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Re: CSM in OPL2 (YM3812)

Posted on 2022-05-16, 17:20

Thank you Jo22 . I will look at it. If there will be something interesting and leaving questions, I return to this thread. Edit: these documentations are very thin. There are no word about CSM. You can only read CSM means "Composite Speech synthesis", register 08, bit 0x80. No more... My question is …

Re: CSM in OPL2 (YM3812)

Posted on 2022-05-16, 12:53

Composite Speech Mode Was it a speech synthesizer? If Yes it will be very interesting to me to implement it but I need data/documents to do it. I have no OPL1/OPL2 or OPL3 chip now. After searching "Composite Speech Mode" (I found Composite Sine Mode) I was found that timer 1 was used to trigger …

CSM in OPL2 (YM3812)

Posted on 2022-05-16, 10:59

Is there any interesting thing in the CSM mode of OPL2 (abandoned in OPL3)? I cannot find any documentation to this mode other than short description that was used to obtain "composited voices". What registers should it controlled after it was turned on? This mode is unimplemented in known emulators …

Re: Drums on truly real OPL2

Posted on 2022-05-15, 22:28

There's also some checks on the header fields for unsupported chips (all other chips than the YM3812 and Game Blaster (SAA1099) being unsupported). Although it drives the Game Blaster in a mono configuration (it sends one command to both left and right chips). In my converter written in PHP I also …

Re: Drums on truly real OPL2

Posted on 2022-05-15, 18:15

After reading your comments, I've now implemented a VGM player into UniPCemu. It's based on https://vgmrips.net/wiki/VGM_Specification Although I don't have any VGM files to test it with. You will find files in this topic It theoretically (as in untested so far) supports playing VGM files for both …

Re: Drums on truly real OPL2

Posted on 2022-05-15, 14:25

superfury , I propose you should make code review after so many changes. Review the waveforms with use of FOLK102. FOLK102 allows you to set each parameter but you need additional program to switch bit 0x20 in register 0x01 (for example SBTimbre) to use other waveforms than sinus. FOLK102 also has …

Re: Drums on truly real OPL2

Posted on 2022-05-15, 13:44

So now the entire OPL2 synthesis part works using integer math. Also the OPL3 (YMF262) will work the same way but OPL3 has better attack and decay curves. DosBox 0.74-3 probably emulates these in OPL2. The only thing that still uses the old floating point method is the Tremolo/Vibrato logic and the …

Re: Drums on truly real OPL2

Posted on 2022-05-15, 09:46

But the data from the exponent table stage is floating point, isn't it? Yes, it isn't. This document should help you to understand. You really use cannon to shoot a fly. out = exp(logsin(phase2 + exp(logsin(phase1) + gain1)) + gain2) Exponential table (store this as static const int16_t[] array): x …

Re: Drums on truly real OPL2

Posted on 2022-05-14, 21:59

Modulator/feedback output - there is needed only int32_t. Why do you use floats/doubles? It has no sense to calculate feedback and modulation on double instead of int32_t. Does the original chip calculated it in double/int64 mode or 32-bit? No. 20 bits - it was the precision of this chip. If you …

Re: Drums on truly real OPL2

Posted on 2022-05-14, 20:13

I'm using the Rhythm.DRO from this post: Do not use DRO files with percussion enabled. DosBox sucks and records them incorrectly to DRO file (bad values of B7 and B8). I finally checked percussion with VGZ. 1) Uncompress it with PHP command gzdecode. 2) String 5A xx yy means: write yy to register …

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