My AUHAL Output Audio Unit
My AUHAL Output Audio Unit
- Subject: My AUHAL Output Audio Unit
- From: Daniel Todd Currie <email@hidden>
- Date: Thu, 24 Jun 2004 23:29:20 -0700
I've just finished implementing my AUHAL Output Audio Unit according to
the sample code and docs available here:
http://developer.apple.com/technotes/tn2002/tn2091.html
I run it and look at the buffer data that comes pouring into my app and
it is just a big long list of zeros. :(
I have no idea where to begin troubleshooting, as the AU setup sample
code seems pretty thorough and I have checked for all of the
ComponentResult errors in my AudioUnitSetProperty calls. I was a bit
perplexed by one of the listings in the link above, so I wonder if it
could be the problem. The block of code from that page:
SInt32 *channelMap =NULL;
UInt32 numOfChannels = DesiredFormat.mChannelsPerFrame; //2 channels
UInt32 mapSize = numOfChannels *sizeof(SInt32);
channelMap = (SInt32 *)malloc(size);
//for each channel of desired input, map the channel from
//the device's output channel.
for(UInt32 i=0;i<numOfChannels;i++)
{
channelMap[i]=-1;
}
//channelMap[desiredInputChannel] = deviceOutputChannel;
channelMap[0] = 2;
channelMap[1] = 3;
AudioUnitSetProperty(InputUnit, kAudioOutputUnitProperty_ChannelMap,
kAudioUnitScope_Output, 1, channelMap, size);
Aside from what seems like a typo where "size" is used instead of
"mapSize", I don't understand why channelMap elements are set once in
the for loop, and then once again after the for loop. I implemented
the AU for my own needs as best I could from this example, but it makes
sense that if I were somehow mapping the channels incorrectly I might
get a bunch of silence. Can anyone shed a little light on the snippet
above?
Thanks a million,
-- Daniel Todd Currie
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.