Re: AudioConverter format not supported error
Re: AudioConverter format not supported error
- Subject: Re: AudioConverter format not supported error
- From: Robert Grant <email@hidden>
- Date: Wed, 13 Aug 2003 15:26:34 -0400
Thanks everyone - all your suggestions put together got me to a happy
AudioConverter :-)
Sorry for the newbie questions. As I said earlier I've been using
QuickTime before and it's AIFF file export is much easier - though, as
I also mentioned, much less flexible.
Thanks again - time to muddle on :-)
Robert.
On Wednesday, August 13, 2003, at 03:01 PM, Philippe Wicker wrote:
On Wednesday, August 13, 2003, at 08:05 PM, Robert Grant wrote:
I'm delving into the realm of AudioFiles and AudioConverters because
QuickTime's AIFF support stops short at 48000 Hz and 16 bits.
So I'm trying to build an AudioConverter that'll take a
non-interleaved 32 bit float stereo buffer and convert it into
interleaved 16 bit integer stereo.
Trouble is I'm getting a 'fmt?' error but I'm not sure which format
is causing trouble. Of course my ignorance is a major factor :-)
Here are the two ASBDs:
sampleRate = 44100; // I want to support various sample rates
bitDepth = 16; // I want to support 24 bits too.
The AIFF format:
AudioStreamBasicDescription inFormat;
inFormat.mSampleRate = sampleRate;
inFormat.mFormatID = kAudioFormatLinearPCM;
inFormat.mFormatFlags = kLinearPCMFormatFlagIsBigEndian;
Are you sure you want **unsigned** integer? The AIF files I have
played with recently were always "signed integer". Anyway, I had to
add "kLinearPCMFormatFlagIsSignedInteger" to make it work.
inFormat.mBytesPerPacket = 2 * (bitDepth / 8);
inFormat.mFramesPerPacket = 1;
inFormat.mBytesPerFrame = 2 * (bitDepth / 8);
inFormat.mChannelsPerFrame = 2;
inFormat.mBitsPerChannel = bitDepth;
The Float format:
AudioStreamBasicDescription rwFormat;
rwFormat.mSampleRate = sampleRate;
rwFormat.mFormatID = kAudioFormatLinearPCM;
rwFormat.mFormatFlags = kLinearPCMFormatFlagIsNonInterleaved |
kLinearPCMFormatFlagIsFloat;
You are requesting **little** endian float, if you add
"kAudioFormatFlagIsBigEndian" then there is no more error. Maybe that
little endian float is an illegal format for AIF files?
I have made a little C routine that prints the format flag in a
readable format. I don't know if such a utility is available somewhere
in the SDK. If not, I'd be glad to share it whit the list.
rwFormat.mBytesPerPacket = 4;
rwFormat.mFramesPerPacket = 1;
rwFormat.mBytesPerFrame = 4;
rwFormat.mChannelsPerFrame = 2;
rwFormat.mBitsPerChannel = 32;
Create a new audio converter with these formats gets me a 'fmt?'
error.
Thanks,
Robert.
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Philippe Wicker
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