media/filters/opus_audio_decoder.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/filters/opus_audio_decoder.h"
   6
   7 #include <cmath>
   8
   9 #include "base/single_thread_task_runner.h"
  10 #include "base/sys_byteorder.h"
  11 #include "media/base/audio_buffer.h"
  12 #include "media/base/audio_decoder_config.h"
  13 #include "media/base/audio_discard_helper.h"
  14 #include "media/base/bind_to_current_loop.h"
  15 #include "media/base/decoder_buffer.h"
  16 #include "media/base/timestamp_constants.h"
  17 #include "third_party/opus/src/include/opus.h"
  18 #include "third_party/opus/src/include/opus_multistream.h"
  19
  20 namespace media {
  21
  22 static uint16 ReadLE16(const uint8* data, size_t data_size, int read_offset) {
  23   uint16 value = 0;
  24   DCHECK_LE(read_offset + sizeof(value), data_size);
  25   memcpy(&value, data + read_offset, sizeof(value));
  26   return base::ByteSwapToLE16(value);
  27 }
  28
  29 // The Opus specification is part of IETF RFC 6716:
  30 // http://tools.ietf.org/html/rfc6716
  31
  32 // Opus uses Vorbis channel mapping, and Vorbis channel mapping specifies
  33 // mappings for up to 8 channels. This information is part of the Vorbis I
  34 // Specification:
  35 // http://www.xiph.org/vorbis/doc/Vorbis_I_spec.html
  36 static const int kMaxVorbisChannels = 8;
  37
  38 // Maximum packet size used in Xiph's opusdec and FFmpeg's libopusdec.
  39 static const int kMaxOpusOutputPacketSizeSamples = 960 * 6;
  40
  41 static void RemapOpusChannelLayout(const uint8* opus_mapping,
  42                                    int num_channels,
  43                                    uint8* channel_layout) {
  44   DCHECK_LE(num_channels, kMaxVorbisChannels);
  45
  46   // Opus uses Vorbis channel layout.
  47   const int32 num_layouts = kMaxVorbisChannels;
  48   const int32 num_layout_values = kMaxVorbisChannels;
  49
  50   // Vorbis channel ordering for streams with >= 2 channels:
  51   // 2 Channels
  52   //   L, R
  53   // 3 Channels
  54   //   L, Center, R
  55   // 4 Channels
  56   //   Front L, Front R, Back L, Back R
  57   // 5 Channels
  58   //   Front L, Center, Front R, Back L, Back R
  59   // 6 Channels (5.1)
  60   //   Front L, Center, Front R, Back L, Back R, LFE
  61   // 7 channels (6.1)
  62   //   Front L, Front Center, Front R, Side L, Side R, Back Center, LFE
  63   // 8 Channels (7.1)
  64   //   Front L, Center, Front R, Side L, Side R, Back L, Back R, LFE
  65   //
  66   // Channel ordering information is taken from section 4.3.9 of the Vorbis I
  67   // Specification:
  68   // http://xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-800004.3.9
  69
  70   // These are the FFmpeg channel layouts expressed using the position of each
  71   // channel in the output stream from libopus.
  72   const uint8 kFFmpegChannelLayouts[num_layouts][num_layout_values] = {
  73     { 0 },
  74
  75     // Stereo: No reorder.
  76     { 0, 1 },
  77
  78     // 3 Channels, from Vorbis order to:
  79     //  L, R, Center
  80     { 0, 2, 1 },
  81
  82     // 4 Channels: No reorder.
  83     { 0, 1, 2, 3 },
  84
  85     // 5 Channels, from Vorbis order to:
  86     //  Front L, Front R, Center, Back L, Back R
  87     { 0, 2, 1, 3, 4 },
  88
  89     // 6 Channels (5.1), from Vorbis order to:
  90     //  Front L, Front R, Center, LFE, Back L, Back R
  91     { 0, 2, 1, 5, 3, 4 },
  92
  93     // 7 Channels (6.1), from Vorbis order to:
  94     //  Front L, Front R, Front Center, LFE, Side L, Side R, Back Center
  95     { 0, 2, 1, 6, 3, 4, 5 },
  96
  97     // 8 Channels (7.1), from Vorbis order to:
  98     //  Front L, Front R, Center, LFE, Back L, Back R, Side L, Side R
  99     { 0, 2, 1, 7, 5, 6, 3, 4 },
 100   };
 101
 102   // Reorder the channels to produce the same ordering as FFmpeg, which is
 103   // what the pipeline expects.
