BD-RB Inverse Telecine Process Question(s) - Help Please??

[SLOVEHEART]

I am at a loss concerning the matter of when to use the IVTC process on a 30fps stream. I understand the concept behind what INTC does ( :) - I think...) - it will take a Telecined track (interlaced) and convert it back to 24fps (progressive) by using 3:2 pulldown flags (added frames + markers???) in the output.

But J. Dobbs said in the changelog for the latest release - "... as executing inverse telecining on a non-telecined source will result in a severely stuttering picture..." !

This brings up my confusion - are all 30 fps (29.97) streams Telecined?? - If so that means all the stock footage originally used by all production houses would be 24fps PERIOD; then if I saw a 29.97fps stream - I could safely use INTC - Right??

Or is there more to the picture - if there are un-telecined 29.97 (30) fps streams - how in the f can one find out whether or not a stream has been telecined??

********

J.Dobbs also mentioned stuff about new labeling of streams that are hybrid or soft telecined...

This again I'm lost in understanding what this means:confused: - could someone please explain what hybrid and hard / soft telecine tracks are??

I really would be thankful if some good soul would take a moment and clue me in on these things - I've read up on telecining, pulldown, etc., - but I can't figure out about the things I mention above - I'm kinda ignorant :)

Cheers...

[Sharc]

how in the f can one find out whether or not a stream has been telecined??

See for example the FAQ here:
http://neuron2.net/

Make .avs script:
DirectShowSource("...path to your source file here ...")
AssumeTFF() # or AssumeBFF()
SeparateFields()
Now serve the script into VirtualDub or MPC-HC and step through the fields in a high motion section. We will label a new picture with a new letter below. If you see a repeating field sequence like this:

... a a b b c c ...
then it is progressive video. If you see this:

... a b c d e f ...
then it is pure interlaced video. If you see this:

... a a a b b c c c d d ...
Then it is 3:2 pulled-down progressive video.

could someone please explain what hybrid and hard / soft telecine tracks are??
See section on Soft/Hard telecine here:
http://en.wikipedia.org/wiki/Telecine

In hard-telecined sources the frame/field pattern (sequence) is encoded in the 29.97 fps stream.
Soft-telecined uses only pulldown flags in the stream, and the player derives the frame/field sequence during playback.

'Hybrid' sources may use both techniques in the same file, or worse even, mix interlaced video and telecined film, or field-blended PAL-to-NTSC conversions. There's lot of space for all kind of crap to fill a 50G blu-ray disc.

Added:
If you don't feel comfortable with the avisynth method above, you may just load your file in a PC player like MPC-HC, de-activate any de-interlacing, and step manually through the frames.
If out of 5 frames 2 are "ghosted" it is an indication of telecined material.
See for example here:
http://www.animemusicvideos.org/guides/avtech/video2_2.htm

[Capsbackup]

@Sharc;
Excellent explanation! :)
Though it sounds pretty easy and straight forward, and with due diligence one can determine the correct method.
However, I think this is going to open up a whole new set of problems and bug reports for jdobbs. :(

[jdobbs]

I am at a loss concerning the matter of when to use the IVTC process on a 30fps stream. I understand the concept behind what INTC does ( :) - I think...) - it will take a Telecined track (interlaced) and convert it back to 24fps (progressive) by using 3:2 pulldown flags (added frames + markers???) in the output.

But J. Dobbs said in the changelog for the latest release - "... as executing inverse telecining on a non-telecined source will result in a severely stuttering picture..." !

This brings up my confusion - are all 30 fps (29.97) streams Telecined?? - If so that means all the stock footage originally used by all production houses would be 24fps PERIOD; then if I saw a 29.97fps stream - I could safely use INTC - Right??

Or is there more to the picture - if there are un-telecined 29.97 (30) fps streams - how in the f can one find out whether or not a stream has been telecined??

********

J.Dobbs also mentioned stuff about new labeling of streams that are hybrid or soft telecined...

This again I'm lost in understanding what this means:confused: - could someone please explain what hybrid and hard / soft telecine tracks are??

I really would be thankful if some good soul would take a moment and clue me in on these things - I've read up on telecining, pulldown, etc., - but I can't figure out about the things I mention above - I'm kinda ignorant :)

Cheers... Inverse Telecining is very complex and is for advanced users only. The bottom line is that if you don't know what it is -- you really shouldn't be using it. I added it because it was requested. I also needed it to IVTC a poorly authored original I bought ("Time Bandits") that was hard telecined.

As to your questions:

are all 30 fps (29.97) streams Telecined?? No, they are not. Telecining is only performed when a source that was originally 24fps (23.976) is converted to 30fps (29.97).I saw a 29.97fps stream - I could safely use INTC - Right??Absolutely not. You'll regret it for 99% of all sources.how in the f can one find out whether or not a stream has been telecined Just click the box in the SETUP menu if you want to IVTC. It will find them safely. The only time you would use the dropdown box is for hard telecined sources -- and frankly most people who "guess" that something is hard telecined will get it wrong almost all the time.

[setarip_old]

@jdobbs

Hi! Just click the box in the SETUP menu if you want to IVTC. It will find them safely.Is this the same concept/procedure used with selecting "Deinterlace" from "Setup" - that, if selected, BD-RB will seek out and apply this ONLY to interlaced video?

