A Vegas rendering problem... definitely a bug

Terje wrote on 10/6/2007, 5:45 PM
Vegas was always slow rendering text, and this has not improved in V8. I am doing a project that has some layers to it, and it has the following (partly).

Track 1 - Digital Juice Motion Design Element, reduced in size using pan/crop, color corrected.
Track 2 - Text to be revealed by DJ MDE, regular Vegas text, not Pro Titler. The text is shown using an animated bezier mask.
Track 3 - Video, tried mt2 from Canon and Cineform, both with the same result

Encoding time for this combo is, on an AMD 64x2 dual core box, about 10-15 minutes or more per frame. I haven't really fully timed it because for the longest time I thought Vegas died. It doesn't seem to.

This is not a processing issue, this is definitely a bug in Vegas. How do I know? Because Vegas uses between zero and one percent CPU when it gets to this point.

Note, this problem appears to become more pronounced the further out the timeline you get. I have one revealer that runs through at a reasonable clip early on in the timeline, but the second one is about 1 minute into the time line, and it basically stalls with Vegas doing close to nothing at all.

Please note - this is not a problem unless rendering to an HD(v) template. If I render to DV or to DVD MPEG, the render moves along at a very nice clip and there are no problems.

Edit: Problem identified, and it is definitely a Vegas issue.
I copied the part of the time line that is slowing down tremendously to a new project and rendered this. I figured I had copied it correctly, but I was wrong. I had forgotten one important thing. The Compositing mode in the new project stayed at @.

In the new project, if I change the compositing mode to 3D, but I add no key frames anywhere, and I do not do any 3D motion whatsoever, that is I only] change the compositing mode, the rendering slows down seriously, not as much as in the full time line, but enough so that I know what the problem is There is also no smart rendering going on at all.

This is probably good news, I can change the compositing mode back to @, and it should render fast. Then I can take the parts of the project where I need 3D compositing and develop in a separate project and put onto the regular time line. The 3D parts include no text, no transition and no Motion Design Elements, so they should not suffer.

Surprised that adding 3D compositing mode, with no 3D compositing, has a serious effect on rendering speed. I don't think it did in SD, but perhaps I am wrong, it isjust more noticeable in HDV.

So warning: Put any HDV clip on a 3D timeline and your rendering time will suffer severely whether you actually do any 3D compositing or not

Comments

jrazz wrote on 10/6/2007, 5:50 PM
Can you loop that section that is troublesome and render out just that portion but muting all tracks but one and systematically adding them back one by one? What happens when you do this?

j razz
Terje wrote on 10/6/2007, 6:23 PM
That was part of what I tried, and when I muted the HDV track things moved along at a reasonable clip. It still didn't dawn on me that the compositing mode of the HDV track was the problem (see edit above). It seems that adding HDV to a track with 3D compositing mode will have a tremendous impact on rendering time. This was compounded by the motion design element with an alpha channel that was also color corrected.
TheHappyFriar wrote on 10/6/2007, 9:36 PM
So warning: Put any HDV clip on a 3D timeline and your rendering time will suffer severely whether you actually do any 3D compositing or not

um..... what else would of happened? You changed the track from a 2d event-only based alpha to 3d event AND track based alpha & each frame must be eval'ed to see if it has any alpha on it.

You've got HD, 3d track motion, pan/crop, FX on events & masking & are expecting it to go fast.
Terje wrote on 10/7/2007, 1:40 AM
I do expect it to go faster than 1 frame every 15-20 minutes with 0% CPU utilization, yes. If the CPU utilization was at 50-100% I know Vegas is working, at 0% nothing is happening.