By default DOSBox's opl emulator is the fast thing Harekiet knocked out from bitshiftery black magic. Try oplemu=compat, it should compare a little better. Also, set your rates to 49716 so the OPL3 emulator has the appropriate frequencies to work with (really matters for all the percussion).

As for accuracy, my ears are getting old so I can't hardly tell the difference between oplemu=compat and the real deal anymore 🙁

*cough*ESFM and CQM FM emulation haven't been investigated yet afaik*cough*

If there's any 'progress' on OPL3 that could possibly be done, it'd probably be integrating that new Nuked OPL emulator into Dosbox somehow (with proper license clearances and etc). That's the most modern recent accuracy-focused development in the opl emulator realm as far as I know.

Okay, I professionally recorded DOSBOX vs my real CT2950 for us to compare.

The "OPL3 Comparison.7z" file (11MB) contains 6 mp3 files at 320kbps from 3 games:
Doom-CT2950.mp3
Doom-DOSBOX.mp3
War2-CT2950.mp3
War2-DOSBOX.mp3
Lemmings-CT2950.mp3
Lemmings-DOSBOX.mp3

http://www.mediafire.com/download/6uv69edrlp6 … 3_Comparison.7z

Dosbox was set to oplemu=compat and rate=49716 everywhere.
Recorded into my Focusrite Saffire Firewire Audio Interface in 48khz 24bit, Normalized and mixed to match volume, Lame 3.99 on Insane quality (320kbps) to create mp3.

Currently I have no idea which one is more "real" dosbox or non-existent-OPL-chip-CT2950...
Next week my Yamaha YMF719E should arrive and I'll add it to the comparison.

Oh the CQM chip is very easy to tell apart. It's far more buzzier and bassier, and can get its polyphony wrecked in certain games completely butchering some songs. Try Doom E2M2. 😀

DOSBox OPL completely stomps on that chip.

EDIT: here's an ogg of a CS4232 (laptop WSS Crystal Semi chipset) playing Doom E1M1 through its true OPL3. It's a little noisy and lowpassy (obviously not studio equipment), and DOSBox resembles closer to this recording than the CQMs. The card you ordered should sound like this but much cleaner/clearer with better highs.

Yes, the CS4232 sounds better than dosbox (but similar) and definitely better than my CT2950, or at least closer to what I remember it was in the 90s.
Okay, waiting for my Yamaha YMF719E.

For the sake of it (no wonder it was cheap), here's my CT2950 (what not to buy):
* Huge closeup of the CT2950 so the chip names are readable (and not a single Yamaha).
http://www.mediafire.com/convkey/4d90/pocbx9fdadasjf8zg.jpg

All in all, the CT2950 with the integrated CQM instead the original Yamaha YMF262 (OPL3), sounds not bad at all, but a little different to the original.
That's not to say that the game will sound completely different, it will not, it will sound like your game but slightly different (I'd say 90%+ there).
Anyway, much better than the PCI128 I used before the CT2950, which uses god knows what for the OPL emulation and sound like a completely different game.

BTW, the original question is still open, where the OPL of dosbox came from? Based on what?

wd and Harekiet made their own cores. This was during a time when the only other OPL emulators were MAME's and Ken Silverman's

could be better

Tertz wrote:

Have tested Legend of Kyrandia v1.3 FM emulation with "Pool of Sorrow" song on the screen with a lake (7:30). Yes, there is an i […]
Show full quote

Have tested Legend of Kyrandia v1.3
FM emulation with "Pool of Sorrow" song on the screen with a lake (7:30).
Yes, there is an issue, not critical though. The song plays differently with next cycles. If in game's options to switch off music and then switch on - the song plays correctly again in the beginning.
Would be good if Kyragem88 name other games he've found with similar FM issues. Maybe developers will look and fix it.

Yes, the music "drifts" and gets out of sync in some old Real Mode games (a pure guess).
In my audio comparison, Lemmings-DOSBOX is actually shorter than the original CT2950 by 2 seconds, even though they are perfectly time aligned in the beginning.

