Simple DVD Question for everyone. Told so many diffrent thin

[Trenton_Net]

Hi,

If I have an unaltered, pure DVD video being sent to TMPGENC, what fillters do I need to remove the interlacing artifacts?

Is it a combination of pulldown, or telecine? Im confused at this point simply because I'v been told so many things.
I used to deinterlace, but thats not correct.

If someone could even explain this in terms of tmpgenc options that would be a great help. Im sure every program likes to label their filters diffrently.

Thanks,

[kinneera]

It depends partly on the framerate. If your DVD video source is 29.97 and you want to keep it that way, you use the deinterlace filter. If your DVD video source is 29.97, and you want to convert it back to 23.97 (applies to the majority of film-DVDs), you use inverse telecine and deinterlacing is not necessary.

[ccngo]

How do you know what video source it is?

[Trenton_Net]

Thanks, but im not quite sure what you mean. Lets say I have a DVD, like most amarican DVDs. I think they are encoded at 23 or 24 point something internalty, but externaly show up as 29 frames per second. So I would need to inverce telecine this video, and it would remove the interlacing artifacts?

Well what do most people do when they rip a standard DVD? I mean filter wise?

Thanks,

[ccngo]

Why would you want to convert the 29.97 to 23.97....is that what you're suppose to do....What's the diff. between them?

[DiViNeLeFT]

i always converted to 23.97 just because the human eye can tell the difference anyway and movies in the theator are played at 24 i beleive... isnt the term "home theator" what we are all after anyway?!?

[ccngo]

So what fps 29.97 or 23.97 is interlaced?

[Vejita-sama]

Ok, here's the 'short' verison. Your TV is setup to display information at 29.97fps interlaced. Interlace refers to the fact that each frame is acutally made up of two fields (odd and even, aka top and bottom). Each field has half the lines necessary to make a picture. So your TV actually shows 60fields/sec.

Film is shot at 23.976fps progressive. It's called progressive because each frame is a complete/shapshot of the action, and they are shown one after the other.

Now in order for your 29.97fps TV to display that 23.976fps movie you have to convert the movie to 29.97fps. This is done my a process known as telecine (aka 3:2 pulldown).

So let's say I have a DVD of a movie. The movie was shot at 23.976fps but has been telecined to 29.97fps. If I rip the DVD to my HD that's whay I'll get (a 29.97fps source).

Now we could just encode that and burn it. But to get the BEST quaility (and to remove interlacing if your using MPEG1) we should convert it back to 23.976fps (a process known as inverse telecine; aka IVTC), encode it, apply telecine again (so it's at 29.97 to play on our TV), and then burn it.

So why would be want to do this. Well a 23.976fps encoded movie will have a higher bitrate/frame then a 29.97fps encoded movie.

23.976fps @ 2000kbit/s = 83.4kbit/frame
29.97fps @ 2000kbit/s = 66.7kbit/frame

That's a 25% increase in bitrate for the same lenght movie. That means much better quaility for the encoded MPEG. Once we've encoded the 23.976fps MPEG, we need to apply pulldown/telecine for it to play on your TV.

So why doesn't everyone use IVTC for all telecined ripped movies. Because it's slow as hell! For me it about doubles the encode time. And as I use MPEG2 and high bitrates it's just not worth it, IMHO.

For those that want to here's how you can tell if your movie has been telecined. First rip the movie to your HD:

Method 1) Open the movie in a program that allows you to look at each frame. Scroll through the movie, if you see 3 progressive frames, 2 interlaced frames, repeat... They you movie has been telecined.

Method 2) Open you rip in DVD2AVI, bring up the statics windows and hit preview. If the movie comes up as film (odds are) it's been IVTC. It it says hybird, 90% NTSC, 10% film, or any variation there in (very common with Anime) you've got a mixture of source material and deinterlacing could be a problem.


I know that was pretty long, but I think I hit all the points. Any questions

[ccngo]

Ok, how do you convert it back to 23.997fps with tmpgenc and what do you mean by applying telecine again?

So let's say I have a DVD of a movie. The movie was shot at 23.976fps but has been telecined to 29.97fps. If I rip the DVD to my HD that's whay I'll get (a 29.97fps source).

Now we could just encode that and burn it. But to get the BEST quaility (and to remove interlacing if your using MPEG1) we should convert it back to 23.976fps (a process known as inverse telecine; aka IVTC), encode it, apply telecine again (so it's at 29.97 to play on our TV), and then burn it.

[Kdiddy]

Im not sure what the process is called I get confused as well..but here's what I use and works fine....for my DVDs (all purchased in the U.S.)

I use DVD2AVI, do the preview first...if the preview reports that it is "film" above "95% progressive" (which it has always been for me)...then in my "video"->"field operations" tab, I select "force film", which forces the movie to be decoded as 23.97 fps progressive (non-interlaced)...that way you dont have to do IVTC (I think).

