--- name: "gom-c" section: "1" platform: "linux" package: "gom" version: "0.29.10-5" release: "Debian 2.1 (Slink)" platforms: ["linux"] url: "https://new.carta.tech/gom" --- # gom-c(1) a generic audio mixer (supports: OSS) Part of [gom(1)](/gom/1.md). ## NAME gom - a generic audio mixer (supports: OSS)\ ## SYNOPSIS **gom {OPTION}**\ ## DESCRIPTION This manual page describes **gom 0.29.10** (1997 Sep 23), a generic audio mixer program; it tries to provide a complete and convenient interface for all kind of audio mixer manipulation. gom's facilities include sound driver (compile time) and sound card (run time) independence, arbitrary mixer selection, loading and saving of mixer settings, volume fading, verbosity-level driven output, "Un\*x-like scripting support", etc. At the moment, gom only supports the Open Sound System (OSS) sound driver. OSS comes with the Linux kernel as free software called OSS/Free, and is available for a number of other platforms. Apart from the exhaustive command line interface described here, gom optionally has two built-in interactive interfaces (that I call gomiis, gom interactive interfaces;): a terminal gomii using ncurses, and a X gomii using the xview toolkit. All gomiis support adjustable (this includes disabling) real time updating. The gomiis are not explained in this manual page; please refer to the specific online help when using one of these gomiis. However, the gomiis handling should be obvious, and actually they "try to resemble" the command line options. Furthermore, **gom** might be compiled leaving out some or all gomiis. And remember: gom is spelled g-o-m, but pronounced backwards for compatibility reasons. Its real, actual and recursive title is **gom, GOM is nOt yet another Mixer** (for reasons beyond the scope of this manual). ## CONFIGURING GOM There is **no mandatory configuration** for gom; it runs fine just as it is, without any configuration. I.e., for senseful use without configuration, one always needs to (at least) specify the mixer to use. For example: gom --device=/dev/mixer2 --mute-all However, whenever gom is started up, it will try to "configure" itself thusly: gom loads \_either\_ the user's (~/.gom/gomrc) or the system's configuration file (/etc/gom/gomrc). The latter is used only if the user config does not exist; if both do not exist, then there is no configuration for gom -- which is perfectly normal. To correct errors, please create and/or change your user's config file. "gomrc-Files" are simply gatherings of command line options to gom. Please see "--get-options" below. For a normal user, I would recommend the following steps: 1\. Create a directory ".gom" in your $HOME. Without it, you can't create a user configuration file, and you can't easily save and load mixer settings. 2\. Create a user configuration file. The configuration file -- as well as the settings files that you can automatically save with gom -- are "free-form" files; all lines starting with '-' are treated as if they were command line options to gom, other lines are ignored. The options in this file are simply read on every startup of gom. Thus, a recommended, minimal "user installation" would be: $ mkdir ~/.gom\ $ echo "-d\" \>~/.gom/gomrc"\ As of version 0.29.10, configuration will be checked if gom is called without arguments. ## TERMINOLOGY, PHILOSOPHY A mixer is a set of channels (e.g. vol, line, cd). Each channel has a set of volume channels (e.g. left, right), and optionally a recording source flag. The evaluation which channels are availabel, and, for an available channel, which volume channels and which flags are available on that specific channel, is being done at runtime; this is sound card, and possibly sound driver dependent. Thus, there are sound driver supported channels and specific sound card supported channels. **gom --info-all** shows all sound driver supported channels, plus indicating their specific availability. Up to the time of this writing, the only sound driver supported is OSS (Open Sound System). This driver exists for a variety of platforms (especially, it is part of the Linux kernel as free software called OSS/Free). (Remark: Gom's point of view on how a "generic" mixer should look like may be strongly influenced by the OSS API; however, the author feels that this view might not (yet) be absolutely generic). At the time of this writing, OSS supports 17 channels, and a maximum of two volume channels per channel (i.e., only "mono" or "stereo"). Of course, as gom depends on the sound driver installed on the system, its proper installation (which is naturally not (and can't be) covered by this man page;) is a necessity for using gom. ## OPTIONS Options can be given in arbitrary order or amount; they are compu ted in sequence from left to right. Default values (if any), are given in \[\]. It might be sane to restrict the options in the conf iguration file to those marked here as "configuration options". F or boolean arguments, "1" means on, "0" means off. Note that for options with \_optional\_ arguments, these must be gi ven like "gom -G\" (or "gom --get-settings=\" resp.) ra ther than "gom -G \" (or "gom --get-settings \" resp.). Otherwise, they will be ignored (or, at least with my implementat ion of getopt;). If no options are given, gom will perform a configuration test. - Configuring options: - **-d, --device, --mixer \** \[ \*\*no mixer\*\* \] Set mixer special device file to \. If the new mixer is valid, the current mixer --if any-- will be closed and the new mixer opened. Current channel, current channel volume, the channel lock setting and the snapshot wil l be resetted to defaults. If this is the \_very\_first\_ given option, gom has a \_special\_ startup behaviour: when loading t he configuration file, this option -- if given there -- is \_i gnored\_ (for the user, this normally has no visual effect, bu t this avoids loading the device twice, or may avoid trying a bogus device from the config if you somehow can't change it). - **-c, --channel \** \[first available channel\] Set current mixer channel to \. The channel may be given as number or as name. - **-C, --volume-channel \** \[first available volume channel on current channel\] Set volum e channel on current mixer channel to \ (e.g., for s tereo, 0 means left, 1 means right volume). - **-k, --lock \** - **-K, --lock-all \** \[1\] Lock or unlock current or all channel(s). Locking means s yncing of the stereo volumes (balance) for all volume setting s gom might do -- this doesn't change any volume settings by itself (i.e., it doesn't auto-balance). Thus, a locked channe l might have unbalanced volumes. - **-F, --fade-interval \** \[5\] Set fade interval to \ seconds. See --fade-to-lo udness. - **-U, --refresh-interval \** \[30\] Set gomii refresh (update) interval to \ second s (zero disables). - **-W, --write-config, --save-config** This option is obsolete since version 0.29.10. - Setting mixer options: - **-l, --loudness, --volume \** Set current volume channel on current channel to \. If the argument is being given with a leading "+" or "-", the given value will be added or substracted, respectively, from the current value. The allowed range is from zero up to a sou ndcard driver dependent maximum. - **-r, --record \** Set recording for current channel on or off. - **-R, --record-single** Set recording for current channel on and disable all other re cording sources. - **-L, --fade-to-loudness, --fade-to-volume \** Like --loudness, but fade to the new volume within a time giv en with --fade-interval. - **-m, --mute** - **-M, --mute-all** Mute current or all channels. Muting means setting all channe l volumes to 0. - Mixer settings options: - **-G, --get-options, --load-options, --get-settings, --load-setting** Get options from/to file \. If no argument is given, the default file (named "default") is used. Non-absolut given filenames will be expanded to "$HOME/.gom/\". Any fr ee-form files with gom one-character command line options in any lines starting with a dash (in column zero) will make sen se to this option. - **-S, --save-settings \[\\]** Save mixer settings to a free-form option file; for the file name, the same rules as for loading option files apply. Files with thusly expanded filenames will be silently overwritten; other files never. When saving, care is being taken that the "last recording source error" can't occur when loading these options (and maybe there are other reasonable side effects ap art from the pure mixer settings (e.g. channel locking, curre nt channel)). The bottom line to these load/save options is t hat you can easily save new and load predefined mixer setting s from anywhere. - **-z, --snapshot-settings** - **-Z, --unsnapshot-settings, --restore-settings** \[mixer settings after opening a new mixer\] Snap- or unsnapsho t to/from current mixer settings. - Informational options: - **-t, --info** Display current channel information. - **-T, --info-all** Display overall information. - **-V, --version** Display version information. - **-w, --copyright, --copyleft, --license, --warranty** Display copyright/license/warranty information. - **-h, --help** - **-H, --help-verbose** Display this help normally or verbose; both helps are still d ependent on the current verbosity level (i.e., higher verbosi ty levels might still show more; "gom -v0 -H" and "gom -h" pr oduce the same output). For the normal verbosity level, these are reasonable macros. - Special options: - **-e, --execute \** Execute the shell command \. - Command line only options: - **-i, --interface, --gomii \** Explicitly start up a build-in gomii (\=t: terminal gomii, \=x: X gomii). - **-v, --verbose \[\\]** \[NORMAL\] Set output verbosity to \ (number, the high er, the more verbose). If no argument is given, verbosity wil l be set to VERBOSE. - **-q, --quiet, --silent** Set output verbosity to QUIET (only error / error help messag es). - **-p, --pure, --print \** Pure-print the current channels value given by \ to stdout (\=l\|r, according to one character options). Useful for getting values "into" scripts together with the -- quiet option. - **-x, --extract-settings** Extract all mixer settings as a gom option line to stdout (e. g. for "setting=\`gom --quiet --extract-settings\`" and "gom -- quiet $settings" later