Linux: midi and sound fighting over soundcard \ VOGONS

Linux: midi and sound fighting over soundcard

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First post, by pbienst

Posted on 2006-10-01, 12:56

pbienst Offline

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Joined: 2006-10-01, 11:37

Hi,

When playing Gabriel Knight 1, which uses both digitized sound output (using the Thunderboard driver) and midi output (using the general midi driver), I can get everything to work fine using either sound or either midi, but not both at the same time.

E.g., Timidity++ 2.13.2 complains with the following messages:
ALSA lib pcm_dmix.c:862:(snd_pcm_dmix_open) unable to open slave
Can't open pcm device 'default'.
Couldn't open ALSA pcm device (`s')

I'm running this kernel: 2.6.17-gentoo-r4, with built-in alsa using an intel8x0 card. I was told that dmix support was enabled by default for this kernel, so I don't have an .asoundrc file.

Is this a dosbox problem, or does the problem lie elsewhere?

Thanks!

Peter

Reply 1 of 6, by Srecko

Posted on 2006-10-01, 19:09

Srecko Offline

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dmix isn't part of kernel. It's alsa-lib plugin, sou you still need .asoundrc to configure it.

Your sound card probably doesn't handle MIDI so it is routed to software synthesizer (timidity) which tries play PCM sound, and if both dosbox sound and timidity try to open sound device at the same time, it of course doesn't work (on cards which don't do hw mixing at least).

Reply 2 of 6, by pbienst

Posted on 2006-10-01, 19:32

pbienst Offline

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Turns out I was albel to solve the permission problem by using thiss variable:

SDL_AUDIODRIVER=alsa

I guess previously SDL used OSS, which was monopolising the sound card.

Reply 3 of 6, by dasen

Posted on 2006-12-16, 01:21

dasen Offline

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Is that variable in linux?

I 'solved' using a sound deamon like arts and then running 'artsdsp dosbox' . Of course arts sucks (the sound efex are lagged) so I'm gonna try with esd later.

Reply 4 of 6, by pbienst

Posted on 2006-12-16, 08:32

pbienst Offline

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Yes, SDL_AUDIODRIVER is a linux environment variable which controls SDL behaviour

Reply 5 of 6, by `Moe`

Posted on 2006-12-16, 19:40

`Moe` Offline

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You are totally right, dmix is enabled by default in moderately recent ALSA versions. This has nothing to do with the kernel, it's libasound that does this (and all ALSA programs use libasound). As you can see fron the error message, dmix is indeed tried, but fails.

Reasons for this can vary, but I'd check if you are trying to run sound using programs using more than one userid (perhaps a timidity MIDI daemon as root?). That can break dmix.

Bottom line: Since SDL is already using ALSA and dmix is clearly being tried, your problem is _not_ with any environment variables. Moreover, it should work without an .asoundrc. You can try to tweak dmix config using one, however.

Reply 6 of 6, by jasonskow

Posted on 2006-12-27, 19:17

jasonskow Offline

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Hi,
I have a similar problem to the one mentioned above. I can get awesome sound using mt32d (munt), but I don't get digitized sound effects. If I don't run mt32d, I get digitized sound, but no Roland music. I'm using Ubuntu 6.06, dosbox-0.65 and a cvs version of munt. The message I get when running dosbox (while mt32d is running) is:

MIXER:Can't open audio: No available audio device , running in nosound mode.
ALSA:Client initialised [128:0]
MIDI:Opened device:alsa

I've tried the to set the environmental variables, as suggested above with:

export SDL_AUDIODRIVER=alsa

However, this has not affected the MIXER error message.

Thanks in advance for any thoughts or suggestions.

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