Custom compositing render quirk

cacher wrote on 6/14/2004, 9:54 AM
I found a little quirk while using custom compositing modes:
I have a 11 minute project that has nothing but cuts and crossfades, with some stills at the end. Last night I set it to render to DVDA video stream mpeg2, and was surprised that the render time was showing 02:20:00 (two hours and 20 min.).
The only thing special about this project is the intro: and here's an easy way to repro:
Track 1: Text from text generator (soft shadow) 10 sec. length
Track 2: Noise texture from media generators (lava) 10 sec. length
Track 3: same as above, make it a child of track 2.
Track 4: 10 min. DV AVI
Go to Track 2 and set the compositing mode (below the automation settings button) to "Custom", select Bump Map with Spotlight style.

Select to render, it will take 1hour 30 min on a Pentium4 3ghz with 512mb ram.
Now delete tracks 2 and 3 and render with same settings, the render will take about 9 minutes.
Shouldn't Vegas see that there is nothing after the first 10 seconds on tracks 2 and 3 and do a more "inteligent" render?
The work around was to render the intro first and then bring it to the timeline as a separate DV AVI. Total render time was 20 minutes.

Cacher.

Comments

cacher wrote on 6/15/2004, 8:57 AM
No one? We're talking of a 10x render time increase caused by an addition of a 10 second effect (maybe even a 1 second efect, for what I've seen)!
cacher wrote on 6/16/2004, 7:02 AM
Ok, seems I'm alone in this but since it involves a 10-fold increase in render time, I really do care.
I've made some more experimenting and found something that suggests this may be some kind of bug. If you move track 4 (the one with the 10 min. DV AVI) to the top of the tracks (making it track 1), the render time will return to normal (9 or 10 mins vs. 95 mins).
I beleive this is something definitively worth looking into.

Greetings,
Cacher.
BillyBoy wrote on 6/16/2004, 4:10 PM
The 64 dollar question is did you actually render out the whole project and see how long it takes under the various arrangements?

As I understand it Vegas gives a rough rendering guess in how long its going to take by looking at the first portion of the project. If a lot of stuff is going on at the start and drops off later then projected time will be distored. To get more accurate would require Vegas to scan the whole project start to finsh which would result is a a far more accurate guess, but also would result in a lot of wasted time.

My motto: It takes as long as it takes to render.