A NOTE has been added to this issue. ====================================================================== <https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2238> ====================================================================== Reported By: Raymond Assigned To: ====================================================================== Project: ALSA - lib Issue ID: 2238 Category: 1_pcm - digital audio Reproducibility: always Severity: minor Priority: normal Status: new ====================================================================== Date Submitted: 06-28-2006 09:53 CEST Last Modified: 06-30-2006 05:22 CEST ====================================================================== Summary: snd_pcm_hw_params() did not return error Description: If alsa-lib require the application to refine hw_params from those values supported by alsa-driver to a set of unique values Why do snd_pcm_hw_params() did not return error in the following code ? Does it mean that snd_pcm_hw_params_set_period_size() or snd_pcm_hw_params_set_buffer_size() is not necessary for some ALSA driver ? #include <alsa/asoundlib.h> int main() { snd_pcm_t* pcm; snd_pcm_hw_params_t* hwparams; int err; unsigned int rate = 44100; unsigned int channels = 2; int dir = 0; if ( snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0) < 0 ) printf("Cannot open pcm.\n"); else { printf("pcm state after pcm open : %d\n",snd_pcm_state(pcm)); snd_pcm_hw_params_alloca(&hwparams); snd_pcm_hw_params_any(pcm, hwparams); snd_pcm_hw_params_set_access(pcm, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); snd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16_LE); snd_pcm_hw_params_set_channels (pcm, hwparams, channels); snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, &dir); printf("pcm state before hw_params : %d\n",snd_pcm_state(pcm)); err = snd_pcm_hw_params(pcm, hwparams) ; if ( err < 0 ) printf("Error setting hw params: %s.\n", snd_strerror(err)); printf("pcm state after hw_params : %d\n",snd_pcm_state(pcm)); snd_pcm_close(pcm); } } ====================================================================== ---------------------------------------------------------------------- Raymond - 06-30-06 04:53 ---------------------------------------------------------------------- device is "default" and driver use dmix pcm state after pcm open : 0 pcm state before hw_params : 0 pcm state after hw_params : 2 period size = 940 device is "hw" or "plughw" pcm state after pcm open : 0 pcm state before hw_params : 0 pcm state after hw_params : 2 period size = 8 #include <alsa/asoundlib.h> int main() { snd_pcm_t* pcm; snd_pcm_hw_params_t* hwparams; snd_pcm_uframes_t size; int err; unsigned int rate = 44100; unsigned int channels = 2; int dir = 0; if ( snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0) < 0 ) printf("Cannot open pcm.\n"); else { printf("pcm state after pcm open : %d\n",snd_pcm_state(pcm)); snd_pcm_hw_params_alloca(&hwparams); snd_pcm_hw_params_any(pcm, hwparams); err = snd_pcm_hw_params_set_access(pcm, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED); if ( err < 0 ) printf("Error set access : %s\n",snd_strerror(err)); err = snd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16_LE); if ( err < 0 ) printf("Error set format : %s\n",snd_strerror(err)); err = snd_pcm_hw_params_set_channels (pcm, hwparams, channels); if ( err < 0 ) printf("Error set channels : %s\n",snd_strerror(err)); err = snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, &dir); if ( err < 0 ) printf("Error set rate near : %s\n",snd_strerror(err)); printf("pcm state before hw_params : %d\n",snd_pcm_state(pcm)); err = snd_pcm_hw_params(pcm, hwparams) ; if ( err < 0 ) printf("Error setting hw params: %s\n", snd_strerror(err)); printf("pcm state after hw_params : %d\n",snd_pcm_state(pcm)); err = snd_pcm_hw_params_get_period_size(hwparams, &size, &dir); if (err < 0) printf("Unable to get period size for playback: %s\n", snd_strerror(err)); else printf("period size = %d\n",size); snd_pcm_close(pcm); } } ---------------------------------------------------------------------- rlrevell - 06-30-06 05:22 ---------------------------------------------------------------------- If you don't set the period size, the default is driver and configuration dependent. Applications cannot rely on the default period size being sane. Issue History Date Modified Username Field Change ====================================================================== 06-28-06 09:53 Raymond New Issue 06-30-06 04:53 Raymond Note Added: 0010717 06-30-06 05:22 rlrevell Note Added: 0010718 ====================================================================== Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
