Difference between revisions of "Tips And Tricks"

Revision as of 23:33, 23 July 2008

Tips

Starting ossxmix minimized to tray on desktop startup

The '-b' option starts ossxmix in the background - minimized to tray if tray support is compiled in, iconfied window if not. The '-S' option prevents ossxmix from trying to use a system tray. ossxmix -Sb' will always start an iconified window.

1. KDE: create a desktop shortcut in ~/.kde/Autostart with the command 'ossxmix -b'.

   Alternative: create a desktop shortcut in the same place, with the command "ossxmix -Sb'. Go to Applications->"Advance options" and select "Place in system tray".

2. Gnome: go to Control center->Session->"Startup Programs" and add "ossxmix -b".
3. X11 in general: edit the Xsession file. Make sure the tray program runs before ossxmix, or use the '-S' switch as well.
4. See [1] for info on other environments.

Changing the default sound output

1. Relink /dev/dsp to the desired /dev/oss/.../ device. The device node matching the desired sound output can be discovered by running 'ossinfo -a'. If OSS insists on recreating /dev/dsp, simply add the appropriate linking command (typically ln -sf /dev/oss/.../ /dev/dsp) to $OSSLIBDIR/soundon.user.
2. Alternative: $OSSLIBDIR/etc/installed_drivers influences the order of sound cards set by ossdetect. By removing other devices or moving the desired sound card to the first place, followed by running 'ossdetect -v', the default device can be modified.

   The root directory $OSSLIBDIR can be found by checking /etc/oss.conf. It is typically /usr/lib/oss/.

Recording sound output of a program

There are several methods to achieve this:

1. Many drivers offer a 'vol' mixer control. If this can be used as a recording source, than the current sound output will be recorded. Note that this is the mixed total of all sound played, not of a single program.

   ossrecord -ivol blah.wav

   • Some drivers have a 'loopback' mixer control, which offers similar functionality.
2. OSS wrappers can be used to record the output of a program. vsound is one such wrapper. (vsound doesn't handle output to /dev/oss/* device nodes, but all OSS-supporting programs are/can be easily made to output to /dev/dsp).

   vsound ossplay test.wav

3. (This method doesn't work in build 1016) vmix loopback driver can record the output of a program. Set vmix_numloops to 1 (or more) in vmix.conf, and make the program output to the newly created /dev/oss/vmix0/loop0 device (after restaring OSS). Then record from that device. e.g.

   ossrecord -s48000 -b16 -c2 -d/dev/oss/vmix0/loop0 test.wav

   • Perhaps audioloop driver can probably be used as well for this purpose? Man page says it needs a "server" and a "client", so if it can be used for this, it's only for a single program.

Using multimedia keys with OSS

1. First, we should check if the keys are recongnized by X11. Run xev, and see if pressing the keys elicits a response.
   • If it does not, than we must make the keys be recognized by X11/WM/some other program, before they can be used for anything. This is outside the scope of this wiki, but is documented at [2] and at [3]. Some WMs, once set up, will automatically connect the multimedia keys to appropriate functions.
2. If/once the keys are recognized, does it work out of the box?
   • If not, it may be a function of old gstreamer version. Gnome uses gstremaer for this, but older gstreamer didn't support OSSv4. See Configuring_Applications_for_OSSv4#Gnome_Volume_Applet for a possible solution.
   • If that does not work or is not applicable, we can connect the keys to external scripts which will perform the appropriate function (See examples below). The method to connect external scripts to keys is better described at [4] and at [5] again.

External scripts which can control volume

lowervolume.sh:

 #!/bin/sh
 CTRL=vmix0-vol
 VOL=$(ossmix | grep $CTRL | awk '{print $4}' | awk -F : '{print $1}')
 VOL=$(echo $VOL | awk '{print $1-2}')
 ossmix $CTRL $VOL

raisevolume.sh:

 #!/bin/sh
 CTRL=vmix0-vol
 VOL=$(ossmix | grep $CTRL | awk '{print $4}' | awk -F : '{print $1}')
 VOL=$(echo $VOL | awk '{print $1+2}')
 ossmix $CTRL $VOL

mute.sh:

 #!/bin/sh
 CTRL=vmix0-vol
 VOLUME=$(cat $HOME/.volume)
 if [ -z "$VOLUME" ]; then
       VOLUME=$(ossmix | grep $CTRL | awk '{print $4}' | awk -F : '{print $1}')
       ossmix $CTRL 0
       echo $VOLUME > $HOME/.volume
 else
       ossmix $CTRL $VOLUME
       > $HOME/.volume
 fi

This will restore the previous volume levels when unmuting. Issue a:

 touch $HOME/.volume

before using the first time.

You may wish to modify a different mixer control than vmix0-vol. In that case, you will need to change the value of CTRL above.