Great documentation! I like it.

Excellent! 👍

jwt27 wrote on 2023-01-01, 17:19:

I figured out the ESFM register
map. As far as I'm aware, this hasn't been done before.

Thank you very much for documenting this!

BTW, we've been testing some games with native ESFM support in this thread. It can sound really nice when the developers use it properly.

Truly many compliments and a huge thank you
I am sure that the gift you have given to the whole community will be appreciated by all considering the possibilities it will give 😄

18 4-op voices with more flexibility than an OPL3?
Wow, what an underused chip.

Great work!

Thanks everyone, appreciate the compliments. I just found some more registers and will document these shortly.

Joseph_Joestar wrote on 2023-01-01, 19:05:

Thank you very much for documenting this!

BTW, we've been testing some games with native ESFM support in this thread. It can sound really nice when the developers use it properly.

I think all games mentioned there use the same Miles Sound System driver, so they all use the same preset bank. If there are any games that do use a different driver I would be very interested to know.

Is there any more reason we know now of why the sound is muffled when using native ESFM? Is this a driver bug?

the3dfxdude wrote on 2023-01-01, 21:09:

Is there any more reason we know now of why the sound is muffled when using native ESFM? Is this a driver bug?

I assume you mean muffled PCM voices? The FM synth has nothing to do with that. The PCM part of these chips is actually well documented, and they have adjustable filters. My guess is that the Miles driver just sets the cutoff frequency too low. So yes, that would be a driver bug, and it should be possible to patch it.

the3dfxdude wrote on 2023-01-01, 21:09:

Is there any more reason we know now of why the sound is muffled when using native ESFM? Is this a driver bug?

If you mean the behavior that Phil demonstrates in this video around the 7:08 mark, that's related to digital audio when the card is working in its proprietary AudioDrive mode. This is different from the native ESFM support which refers to FM synth music.

From my observations, the muffled sound issue only occurs with games which use the HMI Sound System, such as Tomb Raider, Red Alert and Daggerfall. It doesn't happen in games which use the Miles Sound System.

jwt27 wrote on 2023-01-01, 21:00:

I think all games mentioned there use the same Miles Sound System driver, so they all use the same preset bank. If there are any games that do use a different driver I would be very interested to know.

I don't know of any non-Miles DOS games that can use native ESFM.

BTW, if you haven't already seen this, the ESS 1869 datasheet (available on Phil's website) has some info on ESFM, starting from page 41.

I hope to see ESFM added to libadlmidi so I can listen to the the video game XMI files with the ESFM FM instruments.

jwt27 wrote on 2023-01-01, 21:59:

the3dfxdude wrote on 2023-01-01, 21:09:

Is there any more reason we know now of why the sound is muffled when using native ESFM? Is this a driver bug?

I assume you mean muffled PCM voices? The FM synth has nothing to do with that. The PCM part of these chips is actually well documented, and they have adjustable filters. My guess is that the Miles driver just sets the cutoff frequency too low. So yes, that would be a driver bug, and it should be possible to patch it.

Yes. PCM AudioDrive I suppose. But I guess fixing the muffled sound would be for another time for someone who wants to look into the driver.

That is amazing.

Joseph_Joestar wrote on 2023-01-01, 22:38:

BTW, if you haven't already seen this, the ESS 1869 datasheet (available on Phil's website) has some info on ESFM, starting from page 41.

I've seen that. It only mentions that a "native" mode exists - there's no info on how to use it, or even what it's capable of...

jwt27 wrote on 2023-01-02, 17:19:

I've seen that. It only mentions that a "native" mode exists - there's no info on how to use it, or even what it's capable of...

My bad, I just noticed that the register descriptions listed there are only applicable for the emulation mode.

Awesome job there, thanks!
My cherished dream is to see ESS IC's reverse engineered, like genuine Yamaha OPL3.

A real shame it did not see it's full potential used.

I reverse engineered the WDM ES1969 driver which uses the ESFM registers (see NATV.CPP), and compiled a 64bit driver from it, in case anyone is interested:
https://github.com/leecher1337/es1969/

I think the muffled audio problem is only occuring when a game uses Human Machine Interface drivers.

It's fantastic that the info is out now, but I have to say it's also a bit disappointing that the ESFM still doesn't have the ability to reproduce algorithms 2,3,4 from the 4-op Yamaha chips. When I saw the thread title I was thinking an ESFM-enhanced VGM player might be in the cards, but it looks like there is still no way to feed two modulators into a single carrier. Detune is missing, which would limit accuracy as well.