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neil wilkes · Joined: 26 Dec 2003 Posts: 51 Location: London, England

Help!
I am not at all sure what is going wrong, I suspect a field order issue but I do not know.
I have an MPEG-2 video file with some parts unusable.
So we came up with the idea of adding stills instead of the video at these points.
BUT - Whenever I encode to MPEG-2, the result is perfect video and very shaky stills. The stills were added to the AVI by putting them on the next video track in Premiere Pro. The AVI file output is perfect on a PC, but as soon as it goes to MPEG-2 on the DVD the stills are shaky.

Any suggestions very gratefully appreciated. There is not that much hair left on my head and I'm all out of ideas.
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RMN · Posted: Thu 28 Apr 2005, 2:03 Post subject:

Hm... I'm not sure how a still can shake. Smile

Are these real stills (i.e., photos) or frozen frames from a video? If they're frozen frames, you probably need to deinterlace them.

Also, make sure the stills are the right resolution before importing them into Premiere, and apply a gaussian blur filter with a value between 0.3 and 0.6 (also before importing it into Premiere, but after resampling to video size). This will avoid the shimmering caused by detail that is on one field but not the other (it will look slightly blurry on the PC screen but will look fine on TV).

RMN
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neil wilkes · Joined: 26 Dec 2003 Posts: 51 Location: London, England

They are indeed stills from a video sequence.
And boy, do they shake!
It does look exactly like a field order problem.

I will try what you have suggested.....and post back later.
Many thanks
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RMN · Posted: Thu 28 Apr 2005, 15:01 Post subject:

It's not so much a field order thing (if you reversed their field order they would still shake). The problem is the still was taken from a scene where the subject or the camera were moving. Since the two fields correspond to different moments in time (i.e., 1/50th of a second apart). when you hold that frame, the field being displayed flips back and forth between those two. If everything is still, this won't be noticeable. If anything was moving, it will shake.

You need to either take a still from a place where the camera and subjects were perfectly still, or deinterlace the images. You can deinterlace them in Premiere, but it's a bit of a waste (because it will deinterlace each of the new frames). It's usually faster and simpler to load the still into Photoshop, apply an interpolared deinterlace filter (Filters -> Video), and then import them into Premiere. If they come from video, you don't need the gaussian blur.

In Photoshop it should be obvious which parts flicker and which don't (jagged lines = flicker). You can select only the parts that flicker and apply the deinterlace filter only to them. That way you avoid losing vertical resolution in areas that really are still.

RMN
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neil wilkes · Joined: 26 Dec 2003 Posts: 51 Location: London, England

Thanks for the tips.
What I did to solve it was re opened AFter Effects, where they were being compiled into an AVI, and interpreted the stills to Lower Field first.
This solved the problem completely.
What After Effects had done was used both fields, as I was a fool and forgot completely to check this.
Really should know better, but hey.
Pobody's Nerfect!
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Digital Audio Specialists