Skip to content

VGM emulation and slowdown (Thunder Force)

Technical discussion about the VGM format, and all the software you need to handle VGM files.

Moderator: Staff

  • Despatche Offline
  • Posts: 37
  • Joined: 2013-07-27, 23:53:40

VGM emulation and slowdown (Thunder Force)

Post by Despatche »

Hi, crazy question. Was wondering if it would be possible to somehow "fix" the slowdown in some games, specifically Thunder Force III and IV... would it require some kind of overclocking, or maybe some older version/other plugin that doesn't have as much accuracy, etc? I'm sure I'm not the only one who's been bothered by these two games!
  • User avatar
  • Raijin Offline
  • Posts: 41
  • Joined: 2012-08-15, 6:24:35

Post by Raijin »

I'm not sure what you're trying to say. To me, it doesn't sound like a question about VGM's since those don't slow down by simply playing them back, instead it sounds like you are talking about the games themselves.

Sorry, could you be more specific please?
  • Despatche Offline
  • Posts: 37
  • Joined: 2013-07-27, 23:53:40

Post by Despatche »

Well, um, I'm not sure how. Though I'm also not seeing your distinction.

Normally these two slow down when playing music (and sounds, I would think), probably for the sake of processing the rest of the games (this doesn't happen with Elemental Master, for example). If this is true, surely VGM would be emulating this as well as it can, and surely there would be a way to "fix" it? This would be a little easier to demonstrate if I knew anything about the Gold Packs for Saturn, which supposedly have no slowdown of any kind.

Aside from that, this is really a question about being able to under/overclock or otherwise bypass normal sound processing timings in any way.
Last edited by Despatche on 2013-07-28, 2:30:00, edited 1 time in total.
  • User avatar
  • dissident93 Offline
  • Posts: 204
  • Joined: 2012-02-17, 5:54:01
  • Location: USA

Post by dissident93 »

i'm confused by this was well. the game's music isn't slowing on purpose, and if you are asking the team here to fix a game issue that doesn't really have anything to do with the soundchip or the VGM set (rather this is a Motorola 68000 problem) then I don't see how we can help.

sorry if we misunderstood your question but it's pretty vague.
  • Despatche Offline
  • Posts: 37
  • Joined: 2013-07-27, 23:53:40

Post by Despatche »

I don't see how you can't! I don't know a whole lot about what VGM actually does; what all is it emulating to get its output? Surely it would have to emulate the 68000 somewhat well if it's able to even reproduce this behavior?

Again, I'm not asking for a fix, because it's actually a break; I want to know if there are (or could be, heh) any controls to underclock or overclock any given chip or processor involved. I think that is/would be interesting for the same reason it is/would be interesting in a full emulator.
Last edited by Despatche on 2013-07-28, 3:52:13, edited 2 times in total.

Post by GTheGuardian »

I don't think the VGM emulates the sound CPU the games do use (Like in this case,the Zilog Z80). Correct me if I am wrong.
  • User avatar
  • Raijin Offline
  • Posts: 41
  • Joined: 2012-08-15, 6:24:35

Post by Raijin »

Well, speaking of the games themselves, Thunderforce III barely has any noticable slowdown at all. Thunderforce IV does, especially on Maniac difficulty, but the VGM rips for both games don't slow down whatsoever, so I'm not sure what there is to fix.
The MD emulator Regen, iirc doesn't have a VGM ripping ability, but it does have a feature to overclock games. That's only good for playing games though.
Honestly, I'm still kind of lost on what you're trying to do, heh.

Post by GTheGuardian »

I don't hear slowdowns in TF3 and TF4 VGMs either.
Actually, MESS too emulates the MD/Genesis, allows overclocking for both Z80 and 68000 and there is also the VGM modded version.
Last edited by GTheGuardian on 2013-07-28, 4:30:18, edited 2 times in total.
  • Despatche Offline
  • Posts: 37
  • Joined: 2013-07-27, 23:53:40

Post by Despatche »

Actually, you're partly right, I apologize; Thunder Force IV doesn't have much/any of it normally (Fighting Back has a bit). III definitely does though. Pretty much every song has a small bit of it somewhere, but Venus fire (thank god for Hyper Duel), Truth, and Final take a chance are great examples.

