Does the problem scene have a different frame rate or field structure (progressive vs. interlaced) than the rest of the project?

Also, in your main project, do you have "quantize to frames" set? If that scene isn't beginning on a project frame boundary it could explain why it looks good when rendered from a solo project.

Does it judder when played back on a BD device?

Hello,
there is no difference in the frame rate etc.. Also enabling Quantisize to frames made no difference. Thanks anyway.

Yes it does

Hi,
I am very much a beginner at this, it is my retirement project.
How would I enable constant bit rate, please?

"Judder" can be used to describe quite a few different problems.

1. Low frame rate. 24 fps material will always judder when then camera pans horizontally. If your source material is 24 fps, then it will judder. Solution: next time use a higher frame rate.

2. Slow motion. You have used slow motion and have decided to disable resample. This repeats frames and effectively gives you the same thing as #1. Solution: use "smart resample" instead.

3. Undersample. Sometimes people use this feature, not really understanding what it does. It will also result in #1. Solution: don't use undersample.

4. Field reversal. This actually produces a different effect than low frame rate, but it is often described as judder. This happens if the field order flag in your source video is incorrect. This causes fields to get played out of order. If you separate the video into odd and even fields and then play the resulting video, you will see the motion move forward normally for two fields, and then backwards. When the complete, interlaced video is played at full speed, everything looks fine when there is very little motion, but when the actors move rapidly, or the camera pans horizontally, there is a "vibration" to the image (I think that word is more accurate than judder). Solution: go to the offending event(s) and reverse the field order from upper to lower (or vice versa).

5. Source video frame rate doesn't match render frame rate. If your source video is 29.97 interlaced and your are rendering to some other frame rate, fields and frames often have to be dropped and duplicated. This results in a "pulldown" effect which will result in jerkiness that, like most of the other things above, will only show up during rapid motion. Solution: try to render at the same frame rate as your source material.

Please note that bitrate has nothing whatsoever to do with this problem. Do not waste time worrying about constant or variable bitrate. Too low a bitrate will result in fuzzy or blocky video, but will not produce judder. Frame rate and bitrate are two completely different things.

Hello, thanks for your reply but I am afraid it did not help

Render out a section that doesn't judder and then a section that does to the same codec you're using and put it on dropbox/google drive/etc. so we can take a look.

Note that "quantize to frames" has no effect on material already on the timeline. It only affects new material being added. So, if the clip wasn't lined up to the project frames when it was added it still won't be after enabling this. You'll have to either remove it and add it again, or zoom in far enough to see the project frame lines on the timeline and manually adjust the clip to match.

Unless you start editing the clip after you turn off quantize to frames. Them you're in a whole heap of trouble. :)

In game editors there's an option to "snap to grid". It moves all vertices to the current grid setting. That would be an awesome feature for Vegas to fix accidentally editing with quantize to frames in the off position.