PAL 50000 to NTSC 24

[Cunhambebe]

Hi there, I don't know if this subject has been covered before - I couldn't find it using "search" - but I'm trying to go from PAL interlaced 50000 (HD video) to NTSC 24 (rendered in HC Encoder as 23,976 - pulldown 3:2). I have downloaded a video file at www.spacetelescope.org (totally legal for personnal use); the file is PAL HD in a m2t container, interlaced at 50000 (no lines there). In fact, I am in a NTSC land for DVD and the best I could find to do the trick were the following scripts:

1)# script named "hubble.36.avs"
LoadPlugin("C:\unzipped\dgmpgdec158\DGDecode.dll")
MPEG2Source("C:\hubble_36.d2v")
FDecimate(rate=25.000,threshold=1.0,show=false)
Lanczos4Resize(720,480)

2) #serving the script above into the following one:
AVISource("C:\hubble.36.avs")
AssumeFPS(24000,1001)

For the audio I used BeSweet to go from 25 to 23,976. The outcome is acceptable, it seemed to work. But I'm wondering if there's something faster and more direct than using those 2 "tango" scripts for the video.

Thanks in advance.

[Guest]

What does the 50000 refer to? I am unfamiliar with the term "PAL 50000".

Please give the specific link to download the video so we can look at it.

[Cunhambebe]

Thanks so much for taking time to respond. Here is the link:

http://www.spacetelescope.org/videos/heic1007a/

Sorry about putting this way: PAL 50000. In fact DGIndex says Frame Rate: 50,000000. I could speed up the whole thing to 60,000000 but the outcome is a little faster, anyone can notice it easily. DGIndex says also that is interlaced but that's the way HD video is, they duplicate frames, that's all (originally it must be 25 fps). Thanks in advance ;-)

PS: I've downloaded the file HD 720 (broadcast) 1.4 GB.

[Guest]

I guess you mean 50 fps.

But 720 broadcast HD is progressive yet you say it is interlaced.

I will download it and then advise you because your reporting appears unreliable.

One point now: You don't need FDecimate to go from 50 -> 25 fps. Just use SelectEven().

Please clarify what your target format is. You ask for 24 fps and then say you want pulldown. Are you making an NTSC DVD or what?

[Guest]

That video is normal 720P at 50fps. It is not interlaced and it does not have duplicated frames.

Re-reading your post I see you want an NTSC DVD. One way is to do SelectEven() to bring it to 25fps. Then encode
as 720x480 at 25fps followed by DGPulldown with 25->29.97 mode. That way, you do not need to alter the audio.

You can also interlace it if you prefer to keep full temporal resolution.

[Cunhambebe]

Thanks again for taking time to respond. First of all I'd like to apologize for not being so clear on my topic. BTW, that was DGIndex that said the video was interlaced (Honor Pulldown Flags Mode). As you may have noticed, I am from Brazil and here Public TV is PAL-M (same as NTSC but featuring a PAL color carrier; same NTSC screen size and frame rate though - 29,97 or 23,976), but on the other hand, all DVDs are NTSC since all TVs have both systems nowadays. That's why I must render the video as NTSC.

Thanks for your tutorial on how to do the conversion. I assume, as a newbie that I just have to add SelectEven() to the script to bring the video to 25 fps. I had read about DGPulldown, so I guess I must learn a bit more on how to use it. Thanks and I'll reply as soon as I get the final result here.

Cheers,
Mark

[2Bdecided]

NASA providing "PAL" (50fps) videos - strange!

I'm still downloading it, but it sounds like you need a typical 50>60 conversion to maintain the smooth movement. That's the most difficult kind of conversion - you need to use motion compensated frame rate conversion to achieve it smoothly. e.g. see the Alchemist thread from a couple of years back.

Dropping every other frame (to get 25fps), and then slowing down to 24/1.001 to get NTSC compatible frame rate is far easier, but the footage will be more stuttery than the original. (and slightly slower of course!).

Cheers,
David.

[Cunhambebe]

Hi David, thanks for taking time to respond. In fact, Neuron2's got it right. The way he's explained (PAL 50/25 to NTSC using pulldown) it is by far the easiest one, with the following advantage: there's no need to resample the audio file (no need to adjust anything at all). Same thing, I suppose, if we were talking about a VOB file with subtitles. What I was doing was just slowing down the video to 24 FPS in order to render in HC encoder checking the pulldown box there; but I still had to adjust the audio using BeSweet (25 to 23,976). The outcome is known: the video and audio are slightly slower than the original file. What I just did a couple of hours ago was to go from PAL 25 to NTSC 29,97 (using pulldown flags) and keeping the original audio file. That was great and worked perfectly with my authoring application (for NTSC DVDs). BTW, these videos are produced in Germany by the European Space Agency and not only NASA as you have remarked.