 104   const uint8* vorbis_layout_offset = kFFmpegChannelLayouts[num_channels - 1];
 105   for (int channel = 0; channel < num_channels; ++channel)
 106     channel_layout[channel] = opus_mapping[vorbis_layout_offset[channel]];
 107 }
 108
 109 // Opus Extra Data contents:
 110 // - "OpusHead" (64 bits)
 111 // - version number (8 bits)
 112 // - Channels C (8 bits)
 113 // - Pre-skip (16 bits)
 114 // - Sampling rate (32 bits)
 115 // - Gain in dB (16 bits, S7.8)
 116 // - Mapping (8 bits, 0=single stream (mono/stereo) 1=Vorbis mapping,
 117 //            2..254: reserved, 255: multistream with no mapping)
 118 //
 119 // - if (mapping != 0)
 120 //    - N = totel number of streams (8 bits)
 121 //    - M = number of paired streams (8 bits)
 122 //    - C times channel origin
 123 //         - if (C<2*M)
 124 //            - stream = byte/2
 125 //            - if (byte&0x1 == 0)
 126 //                - left
 127 //              else
 128 //                - right
 129 //         - else
 130 //            - stream = byte-M
 131
 132 // Default audio output channel layout. Used to initialize |stream_map| in
 133 // OpusExtraData, and passed to opus_multistream_decoder_create() when the
 134 // extra data does not contain mapping information. The values are valid only
 135 // for mono and stereo output: Opus streams with more than 2 channels require a
 136 // stream map.
 137 static const int kMaxChannelsWithDefaultLayout = 2;
 138 static const uint8 kDefaultOpusChannelLayout[kMaxChannelsWithDefaultLayout] = {
 139     0, 1 };
 140
 141 // Size of the Opus extra data excluding optional mapping information.
 142 static const int kOpusExtraDataSize = 19;
 143
 144 // Offset to the channel count byte in the Opus extra data.
 145 static const int kOpusExtraDataChannelsOffset = 9;
 146
 147 // Offset to the pre-skip value in the Opus extra data.
 148 static const int kOpusExtraDataSkipSamplesOffset = 10;
 149
 150 // Offset to the gain value in the Opus extra data.
 151 static const int kOpusExtraDataGainOffset = 16;
 152
 153 // Offset to the channel mapping byte in the Opus extra data.
 154 static const int kOpusExtraDataChannelMappingOffset = 18;
 155
 156 // Extra Data contains a stream map. The mapping values are in extra data beyond
 157 // the always present |kOpusExtraDataSize| bytes of data. The mapping data
 158 // contains stream count, coupling information, and per channel mapping values:
 159 //   - Byte 0: Number of streams.
 160 //   - Byte 1: Number coupled.
 161 //   - Byte 2: Starting at byte 2 are |extra_data->channels| uint8 mapping
 162 //             values.
 163 static const int kOpusExtraDataNumStreamsOffset = kOpusExtraDataSize;
 164 static const int kOpusExtraDataNumCoupledOffset =
 165     kOpusExtraDataNumStreamsOffset + 1;
 166 static const int kOpusExtraDataStreamMapOffset =
 167     kOpusExtraDataNumStreamsOffset + 2;
 168
 169 struct OpusExtraData {
 170   OpusExtraData()
 171       : channels(0),
 172         skip_samples(0),
 173         channel_mapping(0),
 174         num_streams(0),
 175         num_coupled(0),
 176         gain_db(0),
 177         stream_map() {
 178     memcpy(stream_map,
 179            kDefaultOpusChannelLayout,
 180            kMaxChannelsWithDefaultLayout);
 181   }
 182   int channels;
 183   uint16 skip_samples;
 184   int channel_mapping;
 185   int num_streams;
 186   int num_coupled;
 187   int16 gain_db;
 188   uint8 stream_map[kMaxVorbisChannels];
 189 };
 190
 191 // Returns true when able to successfully parse and store Opus extra data in
 192 // |extra_data|. Based on opus header parsing code in libopusdec from FFmpeg,
 193 // and opus_header from Xiph's opus-tools project.
