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 Post subject: Qsound questions
PostPosted: 2019-09-09, 1:40:09 
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Joined: 2018-09-15, 18:33:08
Posts: 11
Location: UK
I recently heard that MAME's Qsound emulation has been deficient all this time (that's a shock). This has now been fixed in MAME, and having searched these forums, I'm led to believe that this correction has also been addressed in VGM? If so, I have three questions…

1) When exactly was it fixed? I'd like to know as I ripped a ton of music to FLAC last year and not sure if I'll have to update all my files?

2) Is Qsound 100% working properly now, or is this still something of a work in progress? Will there likely be any more big improvements?

3) While I'm here, I have often wondered about the specs of Qsound. Like, how many channels? Operators? Is it FM? Is it anything like, say, the YM2151? For some reason, I can find lots of information online about other chips, but not the mysterious Qsound chip.


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PostPosted: 2019-09-09, 7:16:11 

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Joined: 2013-07-17, 23:32:39
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Qsound itself is a stereo expansion effect, it is designed to create the illusion of the speakers being further apart than they really are.

The Qsound chip in the CPS2 is a wavetable chip with this effect built in. The improved emulation added the stereo expansion effect, previously only the wavetable part was working. The chip had a few other effects that are now emulated also.

First MAME version with improved HLE emulation is 0.201. And vgmplay version 0.40.9. right now it is fully working in MAME, though an "improvement" in the future would be low level emulation, that is emulating the DSP itself. Currently LLE has some issues with timing in MAME.

As for the specs, I think it's easier just to read the source code. I have a document for programmers here though.


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PostPosted: 2019-09-09, 17:53:08 
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Joined: 2018-09-15, 18:33:08
Posts: 11
Location: UK
CTR,

Thanks for the reply. It looks like I did use 0.49.9 to rip my music, which is great as I don't have to go back and re-rip anything. (I did already think the music sounded fantastic, and very wide! :) )

Thanks for that document. I'm not a coder so much of it is too technical for me, but the main thing I wanted to know is that the CPS2 QSound is a wavetable chip, so thanks for clearing that up! :)

These developments in VGM are fantastic, and very much appreciated CTR. Thanks for all your work. I'm still thrilled that CPS2 encryption has been cracked. It's wonderful that we have the internet, so all these clever men around the world could come together to preserve these games and this music forever, which otherwise would be lost.


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