Re: [hatari-devel] sound bug

[Laurent Sallafranque <laurent.sallafranque@xxxxxxx>]

> SDL part is really simple : the callback function needs to be fed 
with a fixed number of samples on each call to achieve proper output 
rate. From the problem described by Doug for example, I'm not sure this 
looks like a SDL problem (but I could be wrong :) )

Maybe I expressed myself wrong : I don't think SDL is in fault here (it 
has proven so much that it is a very capable library with hatari), but 
maybe the way hatari uses SDL sound in Falcon mode (the sound refresh or 
something like this).

It must be a ridiculous bug somewhere, but we'll need time to find it ;) 
(it's always like this ;)

Laurent



Le 27/06/2014 23:17, Nicolas Pomarède a écrit :
> Le 27/06/2014 18:04, Laurent Sallafranque a écrit :
> > Hi,
> >
> > I think there are 2 problems here :
> >
> > - one with the general sound quality of Hatari (which is, from my point
> > of vue, dependant of the CPU accuracy (because the crossbar code is
> > related to the cpu time)
> >
> > - one which is the every 4-5 times crappy sound problem which is not
> > related to the crossbar code (else, we would not have good quality sound
> > sometimes).
> > I think it's more a problem of synchro with SDL or something like that,
> > but I'pm pretty sure that the problem is not in the crossbar algos
> > (switching to 11 khz and back to 50 khz sometimes fix the crappy sound
> > problem, but if you do this and activate  "trace crossbar" in the
> > debugger, you'll notice that there's no crossbar event involved, so no
> > change in the crossbar structure, but only in the "SDL" part of hatari..
> >
> > I don't think the solution is in an improvement of the crossbar algos (I
> > may be wrong of course).
>
> Hello
>
> I haven't look that much at the falcon sound, but I doubt it's SDL 
> related : YM sound and STE sound never shown this kind of behaviour, 
> you can switch repeatedly between several output freq and sound 
> doesn't go wrong. So I'm not sure it's SDL.
>
> Also, you say switching from 50 kHz to 11 kHz doesn't change anything 
> in crossbar, but as you need to play 5 times less samples per second, 
> the crossbar sound part at least needs to adapt to this (if it's not 
> the case, then sound will be really wrong).
>
> SDL part is really simple : the callback function needs to be fed with 
> a fixed number of samples on each call to achieve proper output rate. 
> From the problem described by Doug for example, I'm not sure this 
> looks like a SDL problem (but I could be wrong :) )
>
>
> Nicolas