media/formats/mp2t/es_parser_mpeg1audio.cc

   1 // Copyright 2014 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/formats/mp2t/es_parser_mpeg1audio.h"
   6
   7
   8 #include "base/basictypes.h"
   9 #include "base/bind.h"
  10 #include "base/logging.h"
  11 #include "base/strings/string_number_conversions.h"
  12 #include "media/base/audio_timestamp_helper.h"
  13 #include "media/base/bit_reader.h"
  14 #include "media/base/buffers.h"
  15 #include "media/base/channel_layout.h"
  16 #include "media/base/stream_parser_buffer.h"
  17 #include "media/formats/common/offset_byte_queue.h"
  18 #include "media/formats/mp2t/mp2t_common.h"
  19 #include "media/formats/mpeg/mpeg1_audio_stream_parser.h"
  20
  21 namespace media {
  22 namespace mp2t {
  23
  24 struct EsParserMpeg1Audio::Mpeg1AudioFrame {
  25   // Pointer to the ES data.
  26   const uint8* data;
  27
  28   // Frame size.
  29   int size;
  30
  31   // Number of samples in the frame.
  32   int sample_count;
  33
  34   // Frame offset in the ES queue.
  35   int64 queue_offset;
  36 };
  37
  38 EsParserMpeg1Audio::EsParserMpeg1Audio(
  39     const NewAudioConfigCB& new_audio_config_cb,
  40     const EmitBufferCB& emit_buffer_cb,
  41     const LogCB& log_cb)
  42   : log_cb_(log_cb),
  43     new_audio_config_cb_(new_audio_config_cb),
  44     emit_buffer_cb_(emit_buffer_cb) {
  45 }
  46
  47 EsParserMpeg1Audio::~EsParserMpeg1Audio() {
  48 }
  49
  50 bool EsParserMpeg1Audio::ParseFromEsQueue() {
  51   // Look for every MPEG1 audio frame in the ES buffer.
  52   Mpeg1AudioFrame mpeg1audio_frame;
  53   while (LookForMpeg1AudioFrame(&mpeg1audio_frame)) {
  54     // Update the audio configuration if needed.
  55     DCHECK_GE(mpeg1audio_frame.size, MPEG1AudioStreamParser::kHeaderSize);
  56     if (!UpdateAudioConfiguration(mpeg1audio_frame.data))
  57       return false;
  58
  59     // Get the PTS & the duration of this access unit.
  60     TimingDesc current_timing_desc =
  61         GetTimingDescriptor(mpeg1audio_frame.queue_offset);
  62     if (current_timing_desc.pts != kNoTimestamp())
  63       audio_timestamp_helper_->SetBaseTimestamp(current_timing_desc.pts);
  64
  65     if (audio_timestamp_helper_->base_timestamp() == kNoTimestamp()) {
  66       DVLOG(1) << "Skipping audio frame with unknown timestamp";
  67       SkipMpeg1AudioFrame(mpeg1audio_frame);
  68       continue;
  69     }
  70     base::TimeDelta current_pts = audio_timestamp_helper_->GetTimestamp();
  71     base::TimeDelta frame_duration =
  72         audio_timestamp_helper_->GetFrameDuration(
  73             mpeg1audio_frame.sample_count);
  74
  75     // Emit an audio frame.
  76     bool is_key_frame = true;
  77
  78     // TODO(wolenetz/acolwell): Validate and use a common cross-parser TrackId
  79     // type and allow multiple audio tracks. See https://crbug.com/341581.
  80     scoped_refptr<StreamParserBuffer> stream_parser_buffer =
  81         StreamParserBuffer::CopyFrom(
  82             mpeg1audio_frame.data,
  83             mpeg1audio_frame.size,
  84             is_key_frame,
  85             DemuxerStream::AUDIO, 0);
  86     stream_parser_buffer->set_timestamp(current_pts);
  87     stream_parser_buffer->set_duration(frame_duration);
  88     emit_buffer_cb_.Run(stream_parser_buffer);
  89
  90     // Update the PTS of the next frame.
  91     audio_timestamp_helper_->AddFrames(mpeg1audio_frame.sample_count);
  92
  93     // Skip the current frame.
