Apple

On Feb 27, 2008, at 6:42 AM, Roland Silver wrote:

I'm trying to adapt the code from <CoreAudio/SimpleSDK/DefaultOutputUnit> to serve as a back end to allow my music composition program to play sounds.

In DefaultOutputUnit the audio data is non-interleaved; I need to change it so that the data is interleaved. One obvious thing to change is theFormatFlags, from

UInt32 theFormatFlags =
kLinearPCMFormatFlagIsSignedInteger
| kAudioFormatFlagsNativeEndian
| kLinearPCMFormatFlagIsPacked
| kAudioFormatFlagIsNonInterleaved;

to

UInt32 theFormatFlags =
kLinearPCMFormatFlagIsSignedInteger
| kAudioFormatFlagsNativeEndian
| kLinearPCMFormatFlagIsPacked

Also, since there are two channels, there should be one buffer (twice the size of the buffers in the non-interleaved case), not two.

yes - but this also changes the bytes per packet values, etc... Its probably best to use the CAStreamBasicDescription class in PublicUtility - it has a SetCanonical method that allows you to specify interleaved or not, and it will fill out the ASBD fields for you

References:
	>DefaultOutputUnit with interleaved data (From: Roland Silver <email@hidden>)