Re: [hatari-devel] DMA sound and Falcon

[Laurent Sallafranque <laurent.sallafranque@xxxxxxx>]

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 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. ;)

Regards

Laurent



Le 11/09/2016 à 19:05, Nicolas Pomarède a écrit :
> Le 11/09/2016 à 18:54, Laurent Sallafranque a écrit :
> > Hi,
> >
> > Thanks Nicolas, That's fixed now.
> >
> > I've noticed that sometimes sound unsynchronize and then later,
> > resynchronize (this generates noise and cracles in the sound).
> > With 1.7, if the sound was correct at the beginning, it stayed correct,
> > and if it was noisy at the beginning, it stayed noisy.
>
> I never really had a look at the Falcon part, as I don't know the 
> hardware that much (never had a Falcon or coded for it).
> But I remember we had some similar problems with STE DMA sound that 
> sometimes sounded wrong and it was fixed by improving the frequency 
> computation (ie the ratio between cpu freq, output freq on the OS and 
> replay freq in emulation)
>
> Maybe some similar changes need to be done in the Falcon part, I will 
> try to isolate this using the simple program you sent me that just 
> play a short sample in "ste dma" compatibilty mode.
>
> > For your info, some warnings :
>
> Yes, I'm aware of those :) Will remove them soon, I need to clean some 
> parts of video.c
>
> Nicolas