Update comments about ISO spec on aac parser.

media/formats/mp4/aac.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/formats/mp4/aac.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "media/base/bit_reader.h"
@@ skipping 20 matching lines @@
     return false;
 
   BitReader reader(&data[0], data.size());
   uint8 extension_type = 0;
   bool ps_present = false;
   uint8 extension_frequency_index = 0xff;
 
   frequency_ = 0;
   extension_frequency_ = 0;
 
-  // TODO(msu.koo): Need to update comments after checking which version of
-  // ISO 14496-3 this implementation is according to. Also need to reflect
-  // ISO 14496-3:2009 if ISO 14496-3:2005 was reflected here.
+  // TODO(msu.koo): Need to consider whether ISO 14496-3:2009 needs
+  // to be reflected instead of ISO 14496-3:2005.
   // https://crbug.com/532281
 
-  // The following code is written according to ISO 14496 Part 3 Table 1.13 -
+  // The following code is written according to ISO 14496-3:2005 Table 1.13 -
   // Syntax of AudioSpecificConfig.
 
   // Read base configuration
   RCHECK(reader.ReadBits(5, &profile_));
   RCHECK(reader.ReadBits(4, &frequency_index_));
   if (frequency_index_ == 0xf)
     RCHECK(reader.ReadBits(24, &frequency_));
   RCHECK(reader.ReadBits(4, &channel_config_));
 
   // Read extension configuration.
@@ skipping 97 matching lines @@
   return true;
 }
 
 int AAC::GetOutputSamplesPerSecond(bool sbr_in_mimetype) const {
   if (extension_frequency_ > 0)
     return extension_frequency_;
 
   if (!sbr_in_mimetype)
     return frequency_;
 
-  // The following code is written according to ISO 14496 Part 3 Table 1.11 and
+  // The following code is written according to ISO 14496-3:2005 Table 1.11 and
   // Table 1.22. (Table 1.11 refers to the capping to 48000, Table 1.22 refers
   // to SBR doubling the AAC sample rate.)
   // TODO(acolwell) : Extend sample rate cap to 96kHz for Level 5 content.
   DCHECK_GT(frequency_, 0);
   return std::min(2 * frequency_, 48000);
 }
 
 ChannelLayout AAC::GetChannelLayout(bool sbr_in_mimetype) const {
   // Check for implicit signalling of HE-AAC and indicate stereo output
   // if the mono channel configuration is signalled.
-  // See ISO-14496-3 Section 1.6.6.1.2 for details about this special casing.
+  // See ISO 14496-3:2005 Section 1.6.5.3 for details about this special casing.
   if (sbr_in_mimetype && channel_config_ == 1)
     return CHANNEL_LAYOUT_STEREO;
 
   return channel_layout_;
 }
 
 bool AAC::ConvertEsdsToADTS(std::vector<uint8>* buffer) const {
   size_t size = buffer->size() + kADTSHeaderMinSize;
 
   DCHECK(profile_ >= 1 && profile_ <= 4 && frequency_index_ != 0xf &&
@@ skipping 12 matching lines @@
       (channel_config_ >> 2);
   adts[3] = static_cast<uint8>(((channel_config_ & 0x3) << 6) + (size >> 11));
   adts[4] = static_cast<uint8>((size & 0x7ff) >> 3);
   adts[5] = ((size & 7) << 5) + 0x1f;
   adts[6] = 0xfc;
 
   return true;
 }
 
 // Currently this function only support GASpecificConfig defined in
-// ISO 14496 Part 3 Table 4.1 - Syntax of GASpecificConfig()
+// ISO 14496-3:2005 Table 4.1 - Syntax of GASpecificConfig()
 bool AAC::SkipDecoderGASpecificConfig(BitReader* bit_reader) const {
   switch (profile_) {
     case 1:
     case 2:
     case 3:
     case 4:
     case 6:
     case 7:
     case 17:
     case 19:
@@ skipping 22 matching lines @@
     case 26:
     case 27:
       return false;
     default:
       break;
   }
 
   return true;
 }
 
-// The following code is written according to ISO 14496 part 3 Table 4.1 -
+// The following code is written according to ISO 14496-3:2005 Table 4.1 -
 // GASpecificConfig.
 bool AAC::SkipGASpecificConfig(BitReader* bit_reader) const {
   uint8 extension_flag = 0;
   uint8 depends_on_core_coder;
   uint16 dummy;
 
   RCHECK(bit_reader->ReadBits(1, &dummy));  // frameLengthFlag
   RCHECK(bit_reader->ReadBits(1, &depends_on_core_coder));
   if (depends_on_core_coder == 1)
     RCHECK(bit_reader->ReadBits(14, &dummy));  // coreCoderDelay
@@ skipping 16 matching lines @@
 
     RCHECK(bit_reader->ReadBits(1, &dummy));  // extensionFlag3
   }
 
   return true;
 }
 
 }  // namespace mp4
 
 }  // namespace media