Odd Interlacing Artifacts - Help?

Frenchy wrote on 4/18/2003, 11:52 AM
I'm getting some wierd interlacing artifacts (I think)in my recent project, which I haven't seen in any prior project. These are showing up in motion scenes and an occasional still which has had a pan/crop applied.

SYSTEM: V4b(Build174), P3-600, Win98SE, 384 MB ram

FINAL DESTINATION:SVCD-NTSC, Video Rendering quality=best, CBR=2375, write sequence display extension=checked, DC coefficient=10 bit, Audio sample rate=48KHz (to match original audio in video). All other settings default

SOURCE: DV via firewire (high-motion, skiing, artifacts appear while camera is panned). Additional audio: Music ripped from CD's. Please don't start on copyright issues ;)

PROJECT FLOW: From original timeline, produced a NTSC-DV-avi, Lower field first, Best Rendering Quality, Gaussian motion blur, Blend Fields

Then, dropped rendered avi files into a new project timeline, made no changes, and rendered as above to SVCD-NTSC.

PROBLEM: There appear to be 3-4 narrow horizontal bands (each maybe 20-40 pixels high)of interlacing artifacts (shimmering, etc - typical), while camera is/was panned. These interlacing artifacts are not everywhere on the video, but only in the same 4 narrow horizontal bands, equally spaced vertically, and running all the way across the screen. These appear to come and go, depending on the motion/panning taking place, but are in the same areas, consistently. I hope my verbal description of what I am seeing is coming across clearly...

When I first saw this problem, I rechecked original project settings, and I had failed to reset project properties from progressive (while I was grabbing stills) back to interlaced - lower field first, and thought resetting would fix it - NOT!

Now, I know SVCD's are not of the greatest quality but, I've been satisfied with results obtained for the last year or more with VF, VV3 and now V4, and have not seen this type of interlacing problems before. I haven't made any other system changes, other than installing a new external firewire HDD. Any ideas/direction?

Always

Frenchy

Comments

SonyEPM wrote on 4/18/2003, 1:14 PM
Try "reduce interlace flicker" for the problem scenes- a little blur may also help.
Former user wrote on 4/18/2003, 2:28 PM
You said you rendered the AVI files and put them on the timeline. Did you reset the progressive before you rendered the original files or after you put the rendered files on the final project? In other words, is the error in the original render?

Dave T2
SonyDennis wrote on 4/18/2003, 3:35 PM
Make sure your "deinterlace method" didn't get set to "None" in project properties. Try matching your project settings to the render settings and see if you can duplicate the artifacts while stepping through the timeline. If you can isolate the problem there, it's easier to debug without having to re-render everytime you change something.
///d@
Frenchy wrote on 4/22/2003, 9:51 AM
Dennis:

This is exactly what happened - I (or the default?) had reset the deinterlace method to "none" on the new, second project (where I rendered the new avi > mpeg) properties. Thanks for the feedback - I was gone all weekend, and just getting back this morning. This fixed it beautifully. This of course brings up another question - If there is a conflict, what takes priority, project settings, or render settings?

Dave: That was a thought I had, so I rendered a small segment to verify that the problem was in the avi > mpg render step, and it in fact was. THanks

Frenchy
SonyDennis wrote on 4/22/2003, 6:11 PM
Project settings are for preview, Render settings override for render (frame size, frame rate, quality, but NOT deinterlace method). Many formats have a "default" template that inherits the project settings.
///d@
Frenchy wrote on 4/22/2003, 6:19 PM
Thanks, again
BJ_M wrote on 4/22/2003, 6:36 PM
DC coefficient should be 8 bit anyway for SVCD , as well i would suggest using VBR ..

not that those were your source of your problem ..