YM2612 CSM Mode - Speech Synthesis

walker7 · Post by **walker7** » Tue Aug 21, 2012 5:51 pm

For those of you who have worked with CSM mode on the YM2612, it would be interesting if you could actually do speech synthesis on the Sega Genesis.

One way to do it is with formant synthesis. First, make sure that channels 3 and 6 are in CSM mode (YM2612 register $27 set to %10xxxxxx), and then, for each operator in a channel, you could set a formant. I think that this would also involve Timer A, as well.

You can see a list of vowels and their formants at http://en.wikipedia.org/wiki/Formant_frequency. For example, the vowel "u" has formants f1 = 320 Hz and f2 = 800 Hz.

TmEE co.(TM) · Post by **TmEE co.(TM)** » Tue Aug 21, 2012 7:12 pm

Ch6 has no 4 freq mode.

Stef · Post by **Stef** » Tue Aug 21, 2012 8:11 pm

I have to try that speech synthesis through the CSM mode of the YM2612 chip, this is something that really interest me

I wonder why no game tried to use it, maybe it sounds really too bad for being understandable...

Huge · Post by **Huge** » Tue Aug 21, 2012 8:42 pm

Stef wrote:I have to try that speech synthesis through the CSM mode of the YM2612 chip, this is something that really interest me
I wonder why no game tried to use it, maybe it sounds really too bad for being understandable...

Probably just the documentation sucking.

sega16 · Post by **sega16** » Tue Aug 21, 2012 9:45 pm

One Japaneses girl used it along side an over rated video http://68000.web.fc2.com/bad_apple.html
Also even if it does sound bad/fake I think it would be useful for one of those evil robot takes over world you must save the world type of games or pretty much anything that involves robots.

Mamizou · Post by **Mamizou** » Wed Aug 22, 2012 9:47 pm

One of the sites linked on that Bad Apple video has some CSM programming info for the OPN/OPNA on the PC-8801 here. It also links to a video on NND showing "Sine Wave Synthesis" via MIDI on an 88pro wavetable synth. Pretty amazing. :O

Charles MacDonald · Post by **Charles MacDonald** » Sun Aug 26, 2012 4:11 am

One thing that might be worth looking into is the BASIC ROM for the Yamaha CX5M (MSX) computer, it supports a speak command that uses the CSM of the YM2151.

It's Z80 code so it shouldn't be too hard to figure out how the commands relate to how the YM2151 is programmed, and we may be able to extrapolate from that how the YM2612 CSM works, assuming they have some similarities.

Some overview on how the BASIC command works:

http://www.msx.org/forum/msx-talk/softw ... h-japanese