Re: [alsa-devel] Alsa not working when linked to a library

25 Sep 2009


      Just to add:
(yes I know I didn't free the hwparams structure, but it is done in the 
rest of the code I cut)
the "speaker" device is virtual, generated with dmix on asound.conf:
pcm.pcm1774 {
    type hw
    card 0
}
ctl.pcm1774 {
    type hw
    card 0
}
pcm.buzzer {
        type dshare
        ipc_key 6678293
        ipc_key_add_uid yes
        slave {
                pcm "hw:0,0"
                buffer_size 16384
                period_time 2
                period_size 1024
        }
        bindings {
                0 0
        }
}
pcm.speaker {
        type dshare
        ipc_key 6678293
        ipc_key_add_uid yes
        slave {
                pcm "hw:0,0"
                buffer_size 16384
                period_time 2
                period_size 1024
        }
        bindings {
                0 1
        }
}
Fortini Matteo ha scritto:
...
Hi,
I'm experiencing a very strange behavior.
I'm using alsa 1.0.18 on a powerpc platform.
If I run the following simple code from the main of a .c file, it works 
perfectly, but if I put into a shared .so library (libaudio.so), then I 
link the main with -laudio -lasound, then the hwparams structure is not 
filled with anything, while the alsa functions don't return any error.
Do you have any clue why this could happen?
TIA
############################################################
int play_sample(char *pcm_name, char *samplename)
{
    int res;
    snd_pcm_t *pcm_handle;         
    snd_pcm_hw_params_t *hwparams;           
    const char *name= (pcm_name != NULL) ? pcm_name : "speaker";
if ( (res = snd_pcm_open(&pcm_handle, name, SND_PCM_STREAM_PLAYBACK, 

0)) < 0) {
        fprintf(stderr, "Error opening PCM device %s\n", pcm_name);
        return 1;
    } else {
        printf ("snd_pcm_open returned %d\n", res);
    }
snd_pcm_hw_params_malloc(&hwparams);
if (snd_pcm_hw_params_any(pcm_handle, hwparams) < 0) {
    fprintf(stderr, "Can not configure this PCM device.\n");
    return 1;


snd_pcm_close(pcm_handle);
}
int main (void)
{
    play_sample (NULL, "test_sound.wav);
return 0;

}
############################################################
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