How to get Timidity to work (more or less) as a software synth with OSS 4

Note: This is still fragile, so I can’t help you if it doesn’t work on your system.

I finally got around to trying OSS 4 and I just can’t go back to ALSA. Not only is it less cantankerous, the mixer curve I get by leaving my soundcard on defaults and adjusting the vmix in-kernel mixer is much nicer.

Unfortunately, there was one problem. MIDI support for OSS 4 is still in development and I have old Windows games which use MIDI for their background music. With ALSA, I had been using Timidity as a software synth that Wine could hook into, but I couldn’t get that to work with libsalsa (the OSS 4 ALSA compatibility layer) so I decided to look for an alternative.

It’s a jerry-rig, but I figured out how to strap the ALSA userland onto OSS 4 so that Wine has a way to get MIDI events to Timidity. Details below…

Step 1: Install OSS

(Remember to symlink /dev/dsp to your preferred /dev/dspN if it forgets.)

Make sure alsa-lib (or your equivalent) stays installed and that the lines in /usr/sbin/soundon
for setting up libsalsa are commented out. (The ebuild on bugs.gentoo.org which I used comes with a patch to
do this)

If you want to do this yourself, find the line which says “# Use library based ALSA compatibility”
and comment out the block which follows it. If you don’t know how to do this, I suggest grabbing
the patch from bugs.gentoo.org.

If you want to use the ebuild, it’s at Bug 184123.

Step 2: Create an /etc/asound.conf

It should contain only the following:


pcm.!default {
        type oss
        device /dev/dsp
}

Step 3: Set up your ALSA kernel modules

Set up the following ALSA config in your kernel:


Device Drivers --> Sound -->
	<M> Sound card support
	Advanced Linux Sound Architecture  --->
		<M> Advanced Linux Sound Architecture
		<M>   Sequencer support
		[*]   Support old ALSA API

The following were something I tested but didn’t see any difference to. Your mileage may vary.


		<M>   RTC Timer support
		[*]     Use RTC as default sequencer timer

Everything else should be disabled.

Step 4: Adjust your init scripts

Make sure your init scripts successfully load OSS 4 and then adjust them to run “modprobe snd-seq” after it has checked and found no ALSA.

Step 5: Set up Timidity

This part took the the longest to figure out. Timidity is VERY fickle in this setup, so your mileage may vary. Here’s what I had to do:

  • Timidity had to be run from inside my KDE session. (not from an initscript)
  • I had to use artsdsp and set Timidity to use ALSA output

The command I used was “artsdsp timidity -iA -Os” but the -Os was just to make sure. (It was default on my system)

The second-best I found was “timidity -iA -Op” (Portaudio output without artsdsp) and it could be run from an initscript, but it would go silent after the first song or two.

Plain ordinary ALSA output had a similar problem, but also had timing glitches. Ironically, when Timidity is just playing a midi file directly as opposed to receiving MIDI events via ALSA, the timing glitches are absent.

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One Response to How to get Timidity to work (more or less) as a software synth with OSS 4

  1. Syrec says:

    As far as I can tell this is the defacto guide if you’re interested in learning how to get Timidity working with your OSS setup.

    Thanks for this it really helped and now I’ve got Timidity working flawlessly with my setup.

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