src/media/formats/mpeg/adts_stream_parser.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/mpeg/adts_stream_parser.h"
   6
   7 #include "media/formats/mpeg/adts_constants.h"
   8
   9 namespace media {
  10
  11 static const uint32 kADTSStartCodeMask = 0xfff00000;
  12
  13 ADTSStreamParser::ADTSStreamParser()
  14     : MPEGAudioStreamParserBase(kADTSStartCodeMask, kCodecAAC) {}
  15
  16 ADTSStreamParser::~ADTSStreamParser() {}
  17
  18 int ADTSStreamParser::ParseFrameHeader(const uint8* data,
  19                                        int size,
  20                                        int* frame_size,
  21                                        int* sample_rate,
  22                                        ChannelLayout* channel_layout,
  23                                        int* sample_count) const {
  24   DCHECK(data);
  25   DCHECK_GE(size, 0);
  26   DCHECK(frame_size);
  27
  28   if (size < 8)
  29     return 0;
  30
  31   BitReader reader(data, size);
  32   int sync;
  33   int version;
  34   int layer;
  35   int protection_absent;
  36   int profile;
  37   size_t sample_rate_index;
  38   size_t channel_layout_index;
  39   int frame_length;
  40   size_t num_data_blocks;
  41   int unused;
  42
  43   if (!reader.ReadBits(12, &sync) ||
  44       !reader.ReadBits(1, &version) ||
  45       !reader.ReadBits(2, &layer) ||
  46       !reader.ReadBits(1, &protection_absent) ||
  47       !reader.ReadBits(2, &profile) ||
  48       !reader.ReadBits(4, &sample_rate_index) ||
  49       !reader.ReadBits(1, &unused) ||
  50       !reader.ReadBits(3, &channel_layout_index) ||
  51       !reader.ReadBits(4, &unused) ||
  52       !reader.ReadBits(13, &frame_length) ||
  53       !reader.ReadBits(11, &unused) ||
  54       !reader.ReadBits(2, &num_data_blocks) ||
  55       (!protection_absent && !reader.ReadBits(16, &unused))) {
  56     return -1;
  57   }
  58
  59   DVLOG(2) << "Header data :" << std::hex
  60            << " sync 0x" << sync
  61            << " version 0x" << version
  62            << " layer 0x" << layer
  63            << " profile 0x" << profile
  64            << " sample_rate_index 0x" << sample_rate_index
  65            << " channel_layout_index 0x" << channel_layout_index;
  66
  67   const int bytes_read = reader.bits_read() / 8;
  68   if (sync != 0xfff || layer != 0 || frame_length < bytes_read ||
  69       sample_rate_index >= kADTSFrequencyTableSize ||
  70       channel_layout_index >= kADTSChannelLayoutTableSize) {
  71     MEDIA_LOG(log_cb()) << "Invalid header data :" << std::hex
  72                         << " sync 0x" << sync
  73                         << " version 0x" << version
  74                         << " layer 0x" << layer
  75                         << " sample_rate_index 0x" << sample_rate_index
  76                         << " channel_layout_index 0x" << channel_layout_index;
  77     return -1;
  78   }
  79
  80   if (sample_rate)
  81     *sample_rate = kADTSFrequencyTable[sample_rate_index];
  82
  83   if (frame_size)
  84     *frame_size = frame_length;
  85
  86   if (sample_count)
  87     *sample_count = (num_data_blocks + 1) * kSamplesPerAACFrame;
  88
  89   if (channel_layout)
  90     *channel_layout = kADTSChannelLayoutTable[channel_layout_index];
  91
  92   return bytes_read;
  93 }
  94
  95 }  // namespace media