Detecting Interlacing in VOB Files?

[Astyanax]

Hi:

So today I've learned about interlacing and deinterlacing.

I've found that the StaxRip suite works very well for deinterlacing some of my TV episodes, and it looks great.

The problem is that some TV shows' DVDs have interlaced episodes and some do not. When I play the VOB file directly, I can't tell, but after I rip and encode, it's obvious that I should have deinterlaced in some cases.

So is there an easy way to tell in advance how it will encode? I'd rather not have to encode twice because I guessed wrong! Basically I'm asking for a utility that examines VOB file statistics and gives me that crucial bit of information.

Thanks!

[chipzoller]

Well first you must be clear in understanding the differences between pure interlaced and telecined material. The best way to tell is after you've created your D2V file (assuming you went this route), create a simple .avs script that loads the D2V file and step through it frame by frame in VirtualDub(Mod). This way you can determine and distinguish between pure interlaced and telecined (pulled down) material. Once you've figured this out then you can choose how you'd like to process the video.

[Astyanax]

Okay, thanks for the great tips.

One of the things StaxRip does BEFORE decoding is a Compressibility Check. This produces a small AVS linked to a D2V file that loaded up very nicely in VirtualDub(don't know why "mod" is listed after the name). In stepping through frame-by-frame, I can see significant evidence of the interlacing (perfect parallel lines in scene changes and fast motion), which answers my question in the first place. I have to do the Compressibility Check anyway, and this half-hour saves me the eight hours of a full encode.

However, I am intrigued by your interlacing vs. pulled-telecine distinction. First, how can I tell the difference? Second, why do I care?

Thanks again for your help!

Asty

[unskinnyboy]

However, I am intrigued by your interlacing vs. pulled-telecine distinction. First, how can I tell the difference? Second, why do I care?
Read this (http://www.doom9.org/ivtc-tut.htm) upside down, inside out, top to bottom, right to left. All will be revealed.

[Astyanax]

Okay, I'm beginning to get a feel for the level of complexity...but allow me to put my particular challenge simply:

IF I see interlacing artifacts by looking at the Compressibility-Checked d2v (a small compressed sampling for the purpose of calculating optimum bitrate), and then IF I find that deinterlacing produces a nice clean clip in these circumstances, is it then fair to assume that I can reliably use VirtualDub to indirectly check my VOBs for interlacing?

I'd really rather not add a detailed process to my rip-encode procedure just to spot telecines, when it seems like I'm either not encountering any, or at least my deinterlacing is producing satisfactory TV show content...

Hope that made sense, but it seems this is tricky stuff...

Asty

[unskinnyboy]

IF I see interlacing artifacts by looking at the Compressibility-Checked d2v (a small compressed sampling for the purpose of calculating optimum bitrate), and then IF I find that deinterlacing produces a nice clean clip in these circumstances, is it then fair to assume that I can reliably use VirtualDub to indirectly check my VOBs for interlacing?

I'd really rather not add a detailed process to my rip-encode procedure just to spot telecines, when it seems like I'm either not encountering any, or at least my deinterlacing is producing satisfactory TV show content...
Interlacing and telecining are mutually exclusive. There can be only either one present, if at all present. Usual TV stuff is interlaced, so looks like you are all set, if you got it deinterlaced and the results look satisfactory to you.

And yes, VirtualDub is the ideal tool to use for checking for telecining/interlacing since it allows you to step through the video frame by frame.

[Astyanax]

I see. Thanks for the points and reading material. It seems that ripping most of my own collection will be fairly pedestrian...as are my tastes. ;)

[chipzoller]

Also, it would be in your best interest to identify and remove any telecining for the primary reason that it will increase compresibility drastically by dropping every one in five frames. I wouldn't consider this an unnecessary step in considering an encode and processing strategy, it's simply another step that must be considered.

[Guest]

VirtualDub is the ideal tool to use for checking for telecining/interlacing since it allows you to step through the video frame by frame. To assess interlacing/telecining/field-blending/etc., it's better to step through fields than to step through frames.

[unskinnyboy]

To assess interlacing/telecining/field-blending/etc., it's better to step through fields than to step through frames.
You are right. I only meant "frames" as in using VirtualDub's arrow keys (<-, ->) to step through the video.

[Astyanax]

Thanks. In stepping through frame-by-frame, I'm not seeing any duplicate frames at all. So I think it's fair to say there is no telecining going on.

[Guest]

Thanks. In stepping through frame-by-frame, I'm not seeing any duplicate frames at all. So I think it's fair to say there is no telecining going on. That's not true unless you've applied a field matcher like Telecide(). Did you?