Re: ExtAudioFile and 8-bit samples
Re: ExtAudioFile and 8-bit samples
- Subject: Re: ExtAudioFile and 8-bit samples
- From: tahome izwah <email@hidden>
- Date: Tue, 01 Mar 2011 13:36:39 +0100
Contrary to higher word lengths, 8 bit sample frames in an AIFF are
unsigned by default, not sure why ExtAudioFile doesn't respect that.
I'm not sure if there's a combination of mFormatFlags to make it work.
I am using miniAIFF for reading/writing audio files as it has the
added benefit of being cross platform so I never encountered the
problem in my code.
HTH
--th
2011/3/1 Kevin Wojniak <email@hidden>:
> I've got some raw audio data that is in 8-bit samples. Without knowing any more details about the format (other than sample rate and channel), I threw it into an ExtAudioFile as an AIFF. The output sounded ok right but was very noisy. After googling around I figured out the data was encoded as offset-binary and AIFF expects two's compliment. Applying this conversion before writing the buffer resolved the issue.
>
> I was under the impression ExtAudioFile would do this for me. However, all the various options I tried for mFormatFlags didn't change anything (and none of them seemed to apply, based on their descriptions). Here is what I'm using:
>
> AudioStreamBasicDescription stream = {0};
> stream.mSampleRate = 22000;
> stream.mFormatID = kAudioFormatLinearPCM;
> stream.mFormatFlags = 0;
> stream.mBytesPerPacket = 1;
> stream.mFramesPerPacket = 1;
> stream.mBytesPerFrame = 1;
> stream.mChannelsPerFrame = 1;
> stream.mBitsPerChannel = 8;
>
> Am I just missing the wrong configuration, or is this encoding not supported?
>
> Thanks,
> Kevin
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