-
scale, center, crop motion settings in FCP gives wavy lines
I used a wide angle converter lens on a Sony camcorder. At the full wide angle setting I get the dark corners (vignetting?) So in FCP I used crop, changed the center, and also increased the scale in the motion settings. There is camera movement from a pan around the room that I filmed. When I use the motion settings described, lines that were straight (door james, door steps) become slightly wavy. Is there some way to stop this?
-
4 Replies
-
Make certain that your vertical move is set to an even number and make certain to render at “Full.”
DRW
David Roth Weiss
Director/Editor/Post-production Supervisor
David Weiss Productions, Inc.
Los Angeles -
[GenDelmarva] “lines that were straight (door james, door steps) become slightly wavy”
This is because your original material is 60 fields per second (50 in PAL) rather than the 24 complete frames that film would have. If you examine the original video on a progressive monitor and pause the video, you will notice a comb effect on the left and right edges of objects in the times when you are panning. This is because you are seeing two halves of an image separated in time by 1/60th of a second (1/50 in PAL). Moves such as pans will have one half of an image moved in respect to the other, creating this comb effect on the left and right edges of object that are appearing to move. When you take that video and resize it in a sequence, the alternate lines showing half of a image separated by time now no longer fall into their correct field lines and spill over into the other field’s scanlines and thus you will get some of a field that should be played later are now being played earlier and vice versa. When you see it on the Canvas, the round-off in calculations will show the comb appearing as a castellated (wavy) line on vertical lines in a pan – this is one reason why you shouldn’t rely on the Canvas view on a progressive monitor (e.g. computer monitor) to make decisions on interlaced (i.e. normal) video.
Film wouldn’t have these issues as the frame contains the information from a snapshot in time, and thus won’t have the issues of one field coming from a different time and thus a changed view – although this won’t hold if you are using telecined file to video. 24fps Film (or progressive video) can therefore be scaled without running into these issues.
To avoid this, you can apply a deinterlace filter to the video to reduce the effects of these scaled alternate fields appearing in the other field. The down side is the loss of sharpness caused by this deinterlace filter. No free lunches.
Bill Lee
-
While FCP can de-interlace, the filter is non-adaptive, i.e. reducing the vertical resolution everywhere, not only for moving parts.
If most of your footage is shot from a camera support (and not handheld) I’d recommend a better de-interlacer to preserve as much quality as possible. IMHO, FieldsKit from http://www.revisionfx.com is the best value for the money.Regards,
Uli
Author of “DVDs gestalten und produzieren”, a book on professional DVD-authoring in German.
-
David’s suggestion should fix your problem, but if you happen to de-interlace, Compressor 2
now does very good de-interlacing without losing the resolution that de-interlacing in FCP would
cause.
Ed
Reply to this Discussion! Login or Sign Up