Image overlap on pre-render with Vegas Pro 8 - Why?

D

David W. Richardson

Chapelgrove Films
When I do a selective pre-render in Vegas Pro 8.0c, sometimes I get an overlap of the last frame of the pre-rendered clip and the first frame of the next clip on the timeline.

ImageOverlap.jpg

It doesn't happen on all the clips in the pre-rendered section, only on some. And I can't find any rhyme or reason for it. Clips are identical in all formats. It doesn't matter which track they're on. Doesn't matter if the clips are on the same track or different tracks. Always occurs on the same clips.

If this was just a preview problem, I could live with it. But if I pre-render the footage, and then burn it to DVD, the overlaps burn with it, creating a distracting jump at the cut points.

The template I use for both pre-rendering and rendering to DVD is the "DVD Architect NTSC Widescreen Video Stream" template, unmodified.

I can get rid of the overlapping before I burn the DVD. But I'm curious to know why it's occurring. Any ideas?
 
One other thing.... The two clips don't overlap at all. Not even a single frame. Which only makes it more odd.

Has anyone else experienced this?
 
Have you checked to see if the problem is on the original footage?
Is "Quantize to Frames" enabled?

Mike
 
If it's 23.976 material on a 23.976 timeline, then don't use NTSC Widescreen for your render template. Use DVD Architect 24p Widescreen DVD.

You will find that if you change your timeline to 60i, you will have overlap points right where you see it in your rendered file.
 
Mike, these are two separate clips, so the problem wouldn't appear on the original footage. "Quantize to frames" is turned on, but I turned it off and get the same problem. (It's turned back on now.)

David, I changed the properties of the project to 60i and didn't see any overlap, not even a single frame. (I changed it back.) I don't normally use the 24p NTSC widescreen template to pre-render because I want to use the same template that I use to render out to DVD. I can render out at 24p, but DVD Architect Studio will just change it back to 30fps, so I figure why add the extra step? But I will try pre-rendering with the 24p template and see if that changes things.

Thanks!
 
DVD Architect shouldn't do anything with it if it's a DVD-compliant file (frame rate is individual to the video clip, not determined by the DVD, and video of different frame rates can be on the same DVD), so I don't know why it would change it to 29.97. Of course, I've never used Studio to make a DVD.

But, even if it does, you're cutting on a 24p timeline, so you should do pre-renders which match the timeline. Final render is a separate issue.
 
In DVD Architect Studio, the frame rate is fixed at 29.97. There is no ability to change it, and no templates that use a different frame rate. I try to use the same template for pre-rendering that I use for rendering out to DVD so I can be sure that what I see on my preview screen in Vegas is the same as what I'll get on the DVD. (I've had some problems with that.)

Now I have a new issue. Lately I've noticed that, after working on a project for awhile, Vegas will just stop pre-rendering it. I mean, it goes through the steps as if it is pre-rendering, but when it's done nothing has changed. The selected part of the clip doesn't play smoothly, like it would if pre-rendering had actually occurred. And the black line over the top of the selected area doesn't appear. If I close Vegas and re-start it, pre-rendering works again -- for awhile. It seems I'm having to close it more and more often now, which concerns me. Any ideas?
 
David W. Richardson said:
In DVD Architect Studio, the frame rate is fixed at 29.97. There is no ability to change it, and no templates that use a different frame rate.
Click to expand...

Right, but that doesn't mean the DVD can't have 24p files. It's just the base for the DVD (NTSC as opposed to PAL). You do not set anything in DVD Architect to 24p to make a 24p DVD; you just feed it DVD-compliant 24p files.

It's the way you should go if you have 24p material.

Now I have a new issue. Lately I've noticed that, after working on a project for awhile, Vegas will just stop pre-rendering it. I mean, it goes through the steps as if it is pre-rendering, but when it's done nothing has changed. The selected part of the clip doesn't play smoothly, like it would if pre-rendering had actually occurred. And the black line over the top of the selected area doesn't appear. If I close Vegas and re-start it, pre-rendering works again -- for awhile. It seems I'm having to close it more and more often now, which concerns me. Any ideas?
Click to expand...

I've never seen this happen. But I don't pre-render very much.
 
David Jimerson said:
Right, but that doesn't mean the DVD can't have 24p files. It's just the base for the DVD (NTSC as opposed to PAL). You do not set anything in DVD Architect to 24p to make a 24p DVD; you just feed it DVD-compliant 24p files.
Click to expand...

I understand that. But feeding a 24p file into DVDA Studio is just going to mean DVDA Studio will have to convert it to 29.97fps. Honestly, I feel more comfortable having Vegas Pro do that conversion, rather than DVDA Studio. Maybe it doesn't make any difference, I don't know.

I pre-render in order to get smooth playback of the section I'm working on, as well as to get a better visualization of how the applied effects look. I can't afford to upgrade to a machine that has the power to edit and play HD files smoothly, and I don't want to use proxy files for fear that inserting yet another step into the process will only put me further away from seeing what I will truly get on the finished DVD.
 
David W. Richardson said:
I understand that. But feeding a 24p file into DVDA Studio is just going to mean DVDA Studio will have to convert it to 29.97fps.
Click to expand...

I'm not sure that's the case. It should just use the 24p file as-is, no conversion.


I pre-render in order to get smooth playback of the section I'm working on, as well as to get a better visualization of how the applied effects look. I can't afford to upgrade to a machine that has the power to edit and play HD files smoothly, and I don't want to use proxy files for fear that inserting yet another step into the process will only put me further away from seeing what I will truly get on the finished DVD.
Click to expand...

By "match the timeline," I meant frame rate. You'll actually see smoother playback if you do.
 
David Jimerson said:
I'm not sure that's the case. It should just use the 24p file as-is, no conversion.
Click to expand...

When I go to burn a DVD from a 24p file in DVDA Studio, it goes through a recompression step -- which it doesn't go through when the clip is 29.97. Since the resulting DVD is 29.97fps, I assume this extra step is converting the frame rate. Whatever it is, I try to avoid recompression as much as possible.
 
David W. Richardson said:
When I go to burn a DVD from a 24p file in DVDA Studio, it goes through a recompression step -- which it doesn't go through when the clip is 29.97. Since the resulting DVD is 29.97fps, I assume this extra step is converting the frame rate. Whatever it is, I try to avoid recompression as much as possible.
Click to expand...

OK -- just because I wanted to see what it does, I downloaded the trial version of DVDA Studio.

It does go through the recompression step, but the resulting VOB file on the DVD is still 24p and not 29.97. I don't know what it does in the recompression step, but it doesn't convert it to 29.97.

So, I'd go with 24p all the way.
 
I'm running version 4.5d of DVDA Studio. When I use it to create the .VOB from a 24p rendered .MPG file, the resulting .VOB shows as 29.97fps interlaced.
 
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