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Author Topic: FM and DAC on channel 6 - at the same time (YM2612)  (Read 3944 times)

Offline Alianger

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FM and DAC on channel 6 - at the same time (YM2612)
« on: March 23, 2016, 03:01:45 AM »
https://www.youtube.com/watch?v=Jo4x9LnY99E

I was ripping some instruments from this game and noticed that the FM crash in track 03 (10:13) is playing at the same time as the sampled drums in channel 6.
Anyone know how this is done? Maybe it should be a feature in DM?  :D
YT channel (MD music, romhacks, misc gaming): https://www.youtube.com/user/Alianger/videos

Offline Raijin

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #1 on: March 23, 2016, 03:42:58 AM »
It can already be done. FM and PCM can never play at once in CH6. Matt did it like this (but masked it better than I did).

Offline MegaSphere

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #2 on: March 23, 2016, 06:27:07 AM »
It can already be done. FM and PCM can never play at once in CH6. Matt did it like this (but masked it better than I did).
Wow, I gotta use that technique!
To understand FM, I think of each OP as an OSC that can also be a LFO.

Offline Alianger

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #3 on: March 23, 2016, 12:16:39 PM »
I knew of that, but the FM doesn't get interrupted when I listen to the WC track in Regen so it doesn't sound the same. At least it's not nearly as noticeable. But maybe it has to do with the speed settings?

Uploaded a short ch6 clip in wav.

YT channel (MD music, romhacks, misc gaming): https://www.youtube.com/user/Alianger/videos

Offline Delek

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #4 on: March 23, 2016, 01:15:42 PM »
It interrupts the FM6
http://project2612.org/details.php?id=50#03-stage-1-wolfship
(05 - Stage 2 - Jungle)

Mute DAC and FM1,2,3,4,5 and you will hear little cuts in the FM6. The thing is that the DAC is intelligently being swapped and also have a noisy background. Nice technique.

Offline Raijin

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #5 on: March 23, 2016, 06:06:48 PM »
Yeah, it does interrupt, it's just not as noticeable (which is why I said he masked it better than I did).

Although... Delek, hearing this makes me wonder. Does Deflemask keep the envelope of an FM patch going as the PCM sample is playing? I think it's supposed to, but it doesn't sound like Deflemask is doing that.

Offline Delek

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #6 on: March 23, 2016, 06:19:05 PM »
Defle doesn't control the envelopes because them are inside the soundchip, so:
1) It could be an emulation bug (the envelopes continues even if the DAC mode is turned on)
OR
2) That track doesn't use HW envelopes and it is using a volume decay by modifying the TL values via software (effect 0Axy in Defle)

Offline Raijin

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #7 on: March 23, 2016, 06:45:56 PM »
Well it might be doing it properly, but I can't really tell since note cuts will cut both the FM and PCM. I was trying to test a way to mask it better than it currently is.

Offline Delek

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #8 on: March 23, 2016, 07:17:57 PM »
You can tell by analyzing the .vgm file.

Offline marcb0t

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #9 on: April 21, 2016, 03:54:54 AM »
Alrighty, so after looking at the instrument set, it seems that the original musician had ALL his FM instruments set to "0" for the release. Which basically means the instrument will last forever until interupted by another instrument.

Looking through the set, there are a number of different instruments which are completely blank sounds where all the TL values are set to nothing. Which basically acts as note cuts when those "silent" instruments are played after the regular instruments.

I have attached a little .dmf demo I made using a drum sample loop playing along with "Wolfchild" FM instruments. I use the note cut instrument on the lead track.

ALSOOO... hi-hats are done with 2 different FM instruments. One is basically softer FM noise than the other. They can all do the stereo pan and play in Channel 5 while Channel 6 handles sample loops only.

If what I said does not make sense, just play around with the attached DMF file, and you'll see what I mean.

The laws of FM6 and DAC physics are not violated during this track.

Offline Alianger

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #10 on: April 21, 2016, 11:58:59 AM »
Marc, that's good general info about WC's music but how does it relate to this topic?
YT channel (MD music, romhacks, misc gaming): https://www.youtube.com/user/Alianger/videos

Offline marcb0t

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #11 on: April 23, 2016, 02:35:48 AM »
Marc, that's good general info about WC's music but how does it relate to this topic?

Sorry Alianger, Delek and Raijin are correct. After looking into it more and muting everything except DAC, I heard what Delek was talking about.

Yes, this is quite an impressive technique of FM/DAC swapping. Thank you for bringing this track to our attention!

Offline mihaelkyeah

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #12 on: April 24, 2016, 04:10:41 PM »
In Bram Stoker's Dracula, you can notice that FM envelopes do continue if a sample plays after a note was triggered, especially in the intro where notes get interrupted by thunder samples. I'm not sure if it has to do with, like marcb0t said about this other soundtrack, all the instruments having 0 release rates.

Offline Alianger

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #13 on: April 25, 2016, 02:58:18 PM »
No I'm pretty sure I've had that happen by mistake with other instruments before. Thanks for the replies guys.
YT channel (MD music, romhacks, misc gaming): https://www.youtube.com/user/Alianger/videos

Offline marcb0t

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FM and DAC on channel 6 - at the same time (YM2612)
« Reply #14 on: April 25, 2016, 11:07:32 PM »
In Bram Stoker's Dracula, you can notice that FM envelopes do continue if a sample plays after a note was triggered, especially in the intro where notes get interrupted by thunder samples. I'm not sure if it has to do with, like marcb0t said about this other soundtrack, all the instruments having 0 release rates.
Your instrument does not necessarily need to have a release of "0" in order to continue the envelope after the sample ceases. But the instrument needs to have a slow enough rate of decay to last. It's possible with or without release.

However, I did notice that Matt Furniss's instruments were unusual in that sense where they had "0" release. Which makes sense why he had blank instruments.

I think he didn't realize there was a "release" setting to keep instruments from lasting forever. :P Still, he did a good job with compensating, and overall sound design.