I didn't even think about MESS, though I hope I don't have to make a whole new set of rips just to remove some slowdown, especially if it's being caused by a hard underclocking. Why wouldn't what is essentially an emulator of hardware sound have support for such things?
Last edited by Despatche on 2013-07-28, 5:01:25, edited 1 time in total.
  • User avatar
  • Raijin Offline
  • Posts: 41
  • Joined: 2012-08-15, 6:24:35

Post by Raijin »

Both Hyper Duel and Dragon's Fury have a nice version of Venus Fire :lol:

But anyway, not to get off topic, do you think you can record and post some examples of the VGM's slowing down? It's hard to believe they are slowing down at all to be honest, especially since VGM's tend to be recorded in the Options/Sound Test menu.
  • Despatche Offline
  • Posts: 37
  • Joined: 2013-07-27, 23:53:40

Post by Despatche »

Right, that's the scary thing. In fact, I first witnessed it when listening to Fighting Back in the sound test, through Fusion. And that's exactly the thing; there's not a whole lot I can really show you that the VGM isn't already doing.

This isn't too helpful either, but:

http://www.youtube.com/watch?v=WcWRpJJLtpY
http://www.youtube.com/watch?v=-cLzGjrUTfk

(Ignore that Hyper Duel's version is written a little slower :V)
  • User avatar
  • Raijin Offline
  • Posts: 41
  • Joined: 2012-08-15, 6:24:35

Post by Raijin »

OH! Now I understand! You meant the VGM is playing back the track slower overall. I thought you meant the VGM would have slowdown spikes at certain intervals. Wow, now I feel stupid.

Anyway in that case, there doesn't seem to be anything wrong with Thunderforce III. It plays back just fine as far as I can tell. Thunderforce IV though seems very very slightly slower, so much so it's unnoticable. I question myself sometimes about whether it really is or not. I honestly have no idea. I own Thunderforce III, Lightening Force (US) and Thunderforce IV (JP) for the hardware and they all sound pretty much the same as the VGM rips, but I'm still not positive about Thunderforce IV. It might be inaccurate emulation, and it might be region differences. I really am unsure.
Last edited by Raijin on 2013-07-28, 7:00:57, edited 1 time in total.
  • Despatche Offline
  • Posts: 37
  • Joined: 2013-07-27, 23:53:40

Post by Despatche »

Well, it does have slowdown spikes here and there. With that comparison, III actually runs the track faster than HD's.

That's exactly the thing; the spikes are supposed to be correct behavior, because the printed albums for both games reproduce it (unless there's something I missed about IV). What I want is for there to be a way to change that; for the purposes of this example, being able to remove the slowdown. Again, I don't know how this all works, and I doubt it would be that easy, but that also means I don't know any other questions to ask. At the least, I find it extremely hard to believe that the songs were hardcoded that way instead of just having a limit on the hardware used to play them; the games already stress the entire Mega Drive enough. Really need to get a hold of those Gold Packs...

You see how stupid this is now! :V
Last edited by Despatche on 2013-07-28, 16:11:00, edited 1 time in total.
  • User avatar
  • dissident93 Offline
  • Posts: 204
  • Joined: 2012-02-17, 5:54:01
  • Location: USA

Post by dissident93 »

Raijin wrote:OH! Now I understand! You meant the VGM is playing back the track slower overall. I thought you meant the VGM would have slowdown spikes at certain intervals. Wow, now I feel stupid.
that's exactly what I was thought too xD

perhaps they're different tempos because they (the ost versions) are the original PC-98 recordings? I don't know why they would be different tempos but you never know.
  • Despatche Offline
  • Posts: 37
  • Joined: 2013-07-27, 23:53:40

Post by Despatche »

...Come again? The OSTs for Thunder Force III and IV more or less sound like what emulation (Fusion, VGM, or otherwise) has shown i.e. the slowdown spikes. There's no PC-98 version for any of the games besides the actual original TF itself, though II has the X68000 original.
Post Reply