[timidity-talk] Tempo loss when in ALSA sequencer mode

[Theodoros V. K. <th...@so...>]

Hi,

I am trying to setup Timidity as an ALSA sequencer, to make up for the 
non-existent MIDI capabilities of my sound card. Unfortunately whenever I 
try to use Timidity in this mode, it sounds as if it cannot keep a regular 
tempo while synthesizing. In fact it sounds more as if it piles up MIDI 
events and then tries to play them all at once. As a result in other 
places the piece sounds "slower" and in others it seems rushed with 
several notes coming late and out of place.

I have tried both pmidi and kmid and with several MIDI files, all with the 
same result. Timidity in player mode sounds fine (as long as I get it to 
use a decent patch set, that is). I start the timidity server with:

timidity \
     -iA \
     -Os \
     -s 48000 \
     --no-unload-instruments \
     --no-realtime-load \
     -EFresamp=0 \
     -EFreverb=0 \
     -EFchorus=0 \
     -B2,8

With this I get 1-5% CPU usage with the CPU on its lowest frequency, so it 
is not a CPU problem. I have tried several other options with no improvement.

System details:

Intel Pentium M 1.7GHz, usually clocked at 600MHz
1GB RAM
Intel on-board card (snd-intel8x0 ALSA driver)
Linux kernel 2.6.11.6 with CONFIG_PREEMPT option
ALSA library 1.0.9

The funny thing is that at player mode I can use a full blown timidity 
(reverb, resamp, chorus e.t.c) at 30% CPU usage (@600MHz) with excellent 
results.

I am sorry I could not provide a more accurate description of the problem, 
but I have no knowledge on music, apart from the common-sense based "what 
sounds right".

I would appreciate any comments or suggestions...


Regards,

Theodoros Kalamatianos