly forward 158 // through the buffers. Deletes starting from the back if |reverse_direction| 159 // is true. Returns the number of bytes freed. 160 int FreeBuffers(int total_bytes_to_free, bool reverse_direction); 161 162 // Attempts to delete approximately |total_bytes_to_free| amount of data from 163 // |ranges_|, starting after the last appended buffer before the current 164 // playback position. 165 int FreeBuffersAfterLastAppended(int total_bytes_to_free); 166 167 // Gets the removal range to secure |byte_to_free| from 168 // [|start_timestamp|, |end_timestamp|). 169 // Returns the size of buffers to secure if future 170 // Remove(|start_timestamp|, |removal_end_timestamp|, duration) is called. 171 // Will not update |removal_end_timestamp| if the returned size is 0. 172 int GetRemovalRange(DecodeTimestamp start_timestamp, 173 DecodeTimestamp end_timestamp, int byte_to_free, 174 DecodeTimestamp* removal_end_timestamp); 175 176 // Prepares |range_for_next_append_| so |new_buffers| can be appended. 177 // This involves removing buffers between the end of the previous append 178 // and any buffers covered by the time range in |new_buffers|. 179 // |deleted_buffers| is an output parameter containing candidates for 180 // |track_buffer_| if this method ends up removing the current playback 181 // position from the range. 182 void PrepareRangesForNextAppend(const BufferQueue& new_buffers, 183 BufferQueue* deleted_buffers); 184 185 // Removes buffers, from the |track_buffer_|, that come after |timestamp|. 186 void PruneTrackBuffer(const DecodeTimestamp timestamp); 187 188 // Checks to see if |range_with_new_buffers_itr| can be merged with the range 189 // next to it, and merges them if so. 190 void MergeWithAdjacentRangeIfNecessary( 191 const RangeList::iterator& range_with_new_buffers_itr); 192 193 // Returns true if |second_timestamp| is the timestamp of the next buffer in 194 // sequence after |first_timestamp|, false otherwise. 195 bool AreAdjacentInSequence( 196 DecodeTimestamp first_timestamp, DecodeTimestamp second_timestamp) const; 197 198 // Helper method that returns the timestamp for the next buffer that 199 // |selected_range_| will return from GetNextBuffer() call, or kNoTimestamp() 200 // if in between seeking (i.e. |selected_range_| is null). 201 DecodeTimestamp GetNextBufferTimestamp(); 202 203 // Finds the range that should contain a media segment that begins with 204 // |start_timestamp| and returns the iterator pointing to it. Returns 205 // |ranges_.end()| if there's no such existing range. 206 RangeList::iterator FindExistingRangeFor(DecodeTimestamp start_timestamp); 207 208 // Inserts |new_range| into |ranges_| preserving sorted order. Returns an 209 // iterator in |ranges_| that points to |new_range|. 210 RangeList::iterator AddToRanges(SourceBufferRange* new_range); 211 212 // Returns an iterator that points to the place in |ranges_| where 213 // |selected_range_| lives. 214 RangeList::iterator GetSelectedRangeItr(); 215 216 // Sets the |selected_range_| to |range| and resets the next buffer position 217 // for the previous |selected_range_|. 218 void SetSelectedRange(SourceBufferRange* range); 219 220 // Seeks |range| to |seek_timestamp| and then calls SetSelectedRange() with 221 // |range|. 222 void SeekAndSetSelectedRange(SourceBufferRange* range, 223 DecodeTimestamp seek_timestamp); 224 225 // Resets this stream back to an unseeked state. 226 void ResetSeekState(); 227 228 // Returns true if |seek_timestamp| refers to the beginning of the first range 229 // in |ranges_|, false otherwise or if |ranges_| is empty. 230 bool ShouldSeekToStartOfBuffered(base::TimeDelta seek_timestamp) const; 231 232 // Returns true if the timestamps of |buffers| are monotonically increasing 233 // since the previous append to the media segment, false otherwise. 234 bool IsMonotonicallyIncreasing(const BufferQueue& buffers) const; 235 236 // Returns true if |next_timestamp| and |next_is_keyframe| are valid for 237 // the first buffer after the previous append. 238 bool IsNextTimestampValid(DecodeTimestamp next_timestamp, 239 bool next_is_keyframe) const; 240 241 // Returns true if |selected_range_| is the only range in |ranges_| that 242 // HasNextBufferPosition(). 