Valve Reply *IMPORTANT*


Original Message:

Once again the people from HL2DQ have a question. (Yes we’re pesky devils).

We’ve noticed than when a player bunnyhops (Jumping constantly and only touching the ground every so often) at high speeds and records a demo, the demo play back is very very squiffy. Every time you hit the ground there are a couple of frames that show you falling through it. We had our hopes on demo smoothing curing the issue, and it does…a bit. But the problem is we still have to manually hack out broken frames when porting to AVI.

A one min demo with no smoothing took 1 hour to smooth out. With demo smoothing it took the same amount of time. This involves recording the demo to .tgas at an FPS of around 100 then importing it into a video editing program and hacking out the one to five dodgy frames.

The fastest time to complete HL2 so far is 2 hours (Which the runner did not heavily use bunny hopping). Our time will hopefully be 1hour and 45mins. That’s roughly 100 hours of video editing just to smooth it out.

Back to my main question. Is there a better way to smooth out the demos? (We cannot create a sub mod with better bunny hopping support since itwouldn’t count as a HL2 run)
To show you what the problem looks like, check out this demo:


As a little sub question, what do you guys think of our project? All help is greatly appreciated,

Justin “Bandit5k” Stone


Most folks here think the speed run thing is pretty neat and it’s pretty informative to find ways in which restrictions in the game physics and levels can be ‘circumvented’.
I’ve forwarded this message to Martin Otten here at Valve so that he can take a look a the the .dem file and see what’s up and why you’re having to spend time smoothing out certain frames or simply removing them from the final movie. That sounds like a bug. He’ll follow up with you if he needs to record new .dem files,etc.
Best of luck, Yahn


This reply in it’s self made me very, VERY happy. I mean these guys are cool about the speed running! It might even help them! The next reply from Martin made my day.


It looks like our view interpolation freaks out with these fast movement/view changes.
Try a lower interpolation value like cl_interp 0.015 when playing back the demos.
That should reduce the jitty view. If that doesn’t work for you, please let me know.


This in not a complete fix, but it very drastically reduces the bunny hopping bug to an acceptable level! I think it’s now possible to watch a demo with out barfing!
In under a day, valve has managed to solve a problem that has been plaguing us since the beginning!
Valve Software, I salute you. o/
For all demo play makes make sure cl_interp is set to 0.015. Should fix all the problems. All future replys from Valve will be place in this thread. So keep and eye out!

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