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Last R5E50 Upgrade issue: Audio Volume Control
http://forums.linhes.org/viewtopic.php?f=17&t=15075		 Page 1 of 1
Author:  siasl [ Mon Apr 30, 2007 7:51 am ]
Post subject:  Last R5E50 Upgrade issue: Audio Volume Control
Recently upgraded my FE/BE systems to R5E50 from R5C7.
After many tweaks finally have a nicely working system except :

When I set up 5.1 surround sound every thing works but the channel mappings in alsamixer are weird :

Chip : RealTek ALC658

Speaker-test-------------------------------------Alsamixer channel
RR -------------------------------------------------- LFE
RL -------------------------------------------------Center
LFE,CTR------------------------------------------Surround
FL,FR------------------------------------------------PCM
FL,FR-----------------------------------------------Master

I guess I have two issues :

Most important. How can I get the volumes of All the channels to go up and down proportionately.

I've seen references to manufacturers "nice" controls for this but Logitech does not seem to have anything for my 5.1 speakers.

Less important is if there is a way to get the weird Alsamixer mappings straightened out.

Thanks.
Author:  siasl [ Thu May 03, 2007 9:37 am ]
Post subject:  Audio SoftMaster : Answering my own question
After delving into the less than simple world of ALSA I found a solution to my number one issue : How to control all the 5.1 surround sound channels with one volume control. This link gives the background to the issue.

http://alsa.opensrc.org/How_to_use_softvol_to_control_the_master_volume

First I defined the following .asoundrc file logged in as user mythtv :

Code:
nano ~/.asoundrc

pcm.softvol {
    type            softvol
    slave {
        pcm         "surround51"
    }
    control {
        name        "SoftMaster"
        card        0
    }
}

# Then define the new device as the default

pcm.!default {
    type             plug
    slave.pcm       "softvol"
}


Then test the new control

Code:
speaker-test -Dsoftvol -c6


go into alsamixer. A new control called SoftMaster should be there.
Test that when you use the new control the volumes on ALL channels change.

if the sounds are coming from the correct speakers at the correct time then :

I am using xine to play DVD's so the following relates to xine.

Code:
Edit /home/mythtv/.xine/config

find line :

audio.device.alsa_surround51_device:surround51

subsitute :

audio.device.alsa_surround51_device:softvol


find line :

audio.device.alsa_mixer_name:PCM (or you might be using Master)

substitute :

audio.device.alsa_mixer_name:SoftMaster



That's it. The remote now controls all the channels volumes when playing 5.1 surround sound.
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