No such thing as SD 24p film to video transfer?

[Conrad Yoder]

I recently had a transfer done from Super16 to digital. It was uncompressed 10-bit standard definition, to a QuickTime file on an external hard drive. I was expecting a non-telecine transfer (24p), but I got back a standard 29.97 telecine QT video. When I asked the transfer guy at the lab, he said that SD 24p transfers don't exist - that only happens in HD. I am not doubting his veracity, but I wanted some more info on why SD 24p non-telecine transfers to video can't be done - why does it have to be in HD? I didn't get a chance to discuss all the technical aspects of this with him. Thanks for any info.

[Robert Houllahan]

Hi Conrad,

 

we spoke the other day, perhaps I can clear this up a bit more...

 

All SD video formats are "throwbacks" to the early days of television the two major standards worldwide are NTSC and PAL one is a 60 field format and the other is a 50 field format (more or less) the use of fields instead of full frames came about for several reasons. 1. the electronics of the day could not handle the high frequencies that are required to display a full progressive frame of video at 25fps or 30fps and 2. interlacing is a form of compression allowing half of the video picture to be time delayed i.e. one field is sent and then the next is sent a fraction of a second after it which requires less frequency spectrum than a full frame at a time.

 

 

So 80 years later we are still suffering with the original television standards, to further compound things NTSC is actually 29.97 fps or 59.94 fields per second... this has wreaked havoc with people in post houses for years and there are countless stories of EDL's with hundreds of hours of work in them due to 25 to 29.97 or 24 to 29.97 or 30 to 29.97 conversions in them...

 

With the fairly recent advent of digital video came cameras like the Panasonic DVX100 which is able to run in a 24fps mode on minidv. What this camera is doing is a telecine conversion process with a 3:2 pulldown just like you would find on a Rank or Spirit the 3CCD pickup is clocked and run at a 24fps progressive cadence and then it is "telecined" to the 29.97 frame rate of the Minidv tape. The Panasonic codec has facilities to extract the 24fps progressive material from the 29.97 interlaced tape in post (on FCP or Avid, etc. you choose the 3:2:2:3 advanced setup) so you can now play the material in 24fps progressive but if you are going to look at it on a SD television a 3:2 pulldown and interlacing are re-introduced.

 

So there is one example of 24fps SD material, sort of, We use a Blackmagic SDI card on a G5 for our disk captures there is a 24fps codec (Uncompressed 10bit or 8bit) which removes the pulldown and makes the incoming uncompressed SDI signal into 24fps interlaced (it removes the 3:2 pulldown but does not de-interlace) when I play back a file recorded like this the Blackmagic card does the 3:2 pulldown for playout to our 20" SDI grading monitor. I have had some issues with this codec in the past which is why I do not offer it as a option it is basically unsupported from decklink.

 

 

Post facilities have been doing 3:2 pulldown removal and de-interlacing for years the pulldown removal is fairly easy but de-interlacing can be tricky and requires more cpu power. Programs like Digital Fusion, After Effects, Shake, etc. all have these tools built in. The idea of 24fps progressive SD material is really only in post production because a standard SD monitor would not understand or playback this material and no interface card or deck would play it direct without a interlace and 3;2 pulldown introduction.

 

Enter HD..... When HD was first introduced by NHK it was in a 1035i analog form but that did not last long (I believe that the US required a digital HD broadcast standard) and of course computers were getting faster and faster.. so now we have a whole bunch of HD fromats based on either 1080 or 720 lines and in 24, 25, and 30 fps both progressive and interlaced I think HDCAM and D5 were the first two formats to offer 24p recording to tape.

 

With all of the digital standards and post production manipulations available and the growth of a wide range of HD codecs the lines have blurred considerably. I know that you wanted to make a 24p SD DVD I know that this is supported in newer players (not sure about full backwards compatibility with older players) I would say that even if you could get a 24P SD recording on disk a real time de-interlacing "box" would be less than ideal and even the newest telecine like a Cintel DSX or Spirit 4K (both of which work from SD to HD or 2K or 4K data) would be outputting old interlaced SD when run in Ntsc or Pal...Doing a pulldown removal and then a De-Interlacing in Shake or After Effects will get you the best possible result for a 24p dvd it may just take an overnight render...

 

Hope this helps and I think this long winded post is technically accurate... :rolleyes:

 

-Rob-

[adam berk]

Rob, the method you described for removing pulldown doesn't sound right. "Removing pulldown" is usually a single step process and should not require a 2nd pass through a de-interlacing facility like Shake may offer.

 

The Cinema Tools application that comes with all the recent versions of Final Cut Pro is a fairly easy and reliable way of removing standard 3:2 pulldown from 29.97 telecine material.

