Re: [hatari-devel] DMA sound and Falcon

[Laurent Sallafranque <laurent.sallafranque@xxxxxxx>]

Hi,

There's still a problem with the DMA sound :/

When I use hatari Falcon in 16 Mhz, the DMA sound is OK (except the 
noisy sound but that's another story).

But if I swith to 32 Mhz, the sound plays 2 times too fast again.

And if I swith to 8 Mhz, it does a funny effect ;) (sound seems to 
repeat twice in each slices of sound, a bit like an echo).

Regards
Laurent



Le 11/09/2016 à 19:37, Nicolas Pomarède a écrit :
> Le 11/09/2016 à 19:17, Laurent Sallafranque a écrit :
> > Hi,
> >
> > The sound become noisy after some seconds and then, return to clean
> > after the same amount of time.
> > It seems to be cyclic. clear sound -> degrades -> noisy sound -> becomes
> > better -> clear sound -> ...
> >
> > Something I never added to the crossbar is that there are two 32 bytes
> > buffers for the sound (in and out).
> > I've got the schemas somewhere if someone need them.
> >
> > I know you added 1 little buffer to the Ste DMA that you feed after each
> > hbl, but I don't understand exactly how you did it.
> >
> > I wish this make sense.
>
> I don't think that's related. The STE DMA sound FIFO was only needed 
> for a few programs requiring very strict timings, but it was not 
> related to the frequency computation, it was required for program that 
> monitor the current dma address.
>
> > I think I was very careful with the frequencies conversions (int to frac
> > or rounding), but I'm sure your advise and 4 eyes looking can only
> > improve the code. ;)
>
> I have no real explanation at the moment, I will first add some logs 
> to better understand the difference between a good and a bad rendering.
>
> Nicolas