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First post, by Roxor

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I've got some rather strange speed issues in DOSBox.

Commander Keen 5 runs really slow, even though the CPU cycles are up pretty high at 30000 cycles (I don't dare put them any higher or otherwise It'll be too much for my machine).

Stargunner, which is much more sophisticated (Protected Mode, VGA, GUS sound), runs at full speed, as do the other Commander Keen games.

All sound devices have their mixing rate in dosbox.conf set too 88200 (my soundcard can handle samplerates that high, so I doubt that's causing the problem). The scaler in use is advinterp2x, the core is set to dynamic, and I'm running WinXP x64 Edition.

Any ideas as to why only Keen 5 is affected like this?

Reply 3 of 4, by Lofty

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88200. Wow. That's high! I doubt there's much point in having it higher than 44100. I don't think any DOS games used sound samplerates higher than 44100, and most use 22050 or less. The higher you go, the more CPU time the sound emulation takes.

Try *decreasing* cycles, and/or switching to normal core (a few games do not like dynamic).

Btw, you know that you can't actually damage your machine by setting cycles really high. After a point dosbox's timing will get messed up, and sound will start breaking up, but that's all.

Reply 4 of 4, by Roxor

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Changing the cycles has no effect at all (unless I set it low enough that the game runs rediculously slow). Changing the core from dynamic to normal has sped things up to normal speed. Weird.

The downside is that I end up with tearing until I go and fiddle with some game options (the "SVGA Compatibility Fix" and "Fix Jerky Motion" options). The odd thing is that toggling one of these and then going back to the game seems to fix the problem. Weird.

The GUS and OPL sound does sound a bit better with a higher mixing rate. It's small, but noticeable (if you have good headphones). 88200 isn't that high compared to the 192000 my sound card can output.

I know that setting the cycles high won't actually damage the computer, but I do know how things end up if it gets set too high.