|
MAME/MESS PSX MDEC output compared to hardware
#217636 - 03/23/10 04:35 PM
|
|
|
Does anyone know if the PlayStation 1 MDEC emulation code in mame/machine/psx.c has been compared to actual hardware MDEC output? Is it byte-exact, or is it just an IDCT and YCbCr->RGB estimation? Is there any documentation about such a comparison available that might include an actual hardware memory dump?
If no one really has any of these answers, could anyone direct me to where I might find some answers? Thanks.
|
|
|
| R. Belmont |
|
Cuckoo for IGAvania
|
|
|
|
|
|
Reged: 09/21/03
|
|
Posts: 9716
|
|
Loc: ECV-197 The Orville
|
|
|
|
Send PM
|
|
|
Re: MAME/MESS PSX MDEC output compared to hardware
[Re: m35]
#217671 - 03/23/10 09:39 PM
|
|
|
> Does anyone know if the PlayStation 1 MDEC emulation code in mame/machine/psx.c has
> been compared to actual hardware MDEC output? Is it byte-exact, or is it just an IDCT
> and YCbCr->RGB estimation? Is there any documentation about such a comparison
> available that might include an actual hardware memory dump?
Nobody's done a comparison on that level that I'm aware of, but MAME's MDEC was first to correctly implement a lot of things that common PSX emulators got wrong (e.g. that Cr comes before Cb, not the other way around).
|
|
|
|
Re: MAME/MESS PSX MDEC output compared to hardware
[Re: R. Belmont]
#218076 - 03/28/10 03:06 AM
|
|
|
> Nobody's done a comparison on that level that I'm aware of, but MAME's MDEC was first
> to correctly implement a lot of things that common PSX emulators got wrong (e.g. that
> Cr comes before Cb, not the other way around).
It also uses the uploaded cosine & quantize tables.
|
|
|
|
Re: MAME/MESS PSX MDEC output compared to hardware
[Re: ]
#218126 - 03/28/10 06:55 PM
|
|
|
Ah smf, I'm happy to have caught your attention 
I recently discovered the uploaded (I)DCT cosine table as well, and even just added it to my PSX video format document. I've also been keenly aware of the Cb/Cr swap error thanks to your post about it.
Comparing the various decoders out there (I'll be adding MAME to the list soon), it seems there's only a handful that get it right.
I've been trying to add a 'PSX exact quality' option to my jPSXdec video decoder. Since I only have a PSone and the CD based Gameshark, I don't have easy access to PSX ram, otherwise I'd be dumping it and comparing. MAME's output is the closest thing I have to work with, so I was hoping that careful comparison might have already been done. As it hasn't, I would totally be digging into it right now--if only I had hardware RAM/VRAM dumps of the 24 BPP Tekken 3 or FF9 opening movies. 
|
|
|
Previous 
Index 
Next 
Threaded 
MAME/MESS PSX MDEC output compared to hardware
Reply
[Re: 