243 bool OnlySelectedRangeIsSeeked() const; 244 245 // Measures the distances between buffer timestamps and tracks the max. 246 void UpdateMaxInterbufferDistance(const BufferQueue& buffers); 247 248 // Sets the config ID for each buffer to |append_config_index_|. 249 void SetConfigIds(const BufferQueue& buffers); 250 251 // Called to complete a config change. Updates |current_config_index_| to 252 // match the index of the next buffer. Calling this method causes 253 // GetNextBuffer() to stop returning kConfigChange and start returning 254 // kSuccess. 255 void CompleteConfigChange(); 256 257 // Sets |selected_range_| and seeks to the nearest keyframe after 258 // |timestamp| if necessary and possible. This method only attempts to 259 // set |selected_range_| if |seleted_range_| is null and |track_buffer_| 260 // is empty. 261 void SetSelectedRangeIfNeeded(const DecodeTimestamp timestamp); 262 263 // Find a keyframe timestamp that is >= |start_timestamp| and can be used to 264 // find a new selected range. 265 // Returns kNoTimestamp() if an appropriate keyframe timestamp could not be 266 // found. 267 DecodeTimestamp FindNewSelectedRangeSeekTimestamp( 268 const DecodeTimestamp start_timestamp); 269 270 // Searches |ranges_| for the first keyframe timestamp that is >= |timestamp|. 271 // If |ranges_| doesn't contain a GOP that covers |timestamp| or doesn't 272 // have a keyframe after |timestamp| then kNoTimestamp() is returned. 273 DecodeTimestamp FindKeyframeAfterTimestamp(const DecodeTimestamp timestamp); 274 275 // Returns "VIDEO" for a video SourceBufferStream, "AUDIO" for an audio 276 // stream, and "TEXT" for a text stream. 277 std::string GetStreamTypeName() const; 278 279 // Returns true if we don't have any ranges or the last range is selected 280 // or there is a pending seek beyond any existing ranges. 281 bool IsEndSelected() const; 282 283 // Deletes the range pointed to by |*itr| and removes it from |ranges_|. 284 // If |*itr| points to |selected_range_|, then |selected_range_| is set to 285 // NULL. After the range is removed, |*itr| is to the range after the one that 286 // was removed or to |ranges_.end()| if the last range was removed. 287 void DeleteAndRemoveRange(RangeList::iterator* itr); 288 289 // Helper function used by Remove() and PrepareRangesForNextAppend() to 290 // remove buffers and ranges between |start| and |end|. 291 // |is_exclusive| - If set to true, buffers with timestamps that 292 // match |start| are not removed. If set to false, buffers with 293 // timestamps that match |start| will be removed. 294 // |*deleted_buffers| - Filled with buffers for the current playback position 295 // if the removal range included the current playback position. These buffers 296 // can be used as candidates for placing in the |track_buffer_|. 297 void RemoveInternal( 298 DecodeTimestamp start, DecodeTimestamp end, bool is_exclusive, 299 BufferQueue* deleted_buffers); 300 301 Type GetType() const; 302 303 // See GetNextBuffer() for additional details. This method handles splice 304 // frame processing. 305 Status HandleNextBufferWithSplice( 306 scoped_refptr<StreamParserBuffer>* out_buffer); 307 308 // See GetNextBuffer() for additional details. This method handles preroll 309 // frame processing. 310 Status HandleNextBufferWithPreroll( 311 scoped_refptr<StreamParserBuffer>* out_buffer); 312 313 // See GetNextBuffer() for additional details. The internal method hands out 314 // single buffers from the |track_buffer_| and |selected_range_| without 315 // additional processing for splice frame or preroll buffers. 316 Status GetNextBufferInternal(scoped_refptr<StreamParserBuffer>* out_buffer); 317 318 // Called by PrepareRangesForNextAppend() before pruning overlapped buffers to 319 // generate a splice frame with a small portion of the overlapped buffers. If 320 // a splice frame is generated, the first buffer in |new_buffers| will have 321 // its timestamps, duration, and fade out preroll updated. 322 void GenerateSpliceFrame(const BufferQueue& new_buffers); 323 324 // If |out_buffer| has splice buffers or preroll, sets |pending_buffer_| 325 // appropriately and returns true. Otherwise returns false. 