void Handle(char c)
{
switch(state)
{
case State::Default:
ReadDefault(c);
break;
case State::ReadTagName:
ReadTagName(c);
break;
case State::SkipTag:
SkipTag(c);
break;
case State::ReadTag:
ReadTag(c);
break;
case State::ReadAttribute:
ReadAttribute(c);
break;
case State::SkipAttribute:
SkipAttribute(c);
break;
case State::SkipComment:
SkipComment(c);
break;
}
}
void
ESDSAtom::OnOverrideAudioDescription(AudioDescription *pAudioDescription)
{
// decode for aac and check for HE-AAC which uses a framesize of 2048
// also check for MP3 which has an ESDS
uint32 offset = 0;
BitParser parser;
if (SkipTag(pAudioDescription->theDecoderConfig, 0x03, &offset)) {
offset += 3;
} else {
offset += 2;
}
if (SkipTag(pAudioDescription->theDecoderConfig, 0x04, &offset)) {
parser.Init(&pAudioDescription->theDecoderConfig[offset],
(pAudioDescription->DecoderConfigSize - offset) * 8);
ESDSType = parser.GetValue(8);
StreamType = parser.GetValue(6);
parser.Skip(2);
NeededBufferSize = parser.GetValue(24);
MaxBitRate = parser.GetValue(32);
AvgBitRate = parser.GetValue(32);
pAudioDescription->BitRate = AvgBitRate;
offset+=13;
}
// Find Tag 0x05 that describes the audio format
SkipTag(pAudioDescription->theDecoderConfig, 0x05, &offset);
bool smallFrameSize;
uint32 SampleRate;
// remember where the tag 5 starts
uint32 extendedAudioConfig = offset;
switch (ESDSType) {
case 64: // AAC so use AAC Header details to override ESDS values
parser.Init(&pAudioDescription->theDecoderConfig[offset],
(pAudioDescription->DecoderConfigSize - offset) * 8);
// 5 bits are decoder type
theAACHeader.objTypeIndex = parser.GetValue(5);
if (theAACHeader.objTypeIndex == 31) {
theAACHeader.objTypeIndex = 32 + parser.GetValue(6);
}
// 4 bits are frequency index
theAACHeader.sampleRateIndex = parser.GetValue(4);
if (theAACHeader.sampleRateIndex == 15) {
// Direct encoding of SampleRate
SampleRate = parser.GetValue(24);
} else {
SampleRate = aac_sampling_rate[theAACHeader.sampleRateIndex];
}
// 4 bits are channels
theAACHeader.totalChannels = parser.GetValue(4);
// 1 bit determines small frame size
smallFrameSize = (parser.GetValue(1) == 1);
if (theAACHeader.objTypeIndex < 3) {
pAudioDescription->codecSubType = 'mp4a';
pAudioDescription->FrameSize = 1024;
if (smallFrameSize) {
pAudioDescription->FrameSize = 960;
}
} else {
pAudioDescription->codecSubType = 'haac';
pAudioDescription->FrameSize = 2048;
}
// Override STSD
pAudioDescription->theAudioSampleEntry.SampleRate = SampleRate;
pAudioDescription->theAudioSampleEntry.ChannelCount =
theAACHeader.totalChannels;
// Reset decoder Config memory
memcpy(pAudioDescription->theDecoderConfig,
&pAudioDescription->theDecoderConfig[extendedAudioConfig],
pAudioDescription->DecoderConfigSize - extendedAudioConfig + 1);
break;
case 107: // MP3
pAudioDescription->codecSubType = '.mp3';
// Only set this for mp3, we calc it normally
if (NeededBufferSize > pAudioDescription->BufferSize) {
pAudioDescription->BufferSize = NeededBufferSize;
}
break;
}
}