Subject: Re: [linux-audio-dev] Low latency and WINE?
From: Benno Senoner (sbenno_AT_em.gardena.net)
Date: ma marras 08 1999 - 08:00:10 EST
>
> Just wondering...
>
> Has anyone tried using a lowlatency-patched kernel with WINE and a
> Windows MIDI sequencer?
>
> I'm wondering because last time I tried WINE, about a year ago, it
> was just about good enough to run the ancient version of Cakewalk
> that came with my cheap MIDI keyboard. Ditto for some Voyetra
> sequencer that came with my soundcard. But one of them (I forget
> which) didn't really work; the other looked OK and even found the
> wavetable synth in my Malibu card, but the output timing was
> terrible-- obviously off by hundreds of milliseconds for some notes.
>
> I assume this was a WINE problem, but just wondered if maybe the
> low-latency patches helped any? Has anyone tried this?
> Or is running Windows sequencers on Linux just doomed?
>
I don't know WINE internals, but the "earliest deadline" approach
should work here too:
I don't know how exactly Windoze sequencers are implemented,
but if they run their MIDI/audio stuff as a separate thread,
then it could be definitively possible.
Assume the sequencer runs the GUI in 1 thread and the midi/audio stuff
in an other thread.
On Linux there will be concurrency between these 2 threads and the
other Linux stuff, especially the X server.
If you set the audio/midi thread SCHED_FIFO max priority,
(maybe using an external program, or patching WINE to
set SCHED_FIFO when a thread requests realtime privileges
(is this already implemented?) ),
then it should be possible.
A smart gui has even managed to run a VQF (similar to mp3 made by Yamaha),
decoder to run under Linux. (by using winelib to load the CODEC)
With a similar technique, we could even run
Waves Trueverb with 3ms IOlatency under Linux, and
misuse our Linux bock as a realtime FX.
:-)
But this scares David very much, because he says if it turns out
to be true, then windoze plugin developer will not have any motivation
to port the plugins to our native Mucos plugin API.
But it would be *EXTREMELY FUNNY* runnning windoze plugins
with orders of magnitude lower latencies on Linux than on the
original host operating system.
That would be an extremely impressive technical demo,
for developers which are still sceptical about the capabilities
of Linux.
Benno
This archive was generated by hypermail 2b28 : pe maalis 10 2000 - 07:23:25 EST