What the PSG also can sound like...

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Door ToriHino

Champion (361)

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11-06-2017, 14:23

Found this video in which it is demonstrated what is possible with the PSG, given enough processing power (this one is on the Atari ST):
https://www.youtube.com/watch?v=4xVfuuSty48

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Van Grauw

Ascended (8395)

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11-06-2017, 15:02

Yeah, people did pretty neat stuff with the PSG on the Atari ST. A processor with DMA surely helps a lot!

I like this one a lot myself: Cerror - Datass

By the way, if you could manage to get a VGM capture of that song, I bet VGMPlay for MSX can play it just fine! Perhaps the 300 Hz update resolution on MSX2 is already enough, and if not then at certainly the 4000 Hz on turboR should be just fine! It can play this song too, after all :).

(And if it works fine on VGMPlay on MSX2 then that should also be a good indication that it would be possible for an MSX2 tracker to generate these effects and use in game BGM. The turboR timer isn’t interrupt-driven so not very suitable for BGM.)

Van syn

Paragon (1920)

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11-06-2017, 14:58

Some explaining /discussion of the techniques used here: https://www.msx.org/forum/msx-talk/development/ay3-psg-duty-...

Van ARTRAG

Enlighted (6239)

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11-06-2017, 17:40

The key is to have programmable interrupts at "audible" rates.
IIRC Atari ST has about 7 or 8 programmable clocks that can rise interrupts

Van Grauw

Ascended (8395)

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11-06-2017, 19:10

I wonder though whether they must be variable rate interrupts, or can also be fixed rate interrupts, and what the minimum resolution would have to be. Maintaining fixed point counters to determine the current volume state, you could get the same effect I think, with some aliasing of course but maybe it sounds ok… Then again the ears are sensitive. Trying an Atari ST VGM which uses PWM on VGMPlay will tell us quickly Smile. Problem is finding those VGMs! Seems no-one recorded any Atari ST ones yet.

Van ToriHino

Champion (361)

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11-06-2017, 19:45

Found the tracker (Triplex) with a number of songs and even the sources included. I can even run it within an Atari ST emulator, but this one only records to WAV. So now to look for other emulators to see if it's possible to somehow record the output to VGM or some convertable format. Indeed curious what will come out using VGMPlay.

Van hit9918

Prophet (2866)

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11-06-2017, 20:49

you cannot make a vgm because the ST updates the registers in the timer interrupt,
much higher update rate than usual players and vgm which go vertical blank interrupt, monitor hz.

Van Grauw

Ascended (8395)

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11-06-2017, 21:11

@hit9918: The timing resolution of the VGM file format is 44100 Hz, and VGMPlay for MSX plays back with a timer resolution of 4000 Hz on turboR and 300 Hz on MSX2. PC players obviously use 44100 Hz resolution. So yes, you can make a VGM. As demonstrated by the Skate or Die intro which plays samples on SN76489.

@ToriHino: Maybe you need to write a script for the emulator (like my vgmrec.tcl for openMSX), or modify the emulator source. There are some KSS-like formats for ST, sndh and sc68, could also modify a player for those to log VGM.

Van hit9918

Prophet (2866)

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11-06-2017, 21:15

oh, I didnt know that it is so high spec.

Van yzi

Champion (441)

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11-06-2017, 22:14

The SID is an actual synth chip though. Talking about "SID sound" is a bit funny, because even with all sorts of hackery, let's face it, the PSG is a pretty crappy chip. Big smile

Here's a very interesting and long video by Richard Atkinson exploring the 8580 SID's variety of sounds with a custom controller and oscilloscope.
https://www.youtube.com/watch?v=LQt6j_p3O8U

4-Mat of Ate Bit has recently made an automatic YM player for the C64, capable of playing Atari ST music on the C64.
https://www.youtube.com/watch?v=2C7gHRKr-Uk

I actually like this C64 version of Mad Max's Solidify even better than the original YM tune
https://www.youtube.com/watch?v=BLOa-Zp-SzA

Van AxelStone

Prophet (2674)

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11-06-2017, 22:18

Don't forget titles like Seleniak or Retaliot from MSX1:
https://www.youtube.com/watch?v=HC1DUzplaUg
As you can see you don't need M68k power to generate great tones :-)

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