need some help w/ decomb for a bizzarre clip

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Joined: Tue May 10, 2011 1:57 pm

need some help w/ decomb for a bizzarre clip

Post by bilbofett » Tue May 10, 2011 3:35 pm

Hi, I have a source clip I want to edit in adobe premiere. It is 1280x720 (720p) but the moron set the frame rate to 30fps.
30fps video is outside the spec for 720p format and won't display in premiere. (You can only do 23.976, 24, or 59.94 for 720p content).
What's worse, it was presumably shot in interlaced, then post-blended to become progressive, so wherever theres movement, theres blurry blended frames, and it looks pretty bad. I've already scolded the gentleman and told him theres absolutely no reason he needs to be shooting in 720i for 720p target video. And I told him that if he's at least going to convert interlaced content to progressive from his HD camera, to use interpolation instead of blurry frame-blends. But what's done is done.
In order to edit this video, I have to convert it to standard 720p frame-rate spec, which is going to be 23.976 or 24 (59.94 is not an option).
Obviously when I do frame rate conversion (in something like vdub) to 24, it highlights/heighten the blurry effect and makes it even worse.
I was thinking of using the decomb filter to do a simple decimate to kill the blurry frames entirely and take it from 30 fps to 24 for proper 720p spec for importing into premiere.
So far I haven't had alot of luck (probably doing something wrong).
This clip "technically" isn't interlaced, so I have no purpose to specific TFF or BFF in decomb?
I don't know quite how to set decimate properly to completely remove the extra blurry frames and take it to 24fps.
Any guidance would be appreciated!
Thanks in advance for a great program.
P.S. If you have another plugin/program that you think would better do this, please let me know.


Posts: 22
Joined: Wed Oct 27, 2010 2:19 pm

Re: need some help w/ decomb for a bizzarre clip

Post by Didée » Wed May 11, 2011 2:22 am

It's 99.99% sure that the source was not shot in "720i". Simple reason, this format does not exist. Probably a 1080i sequence was directly downsized to 720p, without respecting the interlacing.

Since the fields have been blended together, there is no combing anymore, therfore there is nothing that could be "decombed". (Once you have mixed milk and coffee together, you cannot separate them again.)

If the original source was "true interlaced" (60 unique motion states per second), then nothing can be done. All frames are blended, dead road, end of story. If it has to be by all means, consider a conversion with BlendFPS(aperture=0.5) (Avisynth, plugin "motion.dll"). But the mess becomes only messier and messier.

If the original source was "film" with field pulldown ("telecine", 24 unique motion states per second), then it should be repairable with the Avisynth script function "FixBlendIVTC".

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