 194 static bool ParseOpusExtraData(const uint8* data, int data_size,
 195                                const AudioDecoderConfig& config,
 196                                OpusExtraData* extra_data) {
 197   if (data_size < kOpusExtraDataSize) {
 198     DLOG(ERROR) << "Extra data size is too small:" << data_size;
 199     return false;
 200   }
 201
 202   extra_data->channels = *(data + kOpusExtraDataChannelsOffset);
 203
 204   if (extra_data->channels <= 0 || extra_data->channels > kMaxVorbisChannels) {
 205     DLOG(ERROR) << "invalid channel count in extra data: "
 206                 << extra_data->channels;
 207     return false;
 208   }
 209
 210   extra_data->skip_samples =
 211       ReadLE16(data, data_size, kOpusExtraDataSkipSamplesOffset);
 212   extra_data->gain_db = static_cast<int16>(
 213       ReadLE16(data, data_size, kOpusExtraDataGainOffset));
 214
 215   extra_data->channel_mapping = *(data + kOpusExtraDataChannelMappingOffset);
 216
 217   if (!extra_data->channel_mapping) {
 218     if (extra_data->channels > kMaxChannelsWithDefaultLayout) {
 219       DLOG(ERROR) << "Invalid extra data, missing stream map.";
 220       return false;
 221     }
 222
 223     extra_data->num_streams = 1;
 224     extra_data->num_coupled =
 225         (ChannelLayoutToChannelCount(config.channel_layout()) > 1) ? 1 : 0;
 226     return true;
 227   }
 228
 229   if (data_size < kOpusExtraDataStreamMapOffset + extra_data->channels) {
 230     DLOG(ERROR) << "Invalid stream map; insufficient data for current channel "
 231                 << "count: " << extra_data->channels;
 232     return false;
 233   }
 234
 235   extra_data->num_streams = *(data + kOpusExtraDataNumStreamsOffset);
 236   extra_data->num_coupled = *(data + kOpusExtraDataNumCoupledOffset);
 237
 238   if (extra_data->num_streams + extra_data->num_coupled != extra_data->channels)
 239     DVLOG(1) << "Inconsistent channel mapping.";
 240
 241   for (int i = 0; i < extra_data->channels; ++i)
 242     extra_data->stream_map[i] = *(data + kOpusExtraDataStreamMapOffset + i);
 243   return true;
 244 }
 245
 246 OpusAudioDecoder::OpusAudioDecoder(
 247     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
 248     : task_runner_(task_runner), opus_decoder_(nullptr) {}
 249
 250 std::string OpusAudioDecoder::GetDisplayName() const {
 251   return "OpusAudioDecoder";
 252 }
 253
 254 void OpusAudioDecoder::Initialize(const AudioDecoderConfig& config,
 255                                   const InitCB& init_cb,
 256                                   const OutputCB& output_cb) {
 257   DCHECK(task_runner_->BelongsToCurrentThread());
 258   InitCB bound_init_cb = BindToCurrentLoop(init_cb);
 259
 260   config_ = config;
 261   output_cb_ = BindToCurrentLoop(output_cb);
 262
 263   if (!ConfigureDecoder()) {
 264     bound_init_cb.Run(false);
 265     return;
 266   }
 267
 268   bound_init_cb.Run(true);
 269 }
 270
 271 void OpusAudioDecoder::Decode(const scoped_refptr<DecoderBuffer>& buffer,
 272                               const DecodeCB& decode_cb) {
 273   DCHECK(task_runner_->BelongsToCurrentThread());
 274   DCHECK(!decode_cb.is_null());
 275
 276   DecodeBuffer(buffer, BindToCurrentLoop(decode_cb));
 277 }
 278
 279 void OpusAudioDecoder::Reset(const base::Closure& closure) {
 280   DCHECK(task_runner_->BelongsToCurrentThread());
 281
 282   opus_multistream_decoder_ctl(opus_decoder_, OPUS_RESET_STATE);
 283   ResetTimestampState();
 284   task_runner_->PostTask(FROM_HERE, closure);
 285 }
 286
 287 OpusAudioDecoder::~OpusAudioDecoder() {
