Problem writing to PCM plugin

["Arve Knudsen" <aknuds-1@broadpark.no>]

I'm currently trying to implement support for user defined pcm plugins in  
PortAudio ALSA (ALSA-lib 1.05), and I've got as far as discovering the  
pcms. In order to test I defined a routing plugin, which moves data from  
channel 0/1 to 16/17 (S/PDIF) on my Hammerfall Lite. With aplay this  
plugin works just fine, but when I open it with PortAudio the same way as  
with any hardware device, the output is simply silent (I can't listen to  
any of the ADAT channels since I lack ADAT gear). Defining a simple plugin  
which does nothing but drive my onboard nForce2 (routing fails with this  
assertion: 'pcm_plug.c:363: snd_pcm_plug_change_channels: Assertion  
`snd_pcm_format_linear(slv->format)' failed') works the same as if I open  
the hw device.

The obvious difference to aplay I can think of is that we use floating  
point format in the PortAudio tests, so there is an intermediate  
conversion before the audio gets to the routing plugin. Could this be the  
cause of the problem? If you wish I can provide output from snd_pcm_dump.

Thanks

Arve Knudsen


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