Jerky SD

Serena wrote on 1/29/2008, 6:44 PM
PAL SD is lower field first? Last December I did post on a wedding video and pans in the DVD are jerky (so was the camera work, but that is a separate matter). This problem didn't show on my systems and when demonstrated to me by the client I guessed that I'd got the field order wrong. Looks fine on a computer (progressive). Not used to working SD and thought I'd used HDV parameters, but not so. Suggestions? What idiot thing have I done?

Comments

johnmeyer wrote on 1/29/2008, 7:24 PM
PAL SD is lower field first?

Yes.

Are you sure the problem is field reversal? There are simple tests that can be done in TMPGEnc or VirtualDub that will tell you, with 100% certainty, if you have reversed fields. If you post a 5-10 frame clip that contains motion, I can easily tell you whether you have field reversal.

Did you use nested VEG files? I ran into all sorts of interesting issues with nested VEG files and fields which I described to tech support in great detail about six months ago. You end up with all sorts of possible combinations of media and project settings, both those in the original project (the one to which the nested VEG points) and in the master project (the one that contains the nested VEG files). You definitely need to be consistent throughout.

As for using HDV parameters, obviously HDV is upper field and DV (PAL or NTSC) is lower field. Vegas should handle field change, but if the source file is incorrectly identified, then you can get the judder/jerkiness that is characteristic of reversed fields.

So, right click on each media element and confirm that the field order is in fact the correct field order for that media. Then, make sure the project properties match what you will finally use for rendering.
farss wrote on 1/29/2008, 7:47 PM
Sounds like the field order is mixed up.
PAL SD is LFF however mepg-2 for DVD is UFF, you didn't change the field order when you encoded?
Vegas takes care of the field order swap itself.

Did you ingest the SD tapes yourself?
I've come across 5 QT files for a project, all SAID LFF but infact 3 were UFF.

Bob.
Serena wrote on 1/29/2008, 8:47 PM
No, I was given the data on a data disk. This had been captured using a default MS codec, which I queried because the quality was poor from a 3 CCD Panasonic camera. However I couldn't persuade the client to check or redo and being a freebee I wasn't going to spend time when they weren't prepared to do some more work.
Thanks John and Bob, you've given me some good pointers for checking.
johnmeyer wrote on 1/29/2008, 9:53 PM
PAL SD is LFF however mepg-2 for DVD is UFF ...

I don't know about PAL, but for NTSC, it actually doesn't matter. TFF OR BFF: either one works (when encoding MPEG-2 for DVD).


John_Cline wrote on 1/29/2008, 11:07 PM
I know that TMPGenc had a utility in it that would actually "look" at the file and determine if it was upper or lower field first instead of relying on a sometime erroneous flag in the header. Someone should (or maybe already has) write a stand-alone utility (preferably freeware) that would do the same thing. This would be quite useful.

And, yes, John is correct, NTSC DVD MPEG2 files can be either UFF or LFF as long as that pesky flag has been set correctly by the encoder.

John
johnmeyer wrote on 1/30/2008, 7:22 AM
I know that TMPGenc had a utility in it that would actually "look" at the file and determine if it was upper or lower field first

Yes. Setting -> Advanced -> Deinterlace - Method (even-odd field).

Make sure you set the Video Source Type on the Advanced tab to Interlaced, and the Field Order to whatever you think the clip should be. Then, double-click on the Deinterlace option.

Within the Deinterlace Option, set the Method to "Even-Odd Field." Once you set the deinterlace method (which you do just to check the field order -- turn it off if you are planning to do something in TMPGEnc), you move forward one frame at a time in the deinterlace dialog's preview. If the field order is correct, everything will look fine. If the field order is reversed, the motion will go OK for a few frames and then go backwards for one frame. You can then quit the deinterlace dialog and change the Field Order in the advanced tab. Go back to the deinterlace dialog, and with the field order now set the opposite to what you originally had, the motion should look normal (no backwards frame). If so, the setting you now have for field order matches the actual field order of the clip.