Video problem - combing on edges

maddogmike

maddogmike

Member
[FONT=verdana,arial][SIZE=-1]I'm stumped on a video artifact I'm getting when I export files from Final Cut Pro.

I usually describe it to people as a "comb" edge, which you see mostly on areas with strong vertical lines during camera moves. Like a door frame, for example.

My first thought was that the interlacing was set wrong. I changed my Final Cut sequence to progressive, but that didn't help.

I'm working with 24p DV widescreen footage. I started to think that the footage was captured into the computer wrong, but it actually plays fine in the FCP "canvas." The combing only occurs after I render with "current settings."[/SIZE][/FONT]
 
maddogmike said:
[FONT=verdana,arial][SIZE=-1]I'm stumped on a video artifact I'm getting when I export files from Final Cut Pro.

I usually describe it to people as a "comb" edge, which you see mostly on areas with strong vertical lines during camera moves. Like a door frame, for example.

My first thought was that the interlacing was set wrong. I changed my Final Cut sequence to progressive, but that didn't help.

I'm working with 24p DV widescreen footage. I started to think that the footage was captured into the computer wrong, but it actually plays fine in the FCP "canvas." The combing only occurs after I render with "current settings."[/SIZE][/FONT]
Click to expand...

I don't know if I'm seeing the 'same' sort of artifact, but I just loaded some footage into Primiere, which was transfered via Final Cut Express. The original material was shot at 1080 24p, on a Panasonic HMC-150. When I look at the footage using quick time, it does in fact indicate that the footage is 24 fps. But Final Cut Express doesn't support 24 fps... but anyway...

When I import this 1080 24 fps into Primiere I see a 'comb' like artifact on edges. So, with Primiere I used the 'interpret footage' option to select odd field first... problem disappeared (I also selected even field first... and problem still gone...).

Somewhere I heard, and have not varified this, but when you see something in FC, it is not the full frame, but every other field 'up resed' vertically. So, if that's true, that would explain why these artifacts are not visible ordinarily.

Primiere supposedly is able to process AVCHD 'natively', so I'm going to look at my original material in the near future...
 
Please post a sample screenshot. Combed edges are interlaced- this is an easy mistake to make.

Noah
 
Okay, here's a thumbnail from my editor. Just a portion of the entire frame.

xgfpicture4thumb.jpg


Here's the full sized frame:

http://maddogmovies.com/forumimages/xgfpicture4.png

For some reason, he seems to have solved the problem by avoiding H264. This doesn't make sense to me, since as far as I know we weren't exporting H264 to begin with.

I'll write to him again to get a clarification on that.
 
Looks like interlacing. Not a problem at all.

Google it and find out what it is before you complain about seeing it.

Then we'll talk.

CaptM
 
Wow, it's fun to be a jerk, isn't it?

If you read my first post, you'll see I already considered interlacing but had trouble removing it anyway. I'm new to FCP, but I've been editing video for close to ten years. I came here to see if someone would recognize the interlace problem that I'm specifically having with Final Cut.

Anyway, moving on.

On another forum, I was directed to this article:

http://www.bayareafilmmakers.com/?p=241

"When I de-interlace the images, they look right in Final Cut, but when I export them out either as a stand-alone file through compressor, or directly through compressor, my images had interlace RE-introduced to them. My guess, is that on export, it conforms to the codec you are using. I searched Final Cut for a way to make the coded progressive, but could not find a way to do it, and maintain the NTSC settings. There are ways to do HD using uncompressed and progressive, but not NTSC."
Click to expand...
Holy cow. If this is true, it justifies my frustration -- Final Cut is out to get me.

His solution was to use Apple's ProRes codec. (I think he applied it to the timeline? Or maybe just when he exported it. I'll ask him.)
 
Here's another jerk question for your 10 years in service...

24p... what does that mean to you?

How was it captured into FCP? You say it is DV... what was it shot on?