  94     SkipMpeg1AudioFrame(mpeg1audio_frame);
  95   }
  96
  97   return true;
  98 }
  99
 100 void EsParserMpeg1Audio::Flush() {
 101 }
 102
 103 void EsParserMpeg1Audio::ResetInternal() {
 104   last_audio_decoder_config_ = AudioDecoderConfig();
 105 }
 106
 107 bool EsParserMpeg1Audio::LookForMpeg1AudioFrame(
 108     Mpeg1AudioFrame* mpeg1audio_frame) {
 109   int es_size;
 110   const uint8* es;
 111   es_queue_->Peek(&es, &es_size);
 112
 113   int max_offset = es_size - MPEG1AudioStreamParser::kHeaderSize;
 114   if (max_offset <= 0)
 115     return false;
 116
 117   for (int offset = 0; offset < max_offset; offset++) {
 118     const uint8* cur_buf = &es[offset];
 119     if (cur_buf[0] != 0xff)
 120       continue;
 121
 122     int remaining_size = es_size - offset;
 123     DCHECK_GE(remaining_size, MPEG1AudioStreamParser::kHeaderSize);
 124     MPEG1AudioStreamParser::Header header;
 125     if (!MPEG1AudioStreamParser::ParseHeader(log_cb_, cur_buf, &header))
 126       continue;
 127
 128     if (remaining_size < header.frame_size) {
 129       // Not a full frame: will resume when we have more data.
 130       // Remove all the bytes located before the frame header,
 131       // these bytes will not be used anymore.
 132       es_queue_->Pop(offset);
 133       return false;
 134     }
 135
 136     // Check whether there is another frame
 137     // |frame_size| apart from the current one.
 138     if (remaining_size >= header.frame_size + 1 &&
 139         cur_buf[header.frame_size] != 0xff) {
 140       continue;
 141     }
 142
 143     es_queue_->Pop(offset);
 144     es_queue_->Peek(&mpeg1audio_frame->data, &es_size);
 145     mpeg1audio_frame->queue_offset = es_queue_->head();
 146     mpeg1audio_frame->size = header.frame_size;
 147     mpeg1audio_frame->sample_count = header.sample_count;
 148     DVLOG(LOG_LEVEL_ES)
 149         << "MPEG1 audio syncword @ pos=" << mpeg1audio_frame->queue_offset
 150         << " frame_size=" << mpeg1audio_frame->size;
 151     DVLOG(LOG_LEVEL_ES)
 152         << "MPEG1 audio header: "
 153         << base::HexEncode(mpeg1audio_frame->data,
 154                            MPEG1AudioStreamParser::kHeaderSize);
 155     return true;
 156   }
 157
 158   es_queue_->Pop(max_offset);
 159   return false;
 160 }
 161
 162 bool EsParserMpeg1Audio::UpdateAudioConfiguration(
 163     const uint8* mpeg1audio_header) {
 164   MPEG1AudioStreamParser::Header header;
 165   if (!MPEG1AudioStreamParser::ParseHeader(log_cb_,
 166                                            mpeg1audio_header,
 167                                            &header)) {
 168     return false;
 169   }
 170
 171   // TODO(damienv): Verify whether Android playback requires the extra data
 172   // field for Mpeg1 audio. If yes, we should generate this field.
 173   AudioDecoderConfig audio_decoder_config(
 174       kCodecMP3,
 175       kSampleFormatS16,
 176       header.channel_layout,
 177       header.sample_rate,
 178       NULL, 0,
 179       false);
 180
 181   if (!audio_decoder_config.Matches(last_audio_decoder_config_)) {
 182     DVLOG(1) << "Sampling frequency: " << header.sample_rate;
 183     DVLOG(1) << "Channel layout: " << header.channel_layout;
 184     // Reset the timestamp helper to use a new time scale.
 185     if (audio_timestamp_helper_ &&
 186         audio_timestamp_helper_->base_timestamp() != kNoTimestamp()) {
 187       base::TimeDelta base_timestamp = audio_timestamp_helper_->GetTimestamp();
 188       audio_timestamp_helper_.reset(
 189         new AudioTimestampHelper(header.sample_rate));
 190       audio_timestamp_helper_->SetBaseTimestamp(base_timestamp);
 191     } else {
 192       audio_timestamp_helper_.reset(
 193           new AudioTimestampHelper(header.sample_rate));
 194     }
 195     // Audio config notification.
 196     last_audio_decoder_config_ = audio_decoder_config;
 197     new_audio_config_cb_.Run(audio_decoder_config);
 198   }
 199
 200   return true;
 201 }
 202
 203 void EsParserMpeg1Audio::SkipMpeg1AudioFrame(
 204     const Mpeg1AudioFrame& mpeg1audio_frame) {
 205   DCHECK_EQ(mpeg1audio_frame.queue_offset, es_queue_->head());
 206   es_queue_->Pop(mpeg1audio_frame.size);
 207 }
 208
 209 }  // namespace mp2t
 210 }  // namespace media