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Post #585330

Author
OmegaMattman
Parent topic
Brooks's Adventures in VHS preservation (Released)
Link to post in topic
https://originaltrilogy.com/post/id/585330/action/topic#585330
Date created
13-Jul-2012, 5:37 AM

Brooks said:

 here's about 100 frames uncompressed from vdub after running the separate fields script if any of you has the free time and inclination to look at it and see if you can help me figure out what frames need to go (57mb)

http://www.mediafire.com/?6i85yub38uzyram

This is a complicated hobby! :)

You shouldn't need to render it to figure out the frames.  Just count by areas of 10s, which is why the later part of the sample script I posted said "Selectevery (10,.....)".  You are literally selecting the the individual frames (which are separated) out of every group of 10.

I had to teach myself how to do this a few years back.  For some reason, I never could find a guide online...and I guess I figured it out by luck.  It is a lot easier than it sounds.  Let me see if I can walk you through it a bit simpler:

1) Start with a basic field-separation script and open it in VirtualDub:

avisource ("yourfile.avi")
separatefields


2) Pick an early set of frames (in the actual movie) which have some movement you can see.  Let's take the "20th Century Fox" logo.  The spotlights move back and forth.  Now, move to a frame in that which ends in "0" (i.e. 270).  The frame numbers are displayed on VirtualDub.

3) Now, slowly go frame-by-frame for 10 frames (i.e. 270 to 280).  You should see a pattern.  2 frames will match, then 3 frames will match, then 2 frames will match, then 3 frames will match.  Your goal is to change that pattern from 2,3,2,3 to all pairs.

4) Grab a pen and write down the pattern based on the last number of the frame (i.e. 0&1, 2&3&4, 5&6, 7&8&9).  You may want to double-check that pattern by slowly moving through the next ten frames.

5) Next, it's time to modify your script to reflect this pattern and actually IVTC the movie.  For the sake of this example, we will use the sample pattern I listed in step 4.  We will throw out the 3rd frame of each group of three in this pattern (i.e. frames 4 and 9).

Update your script by adding the "SelectEvery" and "Weave" functions.  Your pattern will go in the "SelectEvery" function follwing the number "10".  That "10" specifies the number of frames being considered.

avisource ("yourfile.avi")
separatefields
selectevery (10,0,1,2,3,5,6,7,8)
weave

6) Once your script has been modified and saved with the new pattern, reopen the script in VirtualDub.  The fields should be weaved back together into progressive frames.  Now, scan through the film to look for combing.  Because of dropped frames and reel changes, the TC pattern will likely change every so often.  When combing appears, you know the pattern has changed.

7) Create an "mark-out" point where the combing begins and render your video up until that point.  Then, repeat the above steps starting where the new combing began.

8) If you're lucky, there will be no combing and you'll have a single file.  Or, you may wind-up with several videos that you'll need to splice together.

I hope this makes some sort of sense.  Best of luck.