Interlace flicker problem

Nat wrote on 7/24/2008, 3:40 PM
Hello there.

I recently filmed 2 different events : A dance show filmed with a GL1 in Frame mode and another dance show filmed with a DVX100 in 24p mode (normal not advanced).

I captured both shows with a GL2. The tapes from the DVX100 captured fine, but I have very bad interlace artifacts from the GL1 tapes. I tried changing the "Reduce interlace flicker switch" tried setting the project progressive, the footage progressive, nothing seems to work.
Any ideas ?

Thanks,

Nat

Comments

johnmeyer wrote on 7/24/2008, 4:31 PM
I just did a quick search on "frame mode" OR "frame movie mode" on the GL1. Unless I'm missing something, enabling this feature causes the camera to record in 30p instead of 60i. Thus, your footage is progressive.

However, I'll bet that if you right-click on the media, and look at the properties, it will show the footage as interlaced. To fix the problem, you need to change this to progressive.

But I did this, you say. Didn't you read my post?

Well, what I am recommending is different, I think, than what you already did. What you did was change the project properties to progressive. This determines (unless you override it in the Render As dialog) how the project will be rendered, but it doesn't do anything to the source footage. The problem is, if Vegas thinks the video is interlaced when in fact it is progressive (or vice versa) it doesn't matter whether you render it to interlaced or progressive because Vegas will do the wrong thing.

So, check the media properties, and then manually change the Field Order for the media (NOT the project) to progressive. You'll have to do this for each media dropped into the project (I have a script that will do this, but Excalibur definitely can do this, and probably Ultimate S as well, if you have those programs).


Nat wrote on 7/24/2008, 6:30 PM
Thanks for the answer, I tested pretty much all the combinations (setting it at the media level, at the event level etc.) and it doesn't change anything.
What is strange is that I recall filming in frame mode with a GL1 a couple of years ago and I did not notice any interlacing problem...

I will try capturing with another software to see.
Nat wrote on 7/24/2008, 6:59 PM
Update :
Windows Media player seems to play my footage fine without interlacing, VLC and Vegas seem unable to show it as progressive...
johnmeyer wrote on 7/24/2008, 7:28 PM
VLC and Vegas seem unable to show it as progressive...

I don't doubt that Vegas makes the mistake of labeling it as interlaced. However, if you manually change the media "Field Order" flag as I suggested in the past post, and then render to your final output, then I would be very surprised if it shows any problems, especially on a progressive display (since it is progressive already). I am about 90% confident this will fix your problem.

Just to be clear:

This is what you want to change (either for each media, or for each event):


By contrast, this will not make any difference:
Nat wrote on 7/24/2008, 8:06 PM
I did as you suggested and it doesn't change anything :
I switched the media to progressive (as is shown in the screenshot) and the project to progressive. I then chose to render with the DV template and changed the render settings to progressive.
When I reopen the rendered clip in Vegas, it tells me it's progressive (in the media properties) but I still see the interlacing artifacts. If I open it in Windows Media player, no problem, the image is perfect. I tried rendering to MPG2 as this will be my final output. In MPG2, opening the video both in Vegas or WMP shows the interlacing artifacts...
I uploaded a small clip, perhaps you could have a look at it ?
http://www.studioimaginaire.com/nat/interlace.zip
Thanks
jimingo wrote on 7/24/2008, 8:28 PM
You don't want to change the project properties to progressive with footage that was shot in frame mode. The project properties should be interlaced, lower field first. The clip properties can be switched to progressive. Do not render progressive...make sure to render interlaced.
And on a side note, WMP does not display interlaced footage very well...check your final render on a TV.
Nat wrote on 7/24/2008, 8:38 PM
jimingo, thanks for your answer,
Well in this case the strange thing is that WMP seems to be the only software able to play the footage correctly on a progressive monitor which seems strange to me... Shouldn't I be able to render a video that was shot in frame mode correctly and be able to see it as progressive in Vegas ?
jimingo wrote on 7/24/2008, 8:45 PM
Frame mode can't be rendered to 24P without problems.
Are you rendering to 24p or 30p? I never tried to render a 30p mpeg2 so I'm not sure how that would look.
Nat wrote on 7/24/2008, 8:52 PM
I'm not touching the framerate at all.
I tried leaving all to the defaults (lower field)
and render the MPG as progressive. It doesn't show any interlacing artifacts but I think get only 1/2 of the vertical resolution.
I just don't understand how come WMP plays the files full resolution with no artifacts and all else fails.
jimingo wrote on 7/24/2008, 9:07 PM
I just did a test with footage that was shot in frame mode from a GL2.
Rendering to a 30P and a 24P mpeg2 caused ghosting, but no interlace artifacts. Rendering to the standard NTSCDV template (60i), caused no ghosting and only minor interlaced artifacts...none like in the clip you supplied. Rendering to 60i looked the best.
So the best way to render a mpeg2 that was shot in frame mode is to set the project properties to ntscdv and render to the DVDA ntscdv template. Also, set the media properties to progressive as that's what Vegas reads my footage captured in frame mode from the GL2. If that doesn't work, maybe try recapturing with your DVX instead of your GL2 (not sure why that would matter though)
johnmeyer wrote on 7/24/2008, 10:38 PM
Nat,

Thanks for the file. The mystery is solved. I don't know what you think you shot, but the video you sent is not progressive: it is standard interlaced widescreen NTSC DV video, with bottom field first field order (i.e., the standard for DV).