[jdobbs]

@jdobbs

Hi! Is this the same concept/procedure used with selecting "Deinterlace" from "Setup" - that, if selected, BD-RB will seek out and apply this ONLY to interlaced video? Even further, it will seek out, scan the source, and only apply it to interlaced sources that are telecined and have pulldown flags applied. If LAVF is used, the pulldown flags are removed during demuxing. If not, then the source is inverse telecined using DECOMB via AVISYNTH.

[Capsbackup]

Even further, it will seek out, scan the source, and only apply it to interlaced sources that are telecined and have pulldown flags applied.

Do you recommend selecting this option? It sounds like it should just be a default setting. ?? :confused:
Also, do you recommend selectig LAVF?

[jdobbs]

However, I think this is going to open up a whole new set of problems and bug reports for jdobbs. :( You may be right. If it does, it will go away very quickly. I added it as a request from an experienced user.

It is meant for those who understand IVTC, not for those who "think" they understand IVTC. Checking the box in SETUP is safe for anyone. Selecting it when it is not automatically done is usually a bad idea.

[jdobbs]

Do you recommend selecting this option? It sounds like it should just be a default setting. ?? :confused:
Also, do you recommend selectig LAVF? It may be eventually, but I just don't want to keep chasing this thing down rabbit holes... the more I think about it the more I think the selection from the streams list is going to be removed. The last thing I want is a long line of newbies complaining because they ruined their encode through self-inflicted injury due to lack of knowledge. :(

[Edit] IVTC selection via dropdown menu has been removed for the next release.

Also -- it isn't the default right now because PCs don't play it back very well -- and I didn't want to get a hundred reports from people who don't know any better than to test their playback on a computer.

[SLOVEHEART]

"...The last thing I want is a long line of newbies complaining because they ruined their encode through self-inflicted injury due to lack of knowledge. :(

[Edit] IVTC selection via dropdown menu has been removed for the next release.

Also -- it isn't the default right now because PCs don't play it back very well -- and I didn't want to get a hundred reports from people who don't know any better than to test their playback on a computer..."

***********************
First off - Thank You for your response(s) - I really appreciate them...

In my view> I am one of those 'somewhat educated' - but nowhere near expert or even 'close to competent' people...

But> I am learning (when I have a moment)!!!

**I really hope you don't fall too far on the side of the fence in letting the potential errors that may occur by folks who don't do enough research to use a feature properly that you are thinking about / or have added to your superb project(s) deter you from making the application more versitile, etc. I understand the flood of reports that might come in - but you might make a clearly explaned post concerning the issue, and when additional trouble reports come in - you could just reply refering them to the post??***

If I might be so bold as to suggest making some of your options list in a new section - labeled ??For Advanced use?? or something.

==>Or at least - instead of eliminating the option completely (like you are going to do w/ stream selection for IVTC) - could you somehow make it a hidden option ?? That way - someone couldn't easily inflict a disaster - one would have to know about the H.O. and thereby make it more 'idiot proof' - relieving you from a flood of reports; and angry users??

You have several options in DVD-RB Pro - that require more than basic knowledge to use, and some possibilities for mistakes causing a failed or useless encode - like running over availible space by using other encoders than HC etc...

Having the options to make higher quality picture I think are great - if it requires learning - that's the price of admission - hidden option - yesssss :) :)
************

Maybe a hidden option could allow for the selection of stream(s) for IVTC possible - and by default it would be set so this wasn't possible??

[SLOVEHEART]

@ Post #2 http://forum.doom9.org/showthread.php?p=1449573#post1449573
Great Links and Nice explanation(s) courtesy Sharc

Great stuff - I needed that!!!

Thanks...

[Video Dude]

IVTC is a very useful feature to have. I have not yet encountered a Blu-ray disc that would need it, but there were many times I wished DVD-RB had it when I was forced to do those discs manually with MuxMan.

I hope IVTC can stay in BD-RB, whether in an advanced menu or a hidden option.

[jdobbs]

IVTC is a very useful feature to have. I have not yet encountered a Blu-ray disc that would need it, but there were many times I wished DVD-RB had it when I was forced to do those discs manually with MuxMan.

I hope IVTC can stay in BD-RB, whether in an advanced menu or a hidden option. I've encountered ony one -- "Time Bandits" was hard telecined at 1080i (who would do that?). But, I also found that when I convert series DVDs in order to fit them on a single BD I can use it. The entire first season of "Bonanza" was hard telecined. So, essentially I added it because I needed it -- and decided to make it available (since I wrote the code anyway).

I'll put a hidden flag that will enable it from the streams list. But you should read all the e-mails I've gotten... apparently everybody thinks everything on the planet is telecined and wonder why it looks like crap when they IVTC a standard interlaced source. My head hurts.

I thought the rather carefully worded explanation I added to the CHANGE file would make it clear.
- Added the ability to inverse telecine interlaced
sources. You select it by right-clicking on the
stream in the stream list. This can dramatically
improve picture quality on hard or soft telecined
sources by encoding at 23.976 with pulldown flags
rather than 29.97. Note: Please be careful in
using this option as executing inverse telecining
on a non-telecined source will result in a
severely stuttering picture. It is not uncommon
for new users to confuse interlaced "combing" with
telecining. Since some types of inverse telecining
requires AVISYNTH, LAVF usage for a stream may be
by-passed when it IVTC selected.
But I guess nothing is ever enough.

[Video Dude]

Thanks jdobbs. Amazing how your programs make DVD and Blu-ray backup so easy.