Frame Blending in Vdub?

[LoXodonte]

I have a 60 fps video I'd like to convert to 30 fps by blending frames together instead of just dropping them. (for a smoother effect) Can I do this in virtualdub? I figured their would be a setting under the fps section but I didnt' see anything.

[SergeyFedosov]

Go to Video, Filters, Add, Deinterlace (internal), OK, blend fields together, OK.
Then, Video, Framerate, Decimation, decimate by 2.

[LoXodonte]

cool thx I'll give it a shot. I was wondering if deinterlace might work, but I assumed it wouldn't work with 2 sequential images unless they were fields in the same image.

[LoXodonte]

well, it didn't seem to make much difference in the render. Actually, at times it seemed a bit more choppy :(

[SergeyFedosov]

Choppy play is caused rather by some codec errors but not because of the framerate 25-30 fps. For instance, I have observed a jerky movements in some eartlier versions of Xvid. Try to recompress a fragment from your video using another codec and see the result.

[Niddhogg]

Just a wild assumption, but somehow I suspect your video is from a DVD intended for HDTV? ;)
If that's the case, remember that film is shot at 24 fps (in rare cases 30, even rarer 48 is possible for IMAX).
The manufacturer has already frameblended the source material to get at the 60i(nterlaced) or 60p(rogressive) in forst place.
Therefor (I'm assuming assumption is true :) ) your best bet would be to retrace and undo the manufacturer's blending as close to their steps as possible.

[LoXodonte]

nah, the source is from a q3 engine based game. Basicly the game will take a number of screenshots per second, so what I'll do is set the playback speed to half, then take 60 screens per second. Then I'll load the screens into virtual dub and set playback speed to 120fps. At this point it would be nice to blend the frames, but I still haven't found a method. Their is actually a utility that works with q3 that will do this internally. It partially works with the game that I'm using except it doesn't patch the max frame limitation, so basicly I can't capture as many frames as I'd like to.

[Niddhogg]

Almost all games use variable fps, GTA being notable exception. Would think capturing at a fixed rate is bound to cause stuttering playback.
Tried setting a fixed / capped framerate in q3 at a level you're guaranteed to obtain?

[communist]

Choppy play is caused rather by some codec errors but not because of the framerate 25-30 fps.
Wrong. Choppy source in -> choppy encode out.

Unless you're using a codec that requires a lot of processing power which your PC cant deliver and hence you see jerky motion - but that still doesnt mean the codec is the culprit.

[SergeyFedosov]

Communist, choppy play can be caused by some incompatibility of the codec used and the system, where the fault can be ascribed rather to the system. For instance, a couple of years ago I observed jerky motion when playing an Xvid compressed video on WinME computer. Decreased processing parameters did not help. However, no effect was found on an XP-machine. The same video compressed with DivX5 was played smoothly on both machines.