From there I encode my movie as 23.97 fps NTSC non-interlaced progressive using tmpg...I have that set on both my source & output options....and I get great quality out of it....and plays fine through my DVD player to my TV...like I said, I not sure the "name" of my method, I just it works...

footnote, if my preview reports NTSC, then I do 29.97fps on all options where apllicable and dont have probs there either....I may have just confused you worse, but it is a method that works for me.

<font size=-1>[ This Message was edited by: Kdiddy on 2001-09-06 16:34:13 ]</font>

[Vejita-sama]

ccngo - I don't use TMPGenc to perform IVTC, but it can do it. Take a look at http://www.inwards.com/~dbb/index.html, scroll down and there's a section on doing IVTC w/ TMPGenc. There's also a good article on telecine, 24fps vs 30fps, etc. etc. at:

http://www.inwards.com/~dbb/interlace_myths.html


IVTC vs. DVD2AVI's ForceFilm=on. What this does is tell ignore the flags telecine added to make the movie 29.97fps. Short verison:

a. Film is progressive at 23.976fps
b. telecine adds frames to make 29.97fps
c. Remember how I said you can tell if something has been telecined by 3 progressive frames, then 2 interlaced, repeat. Well ForceFilm=on just skips the interlaced frames. (aside - hmm? 3/2, maybe that's why they call it 3:2 pulldown )

This isn't the same as IVTC, but it does generate a 23.976fp source. Forcefilm deletes part of the movie (2frames for every 3) but most people just can't see the difference.

[kinneera]

I'm not going to claim to be absolutely positive of this, but technically speaking, the forced film option in DVD2AVI isn't deleting any of the original movie. It's only deleting (skipping) frames that were artifically added anyway.

[Vejita-sama]

Yes, force film skips the 2 interlaced frames, this produces a 23.976fps source. But it's not the exact same source as if you performed IVTC. Normally when you telecine something it's done like this:

Say I have four progressive frames:

A B C D

I need to convert this to interlace, and 29.97fps. So I'll spilt each frame into an odd/even field:

AA BB CC DD

ok, and now I'll add one more for B and C

AA BBB CC DDD

And now I'll make frames (two fields each) as follows:

AA BB BC CD DD (if I repeated this I would get 3 progressive frames for every two hybrid interlaced frames)

Now, if I just cut out the interlace frames, I get a 'differnt movie' then I started with:

Original
A B C D (repeat)

forcefilm
A B D (repeat)

So I deleted part of the movie. But the total number of frames stayed the same. I've just got different ones from the original movie. This is in affect 'deleting' part of the movie. But from a quaility standpoint it almost never causes problems.

And as far as the bitrate/frame goes it's the same. The potential problem is that there are a LOT of different ways to telecine (the above is just the most common), and forcefilm can leave in interlaced frames if a different format was used. Course, IVTC can make things worst too. Not sure if any of this helps answer the original question

[Kdiddy]

Ok I think I get what you are saying, soooooo if you delete some frames out from the original movie by using Forcefilm.....since it is shown in a frame/second format...would we thus shortening the movie timewise??..of course not by much..prolly like what a few seconds or so....but if I followed you right, through the IVTC method we get to keep all the original frames...in the "A B C D" format as oppose to the forcefilm's "A B D" format...which would also lead me to think that IVTC is a longer movie timewise than Forcefilm...by again a few seconds????

[kinneera]

You have a typo Vejita-sama:

If you add one to the B and C frames you get:

AA BBB CCC DD

whereas you wrote:

AA BBB CC DDD

This is important, because there's a big difference between the two. If you reconstruct the sequence with B and C augmented, you get:

AA BB BC CC DD

This is only one extra interlaced frame per every four, the 4-to-5 conversion theory which (as I understand it) is the most commonly used telecine method. Thus if you drop the interlaced frame, you get:

AA BB CC DD

The same video as the original, nothing deleted!

[Kdiddy]

ya know I saw the typo..and wondered...but he seemed to know what he was talking about...whereas I have no clue..LOL

[Vejita-sama]

OPPS!!! Sorry about that Hope I didn't overly confuse anyone any more then they already are...

I've got to start proof reading this posts. Again sorrry sorry sorry.

[Kdiddy]

ooook so still leaves my question..does IVTC preserve all frames whereas force film drops a small # of frames??

[kinneera]

Well...if you accept the analysis in my correction post, then logically the forced film and IVTC options are functionally equivalent, so no - no frames are lost with force film. It does seem to be a heck of a lot faster though.

[Kdiddy]

Of course I accept anything you say man &quot, LOL, cool, yeah force film sounds faster & whole lot easier to me than all that IVTC jazz.