One thing is for sure, Dosbox is not cycle accurate nor it meant to be, so we can't rely on that for critical medical Life Supporting Systems... 😀

James-F wrote:

Yes, the music "drifts" and gets out of sync in some old Real Mode games (a pure guess).
In my audio comparison, Lemmings-DOSBOX is actually shorter than the original CT2950 by 2 seconds, even though they are perfectly time aligned in the beginning.
One thing is for sure, Dosbox is not cycle accurate nor it meant to be

I think break of FM sync (wich then distorts a music) is the bug that can and should be fixed in DOSBox. It's not about abstract cycles - it's about distortion of music in games.

To whom that still interested;
The Yamaha YMF719 is here and I've already recorded it to have a clear comparison.
Guess what?, Dosbox is 100% accurate to the point that I can't distinguish between the real OPL3-SAx and dosbox on professional studio monitors with ribbon tweeters.

The waveform of dosbox on the distorted guitars is more similar to the OPL3-SAx (YMF719) than to the to the CQM (CT2950), although not similar.
The distorted guitar waveform is a top-half triangle waveform, which dosbox creates to perfection but the real sound cards skew to some degree.
If I would have to guess, I would say that Dosbox emulated the behavior of the OPL3 chip without the peripheral hardware that may affect it's sound.

Anyway, hope it helps other people for future reference.

Cheers! 😀

Digitally recorded OPL3 for comparison:
https://www.dropbox.com/s/7fqynfqcgn4tq45/E1M1.wav?dl=0

Thanks khokh2001,
I mastered and posted your file again to be equal to my recordings.

To me it sounds exactly like the YMF719 and Dosbox.
The waveform is even closer to dosbox, without the minor DC offset that the YMF719 shows.

leileilol wrote:

Oh the CQM chip is very easy to tell apart. It's far more buzzier and bassier, and can get its polyphony wrecked in certain games completely butchering some songs. Try Doom E2M2. 😀

I just tried E2M2, and it does sound quite unsatisfactory with the AWE64, when played as OPL3. DOSBox sounds better. Of course, in the case of DOOM it will sound even better on AWE64 when played as AWE. 🤣

There is a lot of talk about CQM's inadequacy, and I wish there were more comparison recordings showing this inadequacy. There is the "Grand OPL comparison" thread, of course, but somehow the selection of songs there does not seem convincing. When comparing the different OPL implementation with those songs, the differences sound quite minimal, and would often be a matter of taste more than anything else.

If you're looking to test the accuracy of the DOSBox emulator, try playing Commander Keen 6. Warp (press W+F10) to level 6, and listen to the music. There's a bit of percussion at the start, but when some notes start, the DOSBox synth plays them an octave or so too low compared to real hardware (at least the original OPL2.)

Here is a recording made with an Adlib Digisnap in case you don't have a real card handy.

If you don't have a copy of Keen 6, here's the song in IMF format you can play with the DOS program AdPlay (part of AdPlug.)

Thanks for these recordings !

Is there anywhre a list with games wich use TRUE OPL3 features and not just "opl2 in stereo" or/and at least the games wich use the opl3's stereo ? I know there was a thread about this on the MIA QuestStudios 's forum.

Thanks.

Cybersphere's a good start. It relies on OPL3 so hard it screws up on OPL2.

According to FM sync problems.
Diag in 0.74 shows:

Real Time Clock shows some stable mismatch too.

It has just been pointed out to me (thanks NY00123!) that if you set the OPL sample rate in dosbox.conf to 49716 then the Commander Keen song I mentioned above sounds exactly the same as the Adlib digisnap recording! I had the OPL set to 48000 to match my output sample rate but this actually seems to affect the pitch of some notes.

I had no idea this made a difference. Do the other games (e.g. Cybersphere) sound any different with a different OPL sampling rate?

I wonder why this happens? Perhaps the timers are based on the sample rate?

Feedback is strongly influenced by the samplerate

Malvineous wrote:

if you set the OPL sample rate in dosbox.conf to 49716 then the Commander Keen song I mentioned above sounds exactly the same as the Adlib

Yes, this removes some wrong percussions's pitch in OPL emulation.
And adds another problem, - the resampling made by the emulator or by a card adds noisy distortion, as there is no native 49716 Hz mode and quality of resampling is mediocre in DB and on many cards/onboard chips.