Re: [Protux-devel] snd_pcm_hw_params_set_format returns: invalid format

[Remon Sijrier]

Thanks for the answer.

But no it's not an update problem. I changed it by myself after I detected 
that I only can set the parametervalues my sound card supports. 
And the ouput says: 10 channels and 32 bit.

I'm looking right now at JACK, but find it very hard to get a clue of the 
code. Found a piece of code which may be interesting though. Changed it to 
fit into MADM:

        // set the sample format
        // SHOULD CHECK THE BITDEPTH HERE....
         if ((r = snd_pcm_hw_params_set_format (pcmHandle, hwparams, 
SND_PCM_FORMAT_S32)) < 0) {
                if ((r = snd_pcm_hw_params_set_format (pcmHandle, hwparams, 
SND_PCM_FORMAT_S16)) < 0){
                        PERROR("Invalid sample format to bus %s : 
%s",cBusFullReference,snd_strerror(r));
                        goto ALSA_ERROR_AFTER_OPEN_AND_HWPARAMS_ALLOCATION;
               }
        }

this solved the bits problem. ALSA itself is capable of converting it? I read 
it somewhere that the ALSA driver automaticaly converts the given format if 
it doesn't fit.


And this is I nice way of detecting the available channels on the sound card 
:)
        // detect available channels. Maybe detect some upper limit?? say > 
1024 is to much :)
        *nchns = snd_pcm_hw_params_get_channels_max (hwparams);
        PMESG("detected number of channels = %d", *nchns);
        if (*nchns > 1024)
                {
                PERROR("You appear to be using the ALSA software \"plug\" 
layer, probably\n"
                            "a result of using the \"default\" ALSA device. 
This is less\n"
                            "efficient than it could be. Consider using a 
~/.asoundrc file\n"
                            "to define a hardware audio device rather than 
using the plug layer\n"
                            "setting it to a sane default (10 in this case, 
other setting gives\n"
                            "a segfault :( )\n")
                *nchns = 2;
                }

        r = snd_pcm_hw_params_set_channels(pcmHandle, hwparams, *nchns);
        if (r < 0)
                {
                PERROR("Invalid number of channels (%d) to bus %s : 
%s",cBusFullReference,  channels, snd_strerror(r));
                goto ALSA_ERROR_AFTER_OPEN_AND_HWPARAMS_ALLOCATION;
                }


Op donderdag 5 juni 2003 23:49, schreef Luciano Giordana:
> Are you sure this code is from current CVS ?
>
> > Also the setting of the channels isn't working:
> >
> >         // set the count of channels
> >         r = snd_pcm_hw_params_set_channels(pcmHandle, hwparams, 10);
> >         if (r < 0)
>
> I checkd it on my current CVS snapshot,  and it is
>
>         // set the count of channels
>         r = snd_pcm_hw_params_set_channels(pcmHandle, hwparams, channels);
>         if (r < 0)
>
> maybe just an update problem?
>
> anyway, I am adding a way to easy change the format, by modifying the API.
> might be available on next releases ( 0.17.6 or 0.17.7 )
>
> Thanks