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Anyone have a idea why the music tempo in Descent fluctuates so bad on OPL?

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First post, by DracoNihil

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I don't know if this is the right forum to ask this question because it happens in emulation or on a real MS-DOS system. You can even find videos of this happening on real hardware too.

But, to the point: Why does the music tempo slow down and speed up variably when you're using either OPL2 or OPL3 for MIDI music in Descent? It slows down even worse in OPL3 I might add as well... This is the only game I know of that has this strange problem.

If you use MPU-401 for music the tempo stays consistent throughout the songs, but the OPL versions of some of the tracks sound better and are more unique sounding compared to the GM versions.

“I am the dragon without a name…”
― Κυνικός Δράκων

Reply 2 of 3, by Gemini000

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While I don't know that this is the reason as I've never looked at the source code, I can hazard an educated guess that the MIDI support is working on a separate interrupt timer while the OPL2/3 support is tied to the game logic and thus can't process as fast if things get too tough for the CPU to handle easily.

--- Kris Asick (Gemini)
--- Pixelmusement Website: www.pixelships.com
--- Ancient DOS Games Webshow: www.pixelships.com/adg

Reply 3 of 3, by DracoNihil

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That's quite a good educated guess as I'm thinking the same thing now that you mention it, though why on earth would the HMI driver act like that? I don't remember if the official Parallax release of the source code included the HMI related code or not though so you probably can't really examine the source to find the answer...

“I am the dragon without a name…”
― Κυνικός Δράκων

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