Pulldown - PAL to NTSC - DVSD

[Cunhambebe]

Hi there. I've recently downloaded a bunch of clips from the European Space Agengy.
http://www.spacetelescope.org/bin/videos.pl?viewtype=&searchtype=freesearch&string=15+...s+of+discovery
I' ve tried to open them with Vegas and then I knew they were PAL - and what I thought very strange; PAL dvsd (maybe a codec).
I was trying to pulldown from PAL to NTSC using Vegas' MC built-in and TMPGEnc (I've read a guide around here using TMPGEnc and DGPulldown).
To get what I wanted, I encoded the AVI to MPEG2 PAL 25, then dropped the file in TMPGEnc MPEG tools and de-multiplexed it to m2v (DGPulldown only accepts m2v - video stream). Finally, after all these steps I got (I guess) the NTSC.
Back to that site, I've learned the images are AVI - " Broadcast PAL: 720 x 576 pixels, Uncompressed AVI, Broadcast quality (CCIR 601 PAL). Zipped with Winzip. THIS FORMAT CAN BE IMPORTED BY ANY BROADCAST VIDEO EDITING SYSTEM AND EDITED."
http://www.spacetelescope.org/pressroom/video_formats.html
Question: Would there be any way to pulldown directly from AVI to AVI??? I mean, without all those steps (loss of quality) in Vegas and TMPGEnc?
Thanks in advance.

[bugster]

You could simply change the framerate from 25fps for PAL to 23.976fps for NTSC. This is the framerate used for NTSC film and the speed change is not noticeable to most viewers (audio pitch may change little though!) The problem then is the resolution. NTSC requires 720x480 but you have 720x576, so to make it NTSC compatible you need to either crop some lines off the top and bottom, or resize. Either of these will require you to re-encode.

[Abond]

Interesting what would be the purpose of pulldowning avi files?

[Cunhambebe]

Thanks for taking time to respond, folks...
bugster:
You could simply change the framerate from 25fps for PAL to 23.976fps for NTSC.
-please tell me how and with what tool?
-One more thing: I want to change it to DV which is 29.97....I wonder if 23.976 will show correctly as I render DV at 29.97...
Resizing from 720x576 t 720x480 may be easily done with Pan/Crop with Vegas.
Abond:
what would be the purpose of pulldowning avi files?
Burning and playing a DVD with NTSC compatible devides, what else?

[bugster]

You can change the framerate of an avi using avifrate or virtualdub. But if what you want to end up with is a DVD compliant mpeg, I don't see whats wrong with your current method.

BTW, with 23.976fps avi, when you encode to DVD compliant mpeg, you need to add 3:2 pulldown flags, and the source material should be progressive.

[Cunhambebe]

Thanks a lot for replying, bugster...

You can change the framerate of an avi using avifrate or virtualdub.

-I've already tried VD. It cannot open the file - don't know why (maybe becasue it's ab AVI dvsd- what a mess!)

But if what you want to end up with is a DVD compliant mpeg, I don't see whats wrong with your current method.

- OK....

BTW, with 23.976fps avi, when you encode to DVD compliant mpeg, you need to add 3:2 pulldown flags, and the source material should be progressive.

- What? Are yu kidding? lol I am not an advanced user as you are, so please, I beg you to make things easier - lol. No, really, I never understood why a 23.976 NTSC. I'm encoding NTSC DV at 29.97 so I guess this option (23.976) will not work here. BTW, (just curious) are all Hollywwod DVDs 29.97?
Thanks in advance.

[bugster]

BTW, with 23.976fps avi, when you encode to DVD compliant mpeg, you need to add 3:2 pulldown flags, and the source material should be progressive.

- What? Are yu kidding? lol I am not an advanced user as you are, so please, I beg you to make things easier - lol. No, really, I never understood why a 23.976 NTSC. I'm encoding NTSC DV at 29.97 so I guess this option (23.976) will not work here. BTW, (just curious) are all Hollywwod DVDs 29.97?
Thanks in advance.

Think about movies shot on Film. Film is 24fps. In order to display on an NTSC TV, it is slowed down (ever so slightly) to 23.976fps and 3:2 pulldown applied. Most movie DVD's are encoded like this. The mpeg encoder only encodes enough frames for 23.97fps play back. But flags are added to instruct the player to repeat certain fields such that the result is 29.97fps. 23.97fps is often referred to as NTSC film frame rate because of this.

So if you have a PAL avi and want to encode it to an NTSC DVD (and the avi is progressive, most are), the simplest way is to slow the avi down to playback at 23.97fps (you will need to lengthen the audio to match) and then add 3:2 pulldown when you encode to DVD. (Avi doesn't support pulldown AFAIK).

The slowdown from 25fps to 23.97fps is about 4% and is not noticeable to most people. The technique you are currently using with DGPulldown is similair, but it doesn't slow down the original video. It simply adds 'repeat this field' flags in a slightly different pattern to the normal NTSC 3:2 pulldown so that the final playback rate is 29.97fps.


