[alsa-devel] Errors iterating over PCM stream hints and opening based on NAME/IOID

[Trent Reed]

Hey All,

I'm still having trouble understanding this, is anyone able to help me?

Thanks,
- Trent Reed

On Fri, May 6, 2016 at 8:19 PM, Trent Reed <treed0803 at gmail.com> wrote:
> Hey All,
>
> (Tried to send an email earlier, it didn't seem to send?)
>
> I'm trying to understand ALSA, having a little trouble with some
> errors that I can't ration over.
> Gist Repro: https://gist.github.com/TReed0803/353ce27d37bc1ebe965854ea88c8b97b
>
> Whenever I run the above simple code (iterate over PCM stream hints,
> open for Playback/Capture depending on IOID; output also provided at
> link above) I notice that I sometimes hit errors. I'm having trouble
> understanding these errors, because as I understand I'm using the ALSA
> library correctly. For example, dmix is telling me that it "Only
> supports playback streams", well then, why does the hint IOID return
> that it supports capture as well? (same for dsnoop). More confusing
> are the "ALSA lib pcm_route.c:867:(find_matching_chmap) Found no
> matching channel map" errors.
>
> Can someone help me understand these issues, and perhaps what I'm
> doing wrong here? Would this point to something wrong with an
> installed package which perhaps configures these hints incorrectly?
> (Assuming that is probably the case, but I'd like to know for sure).
> I'm on a fairly new install of Ubuntu 16.04 LTS.
>
> Thanks,
> - Trent Reed