Thankyou for your response Takashi!

On Tue, 05 Jun 2007 12:44:52 +0200 "Takashi Iwai" tiwai@suse.de wrote:

At Mon, 4 Jun 2007 15:23:06 -0700, John L. Utz III wrote:

...

Hello;

I am working with an CMEDIA 8738-MC6 and i am trying to gain control of the second DAC by way of softvolume. i have modified it to look thusly:

# 2nd DAC CMI8738-MC6.pcm.rear.0 { @args [ CARD ] @args.CARD { type string } type softvol slave.pcm { type hw card $CARD device 1 } control { name "Rear Playback Volume" card $CARD } }

The control is created first when you access this defined PCM. Try to open "rear" PCM first, then check amixer.

Once after a user-defined control is created, it can be saved/restored via alsactl save/restore command.

So i added the following code to our app and the device now shows up in amixer, but it doesnt actually change the volume! dang!

Here's the code snippet that creates and closes the device

if(!snd_pcm_open(&pPcm, "rear", SND_PCM_STREAM_PLAYBACK, 0)) snd_pcm_close(pPcm);

Here's the code snippet that instantiates the mixer elemement, it used to fail to find the 'Rear' element, but now it works:

snd_mixer_selem_id_t *pSndMxrSlem;

snd_mixer_selem_id_alloca(&pSndMxrSlem); snd_mixer_selem_id_set_name(pSndMxrSlem, pNameElem);

pSndMxrElemCard1 = snd_mixer_find_selem(pSndMxr, pSndMxrSlem);

Heres code that doesnt return an error, but based on the amixer output, it doesnt actually work for the 'Rear' element. Note that it works for the 'PCM' and 'Master' devices:

int card_setvol_alsa(int iNumCard, unsigned char ucVolLeft, unsigned char ucVolRight, int iCtl) { int iErr = 0; char acLog[256] = ""; snd_mixer_elem_t *pSndMxrElem = NULL;

if(iCtl) pSndMxrElem = iNumCard ? pSndMxrElemCard1 : pSndMxrElemCard0; else pSndMxrElem = pSndMxrElemCardV;

if(!pSndMxrElem) { aeiu_logprint("PCMX", AEIU_LOG_INFO, "SETVOL pSndMxrElem=NULL"); return iErr; }

if((iErr = snd_mixer_selem_set_playback_volume(pSndMxrElem, SND_MIXER_SCHN_FRONT_LEFT, ucVolLeft))) goto fin;

iErr = snd_mixer_selem_set_playback_volume(pSndMxrElem, SND_MIXER_SCHN_FRONT_RIGHT, ucVolRight); fin:

if(iErr) { sprintf(acLog, "pcm_setvol_alsa: Card: %d Failed: %s", iNumCard, snd_strerror(iErr));

aeiu_logprint("PCMX", AEIU_LOG_ERROR, acLog); } return iErr; }

Here's the outputs: PCM, Master are great, Rear is bad

[root@DMX-98165 jutz]# amixer sget Rear Simple mixer control 'Rear',0 Capabilities: pvolume Playback channels: Front Left - Front Right Limits: Playback 0 - 31 Mono: Front Left: Playback 0 [0%] Front Right: Playback 0 [0%]

[root@DMX-98165 jutz]# amixer sget Master Simple mixer control 'Master',0 Capabilities: pvolume Playback channels: Front Left - Front Right Limits: Playback 0 - 31 Mono: Front Left: Playback 20 [65%] Front Right: Playback 20 [65%]

[root@DMX-98165 jutz]# amixer sget PCM Simple mixer control 'PCM',0 Capabilities: pvolume pswitch pswitch-joined cswitch Playback channels: Front Left - Front Right Capture channels: Front Left - Front Right Limits: Playback 0 - 31 Front Left: Playback 20 [65%] [on] Capture [off] Front Right: Playback 20 [65%] [on] Capture [off]

Can you or anybody else offer any further suggestions?

tnx!

johnu

Takashi