There's just one thing I did not understand: Neuron2 has said that I could interlace the whole thing to keep full temporal resolution. As fas as I know temporal resolution is in the realm of "fields" for HD video. There is a fair explanation here at:

http://www.highdefinitionblog.com/?page_id=237

That'd be great to learn more about this and the advantages to interlace the video to keep "temporal resolution" :rolleyes:

Thanks again, Neuron.

Cheers,
Mark

[Cunhambebe]

As Neuron have remarked: "One way is to do SelectEven() to bring it to 25fps. Then encode as 720x480 at 25fps followed by DGPulldown with 25->29.97 mode. That way, you do not need to alter the audio."

:mad: Now I see there's still a problem with the audio (out of sync). When you finish rendering the file using HC encoder and AviSynth, yo've got a PAL file with a DAR of 720x480. Here the audio works fine, but when you drag and dropp the file in DGPulldown, the new file is 23,976 as anyone can check it out using GSpot. Then, the problem begins: the audio is out of sync. You'll have to use BeSweet to fix the audio file (25->23,976 - it will be slower than the original file).

So Neuron, are you sure I can keep the audio as you had remarked? Thanks in advance.

[Guest]

You must be doing something wrong.

You encode with HC at 25fps. You open that with DGPulldown and do 25->29.97. The audio will remain in sync. This process is well proven and often used by many.

I suspect you have actually encoded it at 23.976 in HC because you left DVD compliance enabled.

Regarding the interlaced way, that is basically what 2Bdecided was talking about. You've said that does not interest you so I won't elaborate further.

[Cunhambebe]

Hi Neuron,
In fact I rendered the file as PAL 25 FPS, autogop box was checked, there was the figure 15 (GOP lenght valid for PAL, 29.97 NTSC,not for pulldown) that I changed to 12 as I have read that this would make the file more appropriate for DGPulldown. Now I am leaving the autogop at 15 and the application is showing a warning sign: resolution and framerate don't match. Rendering is in progress, let's see what happens. One more thing: we could blame the the authoring application, but I doubt it.

About what 2bDecided said: yes, I am interested. I would like to get a link to that thread if possible. Thanks in advance.

PS: I am not encoding audio + video, just the video file.

[2Bdecided]

That video is normal 720P at 50fps. It is not interlaced and it does not have duplicated frames.At the risk of teaching my grandmother to suck eggs, it certainly does have duplicate frames!

The master is clearly 25p. The 720p50 version simply has each and every frame twice. selectevery(2,0) doesn't lose anything at all.

There's no point at all in trying to preserve the full 50fps smooth motion, because there isn't any in the source. So forget about what I said earlier in the thread - it's not needed here.

(btw, the SD broadcast version available for download (in DV format) is also 25p, not native 50i).


Obviously DGpulldown does work as advertised (not sure what's going wrong for you Cunhambebe), but if you have a modern DVD player and/or TV that can recover 24p properly and display progressive frames, I'd re-encode the audio 4% slower and do a proper 24p encode.

AFAIK no modern TV (or DVD player) can unpick the 25p-in-60i which DGpulldown produces (please correct me if I'm wrong), and so will drop back to interlaced (bobbing) mode - that's a fairly nasty thing to do on such lovely images. It is the images that matter here - far more than the audio in this particular content - so change the audio in order to preserve the images at their best!

If you're going to watch it on an interlaced CRT, it doesn't matter either way, though 24p-in-60i may look slightly smoother than 25p-in-60i.

Cheers,
David.

[Cunhambebe]

Hi David. Thanks for taking time to respond.
At the risk of teaching my grandmother to suck eggs, it certainly does have duplicate frames!
The master is clearly 25p. The 720p50 version simply has each and every frame twice. selectevery(2,0) doesn't lose anything at all.


-LOL - I agree here. The HD file does have duplicate frames as you have stated right above. In fact the problem was that I was loading it in the authoring application (on old version of DVD Architect - 4.0b) the *.m2v file. As soon as I multiplexed the video file (no audio) before dropping it there, it worked great (audio and video matched perfectly). The same process would work if one encoded the video at 24 using AssumeFPS (24000, 1001) using BeSweet to slow down the audio. Thank you very much David. Those images, as you've noticed, are great and the videos are free for personal use. Thanks again and greetings from Brazil :)

[Guest]

At the risk of teaching my grandmother to suck eggs, it certainly does have duplicate frames! I won't argue with you, but the video I downloaded does not have duplicates. I open it in DGIndexNV and enable full size display, then go to single step mode. Every frame step produces a new frame.

[2Bdecided]

I downloaded the "720p broadcast" file.
It's a zip containing an m2t file containing a 1280x720p50 video.
I used DGindex to create a d2v.
It warns about field order reversal somewhere in the clip(!) but I didn't fix it.
I used the simple 1-line avisynth script mpeg2source("filename.d2v") and dropped this into VirtualDub. It recognises it correctly as a 12 minute 1280x720p50 video.

I couldn't find any sequence in the file with true 50fps motion. The titles, image pans+zooms, presenter, CGI studio, and even the advert on the end, are all 25p-in-50p, i.e. all duplicate frames.

