Re: kAudioFileAAC_ADTSType for aac plus?
Re: kAudioFileAAC_ADTSType for aac plus?
- Subject: Re: kAudioFileAAC_ADTSType for aac plus?
- From: William Stewart <email@hidden>
- Date: Tue, 22 Sep 2009 18:02:13 -0700
HE-AAC is a layered audio format - it has a core layer which is AAC
(which is what you see here), and then an enhanced layer (which is
that for a few extra bits, alot of extra work, you can get a richer
format decoded).
We implement this with what we call an AudioFormatList - if you use
this property with audio file (and audio format) you will see both
'aac ' and 'aach' listed and then you can chose which format you want
to actually decode.
Have a look through AudioFile.h and AudioFormat.h for comments. aqplay
also uses audio format lists as an example of how this can be used
Bill
On Sep 15, 2009, at 2:33 AM, Jacobson981 wrote:
i'm using AudioFileStreamOpen to listen aac plus streams.
i initialize queue with kAudioFileAAC_ADTSType.
i get AudioStreamBasicDescription filled in
kAudioFileStreamProperty_ReadyToProducePackets with
AudioFileStreamGetProperty(inAudioFileStream,
kAudioFileStreamProperty_DataFormat, &descSize, &desc);
it plays perfectly. But,
NSLog(@"samplerate: %f",asbd.mSampleRate);
NSLog(@"mBitsPerChannel: %f",asbd.mBitsPerChannel);
NSLog(@"mChannelsPerFrame: %f",asbd.mChannelsPerFrame);
NSLog(@"mBytesPerPacket: %f",asbd.mBytesPerPacket);
NSLog(@"mFramesPerPacket: %f",asbd.mFramesPerPacket);
Outputs:
samplerate: 22050.000000
mBitsPerChannel: 22050.000000
mChannelsPerFrame: 22050.000000
mBytesPerPacket: 22050.000000
mFramesPerPacket: 22050.000000
this means, audio library is unable to correctly identify stream
information, right? Why is this? Because of aacp codec?
Is there anything that can be done?
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