Nested Veg Render Problem

JasonATL wrote on 1/18/2010, 7:04 PM

I have a large project (for me) of multiple chapters. I have worked on each chapter within its own .veg file.

I thought I would assemble the chapters by loading the .veg files on the timeline of a "master" .veg project.

My problem is that the render speed is significantly reduced for some reason. My quad core machine reports only about 30% of the CPU is used. When I render an individual .veg by itself, it takes 100% of all 4 cores.

1. What is going on? Why won't the video render in a nested .veg file just like in a standalone .veg file?
2. Is there a work-around?

Thanks in advance.

Comments

ingvarai wrote on 1/19/2010, 12:30 AM

What version of Vegas?
I had to revert to 9b (64 bit) because the 9c 64 failed to nest render, I repeatedly got black frames. This was when using AVCHD on the time line.
Ingvar

JasonATL wrote on 1/19/2010, 4:50 AM

INgvar,
Thanks for the reply. I'm using 9c, 64-bit on Windows 7. I've been very happy with 9c compared to prior versions, so I have not yet tried to revert. I'm rendering to Main Concept MPEG-2, 1920x1080, 60i. No AVC media in any of the vegs.

I have tried only nesting one veg on the timeline with the same results.

In reading about network rendering, it says to have all media on the same drive. I'm not doing a network render, but this makes me wonder if my problem might be that I have media on two different drives (and not the same drives as the projects themselves). Any thoughts?

Chienworks wrote on 1/19/2010, 5:37 AM

That shouldn't be a problem at all.

An alternative you might consider if you just need to "get this job done" for now is to render each .veg file separately into a uncompressed or lightly-compressed format. You can then create a new project and dump all the partial renders onto the timeline. Call it "poor man's nesting". It lets you break the render up into smaller sections that have a better chance of succeeding. Then on simple pass at the end stitches them together.

kkolbo wrote on 1/19/2010, 6:29 AM

There is no question that rendering nested projects slows the render down. For the convenience and improved flexibility you pay a performance hit in all versions. Thisnk about what the software is doing. It is applying all of the render setting of the nested project at all layers to the nested project and then adding all of the operations from the master project at all layers. In short, it has a lot of data to juggle and transfer around. memory and disc bottlenecks just make it worse. I am not surprised that a quad core is using less than optimum horsepower, 30%, in this operation because of all that has to happen shifting things around.

KK

wwaag wrote on 1/19/2010, 8:44 AM

I tried nesting some time ago and gave up with the same result--it was very slowwwww. My solution has been to render the individual segments or chapters and then combine them into the final production using a simple MPEG editor. I've used Tmpgenc's MPEG Editor for HDV material, but understand that others such as VideoReDo will work as well. I've also created a final project within Vegas to add these individual renders together, but found it to be slow compared to Tmpgenc's software. An added advantage is that if you later discover a "mistake", you only have to re-render the individual chapter and not the entire production.

wwaag

xberk wrote on 1/19/2010, 5:32 PM

I usually go with Chienworks solution. I've tried both ways. It seems like you save a step by nesting the veg files but actually I find it faster to render each section to AVI format and then combine them in the final render.

Side note: I think a high percentage of problems can be avoided by working in sections and doing your final (and largest) renders from "lightly compressed" sources.

JasonATL wrote on 1/19/2010, 6:12 PM

Thanks all. Unfortunately, I'm not hearing what I was hoping for -- not anyone's fault, except Vegas's (not bashing -- just the way it is).

I was hoping to find a useable way to get the same project to render to both BD and DVD targets from the original source media (with no intermediaries and no recompressing) by just re-rendering the same project once. Alas, my choices are to do this and let the render take an estimated 20+ hours or so (each); or to take the "poor man's nesting" approach, which takes a lot of manual intervention.

The "poor man's nesting" approach has a sort of side benefit. I am using multichannel audio in this project, which doesn't work in the nesting anyway -- another unhappy nesting surprise. Thus, I have to render out each veg's audio separately and put them together on a timeline anyway.

Thanks for the advice and help.

JasonATL wrote on 1/21/2010, 6:19 AM

For future reference, in case anyone searches on this topic, here's a little more of what I've experienced.

I decided to give the nested render a shot, thinking that I could spend 24 hours trying to find a work around, or bite the bullet and let the computer render for 24 hours. Well, 35 hours later....

I'm rendering an 85 minute project of 15 chapters (each its own project with no further nesting) to a DVDA BD 1920x1080, 60i MPEG-2 profile, custom set VBR, two-pass, average bit rate of 25Mbps. The render is nearly complete. What I've observed is the following:
- Photos (jpg) render very slowly at about a 2 frames per second, 30% or so of the CPU (Quad Core) used. Most pictures are keyframed with motion. I don't have enough without motion to say whether a static image would go faster, as I suspect it would (see next item).
- Vegas generated titles and backgrounds render slowly during transitions (mostly fades and page peels in this project), but speed up when a static image is on the screen.
- Video (sourced from a Sony EX1 shot at 1920x1080 30p) renders at near real-time (perhaps about 20 frames per second), using about 95% of CPU, except at transitions where it drops to about 85% CPU.

The project render is 98% complete at this point. After I've completed this project, I plan to experiment with photos, video, and titles to see if I can determine why nesting has this effect.

I'm interested to hear others' experiences.

Thanks.