Reversing Field Order

[drak23]

I recently discovered that a number of my captures were done with the wrong field order. I would like to try reversing the field order and reprocessing. I've researched this enough to know that it is possible but I can't quite seem to get the AVISynth script right. This is the procedure I am attempting:

Rip the VOBs and create an AVI proxy with DVD2AVI and VFAPIConv. (this I can do)
Create an AVISynth script that reverses field order (failed miserably)
Reprocess in TMPGenc (should be easy)

Anyone care to post a sample script? If there is a better way to do this, feel free to point it out.

Thanks and Regards,
Drak

[pijetro]

To answer your first question, ReStream does a great job in reversing your field order. It requires an elementary (.M2V) stream, so you might have to Demux your .MPG...

As far as AviSynth reversing your field order goes, I would rather have Tmpgenc do it for me during the encode...


Good luck!!!

[fmctm1sw]

Right out of the avisynth "decomb" package download. I use it, field order problems will become VERY apparent:

Step 1. Determine and Set the Field Order
It is essential to set the field order properly for correct rendering. The field order is set using the mandatory parameter order. Set order=1 for top field first; set order=0 for bottom field first. Because setting it correctly is so important, you are strongly encouraged not to make assumptions about the field order of a clip, but rather to verify the field order using the following procedure.

To determine the field order, make an Avisynth script that serves the raw clip without any processing. If it were an AVI, then just AviSource() would be used. For our examples, we'll use AviSource(). Add a script line to separate the fields using top field first, as follows:

AviSource("your_clip.avi")
AssumeTFF().SeparateFields()
Now serve the script into VirtualDub and find an area with motion. Single step forward through the motion. Note whether the motion progresses always forward as it should, or whether it jumps back and forth as it proceeds. For example, if the field order is wrong, an object moving steadily from left to right would move right, then jump back left a little, then move right again, etc. If the field order is correct, it moves steadily to the right.

If the motion is correct with AssumeTFF().SeparateFields(), then your field order is top field first and you must set order=1. If the motion is incorrect, then your field order is bottom field first and you must set order=0. If you are want to double check things, you can use AssumeBFF.SeparateFields() to check correct operation for bottom field first.

Let's assume we have a top field first clip in the following steps. You would of course use the correct field order for your clip. So far, then, our script is as follows:

AviSource("your_clip.avi")
Telecide(order=1)

[drak23]

Thanks guys! Your references got me on the right track. The main source of my confusion was that I was using an older version of AVISynth, and the guides I found were referring to the 2.5 version. It works! No discernable loss in quality, and the frame-error jerkiness completely gone. Its a beautiful thing.