On Dec 16, 2011, at 8:09 AM, Iain McCowan <
email@hidden> wrote:
> Hello,
>
> I am working to implement a custom DSP plug-in to the standard USB audio driver following Apple's SampleUSBAudioPlugin example.
>
> Can anyone out there tell me what the specified behaviour is for the numSampleFrames in the process function:
>
> pluginProcess (float * mixBuf, UInt32 numSampleFrames, UInt32 numChannels)
>
> My DSP needs a fixed buffer size, so I imagine I need to implement a circular buffer in my code to guarantee this, in case numSampleFrames varies.
>
> I can log this to get empirical numbers, but wondered if there is a specification that tells me:
>
> - what the min and max values for numSampleFrames will be,
> - or whether the numSampleFrames will be fixed
> - or whether it is possible to configure the numSampleFrames you want
>
> Is this just related to the USB packet size? My device is class 2.0 compliant, 48 kHz, 24-bit, 7 channel.
>
> thanks,
>
> Iain.