CaptM
 
Yes, the DV footage was shot on the 24 frames per second, progressive setting, on mini-DV tape.

My experience has been mostly in the 30 frame realm, so I'm not well-versed with pull-down. (One of the things I'm trying to determine is if this is an interlace or frame rate issue.)

I wondered if the footage had been captured incorrectly, especially since my partner had chosen "DV NTSC 48khz Advanced (2:3:3:2) Pull down removal" as his capture preset.

To rule that out, we also grabbed a test with the "DV NTSC 48khz Anamorphic" capture preset.

(Are these two settings mutually exclusive? What if you want anamorphic with pull down removal? Puzzling.)

I don't see any NTSC capture presets that specifically mention progressive.

Our sequence setting is "DV NTSC 48khz 23.98."

Again, looked good in the canvas, but combed on output.

In the sequence settings, we tried changing the fields from "lower" to "none." Still problematic. I suppose we could try "upper," but that would make it interlaced again.
 
maddogmike said:
Yes, the DV footage was shot on the 24 frames per second, progressive setting, on mini-DV tape.
Click to expand...

MiniDV tape cannot actually record 24 frames per second progressive... was it shot on the DVX? The dvx will either shoot 24p mode and add 2 combined frames per every 3 progressive frames OR it will shoot in 24pA mode and add 1 combined frame for every 4 progressive frames. Either way, the footage ON the tape is 29.97 and needs to be captured that way (kind of).

maddogmike said:
I wondered if the footage had been captured incorrectly, especially since my partner had chosen "DV NTSC 48khz Advanced (2:3:3:2) Pull down removal" as his capture preset.

To rule that out, we also grabbed a test with the "DV NTSC 48khz Anamorphic" capture preset.
Click to expand...

Ok good. Since your partner chose 2:3:3:2 Pulldown removal as the capture preset AND (let's assume) it actually worked it was shot in 24pA mode. USUALLY FCP will quit on capture if it cannot find the ADVANCED PULLDOWN (vs 3:2 standard with 24p mode). SO... this capture preset CAPTURES the tape at 29.97, but removes the combined frame leaves you with 23.98 footage... when it works.

Capturing it at DV NTSC Anamorphic will bring it in at 29.97 all combined frames in tact.

One thing I suggest you do now is look at THAT footage if you still have it in FCP in a 29.97 timeline/sequence with the canvas window set to 100%. Then, step thru frame by frame and you should see 4 progressive and 1 combined frame. Do it with some camera movement so it is VERY clear to you. IF you see 3 progressive and 2 combined we have a problem (that we'll fix later).

maddogmike said:
(Are these two settings mutually exclusive? What if you want anamorphic with pull down removal? Puzzling.)
Click to expand...

AGREE!!! Gah, but I just duplicated my 2:3:3:2 preset and clicked the anamorphic tag and saved it as AdvancedAnamorphic. But no big deal, you can flag the footage in the browser with one mouse click.

maddogmike said:
Again, looked good in the canvas, but combed on output.
Click to expand...

If you don't have the canvas set to 100% you won't see ALL the fields. FCP uses a proxy image for display in the canvas. Make sure your RT settings aren't set to anything like dynamic and are all set to HIGH (RT button upper left of sequence window).

--

SO, I really hope you don't think I'm a jerk. You just need to understand what you are dealing with from start to stop before you make rash decisions about quality. It is really simple once you figure out what the properties of the clip you are working with are and what your sequence settings are.

Now... Check the clips in the browser to make sure what the frame rate is. Select the clip and slide to the right and look for the TC or FRAME RATE (or whatever it says) and use THAT number to create a sequence. THOSE HAVE TO MATCH or you'll get bizarre results.

With all of those things in mind... NOW what do you see?

CaptM
 
No hard feelings. I just got defensive. I hate flame wars, and had no intention of starting one!

Thanks for the advice. I'll refer my partner to this thread and see what he comes up with.
 
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