326 bool SetPendingBuffer(scoped_refptr<StreamParserBuffer>* out_buffer); 327 328 // Callback used to report error strings that can help the web developer 329 // figure out what is wrong with the content. 330 LogCB log_cb_; 331 332 // List of disjoint buffered ranges, ordered by start time. 333 RangeList ranges_; 334 335 // Indicates which decoder config is being used by the decoder. 336 // GetNextBuffer() is only allows to return buffers that have a 337 // config ID that matches this index. If there is a mismatch then 338 // it must signal that a config change is needed. 339 int current_config_index_; 340 341 // Indicates which decoder config to associate with new buffers 342 // being appended. Each new buffer appended has its config ID set 343 // to the value of this field. 344 int append_config_index_; 345 346 // Holds the audio/video configs for this stream. |current_config_index_| 347 // and |append_config_index_| represent indexes into one of these vectors. 348 std::vector<AudioDecoderConfig> audio_configs_; 349 std::vector<VideoDecoderConfig> video_configs_; 350 351 // Holds the text config for this stream. 352 TextTrackConfig text_track_config_; 353 354 // True if more data needs to be appended before the Seek() can complete, 355 // false if no Seek() has been requested or the Seek() is completed. 356 bool seek_pending_; 357 358 // True if the end of the stream has been signalled. 359 bool end_of_stream_; 360 361 // Timestamp of the last request to Seek(). 362 base::TimeDelta seek_buffer_timestamp_; 363 364 // Pointer to the seeked-to Range. This is the range from which 365 // GetNextBuffer() calls are fulfilled after the |track_buffer_| has been 366 // emptied. 367 SourceBufferRange* selected_range_; 368 369 // Queue of the next buffers to be returned from calls to GetNextBuffer(). If 370 // |track_buffer_| is empty, return buffers from |selected_range_|. 371 BufferQueue track_buffer_; 372 373 // The start time of the current media segment being appended. 374 DecodeTimestamp media_segment_start_time_; 375 376 // Points to the range containing the current media segment being appended. 377 RangeList::iterator range_for_next_append_; 378 379 // True when the next call to Append() begins a new media segment. 380 bool new_media_segment_; 381 382 // The timestamp of the last buffer appended to the media segment, set to 383 // kNoDecodeTimestamp() if the beginning of the segment. 384 DecodeTimestamp last_appended_buffer_timestamp_; 385 bool last_appended_buffer_is_keyframe_; 386 387 // The decode timestamp on the last buffer returned by the most recent 388 // GetNextBuffer() call. Set to kNoTimestamp() if GetNextBuffer() hasn't been 389 // called yet or a seek has happened since the last GetNextBuffer() call. 390 DecodeTimestamp last_output_buffer_timestamp_; 391 392 // Stores the largest distance between two adjacent buffers in this stream. 393 base::TimeDelta max_interbuffer_distance_; 394 395 // The maximum amount of data in bytes the stream will keep in memory. 396 int memory_limit_; 397 398 // Indicates that a kConfigChanged status has been reported by GetNextBuffer() 399 // and GetCurrentXXXDecoderConfig() must be called to update the current 400 // config. GetNextBuffer() must not be called again until 401 // GetCurrentXXXDecoderConfig() has been called. 402 bool config_change_pending_; 403 404 // Used by HandleNextBufferWithSplice() or HandleNextBufferWithPreroll() when 405 // a splice frame buffer or buffer with preroll is returned from 406 // GetNextBufferInternal(). 407 scoped_refptr<StreamParserBuffer> pending_buffer_; 408 409 // Indicates which of the splice buffers in |splice_buffer_| should be 410 // handled out next. 411 size_t splice_buffers_index_; 412 413 // Indicates that all buffers before |pending_buffer_| have been handed out. 414 bool pending_buffers_complete_; 415 416 // Indicates that splice frame generation is enabled. 417 const bool splice_frames_enabled_; 418 419 DISALLOW_COPY_AND_ASSIGN(SourceBufferStream); 420 }; 421 422 } // namespace media 423 424 #endif // MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_ 425