Assuming you downloaded the same file, I'm sure you're in a far better position than me to figure out why DGIndexNV hide the duplicates from you.

Cheers,
David.

[Guest]

I'll check again when I get home.

[Guest]

Mystery solved! Actually we are both right. There are no encoded duplicates but there are displayed duplicates.

The duplicates are done with soft frame repeat flags. I didn't notice the Frame Repeats field incrementing in the DGIndexNV Info dialog until I looked again just now.

So you can simply use Ignore Pulldown in DGIndex and not have to decimate in your script.

Given that the temporal resolution is 25 fps progressive, the re-interlacing idea is inapplicable. You either use DGPulldown or some kind of frame interpolation.

[2Bdecided]

Given that the temporal resolution is 25 fps progressive, the re-interlacing idea is inapplicable. You either use DGPulldown or some kind of frame interpolation....or 23.976! ;)

Cheers,
David.

[Guest]

Missed your point. Care to explain it?

[2Bdecided]

Missed your point. Care to explain it?

I meant...

...if you have a modern DVD player and/or TV that can recover 24p properly and display progressive frames, I'd re-encode the audio 4% slower and do a proper 24p encode.

AFAIK no modern TV (or DVD player) can unpick the 25p-in-60i which DGpulldown produces (please correct me if I'm wrong), and so will drop back to interlaced (bobbing) mode - that's a fairly nasty thing to do on such lovely images. It is the images that matter here - far more than the audio in this particular content - so change the audio in order to preserve the images at their best!

If you're going to watch it on an interlaced CRT, it doesn't matter either way, though 24p-in-60i may look slightly smoother than 25p-in-60i.

Cheers,
David.

[Guest]

Still don't get your point, but never mind.

[manono]

please correct me if I'm wrong
OK, you're wrong. It's been encoded as progressive. The cheapest flag reading DVD player will pull out the progressive frames for output. No deinterlacing. Better cadence players will do the same. Heck, open a 25->29.97fps M2V in VDubMod and you don't even see any interlacing. It has no trouble finding the progressive frames. Returning the progressive non-deinterlaced frames is the easiest thing in the world.
...though 24p-in-60i may look slightly smoother than 25p-in-60i.
If it looks smoother it's only because we're more used to 3:2 pulldown, instead of 3:2:3:3:2. It's just a different kind of jerkiness. As far as that goes, neither bothers me at all, although more sensitive PAL people might be bothered by both. And you'll get the same effect with a progressive display, just with frames being played at 59.94fps, rather than the fields of a CRT.

I'm not arguing against slowing it to 23.976fps. I usually do that myself, if only to get rid of the higher pitched and out-of-tune audio

[2Bdecided]

If it looks smoother it's only because we're more used to 3:2 pulldown, instead of 3:2:3:3:2. It's just a different kind of jerkiness. As far as that goes, neither bothers me at all, although more sensitive PAL people might be bothered by both.As a "PAL person", I find 3:2 an abomination, and 3:2:3:3:2 looks even worse - but I accept it's all subjective.

I believe what you say about all players finding the progressive frames.

So the "only" thing 25p-in-60i will break is TVs that do 24p detection and each frame the same number of times (i.e. display it at a multiple of 24fps) to avoid judder. On such Tvs, 25p-in-60i will have far more judder than 24p. It might not bother you, but then again, people who made the effort to find such a TV might find it quite annoying.

FWIW some TVs which re-create smooth video motion from film via frame interpolation (e.g. those from Philips) can lock on to the most bizarre pulldown patterns, so they might still work.

I'm not arguing against slowing it to 23.976fps. I usually do that myself, if only to get rid of the higher pitched and out-of-tune audioThis original is native 25p. The audio is already the correct pitch. 24p will make it too low/slow.

Cheers,
David.

[manono]

This original is native 25p. The audio is already the correct pitch. 24p will make it too low/slow.
You're right. Sorry. I came to this thread late in the game and either didn't read or read and promptly forgot that the source was true 25fps. My main purpose was to defend DGPulldown which, for me, has been a godsend for PAL2NTSC projects, field-blended PAL2NTSC stuff, and for silent films at unusual framerates. For encoder efficiency it allows progressive encoding of material that has traditionally been encoded as interlaced.
So the "only" thing 25p-in-60i will break is TVs that do 24p detection and each frame the same number of times (i.e. display it at a multiple of 24fps) to avoid judder. On such Tvs, 25p-in-60i will have far more judder than 24p. It might not bother you, but then again, people who made the effort to find such a TV might find it quite annoying.
Yes, I agree. There are the 72Hz sets, and also the 120Hz or 240Hz ones, and they'll leave PAL 25fps stuff playing jerky. But the same will happen with NTSC stuff on PAL systems with 100 or 200 Hz TV sets.

[2Bdecided]

But the same will happen with NTSC stuff on PAL systems with 100 or 200 Hz TV sets.Maybe. Many modern displays over here support 24p properly because of BluRay, so I think at least some recover it from 60fps properly.

Cheers,
David.