Re: old mtcoreaudio code doesn't work now
Re: old mtcoreaudio code doesn't work now
- Subject: Re: old mtcoreaudio code doesn't work now
- From: dudley ackerman <email@hidden>
- Date: Tue, 8 Jan 2008 16:08:47 -0800
On Jan 8, 2008, at 3:32 PM, dudley ackerman wrote:
<snip>
is it possible that we used to be able specify that we wanted data
as 16 bit frames and we can't do that in the latest version of
mtcoreaudio?
we used this setup for the app side specification for source of
output and destination of input:
AudioStreamBasicDescription shtoomDescription;
shtoomDescription.mSampleRate = [self sampleRate];
shtoomDescription.mFormatID = kAudioFormatLinearPCM;
shtoomDescription.mFormatFlags = kLinearPCMFormatFlagIsPacked |
kLinearPCMFormatFlagIsSignedInteger |
kLinearPCMFormatFlagIsBigEndian | kAudioFormatFlagIsNonInterleaved;
shtoomDescription.mBytesPerFrame = sizeof(SInt16);
shtoomDescription.mFramesPerPacket = 1;
shtoomDescription.mBytesPerPacket = sizeof(SInt16);
shtoomDescription.mChannelsPerFrame = 1;
shtoomDescription.mBitsPerChannel = 16;
shtoomDescription.mReserved = 0;
do i now have to expect Float32 frames and have to convert that to
16bit integer frames in my own code.
i'm sure that is my problem -- i just had to stare at the code long
enough to see it.
ok, so maybe i am not so sure.
the old code used the mBytesPerFrame where the new code just uses '2'.
so, what is the meaning of this snippet in MTConversionBuffer.m:
srcFrames = ((srcFrames * 2) / srcChans) / sizeof(Float32);
dstFrames = ((dstFrames * 2) / dstChans) / sizeof(Float32);
what is Float32 in the conversion and what is 16 bit?
and while i am here, how about this snippet in the same method in the
old code:
BOOL srcInterleaved = !(srcDescription.mFormatFlags &
kAudioFormatFlagIsNonInterleaved);
BOOL dstInterleaved = !(dstDescription.mFormatFlags &
kAudioFormatFlagIsNonInterleaved);
audioBuffer = [[MTAudioBuffer alloc]
initWithCapacityFrames:totalBufferFrames channels:srcChans
interleaved:srcInterleaved];
now, in the latest version of mtcoreaudio i see:
conversionChannels = MIN ( srcChans, dstChans );
audioBuffer = [[MTAudioBuffer alloc]
initWithCapacityFrames:totalBufferFrames channels:conversionChannels];
doesn't interleaving matter, anymore?
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