[alsa-devel] How to tell user level hardware not support a certain format in a certain sample rate

Hi,

runtime->hw.rates and runtime->hw.formats indicate the rate and formats hardware can support, so the user level plugins can auto-convert the audio data. But hardware may not support a certain combin of sample rate and format, and will cause hw_parm fail. In such case, plugin auto-convert will not work. How can I let userlevel know the failure conbin, so let auto-convert work?

Thanks Richard