Command Line Audio Mixer for Sun Solaris

[Image]
mpg123.el running in Emacs

Introduction

Sun Solaris 10 operating system comes with several tools to control audio. For example, you can use sdtaudiocontrol to set the volume level graphically and mixerctl to control mixer modes. However, neither of these tools can set volume level from command line.

Setting the volume level from command line is important for graphical user interfaces which are written in scripting languages such as Tcl/Tk, Python and Lisp. As very few scripting languages have direct access to the hardware, the graphical user interfaces usually depend on external utilities to play mp3 files and get/set audio volume.

I use Hirose Yuuji´s front-end to mpg123 which requires an external utility to set the audio volume. As Solaris 10 did not come with a suitable utility, I decided to write one myself. I hope that the utility is useful for other front-ends too.

Download & Install

Install Mixer

Download mixer 1.3 installation package.

Unpack the installation packag as

gunzip -c mixer-1.3.tar.gz | tar xf -
cd mixer-1.3

Compile the command line audio mixer in Sun Solaris 10 as

cc -o mixer mixer.c

If no warnings appear, copy the produced mixer file to somewhere in your search path. For example, directory /usr/bin will do fine.

Install Updated mpg123.el

In order to use the audio mixer in Emacs, either copy the mpg123.el file from the installation package to your Emacs lisp directory. If you are already using mpg123.el, then overwrite the existing file in your hard disk.

Alternatively, if you want to use the audio mixer with the later version of mpg123.el, then download the mpg123.el from Hirose Yuuji´s site and apply a patch file. To apply the patch file, copy the mpg123.el you downloaded from Hirose Yuuji´s site and the solaris-mixer.patch file from the installation package to the very same directory and issue command

patch -i solaris-mixer.patch mpg123.el 

Copy the patched mpg123.el file to a directory where Emacs can find it. If you are already using mpg123.el, then overwrite the existing file in your hard disk.

Modify Emacs Startup Files

In order to use the mpg123.el in Emacs, make sure that your .emacs file contains the line

(autoload 'mpg123 "mpg123" "A Front-end to mpg123/ogg123" t)

In order to use the audio mixer in Solaris, add the following lines to your .emacs file

(setq mpg123-mixer-type 'mixer.exe)
(setq mpg123-mixer-command "mixer")
(setq mpg123-mixer-setvol-target-list (list "-v"))

Restart Emacs and start mpg123.el by pressing M-x and type mpg123. Press enter and navigate to a directory that contains some mp3 files. Press enter to load mp3 files to Emacs and start the playback with space. You should now be able to change the volume level with + and - keys.

Using the Mixer from Command Line

Query Audio Volume

To get the current audio volume for left and right channels, invoke the mixer command without any command line parameters. The volume levels for the left and right channels will be printed to standard output in the form left:right.

Set Audio Volume

To set the audio volume, invoke the mixer with a single numeric argument between 0 and 100. For example, set the master volume level to 75% as

mixer 75

Alternatively, specify the volume level for left and right audio channels as LEFT:RIGHT. For example, set left channel to 50% and right to 80% as

mixer 50:80

Version History

Nov 5, 2008: now works for SunRay clients. Thanks to Martin Rehak for the patch.