[hatari-devel] New STE DMA audio emulation

Laurent Sallafranque laurent.sallafranque at free.fr
Wed Jul 6 22:46:34 CEST 2011


Hi,

I think that Falcon sound is worse with the latest DMA changes.

Is it me ? (I've tested with Amanita)


For the Falcon part, there's a possibility to compute VBL cycles precisely :

A screen (VBL) in the videl is composed of a certain amount of halflines.
And we know the number of Videl cycles of a halfline.

So, I can add a function that would return the number of cycles for a 
Falcon VBL.

It would be something like :


VBL_cycles = (HHT+2) * 2 * VFT

// HHT = number of cycles minus 2 per halfline
// VFT = number of halflines per screen

If Videl clock is 32 Mhz,
    VBL_cycles /=2
else
    VBL_cycles = VBL_cycles / (25/16)


It's what I've started to implement in the Videl emulation.

Like this, we would have a correct value for Falcon VBL cycles and this 
could improve music, no ?

Nicolas, do you  agree here ? How could I call this for Falcon crossbar 
sound ? (maybe a function in videl.c that would return cycles in vbl ?)

regards

Laurent




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