[SDL] audio lagging when compiling SDL/SDL_mixer by myself

[Thomas Unterthiner]

Hello everyone!
I'm having a very strange problem with SDL_mixer. Im developing under 
Windows, using GCC 4.2.1 (grabbed from 
http://sourceforge.net/projects/tdm-gcc/ ). When trying to compile SDL 
1.2.12 and SDL_mixer 1.2.7 for use in one of my games I bumped into a 
strange problem:

When I compile my program using my home-brewed version of SDL all the 
sounds are played with a little delay ( about 0.5 seconds), and when the 
game is playing too many samples at once (hard to say, maybe 5-8 sounds) 
the sound "doesn't come out right". It's a bit hard to explain, so you 
might want to check it out yourself:  
http://bluetiger.bauchlandung.org/misc/ZombieShooter.zip
(try clicking very fast to generate many shooting-sounds). In case you 
need to look at the source code, it's also included in the package. All 
the sound-related stuff is located in "SoundManager.cpp". However I am 
not aware of doing anything out of the ordinary.

If you exchange the SDL.dll you find in that package with the official 
one from http://www.libsdl.org/release/SDL-1.2.12-win32.zip  you will 
notice that the sound works correctly. I tried out a myriad of different 
./configure-settings (enabling/disabling things, linking statically, 
using SDL 1.2.11, ...) when compiling SDL without getting rid of the 
problem. Also the problem is independent of the audio-format used (I've 
tried with both WAV and OGG-files). I noticed that reducing the 
chunksize when calling Mix_OpenAudio to insanely small values (e.g. 32 
instead of 1024) reduces the lag-problem, but the audio still remains 
distorted when playing multiple samples at once (even when using 
Mix_AllocateChannels(1024) ).

The SDL.dll included in my package was compiled without any 
compiler-options, whilst SDL_mixer.dll was compiled with support for WAV 
and OGG only. However even when doing a "plain" ./configure (w/o any 
special parameters) the problem still persists, and since the problem 
comes and goes by exchanging SDL.dll I assume it isn't related to 
SDL_mixer at all. Is this a bug in SDL, am I missing something or what 
exaclty is going on here? I hope you can help me out :)


P. S. I already submitted this message to the list some days ago (before 
i was registered on the list), but it seems to have gone lost. If it 
didn't I'm sorry for reposting it now!

best regards

Thomas Unterthiner