in a bash script). - **-I, --read-stdin** Read options from stdin (until EOF). ## ENVIRONMENT - *HOME* used as prefix for the configuration directory *.gom/* for a non-root user. ## FILES - */etc/gom/* system configuration directory (user root). - *$HOME/.gom/* user configuration dir (all non-root users). - Files inside the configuration directory: - *gomrc* configuration file (quietly loaded on startup). - *default* default options file (loaded with --get-options). - *\** other files (most likely mixer settings) that can be easily accessed just by their names with gom. ## DIAGNOSTICS Exit status is 0 if no errors were detected while running gom; it is greater than 0 if one or more errors were detected. This should be interpreted as warning, not necessarily as failure. (The amount of detected errors will be printed out if the verbosity level is VERBOSE or higher; the warning exit status is currently always 2, but this may change). ## EXAMPLES (This section is incomplete and most likely confusing ;). - **1. gom as system startup** On my soundcard, one chip gets very hot when there is some throughput. So, to be gentle to the card, I'd like to mute all channels to be the default when the system starts. So I created /etc/gom/gomrc with a line "-d/dev/mixer", and then, as root, i did "gom --verbose --mute-all --save-settings". Thusly prepared, all you have to do is adding "gom --get-options" in some system startup file. - **2. gom as user startup** Of course, the same as for the system applies for normal users of gom, with your own configuration dir, and the calling line for gom must go somewhere that is executed on login. - **3. gom in a running session** % - **4. gom in scripts** % - **5. Some more detailed examples** - **gom --interface=t, gom -it** Interactively manipulate mixer settings with the terminal gomii. - **gom --get-settings, gom -G** (e.g. when you log in as user). Loads user's default options file. - **gom --get-settings=cd, gom -Gcd** Loads options file "cd" (most likely a setting for playing cds). - **gom -d/dev/mixer0 -M -d/dev/mixer1 -l100** First, mute mixer 0, then set the volume of the first channel on mixer 1 to 100. - **gom -M -c vol -l 90 -c pcm -l 90 -e bplay super.voc -Z** Plays the sample *super.voc* on channel 4=pcm with all other channels muted, restoring original mixer settings afterwards. - **gom -ix -e \ -Z** Plays any sound, interactively setting the mixer before with the X gomii and restoring settings afterwards. ## AUTHOR The gom package is Copyright (c) Stephan Suerken \ 1996, 1997. The X gomii of the gom package is also Copyright (c) Hannu Savolainen 1993 (as it is originally based on "xvmixer" by Hannu Savolainen). The gom package is licensed under the GPL (GNU General Public License). The files "README" and "COPYING" in the original distribution contain the exact terms. The GOM Home Page on the web can currently (1997 Mar 18) be found at "http://www.fh-worms.de/~suerken/gom.html".\ ## SEE ALSO Information about OSS can currently (1997 Mar 18) be found at "http://www.4front-tech.com/".\ ## KNOWN BUGS At the moment (0.29.10), it is not possible to load another file from an options file (frankly, gom crashes). When this bug is fixed, it might be possible to throw gom into infinite loops and such when loading option files -- e.g. by adding a "-Gcd" to an options file named "cd". The mixer settings files may be inconsistent between different sound drivers (i.e., if the channel numbering is different). Loading settings from a options file that was saved from a different mixer may lead to errors (if some option is not available on the current mixer), or to silently not-setting of newly available options of the current mixer. The "text blocking output" cuts words (true, too, for the OPTIONS section of this manual page). X gomii bugs: The X gomii has some "bugs" due to xview and/or the lack of documentation available for the author (all the rest of this section): The X gomii creates its display objects with xview, but doesn't check for allocation errors. I guess xview somehow handles this ;). The X gomii's scroll window displays in a non-fixed font. Some placements in the X gomii are still static; it could imagine that the display might look a little bit screwed up if you use a different configuration than mine (e.g. a different font). Xview, in general, "seems to be a little bit unstable" (the author itself locked all his major input devices (i.e., mouse & keyboard (you should be so clever to have some other means to access your computer when programming xview ;)) several times by using xview applications under X (not necessarily the X gomii) for whatever unknown reasons (and without being able to reproduce the bug properly). (()()) ## KNOWINGLY NO BUGS If starting gom results in loading and initializing the kernel sound driver (e.g. if the sound driver gets kerneld-autoloaded under Linux), the sound card's settings are set to the driver's default by the driver itself. **gom** has nothing to do with these defaults and doesn't change any settings -- any program using the sound driver in that situation would have the same effect.