Re: some questions regarding multichannel devices

[Lee Revell <rlrevell@joe-job.com>]

On Mon, 2006-01-23 at 13:35 +0100, Daniel Mack wrote:
> Hi Lee,
> 
> On Jan 23, 2006, at 1:09 AM, Lee Revell wrote:
> > Look at some existing drivers for details or the "Writing an ALSA
> > driver" document.
> 
> I read that. But besides the fact that it seems to be somewhat
> outdated ('struct snd_pcm' vs. 'snd_pcm_t' confusion all over
> the place), I couldn't find this issue explained. Thanks for
> the hint.
> 

You must be looking at an old version of the document or ALSA.  The
typedefs were removed from the ALSA code. 

> > You have to use "aplay -d plughw:0", not "aplay -d hw:0".
> 
> I guess you mean '-D', not '-d'? Unfortunately, This also does
> not help. I still get:
> 
> $ aplay -D plughw:0 test.wav
> Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz,  
> Stereo
> aplay: set_params:935: Unable to install hw params:
> ACCESS:  RW_INTERLEAVED
> FORMAT:  S16_LE
> SUBFORMAT:  STD
> SAMPLE_BITS: 16
> FRAME_BITS: 32
> CHANNELS: 2
> RATE: 44100
> PERIOD_TIME: (46439 46440)
> PERIOD_SIZE: 2048
> PERIOD_BYTES: 8192
> PERIODS: 4
> BUFFER_TIME: (185759 185760)
> BUFFER_SIZE: 8192
> BUFFER_BYTES: 32768
> TICK_TIME: 4000
> 
> and I suspect the S16_LE to be the reason. My snd_pcm_hardware_t looks
> like this:
> 

It should be a struct snd_pcm_hardware, upgrade your ALSA version.

> {
>          .info           = (SNDRV_PCM_INFO_MMAP |  
> SNDRV_PCM_INFO_DOUBLE | SNDRV_PCM_INFO_INTERLEAVED |
>                             SNDRV_PCM_INFO_BLOCK_TRANSFER),
>          .formats        = SNDRV_PCM_FMTBIT_S24_BE |  
> SNDRV_PCM_FMTBIT_S16_BE,
>          .rates          = (SNDRV_PCM_RATE_44100 |  
> SNDRV_PCM_RATE_48000 |
>                             SNDRV_PCM_RATE_96000 |  
> SNDRV_PCM_RATE_192000),
>          .rate_min       = 44100,
>          .rate_max       = 192000,
>          .channels_min   = 2,
>          .channels_max   = 2,
>          .buffer_bytes_max = 32768,
>          .period_bytes_min = 4096,
>          .period_bytes_max = 32768,
>          .periods_min    = 1,
>          .periods_max    = 1024,
> };
> 
> I have *no* ~/.asoundrc and no special entries about my hardware in
> /etc/asound* or /usr/share/alsa/*/*.
> 
> What do I have to do to get the glue logic working?
> 

AFAICT this should work... maybe someone else on the list can help.

Lee



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