Swap field order of DVD on track-by-track basis

[miamicanes]

I have a bunch of DVDs that were ripped to .iso for playing on my Seagate Free Agent Theater (non-plus). One thing that's annoyed me on about a half-dozen discs is that the field order appears to be reversed on some/most of the tracks.

When played on a normal DVD player (or the FAT) and viewed on a non-HD CRT, the video lurches and shudders (think: two steps forward, one step back for every frame). But if I view the original disc or .iso on my computer, or on my LCD TV (but not my older DLP), or play it from a Blu-Ray player, it looks like either the TV or player is able to detect the field-order lurching and fix it automatically.

Anyway, is there any easy and straightforward way (ideally free, preferably Windows, though I have Linux available too) to fix bad field order in an existing .iso file without going through the whole tedious workflow of extracting to DVD files, demultiplexing to AVI, modifying with Avisynth, remultiplexing, re-encoding to MPEG-2 again, and re-packaging it back into a .iso file?

I could swear I remember reading somewhere that there's a flag the author is supposed to set if he joins two odd or two even fields while editing to let the player know that the field order is reversed, but I might just be confusing that with an option in TMPGenc or HCenc.

[TheSkiller]

Without unpacking the ISO and demux-remux it's probably possible only by using a Hex Editor but I think before you manage to fix the field order of the ISO in place using a Hex Editor you have spent enough time to do the regular way several times in a row...


You do not need to reencode, it's just a flag. You'd need to unpack the ISO to VIDEO_TS folder and then demux everything, change the flag, remux and put it all together using Vobblanker.

[miamicanes]

OK, thanks! I'll give it a try tomorrow.

Is it just my imagination, or does it seem like the number of DVDs with reversed field order in at least one scene has increased exponentially over the past 2-3 years? It used to be something that happened once in a blue moon. I think I have 2 discs from before 2006 that had a scene or two with the problem. Now, Jesus... it seems like literally a quarter of the discs I see have at least once scene with reversed field order.

[TheSkiller]

That's very odd, I have never even heard of commercial DVDs with wrong field order, it's usually only a problem when inexperienced people make a home DVD from camcorder footage.

Are you sure it's not a problem related to the way you play the video?

[miamicanes]

(blush) If it clarifies the situation any, it's pr0n (ie, occupying the big area between amateur and Hollywood/broadcast-professional, with plenty of discs produced by people who should know better... but apparently don't. I did some research last night. Apparently, Adobe Premiere is *notorious* for screwing up field order for content of DV (and presumably HDV) origin.

My guess is that the problem has gotten worse because there's now a large group of people whose first introduction to video editing and production was with 30fps HD, where it didn't particularly MATTER which field came first as long as both came from the same frame, and by the time they graduated to remastering 60fps progressive down to 60fps interlaced, they either didn't realize that it mattered, and/or previewed the DVD before sending it off for duplication by playing it on a Blu-Ray player that automatically fixed their field order on the fly (so they never even realized anything was wrong).

Incidentally, swapping the field order with Restream fixed the problem 100%. Now I just need to find a slightly more convenient workflow, because all the program info was lost when I demuxed it with PgcDemux, and when I put it back together again into a .vob file, it was just one long track. I'm not averse to spending money, but for anything more than $25-40 or so, it would pretty much have to be "give it the ISO file, indicate the programs to field-swap, and click go"