Re: [B2-devel] problems caused(?) by recent patches

[Charles S. <bas...@ch...>]

On Jan 14, 2010, at 7:18 AM, Ronald P. Regensburg wrote:

> 
> In Emaculation.com forums, Alexei Svitkine asked me to mail to this  
> list about patches I needed to revert before building SheepShaver (and  
> BasiliskII) for Mac OS X in order to avoid problems.
> 
> 
> The problems with the "precise timer patch" were discussed in the  
> basilisk-devel list between October 23 and October 28. Those problems  
> were the reason for me to make the 25-10-2009 build for  
> Emaculation.com within days after the 18-10-2009 build.
> 
> In my last October 25 message to the basilisk-devel list I told which  
> files I used for the 25-10-2009 build to omit the "precise timer  
> patch" and the "sdl-audio patch".
> 
> The "sdl-audio patch" apparently made sound for most users worse  
> rather than better. Users of both BasiliskII and SheepShaver builds  
> created after that patch was added, complained about the problems for  
> months and reported considerable improvement when I posted builds of  
> both without the patch. That happened before I joined this mailing  
> list. The problems were sound delays, stuttering, even skipping of  
> sounds. The problem was more serious in BasiliskII than in SheepShaver.
> 
> I do not know whether these patches actually cause the problems or  
> just make bugs in other parts of the code apparent.

The crash with the precise timer patch was mostly limited to running the app on PPC machines if I remember correctly, wasn’t it? Since SheepShaver runs completely different code paths on PPC and Intel, with the PPC version running native code and the Intel using emulation, I can see how the change could have caused problems with one that would not have come up on the other. The best solution in this case may be to enable the precise timer patch only when building for Intel.

The SDL audio patch, on the other hand, is simply ill-advised in my opinion. The docs for SDL recommend using a value between 512 and 8192 for the ‘samples’ field of an SDL_AudioSpec. The patch in the SheepShaver source sets it to 16384. The result is laggy audio. I think the patch was made to reduce the demands on processing power for older machines, but for those with modern hardware it seems to cause more problems than it solves.

Charles