media/webm/webm_cluster_parser.cc

   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 #include "media/webm/webm_cluster_parser.h"
   6
   7 #include <vector>
   8
   9 #include "base/logging.h"
  10 #include "base/sys_byteorder.h"
  11 #include "media/base/buffers.h"
  12 #include "media/base/decrypt_config.h"
  13 #include "media/webm/webm_constants.h"
  14 #include "media/webm/webm_crypto_helpers.h"
  15
  16 namespace media {
  17
  18 WebMClusterParser::TextTrackIterator::TextTrackIterator(
  19     const TextTrackMap& text_track_map) :
  20     iterator_(text_track_map.begin()),
  21     iterator_end_(text_track_map.end()) {
  22 }
  23
  24 WebMClusterParser::TextTrackIterator::TextTrackIterator(
  25     const TextTrackIterator& rhs) :
  26     iterator_(rhs.iterator_),
  27     iterator_end_(rhs.iterator_end_) {
  28 }
  29
  30 WebMClusterParser::TextTrackIterator::~TextTrackIterator() {
  31 }
  32
  33 bool WebMClusterParser::TextTrackIterator::operator()(
  34   int* track_num,
  35   const BufferQueue** buffers) {
  36   if (iterator_ == iterator_end_) {
  37     *track_num = 0;
  38     *buffers = NULL;
  39
  40     return false;
  41   }
  42
  43   *track_num = iterator_->first;
  44   *buffers = &iterator_->second.buffers();
  45
  46   ++iterator_;
  47   return true;
  48 }
  49
  50 WebMClusterParser::WebMClusterParser(
  51     int64 timecode_scale, int audio_track_num, int video_track_num,
  52     const WebMTracksParser::TextTracks& text_tracks,
  53     const std::set<int64>& ignored_tracks,
  54     const std::string& audio_encryption_key_id,
  55     const std::string& video_encryption_key_id,
  56     const LogCB& log_cb)
  57     : timecode_multiplier_(timecode_scale / 1000.0),
  58       ignored_tracks_(ignored_tracks),
  59       audio_encryption_key_id_(audio_encryption_key_id),
  60       video_encryption_key_id_(video_encryption_key_id),
  61       parser_(kWebMIdCluster, this),
  62       last_block_timecode_(-1),
  63       block_data_size_(-1),
  64       block_duration_(-1),
  65       block_add_id_(-1),
  66       block_additional_data_size_(-1),
  67       cluster_timecode_(-1),
  68       cluster_start_time_(kNoTimestamp()),
  69       cluster_ended_(false),
  70       audio_(audio_track_num, false),
  71       video_(video_track_num, true),
  72       log_cb_(log_cb) {
  73   for (WebMTracksParser::TextTracks::const_iterator it = text_tracks.begin();
  74        it != text_tracks.end();
  75        ++it) {
  76     text_track_map_.insert(std::make_pair(it->first, Track(it->first, false)));
  77   }
  78 }
  79
  80 WebMClusterParser::~WebMClusterParser() {}
  81
  82 void WebMClusterParser::Reset() {
  83   last_block_timecode_ = -1;
  84   cluster_timecode_ = -1;
  85   cluster_start_time_ = kNoTimestamp();
  86   cluster_ended_ = false;
  87   parser_.Reset();
  88   audio_.Reset();
  89   video_.Reset();
  90   ResetTextTracks();
  91 }
  92
  93 int WebMClusterParser::Parse(const uint8* buf, int size) {
  94   audio_.Reset();
  95   video_.Reset();
  96   ResetTextTracks();
  97
  98   int result = parser_.Parse(buf, size);
  99
 100   if (result < 0) {
 101     cluster_ended_ = false;
 102     return result;
 103   }
 104
 105   cluster_ended_ = parser_.IsParsingComplete();
 106   if (cluster_ended_) {
 107     // If there were no buffers in this cluster, set the cluster start time to
 108     // be the |cluster_timecode_|.