Now, if you want to render to progressive, you will have to deinterlace. I started a thread about this just a week ago, but that thread was really designed to figure out WHEN to deinterlace, not how to do it. Clearly in this case, because you want to match footage from other cameras that filmed in progressive, you need to do this. However, if you do it incorrectly you will indeed lose 1/2 the vertical resolution. I know ways, using AVISynth, to do some amazingly good deinterlacing, but it isn't something easy to describe.

I suggest you search this forum ("deinterlace" is an easy search and will turn up answers very quickly). I think there are settings in Vegas that may be able to avoid the resolution hit. If not, then I think you may be able to use Mike Crash's deinterlacing filter.

Also ... wait a minute ... yes, I still have it. There was an article many years ago about how to deinterlace in Vegas. I have it on my hard drive, but I just found it on the Internet:

video de-interlacing with Vegas

Good luck!
farss wrote on 7/25/2008, 1:52 AM
There's better ways to do a de-interlace now than using Blend or Interpolate. Mike Crash's Smart De-Interlacer (free) does a better job. Somewhere on Glenn Chan's web site is instructions on how to use the various controls.

Bob.
Grazie wrote on 7/25/2008, 3:32 AM
Where does it state that Canon's "Frame" mode is progressive?

I loaded your sample into Vegas Movie Studio and allowed the Project Properties be directed by the Match Media option. And this comes back with:

* NTSC DV (720x480, 29.970 fps)
* Lower Field First
* 0.9091 (NTSC DV)

Your Frame mode capture is coming back as interlaced.

If haven't already, you cold go to DVInfo site for the XM2/GL2 forums and do a search and search on Frame Mode Interlace you'll get some interesting valuable information on when people deinterlace Frame.

Grazie
Nat wrote on 7/25/2008, 7:01 AM
Thanks for all the tips guys !

The funny thing is I remember shooting with a GL1 a couple of years ago and ending up with similar issues and I recall I found a solution back then, but it's been too long :P

Since the final media will be DVD I'll just leave the footage intact.

I assume modern progressive TVs will de-interlace in hardware ?
The only thing that worries me is if they watch it on a computer, but I'll just say it works better with WMP...
farss wrote on 7/25/2008, 7:21 AM
I just tried playing around with it and the problem I think starts with how the camera generated it's frame mode, the interlace artifacts look bigger than you get from shooting 60i even.
Best results seem to come from telling Vegas to use Interpolate as the de-interlace method in a progressive project. You seem to loose a bit of vertical resolution but the jaggies are much smaller. That's looking at it on a progressive monitor though.

But I'm not 100% certain about this and couldn't find a definative answer to just what's in the 60i stream. If it's 24p with pulldown then it's difficult to remove the pulldown as the camera doesn't flag the fields unlike the DVX100 which Vegas can remove pulldown from. It's not totally impossible though, Cineform claim to be able to identify the type of pulldown and the cadence to get back the original frames, could be worth a try if you've got CF.

Bob.
johnmeyer wrote on 7/25/2008, 9:13 AM
There is definitely no pulldown in the sample clip. When I posted that it was not progressive, I didn't make that determination by looking at what Vegas thought it was, because I have seen Vegas misidentify progressive vs. interlaced. So, I first dropped the clip on G-spot. It reported interlaced. I then put it into TMPGEnc and used the "trick" I have describe before, using the TMPGEnc deinterlacer, BTW, which lets you see whether the interlace is upper or lower field. Finally, I wrote a brief AVISynth script that uses the "separatefield" function which creates half-height frames using alternating fields. Thus, I end up with twice the frame count, with each new "frame" consisting of even, then odd fields. I walked through that one field at a time. When I do this with material which contains pulldown, I see the repeated fields (i.e., no temporal motion between certain fields; just the normal one-scan-line up/down motion). I detected no duplicate field motion. I just re-ran that script on this clip and verified: there is no pulldown.

As for delivering it as interlaced on DVD for viewing on a standard TV monitor, I heartily agree, as long as this footage is a separate titleset from the footage you shot with your progressive cameras. You can easily intermix progressive and interlaced this way, and each will be flagged, decoded, and played properly by your DVD player.