[SDL] Re: Converting push sound model to SDL

Leo Broukhis leob at mailcom.com
Thu Jun 23 18:54:30 PDT 2005


Stephen Anthony <stephena <at> users.sourceforge.net> writes:
 
> If I'm understanding you correctly, you want to move from a "push the 
> sound bytes down the pipe" model to a callback model?  If so, I 
> encountered and eventually solved (with a great amount of misery) the 
> exact same problems with Stella, the Atari 2600 emulator.
> 
> Originally, the sound processing was done in a separate sound server, 
> where updates were simply done with 'write' and using OSS.  Later, the 
> code was converted to use SDL.
> 
> Have a look at the web repository on stella.sf.net.  Specifically, look 
> for the old OSS sound code in 'src/ui/sound/Attic/OSS.c' and the new 
> code in 'src/common/SoundSDL.cxx'.  To be sure, there are some things 
> there that you can ignore, but it might give you some ideas on how to 
> proceed.

Thanks a lot.  As far as I can see from the CVS comments there are still
problems with matching the speed of the emulator to the speed of the original
Atari.  In my emulator I never need to compute how much ahead I am and to call
SDL_Delay if the audio is enabled - the sound system does the speed matching for
me - this is what I'm trying to achieve in SDL.  In your code you apparently
rely on some other means of slowing the emulator down.

Leo






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