 109     if (cluster_start_time_ == kNoTimestamp()) {
 110       DCHECK_GT(cluster_timecode_, -1);
 111       cluster_start_time_ = base::TimeDelta::FromMicroseconds(
 112           cluster_timecode_ * timecode_multiplier_);
 113     }
 114
 115     // Reset the parser if we're done parsing so that
 116     // it is ready to accept another cluster on the next
 117     // call.
 118     parser_.Reset();
 119
 120     last_block_timecode_ = -1;
 121     cluster_timecode_ = -1;
 122   }
 123
 124   return result;
 125 }
 126
 127 WebMClusterParser::TextTrackIterator
 128 WebMClusterParser::CreateTextTrackIterator() const {
 129   return TextTrackIterator(text_track_map_);
 130 }
 131
 132 WebMParserClient* WebMClusterParser::OnListStart(int id) {
 133   if (id == kWebMIdCluster) {
 134     cluster_timecode_ = -1;
 135     cluster_start_time_ = kNoTimestamp();
 136   } else if (id == kWebMIdBlockGroup) {
 137     block_data_.reset();
 138     block_data_size_ = -1;
 139     block_duration_ = -1;
 140   } else if (id == kWebMIdBlockAdditions) {
 141     block_add_id_ = -1;
 142     block_additional_data_.reset();
 143     block_additional_data_size_ = -1;
 144   }
 145
 146   return this;
 147 }
 148
 149 bool WebMClusterParser::OnListEnd(int id) {
 150   if (id != kWebMIdBlockGroup)
 151     return true;
 152
 153   // Make sure the BlockGroup actually had a Block.
 154   if (block_data_size_ == -1) {
 155     MEDIA_LOG(log_cb_) << "Block missing from BlockGroup.";
 156     return false;
 157   }
 158
 159   bool result = ParseBlock(false, block_data_.get(), block_data_size_,
 160                            block_additional_data_.get(),
 161                            block_additional_data_size_, block_duration_);
 162   block_data_.reset();
 163   block_data_size_ = -1;
 164   block_duration_ = -1;
 165   block_add_id_ = -1;
 166   block_additional_data_.reset();
 167   block_additional_data_size_ = -1;
 168   return result;
 169 }
 170
 171 bool WebMClusterParser::OnUInt(int id, int64 val) {
 172   int64* dst;
 173   switch (id) {
 174     case kWebMIdTimecode:
 175       dst = &cluster_timecode_;
 176       break;
 177     case kWebMIdBlockDuration:
 178       dst = &block_duration_;
 179       break;
 180     case kWebMIdBlockAddID:
 181       dst = &block_add_id_;
 182       break;
 183     default:
 184       return true;
 185   }
 186   if (*dst != -1)
 187     return false;
 188   *dst = val;
 189   return true;
 190 }
 191
 192 bool WebMClusterParser::ParseBlock(bool is_simple_block, const uint8* buf,
 193                                    int size, const uint8* additional,
 194                                    int additional_size, int duration) {
 195   if (size < 4)
 196     return false;
 197
 198   // Return an error if the trackNum > 127. We just aren't
 199   // going to support large track numbers right now.
 200   if (!(buf[0] & 0x80)) {
 201     MEDIA_LOG(log_cb_) << "TrackNumber over 127 not supported";
 202     return false;
 203   }
 204
 205   int track_num = buf[0] & 0x7f;
 206   int timecode = buf[1] << 8 | buf[2];
 207   int flags = buf[3] & 0xff;
 208   int lacing = (flags >> 1) & 0x3;
 209
 210   if (lacing) {
 211     MEDIA_LOG(log_cb_) << "Lacing " << lacing << " is not supported yet.";
 212     return false;
 213   }
 214
 215   // Sign extend negative timecode offsets.
