Re: [Linphone-developers] sound card

[Benjamin]

Hi Edwin,

Edwin Cordeiro wrote:
> Hi,
>
> I have a few questions:
> 1) In which part of the code the sound card is configured or selected? 
> Because linphone can't find a sound card on my ARM Linux system and I 
> was thinking to get and send the audio from/to pipes for comunication 
> with annother program.
Mh, that depends a bit on what version of linphone you're using, 
specifically if it's mediastreamer/mediastreamer2,
are you talking about OSS or ALSA?

Try out 
http://download.savannah.nongnu.org/releases/linphone/unstable/source/linphone-1.3.99.5.tar.gz 
or the latest CVS.

For ALSA, check out <srcdir>/mediastreamer2/alsa.c

....
static void alsa_card_detect(MSSndCardManager *m){
   int i;
   for (i=-1;i<10;i++){
       MSSndCard *card=alsa_card_new(i);
       if (card!=NULL)
           ms_snd_card_manager_add_card(m,card);
       else
           return;
   }
}
....

static MSSndCard * alsa_card_new(int id)
{
   MSSndCard * obj;
   char *name=NULL;
   AlsaData *ad;
   int err;
   if (id!=-1){
       err=snd_card_get_name(id,&name);
       if (err<0) {
           return NULL;
       }
   }
   obj=ms_snd_card_new(&alsa_card_desc);
   ad=(AlsaData*)obj->data;
   if (id==-1) {
       /* the default pcm device */
       obj->name=ms_strdup("default device");
       ad->pcmdev=ms_strdup("default");
       ad->mixdev=ms_strdup("default");
   }else{
       obj->name=ms_strdup(name);
       ad->pcmdev=ms_strdup_printf("plughw:%i,0",id);
       ad->mixdev=ms_strdup_printf("hw:%i",id);
   }
   free(name);
   /*ms_message("alsa device %s found",obj->name);*/
   return obj;
}


maybe add some debug output here.

For OSS, check out oss.c ( surprise ;-) ), but I haven't used oss for a 
long time, so I don't know how the support
works in linphone.

Have you created all the necessary devicefiles in /dev/... ? In the 
alsa-driver package, there's a script called "snddevices" for that...

You could run linphone on the console with debugging output:

$>  MEDIASTREAMER_DEBUG=666 linphonec -d 6

Not sure about the pipe stuff, I don't know if linphone reads anything 
from stdin.

> 2) What file type of sound  is sent and received, for a playback? Is 
> it pcm or .wav or another one?
I don't really understand what you are talking about here... normally 
you have:

SOUNDCARD -> 16bit linear PCM samples in host endianess at a given 
sample rate -> some codec like SPEEX, GSM, etc. -> codec specific 
bitstream in frames -> RTP packet  -> network connection

and backwards.

regards,
Benjamin