 

I don't have the application in front of me right now, but I can give you the basic steps for using it to remove pulldown.

 

The process is as follows:

 

1. Open the clip in Cinema Tools

 

2. Step through the frames with the left and right arrow key until you find the first full group of 3 clean + 2 jitter frames.

 

3. Park the playhead on the first of those 2 jitter frames.

 

4. Step back two frames (the 2nd clean frame of the 3:2 sequence).

 

5. Hit the inverse telecine button.....leave all options @ their default

 

 

 

This method only works for normal(telecine) pulldown material, not the panasonic "advanced" pulldown.

 

 

Conrad, if you don't have access to Cinema Tools, I know of lots of other tricks to get that pulldown removed reliably.

[Robert Houllahan]

Rob, the method you described for removing pulldown doesn't sound right. "Removing pulldown" is usually a single step process and should not require a 2nd pass through a de-interlacing facility like Shake may offer.

 

The Cinema Tools application that comes with all the recent versions of Final Cut Pro is a fairly easy and reliable way of removing standard 3:2 pulldown from 29.97 telecine material.

 

 

 

 

This method only works for normal(telecine) pulldown material, not the panasonic "advanced" pulldown.

 

 

I believe that just removing the 3:2 pulldown does not make the result truly progressive but does make it 24fps, you can step through a fcp timeline setup for 24fps pulldown removed video without seeing the telltale 3:2 cadence but it's still interlaced.

 

I think , I could be wrong it's happened once or twice before.... :rolleyes:

 

-Rob-

[adam berk]

I believe that just removing the 3:2 pulldown does not make the result truly progressive but does make it 24fps, you can step through a fcp timeline setup for 24fps pulldown removed video without seeing the telltale 3:2 cadence but it's still interlaced.

 

I think , I could be wrong it's happened once or twice before.... :rolleyes:

 

-Rob-

 

 

Removing the pulldown through proper utilities does indeed leave you with 24 progressive frames per second.

[Robert Houllahan]

Removing the pulldown through proper utilities does indeed leave you with 24 progressive frames per second.

 

 

I have asked around on the TIG and it seems I am wrong, :o and that doing a 3:2 removal does leave you with 24PsF frames like a F900 I believe..but doing the pulldown removal in post using cinema tools is the best way as I and others have run into issues with using the realtime on card inverse telecine as it does not always get the cadence right and leaves interlace artifacts sometimes....

 

 

-Rob-

[Conrad Yoder]

Thanks for all the info guys - really helpful. I own both FCS 5.1 and AE CS3 Pro (a nice benefit of having worked in Silicon Valley). So is there any consensus on whether After Effects is better/worse than Cinema Tools for pulldown removal? If I use After Effects there are a few settings I need: is the upper or lower field first? What is the phase of the pulldown - options are WSSWW, SSWWW, SWWWS, WWWSS or WWSSW. And should I change the pixel aspect ratio here from square to anamorphic or do that at a later stage? Thanks again for the input.

[Thomas Worth]

All of this pulldown nonsense is a complete waste of time, guys. All you have to do is run the telecine at 30fps and transfer the frames 1:1. So, you'll end up a 29.97fps product that if PLAYED at 29.97 would be slightly sped up. But nobody's going to do that -- you only need a way to get it into FCP. You can easily take the QuickTimes and conform them to 24fps before importing them. Plus, you can do this without any recompression if you happened to transfer to a compressed format.

 

This way you get a TRUE 24p version of the footage without having to do any reverse telecine.

 

The only caveat to this method is that if you are syncing the audio during transfer (which is a complete waste of money), it will not sync.

[Conrad Yoder]

All you have to do is run the telecine at 30fps and transfer the frames 1:1.

It seems to me that if the transfer device could do this, then it could also be set to run at 24fps and transfer the frames 1:1, which is what I was originally envisioning. Sounds like this isn't possible. But I would be interested in hearing the mechanics of the transfer machine, if Rob hasn't tired of my questions yet.

Edited November 8, 2007 by Conrad Yoder

[Thomas Worth]

It seems to me that if the transfer device could do this, then it could also be set to run at 24fps and transfer the frames 1:1, which is what I was originally envisioning. Sounds like this isn't possible. But I would be interested in hearing the mechanics of the transfer machine, if Rob hasn't tired of my questions yet.

It CAN do this. The telecine can run at any frame rate you want. The problem is with the DECK, or whatever is being recorded to. If it's an NTSC deck, it will only accept an NTSC signal, which is invariably 29.97fps. So it doesn't matter whether the telecine can run at 24fps or not, because the deck can only record at 29.97fps. The standard method of transferring 24fps material to NTSC is by using 3:2 pulldown. This is a bad leftover from prehistoric times (i.e. before NLEs). Nowadays, it's not necessary to use pulldown at all during transfer, unless it is absolutely necessary to have sound synced during transfer. You can easily use Cinema Tools or something similar to conform the files to 24p, without having to perform an inverse pulldown.