 216   if (timecode & 0x8000)
 217     timecode |= ~0xffff;
 218
 219   const uint8* frame_data = buf + 4;
 220   int frame_size = size - (frame_data - buf);
 221   return OnBlock(is_simple_block, track_num, timecode, duration, flags,
 222                  frame_data, frame_size, additional, additional_size);
 223 }
 224
 225 bool WebMClusterParser::OnBinary(int id, const uint8* data, int size) {
 226   switch (id) {
 227     case kWebMIdSimpleBlock:
 228       return ParseBlock(true, data, size, NULL, -1, -1);
 229
 230     case kWebMIdBlock:
 231       if (block_data_) {
 232         MEDIA_LOG(log_cb_) << "More than 1 Block in a BlockGroup is not "
 233                               "supported.";
 234         return false;
 235       }
 236       block_data_.reset(new uint8[size]);
 237       memcpy(block_data_.get(), data, size);
 238       block_data_size_ = size;
 239       return true;
 240
 241     case kWebMIdBlockAdditional: {
 242       uint64 block_add_id = base::HostToNet64(block_add_id_);
 243       if (block_additional_data_) {
 244         // TODO(vigneshv): Technically, more than 1 BlockAdditional is allowed
 245         // as per matroska spec. But for now we don't have a use case to
 246         // support parsing of such files. Take a look at this again when such a
 247         // case arises.
 248         MEDIA_LOG(log_cb_) << "More than 1 BlockAdditional in a BlockGroup is "
 249                               "not supported.";
 250         return false;
 251       }
 252       // First 8 bytes of side_data in DecoderBuffer is the BlockAddID
 253       // element's value in Big Endian format. This is done to mimic ffmpeg
 254       // demuxer's behavior.
 255       block_additional_data_size_ = size + sizeof(block_add_id);
 256       block_additional_data_.reset(new uint8[block_additional_data_size_]);
 257       memcpy(block_additional_data_.get(), &block_add_id,
 258              sizeof(block_add_id));
 259       memcpy(block_additional_data_.get() + 8, data, size);
 260       return true;
 261     }
 262
 263     default:
 264       return true;
 265   }
 266 }
 267
 268 bool WebMClusterParser::OnBlock(bool is_simple_block, int track_num,
 269                                 int timecode,
 270                                 int  block_duration,
 271                                 int flags,
 272                                 const uint8* data, int size,
 273                                 const uint8* additional, int additional_size) {
 274   DCHECK_GE(size, 0);
 275   if (cluster_timecode_ == -1) {
 276     MEDIA_LOG(log_cb_) << "Got a block before cluster timecode.";
 277     return false;
 278   }
 279
 280   // TODO(acolwell): Should relative negative timecode offsets be rejected?  Or
 281   // only when the absolute timecode is negative?  See http://crbug.com/271794
 282   if (timecode < 0) {
 283     MEDIA_LOG(log_cb_) << "Got a block with negative timecode offset "
 284                        << timecode;
 285     return false;
 286   }
 287
 288   if (last_block_timecode_ != -1 && timecode < last_block_timecode_) {
 289     MEDIA_LOG(log_cb_)
 290         << "Got a block with a timecode before the previous block.";
 291     return false;
 292   }
 293
 294   Track* track = NULL;
 295   std::string encryption_key_id;
 296   if (track_num == audio_.track_num()) {
 297     track = &audio_;
 298     encryption_key_id = audio_encryption_key_id_;
 299   } else if (track_num == video_.track_num()) {
 300     track = &video_;
 301     encryption_key_id = video_encryption_key_id_;
 302   } else if (ignored_tracks_.find(track_num) != ignored_tracks_.end()) {
 303     return true;
 304   } else if (Track* const text_track = FindTextTrack(track_num)) {
 305     if (is_simple_block)  // BlockGroup is required for WebVTT cues
 306       return false;
 307     if (block_duration < 0)  // not specified
 308       return false;
 309     track = text_track;
 310   } else {
 311     MEDIA_LOG(log_cb_) << "Unexpected track number " << track_num;
 312     return false;
 313   }
 314
 315   last_block_timecode_ = timecode;
 316
 317   base::TimeDelta timestamp = base::TimeDelta::FromMicroseconds(
 318       (cluster_timecode_ + timecode) * timecode_multiplier_);
 319
 320   // The first bit of the flags is set when a SimpleBlock contains only
 321   // keyframes. If this is a Block, then inspection of the payload is
 322   // necessary to determine whether it contains a keyframe or not.
