Sorry for void subject of before

Hi all,

I am building a solution on a Debian platform that should playback an audio recorded in G711 ulaw format. I am using Alsa to interfacing with the audio device, it's a snd_cs5535audio. Below there is a fragment of the code I am using. I don't have any problems accessing the device using the "plughw:0,0" device, where I can correctly set directly the ulaw 8000Hz format.

Now I was needing an multiband equalizer, and found that Alsa supports some ladspa plugins, I choosed mbeq. But if I use a device name different from "plughw:0,0", as for example the "default" device or "plug", the final function snd_pcm_hw_params() returns an error: "cannot set hw params (Invalid argument)"

I was thinking that maybe my problem is that only the "plughw" device accept directly the G711 ulaw format. Anyone can confirm my thought? There is a way to access a device directly in G711 ulaw format that can be equalized with a plugin?

My initialisation source code:

----------8<---------- // #define AUDIODEV "plughw:0,0" #define AUDIODEV "default"

[...]

pcm_name = strdup(AUDIODEV);

if((err = snd_pcm_open(&playback_handle, pcm_name, stream, 0)) < 0){ printf(" E> cannot open audio device %s (%s)\n", pcm_name, snd_strerror(err)); closeall(1); } if((err = snd_pcm_hw_params_any(playback_handle, hw_params)) < 0){ printf(" E> cannot initialize hardware parameter structure (%s)\n", snd_strerror(err)); closeall(1); } if((err = snd_pcm_hw_params_set_access(playback_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0){ printf(" E> cannot set access type (%s)\n", snd_strerror(err)); closeall(1); } err = snd_pcm_hw_params_set_format(playback_handle, hw_params, SND_PCM_FORMAT_MU_LAW); if(err < 0){ printf(" E> cannot set ulaw format (%s)\n", snd_strerror(err)); closeall(1); } val = 8000; if((err = snd_pcm_hw_params_set_rate_near(playback_handle, hw_params, &val, 0)) < 0){ printf(" E> cannot set rate (%s)\n", snd_strerror(err)); closeall(1); }

[...]

if((err = snd_pcm_hw_params(playback_handle, hw_params)) < 0){ printf(" E> cannot set hw params (%s)\n", snd_strerror(err)); closeall(1); } ---------->8----------

My /etc/asound.conf :

----------8<---------- defaults.ctl.card 0 defaults.ctl.device 0 defaults.pcm.card 0 defaults.pcm.device 0

ctl.equal { type equal; library "/usr/lib/ladspa/mbeq_1197.so"; module "mbeq"; controls "/usr/local/webif/.alsaequal.bin"; }

pcm.plugequal { type equal; slave.pcm "plughw:0,0"; library "/usr/lib/ladspa/mbeq_1197.so"; module "mbeq"; controls "/usr/local/webif/.alsaequal.bin"; }

pcm.!default { type plug; slave.pcm plugequal; hint { show on description "Default equalized" } }

pcm.dsp0 { type plug slave.pcm plugequal; } ---------->8----------

Many thanks Best Regards -- E.Richiardone