Does this help?

BTW, when film is transferred to PAL, it is usually simply sped up from 24 to 25fps.

[Cunhambebe]

Does this help?
- A lot! Thank you very much for the detailed explanation (I've always known that movies were shot at 24 fps). What I still don't understand is that when I backup my DVDs with DVD Decrypter and DVD Shrink, they seem to deal with 29.97 (NTSC here). One more thing: When I encode my projects to MPEG2 with Vegas' MainConcept, Canopus Procoder or TMPGEnc why I have to select 29.97?????

just curious - Please think about this (all NTSC):

1.DVD>DVD Decrypt>VOB>De-Multiplex>m2v (is this 23.976?)>edit>back to MPEG2 at 29.97.....Does that work? I guess so.
or
2.DVD>AVI2DVD>AVI (is this 23.976?)>edit>encode it to MPEG2 at 29.97...Does it work this way, or before getting back to MPEG2 I'll have to pulldown from 23 something to 29.97 (if my final goal is DV)?
Thanks in advance.

[bugster]

What you get from a DVD source depends on how it was encoded. It may be 23.97fps with pulldown, it may be 29.97fps, or it may be a mixture.

Film tends to be 23.97fps, but if it includes scenes that are CGI, these are often 29.97fps. If it was shot on video (as many TV shows are) these tend to be 29.97fps too.

[Cunhambebe]

bugster:

It may be 23.97fps with pulldown, it may be 29.97fps, or it may be a mixture.

- now I'm sure you want to make me crazy- lol
Thanks a lot, bugster.

[darkskies]

What always confuses me is why in tmpg do we select 23.976 with 3:2 pulldown instead of just selecting the 29.97 fps.

Also what about these files that are like 15 or 14 fps what in the world are those pal?

[bugster]

What always confuses me is why in tmpg do we select 23.976 with 3:2 pulldown instead of just selecting the 29.97 fps.

If your source is 23.97fps and you select 29.97fps in TmpGenc, it will make up the difference by repeating enough frames per second (6) to make it up to 29.97fps. This will usually result in jerky playback due to the repeated frames. With 3:2 pulldown you are only encoding 23.976fps, same as the source file, so no frames should be repeated. Also, less frames means either less bitrate overall required, so a smaller file size, or more bitrate available to encode each frame, so higher quality (possibly). By adding the 3:2 pulldown flags, you tell your player to repeat certain fields. Not I say fields, not frames. By repeating fields in a certain pattern you can achieve 29.97fps output without the stutter associated with encoding at that framerate from a 23.97fps source in the 1st place. Of course if your source is 29.97fps, encode with that framerate.

Also what about these files that are like 15 or 14 fps what in the world are those pal?

They are not PAL or NTSC. They are low quality crap intended for PC playback only.

[Cunhambebe]

Now please think about a timeline. It's a DV project to be rendered as NTSC at 29.97. Some video sources are 23.97, others 29.97. I was just wondering how to render the whole thig as 29.97. Please, should I pulldown those 23.97 to 29.97 or....or what? Can someone please explain that?
Thanks in advance.

[darkskies]

Now please think about a timeline. It's a DV project to be rendered as NTSC at 29.97. Some video sources are 23.97, others 29.97. I was just wondering how to render the whole thig as 29.97. Please, should I pulldown those 23.97 to 29.97 or....or what? Can someone please explain that?
Thanks in advance.

I would assume to leave the files that are 29.97 alone and just do the 3:2 pulldown on the 23.97 files (29.97 internally).

[darkskies]

What always confuses me is why in tmpg do we select 23.976 with 3:2 pulldown instead of just selecting the 29.97 fps.

If your source is 23.97fps and you select 29.97fps in TmpGenc, it will make up the difference by repeating enough frames per second (6) to make it up to 29.97fps. This will usually result in jerky playback due to the repeated frames. With 3:2 pulldown you are only encoding 23.976fps, same as the source file, so no frames should be repeated. Also, less frames means either less bitrate overall required, so a smaller file size, or more bitrate available to encode each frame, so higher quality (possibly). By adding the 3:2 pulldown flags, you tell your player to repeat certain fields. Not I say fields, not frames. By repeating fields in a certain pattern you can achieve 29.97fps output without the stutter associated with encoding at that framerate from a 23.97fps source in the 1st place. Of course if your source is 29.97fps, encode with that framerate.

Also what about these files that are like 15 or 14 fps what in the world are those pal?

They are not PAL or NTSC. They are low quality crap intended for PC playback only.

Actually the source i was talking about would be 25 pal

[Cunhambebe]

darkskies:
I would assume to leave the files that are 29.97 alone and just do the 3:2 pulldown on the 23.97 files (29.97 internally).Can you please tell me how? How about Vegas? Vegas has a feature that lets you choose resample, smart resample or force resample.