 323   // http://www.matroska.org/technical/specs/index.html
 324   bool is_keyframe =
 325       is_simple_block ? (flags & 0x80) != 0 : track->IsKeyframe(data, size);
 326
 327   scoped_refptr<StreamParserBuffer> buffer =
 328       StreamParserBuffer::CopyFrom(data, size, additional, additional_size,
 329                                    is_keyframe);
 330
 331   // Every encrypted Block has a signal byte and IV prepended to it. Current
 332   // encrypted WebM request for comments specification is here
 333   // http://wiki.webmproject.org/encryption/webm-encryption-rfc
 334   if (!encryption_key_id.empty()) {
 335     scoped_ptr<DecryptConfig> config(WebMCreateDecryptConfig(
 336         data, size,
 337         reinterpret_cast<const uint8*>(encryption_key_id.data()),
 338         encryption_key_id.size()));
 339     if (!config)
 340       return false;
 341     buffer->set_decrypt_config(config.Pass());
 342   }
 343
 344   buffer->set_timestamp(timestamp);
 345   if (cluster_start_time_ == kNoTimestamp())
 346     cluster_start_time_ = timestamp;
 347
 348   if (block_duration >= 0) {
 349     buffer->set_duration(base::TimeDelta::FromMicroseconds(
 350         block_duration * timecode_multiplier_));
 351   }
 352
 353   return track->AddBuffer(buffer);
 354 }
 355
 356 WebMClusterParser::Track::Track(int track_num, bool is_video)
 357     : track_num_(track_num),
 358       is_video_(is_video) {
 359 }
 360
 361 WebMClusterParser::Track::~Track() {}
 362
 363 bool WebMClusterParser::Track::AddBuffer(
 364     const scoped_refptr<StreamParserBuffer>& buffer) {
 365   DVLOG(2) << "AddBuffer() : " << track_num_
 366            << " ts " << buffer->timestamp().InSecondsF()
 367            << " dur " << buffer->duration().InSecondsF()
 368            << " kf " << buffer->IsKeyframe()
 369            << " size " << buffer->data_size();
 370
 371   buffers_.push_back(buffer);
 372   return true;
 373 }
 374
 375 void WebMClusterParser::Track::Reset() {
 376   buffers_.clear();
 377 }
 378
 379 bool WebMClusterParser::Track::IsKeyframe(const uint8* data, int size) const {
 380   // For now, assume that all blocks are keyframes for datatypes other than
 381   // video. This is a valid assumption for Vorbis, WebVTT, & Opus.
 382   if (!is_video_)
 383     return true;
 384
 385   // Make sure the block is big enough for the minimal keyframe header size.
 386   if (size < 7)
 387     return false;
 388
 389   // The LSb of the first byte must be a 0 for a keyframe.
 390   // http://tools.ietf.org/html/rfc6386 Section 19.1
 391   if ((data[0] & 0x01) != 0)
 392     return false;
 393
 394   // Verify VP8 keyframe startcode.
 395   // http://tools.ietf.org/html/rfc6386 Section 19.1
 396   if (data[3] != 0x9d || data[4] != 0x01 || data[5] != 0x2a)
 397     return false;
 398
 399   return true;
 400 }
 401
 402 void WebMClusterParser::ResetTextTracks() {
 403   for (TextTrackMap::iterator it = text_track_map_.begin();
 404        it != text_track_map_.end();
 405        ++it) {
 406     it->second.Reset();
 407   }
 408 }
 409
 410 WebMClusterParser::Track*
 411 WebMClusterParser::FindTextTrack(int track_num) {
 412   const TextTrackMap::iterator it = text_track_map_.find(track_num);
 413
 414   if (it == text_track_map_.end())
 415     return NULL;
 416
 417   return &it->second;
 418 }
 419
 420 }  // namespace media