 288   DCHECK(task_runner_->BelongsToCurrentThread());
 289
 290   if (!opus_decoder_)
 291     return;
 292
 293   opus_multistream_decoder_ctl(opus_decoder_, OPUS_RESET_STATE);
 294   CloseDecoder();
 295 }
 296
 297 void OpusAudioDecoder::DecodeBuffer(
 298     const scoped_refptr<DecoderBuffer>& input,
 299     const DecodeCB& decode_cb) {
 300   DCHECK(task_runner_->BelongsToCurrentThread());
 301   DCHECK(!decode_cb.is_null());
 302   DCHECK(input.get());
 303
 304   // Libopus does not buffer output. Decoding is complete when an end of stream
 305   // input buffer is received.
 306   if (input->end_of_stream()) {
 307     decode_cb.Run(kOk);
 308     return;
 309   }
 310
 311   // Make sure we are notified if http://crbug.com/49709 returns.  Issue also
 312   // occurs with some damaged files.
 313   if (input->timestamp() == kNoTimestamp()) {
 314     DLOG(ERROR) << "Received a buffer without timestamps!";
 315     decode_cb.Run(kDecodeError);
 316     return;
 317   }
 318
 319   scoped_refptr<AudioBuffer> output_buffer;
 320
 321   if (!Decode(input, &output_buffer)) {
 322     decode_cb.Run(kDecodeError);
 323     return;
 324   }
 325
 326   if (output_buffer.get()) {
 327     output_cb_.Run(output_buffer);
 328   }
 329
 330   decode_cb.Run(kOk);
 331 }
 332
 333 bool OpusAudioDecoder::ConfigureDecoder() {
 334   if (config_.codec() != kCodecOpus) {
 335     DVLOG(1) << "Codec must be kCodecOpus.";
 336     return false;
 337   }
 338
 339   const int channel_count =
 340       ChannelLayoutToChannelCount(config_.channel_layout());
 341   if (!config_.IsValidConfig() || channel_count > kMaxVorbisChannels) {
 342     DLOG(ERROR) << "Invalid or unsupported audio stream -"
 343                 << " codec: " << config_.codec()
 344                 << " channel count: " << channel_count
 345                 << " channel layout: " << config_.channel_layout()
 346                 << " bits per channel: " << config_.bits_per_channel()
 347                 << " samples per second: " << config_.samples_per_second();
 348     return false;
 349   }
 350
 351   if (config_.is_encrypted()) {
 352     DLOG(ERROR) << "Encrypted audio stream not supported.";
 353     return false;
 354   }
 355
 356   // Clean up existing decoder if necessary.
 357   CloseDecoder();
 358
 359   // Parse the Opus Extra Data.
 360   OpusExtraData opus_extra_data;
 361   if (!ParseOpusExtraData(config_.extra_data(), config_.extra_data_size(),
 362                           config_,
 363                           &opus_extra_data))
 364     return false;
 365
 366   if (config_.codec_delay() < 0) {
 367     DLOG(ERROR) << "Invalid file. Incorrect value for codec delay: "
 368                 << config_.codec_delay();
 369     return false;
 370   }
 371
 372   if (config_.codec_delay() != opus_extra_data.skip_samples) {
 373     DLOG(ERROR) << "Invalid file. Codec Delay in container does not match the "
 374                 << "value in Opus Extra Data. " << config_.codec_delay()
 375                 << " vs " << opus_extra_data.skip_samples;
 376     return false;
 377   }
 378
 379   uint8 channel_mapping[kMaxVorbisChannels] = {0};
 380   memcpy(&channel_mapping,
 381          kDefaultOpusChannelLayout,
 382          kMaxChannelsWithDefaultLayout);
 383
 384   if (channel_count > kMaxChannelsWithDefaultLayout) {
 385     RemapOpusChannelLayout(opus_extra_data.stream_map,
 386                            channel_count,
 387                            channel_mapping);
 388   }
 389
 390   // Init Opus.