 

I've done this a thousand times. It works, and as far as I'm concerned it's the best, highest quality way to transfer SD material. Any competent colorist should be familiar with this technique, and any competent editor should know how to deal with footage transferred this way.

[Robert Houllahan]

It seems to me that if the transfer device could do this, then it could also be set to run at 24fps and transfer the frames 1:1, which is what I was originally envisioning. Sounds like this isn't possible. But I would be interested in hearing the mechanics of the transfer machine, if Rob hasn't tired of my questions yet.

 

 

All proper telecine suites are capable of transfering film at just about any frame rate from 1fps to 40 fps and 30fps is no problem, actually it would be 29.97 run speed on the film to 29.97 run on the G5 or Deck so 1:1 is possible and easy to do. To make it 24fps you can then do a speed change in FCP.

 

 

Rob "tireless answerer of questions and occasionally technically ignorant" Houllahan

[Walter Graff]

Also it was Panasonic that introduced the first 1125 HDTV in 1974 seven years before NHK's MUSE analog transmission system that was also 1125(1035 visible). But if you really want to go back further some would argue that the French 755i system in 1948 beat them all. But history usually gives the invention of higher than 500 line systems to the Japanese and the successful implementation of HD to the US, which in simplest terms was not for anything other than fear that the government would give away spectrum (already had done that and was planning to give away more) and stations thought that would drive people to cable. And if you look on Mark Schubin's site you might find his old article about how HD was invented before 1948 depending on what you call HD and how you define it.

[Robert Houllahan]

Also it was Panasonic that introduced the first 1125 HDTV in 1974 seven years before NHK's MUSE analog transmission system that was also 1125(1035 visible).

 

 

I was 1 :blink:

 

I did see that NHK system at CineGear in NYC back in the day, it was some 16mm xfered to analog HD I thought it looked great.

 

Did not know (other than vaguely) about the 1948 7551 system....

 

-Rob0

[John Sprung]

But if you really want to go back further some would argue that the French 755i system in 1948 beat them all.

Here's some examples from that system. It appears to have been 819 total/755 active:

 

http://www.vintage-radio.net/forum/showthr...hlight=819+line

 

 

 

 

-- J.S.

[Charles Haine]

Anyone know if it would be possible to AUTOMATE the 24fps conform of 29.97 material?

 

I only ask since I am running a telecine which will be making files straight into a MacPro on a regular basis (all day, every day), and I would love to automate the process, to save the telecine operator a step.

 

thanks,

Charles Haine

[Michael Most]

Anyone know if it would be possible to AUTOMATE the 24fps conform of 29.97 material?

 

I only ask since I am running a telecine which will be making files straight into a MacPro on a regular basis (all day, every day), and I would love to automate the process, to save the telecine operator a step.

 

If you have time code coming out of the telecine room, and can insert VITC into the SD video stream, any Aja or Blackmagic card will remove the 3:2 pulldown based on the now-standard convention of "A" frames on time codes ending in 0 and 5.

 

However, the highest quality and simplest way to do this is to run the telecine in 1080/24p HD. Send it to a Mac with a Kona 3 card and let it do the downconversion and write to the disk array using whatever codec the client requests. That eliminates any frame rate changes completely, and gives you some quality advantages by using an HD source.

 

Of course, you haven't said how you plan to control the Mac, and since there's no VTR emulation software available to facilitate that, you might have some issues.

[Michael Most]

All of this pulldown nonsense is a complete waste of time, guys. All you have to do is run the telecine at 30fps and transfer the frames 1:1. So, you'll end up a 29.97fps product that if PLAYED at 29.97 would be slightly sped up. But nobody's going to do that -- you only need a way to get it into FCP. You can easily take the QuickTimes and conform them to 24fps before importing them. Plus, you can do this without any recompression if you happened to transfer to a compressed format.

 

This way you get a TRUE 24p version of the footage without having to do any reverse telecine.

 

The only caveat to this method is that if you are syncing the audio during transfer (which is a complete waste of money), it will not sync.

 

The additional caveat is that time code becomes useless. Of course, if you never plan on going back for a retransfer, or doing an online conform, I guess that's not a limitation. There is also the additional issue of image quality if you happen to be using a Cintel telecine - which you just might be doing if you're trying to transfer to standard def and do it cheap. Flying spot telecines are quieter and have generally better performance at 24fps than they do at 30. This is less of an issue with the newer machines, such as the Ursa Diamond and Y-Front models, and something of a non-issue with CCD telecines like the Spirit and Shadow.