Determining field order of AVI files?

[SaSi]

I am encoding different AVI files captured in different ways. All are PAL. It appears that some of these files are TFF interlaced while others are BFF.

I reached this conclusion, because encoding some files to MPEG-2 as TFF cause terrible flicker when viewed on TV. Changing the field order flag with restream totaly fixes the problem.

Now, restream is a solution, but how about being able to determine the field type before encoding to MPEG2?

Is there any tool that can show how the AVI file is interlaced?

TIA

[erratic]

If you use the Project Wizard in TMPGEnc it will judge the field order of your AVI file. But if your AVI file is not interlaced it usually defaults to bottom field first. Some files are assumed to be progressive though, like 23.976 fps avi files. DV files are assumed to be bottom field first of course.

[vhelp]

@ SaSi

Have you done and Resizing in your filtering ??

I've had issues with this too, (or worse, when I do manual IVTC) and get
the resizing increments wrong (or cought in odd line) as the increments have
to be in either 2; 4; 8 scanlines.

So, flickers come in other favors too, as in the above. Some experince their
source flickers, while others see jitter and yet others, pauses.

Anyways.

Cheers,
-vhelp

[fmctm1sw]

Now, restream is a solution, but how about being able to determine the field type before encoding to MPEG2?

TIA

avisynth is the best thing I have found for this. The separatefields() and assume(t/b)ff() commands in specific.

[lordsmurf]

If you can fix later with RESTREAM, I'd just do that. Encoding in the wrong order rarely has negative effects. It's just the wrong order, the encode is the same either way.

This is me being lazy, but it'll still work just as easily.

I hate digital source that's not my own.

[pijetro]

fmctm1sw wrote:

avisynth is the best thing I have found for this. The separatefields() and assume(t/b)ff() commands in specific.

So in essence, is it possible to force any video to Bottom field, regardless of what the original field order was??

I believe dropping the video into AfterEffects 6.0 and doing a frame by frame look during motion, will tell you that your field order is correct or incorrect to the current project settings (usually bottom field first).

[SaSi]

If you can fix later with RESTREAM, I'd just do that. Encoding in the wrong order rarely has negative effects. It's just the wrong order, the encode is the same either way.

This is me being lazy, but it'll still work just as easily.

I hate digital source that's not my own.

That's what I do until I find a better solution. If you see my other current posting on selecting Field order with CCE you will understand why I am pulling my hair.

The source is my own. VHS and TV broadcast captures. The problem is that I have a backlog of captures with Pinnacle PCTV (which captured TFF until it died), a lot of Mainconcept captures (which have a strange field order interlace problem and have converted the video to progressive to make it watchable) and the newest captures are with Hauupauge WinTV-USB, which - I found out - captures BFF.

Currently, I have to encode a part of the AVI to Mpeg, author it, view it on TV and decide what I need to do with Field order after that. Once I finish the DVD, I record it on RW, verify playback on TV and redo some of the clips that I missed on the first try.

Four F1 GPs and 17 days of Olympics have filled up my 900Gb of HD storage. I either need to improve my speed or buy a 6th HD

[fmctm1sw]

fmctm1sw wrote:

avisynth is the best thing I have found for this. The separatefields() and assume(t/b)ff() commands in specific.

So in essence, is it possible to force any video to Bottom field, regardless of what the original field order was??

I think that's the idea. I know one way will be very jerky and the other will be smooth. I've never used it to actually change the order, just to fugure out what the order was.

[SaSi]

fmctm1sw wrote:

avisynth is the best thing I have found for this. The separatefields() and assume(t/b)ff() commands in specific.

So in essence, is it possible to force any video to Bottom field, regardless of what the original field order was??

I think that's the idea. I know one way will be very jerky and the other will be smooth. I've never used it to actually change the order, just to fugure out what the order was.

I don't believe you can force the video to become what you want it to be.

Interlaced video capture is 50 FPS (for PAL) and each field are on a separate time axis location. This means that if the video is top field first, the odd lines are captured before the even lines.

If you force it to become the other way round, then early capture lines will be played AFTER the late captured lines, causing the terrible flicker effect.

[fmctm1sw]

Interlaced video capture is 50 FPS (for PAL) and each field are on a separate time axis location. This means that if the video is top field first, the odd lines are captured before the even lines.

If you force it to become the other way round, then early capture lines will be played AFTER the late captured lines, causing the terrible flicker effect.

Could be. All I know is my projects are never in the wrong field order when I use that script, check it, and encode with tmpgenc according to that field order. Dumb luck maybe, but I'll take it...

[vhelp]

If you can fix later with RESTREAM, I'd just do that. Encoding in the wrong order rarely has negative effects. It's just the wrong order, the encode is the same either way.

One of the reasons why you would not want to go this route is beause those
field order issues could cause some distortions in the horizantal.., specially
during the Resizing or Filtering prior to Encoding (or during, for that matter)

Correct me if I'm wrong, but from what I can tell, there are TWO kinds of
Field Order (or FieldSwaps) of which I see as Light field orders vs. Heavy
field order.

* The Heavy field order is when you swap the fields during the editing stages,
... your soruce will distort heavily.

* The Light field order is when you swap the fields (or is it plains) and only
... a minor distortion is noticable.

Anyways.

Cheers,
-vhelp

[erratic]

Why make it more difficult than necessary. Like I wrote earlier, TMPGEnc's Project Wizard can determine the field order of an interlaced avi file correctly. It doesn't mean you have to use the Project Wizard or TMPGEnc to encode the file. You can use the Project Wizard just to determine the field order.

The default in TMPGEnc is BFF. All my ATI captures are TFF. If I open those AVI files with the Project Wizard they're correctly recognized as TFF. If I convert a TFF AVI file to BFF and open it with the Project Wizard the file is correctly recognized as BFF.

Yes, the avisynth script works, but so does the TMPGEnc Project Wizard. It has always determined the field order of my interlaced AVI files correctly so far.

[SaSi]

I admit I haven't tried this yet. Will do as soon as I go back home.

You mentioned that the project wizzard recognizes the field order. Does this mean that the wizzard must be enabled for field order to be recognized? I don't have the wizzard enabled. I guess I will try both ways to see how this works.

You know, there is an extra complexity in this mess.

If I capture to MPEG-2, then edit out commercials etc with VirtualDUB and save as a DivX file, DivX v.5.1.1 has an option "Encode as interlaced" and then a flag for field order.

If this setting is wrong, then the original field order will be scrambled and there is no way for the final MPEG 2 file to be viewable. Have had to deinterlace some captures before re-encoding to MPEG2 to fix them.

[erratic]

After running TMPGEnc start the Project Wizard (Ctrl+W or File -> Project Wizard). Then select a (DVD) template, click Next, and open your file. Now the wizard will scan your file to determine the field order. This certainly works with interlaced Huffyuv and MJPEG files.

If your video is MPEG-2 I assume the wizard will use the flag stored in the MPEG-2 file, which may not be correct. It doesn't seem to work with DivX files either. The Project Wizard automatically assumes they're not interlaced. For such files I would use Avisynth, if necessary.

But I use PICVideo MJPEG (or sometimes Huffyuv) for capturing, and the field order of all those avi files is determined correctly, as long as the files are really interlaced. If the files happen to be non-interlaced, the Project Wizard will default to BFF.

[xxiangg]

Like erratic said, I also used TMPGEnc project wizard. It is very easy
to use and worked well.

[erratic]

This should work for interlaced MPEG-2 and DivX/XviD files: open with VirtualDubMod, frameserve to TMPGEnc's Project Wizard. Now it will scan your video to determine the field order.