 391   int status = OPUS_INVALID_STATE;
 392   opus_decoder_ = opus_multistream_decoder_create(config_.samples_per_second(),
 393                                                   channel_count,
 394                                                   opus_extra_data.num_streams,
 395                                                   opus_extra_data.num_coupled,
 396                                                   channel_mapping,
 397                                                   &status);
 398   if (!opus_decoder_ || status != OPUS_OK) {
 399     DLOG(ERROR) << "opus_multistream_decoder_create failed status="
 400                 << opus_strerror(status);
 401     return false;
 402   }
 403
 404   status = opus_multistream_decoder_ctl(
 405       opus_decoder_, OPUS_SET_GAIN(opus_extra_data.gain_db));
 406   if (status != OPUS_OK) {
 407     DLOG(ERROR) << "Failed to set OPUS header gain; status="
 408                 << opus_strerror(status);
 409     return false;
 410   }
 411
 412   ResetTimestampState();
 413   return true;
 414 }
 415
 416 void OpusAudioDecoder::CloseDecoder() {
 417   if (opus_decoder_) {
 418     opus_multistream_decoder_destroy(opus_decoder_);
 419     opus_decoder_ = nullptr;
 420   }
 421 }
 422
 423 void OpusAudioDecoder::ResetTimestampState() {
 424   discard_helper_.reset(
 425       new AudioDiscardHelper(config_.samples_per_second(), 0));
 426   discard_helper_->Reset(config_.codec_delay());
 427 }
 428
 429 bool OpusAudioDecoder::Decode(const scoped_refptr<DecoderBuffer>& input,
 430                               scoped_refptr<AudioBuffer>* output_buffer) {
 431   // Allocate a buffer for the output samples.
 432   *output_buffer = AudioBuffer::CreateBuffer(
 433       config_.sample_format(),
 434       config_.channel_layout(),
 435       ChannelLayoutToChannelCount(config_.channel_layout()),
 436       config_.samples_per_second(),
 437       kMaxOpusOutputPacketSizeSamples);
 438   const int buffer_size =
 439       output_buffer->get()->channel_count() *
 440       output_buffer->get()->frame_count() *
 441       SampleFormatToBytesPerChannel(config_.sample_format());
 442
 443   float* float_output_buffer = reinterpret_cast<float*>(
 444       output_buffer->get()->channel_data()[0]);
 445   const int frames_decoded =
 446       opus_multistream_decode_float(opus_decoder_,
 447                                     input->data(),
 448                                     input->data_size(),
 449                                     float_output_buffer,
 450                                     buffer_size,
 451                                     0);
 452
 453   if (frames_decoded < 0) {
 454     DLOG(ERROR) << "opus_multistream_decode failed for"
 455                 << " timestamp: " << input->timestamp().InMicroseconds()
 456                 << " us, duration: " << input->duration().InMicroseconds()
 457                 << " us, packet size: " << input->data_size() << " bytes with"
 458                 << " status: " << opus_strerror(frames_decoded);
 459     return false;
 460   }
 461
 462   // Trim off any extraneous allocation.
 463   DCHECK_LE(frames_decoded, output_buffer->get()->frame_count());
 464   const int trim_frames = output_buffer->get()->frame_count() - frames_decoded;
 465   if (trim_frames > 0)
 466     output_buffer->get()->TrimEnd(trim_frames);
 467
 468   // Handles discards and timestamping.  Discard the buffer if more data needed.
 469   if (!discard_helper_->ProcessBuffers(input, *output_buffer))
 470     *output_buffer = nullptr;
 471
 472   return true;
 473 }
 474
 475 }  // namespace media