Kontron KTAM3874-pITX - Manual (Page 112)

KTD-S0057-I Page 108 Linux® Programming Examples (DebianTM)
KTAM3874/pITX Software Guide
if ((err = set_hwparams (handle, hwparams, transfer_methods[method].access)) < 0)
{
printf ("Setting of hwparams failed: %s\n", snd_strerror (err));
exit (EXIT_FAILURE);
}
if ((err = set_swparams (handle, swparams)) < 0)
{
printf ("Setting of swparams failed: %s\n", snd_strerror (err));
exit (EXIT_FAILURE);
}
if (verbose > 0)
snd_pcm_dump (handle, output);
samples = malloc ((period_size * channels * snd_pcm_format_physical_width (format)) / 8);
if (samples == NULL)
{
printf ("Not enough memory\n");
exit (EXIT_FAILURE);
}
areas = calloc (channels, sizeof (snd_pcm_channel_area_t));
if (areas == NULL)
{
printf ("No enough memory\n");
exit (EXIT_FAILURE);
}
for (chn = 0; chn < channels; chn++)
{
areas[chn].addr = samples;
areas[chn].first = chn * snd_pcm_format_physical_width (format);
areas[chn].step = channels * snd_pcm_format_physical_width (format);
}
err = transfer_methods[method].transfer_loop (handle, samples, areas);
if (err < 0)
printf ("Transfer failed: %s\n", snd_strerror (err));
free (areas);
free (samples);
snd_pcm_close (handle);
return 0;
}
The most important PCM ALSA interfaces use the identifiers
plughw and hw . For the plughw identifier you
need no information about the sound hardware - data will be automatically converted. In contrast you have
to check whether the
hw interface supports your hardware configuration. The two statements after the
colon represent the card and the device number which can be reliably determined by
aplay -l