Confused about 24p

Peter Moretti · July 26th, 2007, 02:21 PM

Quote:

Originally Posted by David Newman

...
Yes you can deinterlace 60i material to make it 24p using NEO HD. When you removal pulldown form 24p sources like the HV20, no vertical resolution is lost. When you deinterlace 60i source, the resolution drops about 30% vertically, not in half like some dinterlacers. So you should get a reasonable mix between the FX1 and the HV20.
...

David, I imagine shooting the HV20 at 24p and removing the pulldown will yield a better picture than shooting the HV20 at 60i and deinterlcaing to 24p.

Do you feel that is correct?

Thanks!

David Newman · July 26th, 2007, 03:58 PM

Quote:

Originally Posted by Peter Moretti

David, I imagine shooting the HV20 at 24p and removing the pulldown will yield a better picture than shooting the HV20 at 60i and deinterlcaing to 24p.

Do you feel that is correct?

Thanks!

Yes, many times better to shoot 24p than 60i.

Paul V Doherty · July 26th, 2007, 04:19 PM

The author of this thread clearly does not understand the industry-standard practise of embedding progressive material in an interlaced stream by using Progressive Segmented Frames (PsF).

The HV20 records true 24p material from the camera head into a 60i stream by implementing the 60 year old technique of 2:3 pulldown and embedding PsF in the 60i stream. This is the EXACT same recording process as used in the HIGHEST-end HDCAMSR cameras and no-one but the author of this thread would try to make the futile argument that those camera are not 24p either.
The author of this thread loses all credibility by the aggressive and ignorant nature of his approach, and his inability to comprehend basic concepts of decades-old telecine methods is simply mind boggling.

The HV20 contains an ingenious and economical true 24p camera head coupled with a robust and industry standard telecine engine to deliver the 24p material in a 60i HDV stream. Users who want true 24p performance can extract full HD 24p via HDMI from the HV20, or they can fork out 3 times the price for the A1.

Ian G. Thompson · July 26th, 2007, 05:46 PM

Quote:

Originally Posted by Joseph H. Moore

Interlacing is an NTSC hack whose time is up.

Not trying to go off topic (much) but this statement made me think. I don't own an LCD TV yet but with the airwaves going totally digital in a couple of years here it makes me wonder if the industry standards over this neck of the woods will change. There really does not seem to be a need for interlaced footage even now. I don't kow if it has anything to do with going fully digital but i ask because that will certainly affect the way manufacturers make their cams.

Nathan Shane · July 26th, 2007, 06:22 PM

Quote:

Originally Posted by Joseph H. Moore

1) HD can't undo 100 years of ingrained perception overnight. 24p/48th sec. motion rendering just feels "cinematic."

Joseph, I was wondering if you could elaborate on this more technically. I guess what I'm asking is how is most HD content being captured these days? What kind of gear and frame rates? Is most of it it all done fully digital?

I love the look of HD compared to SD and also compared to most movies - but that's because I really like seeing the sharp details you see in the footage. And not all HD shows being broadcast have the sharp image details, some widescreen HD broadcasts appear as though they are better than SD but far less than the HD you see in other shows. Even within the same shows you can see when they make use of SD footage (most often a clip from the recent past).

To me, HD initially seems like a medium for documentaries - but as you've rightly said, the public has a "specific image perception" ingrained and that's why HD captures people visual attention, because IT LOOKS NEW. But many years from now it will all look normal and typical.

Joseph H. Moore · July 26th, 2007, 07:44 PM

Nathan,
Not only does HD offer a big jump in spacial resolution from standard definition, but it offers a big jump in *temporal* resolution from film. 60 FPS is a lot more visual information per second than 24, so it's much smoother and more lifelike. For content like nature documentaries, that temporal resolution really helps sell the image as "real." But for some uses, it's too real.

Huh? Explain?

Well, film, which has traditionally been a more narrative medium ... storytelling ... has always been at 24 FPS. That stacato motion is one of several cues (motion blur, controlled depth of field, etc.) from film that tell our brains "sit back, enjoy, this is fine storytelling, this isn't real, this is something different."

That's why you'll find HD dramas and comedies, etc. on network TV shooting at 24p, but HD sports and a specials about sharks shooting at 60i/p.

Peter Moretti · July 27th, 2007, 03:55 AM

Quote:

Originally Posted by David Newman

Yes, many times better to shoot 24p than 60i.

And how about with the Sony HDR-FX1? Would recommend shooting in CineFrame (Sony's verson of 24p simulation) and running the footage through Cinefom? Thanks A LOT!

David Newman · July 27th, 2007, 09:06 AM

Quote:

Originally Posted by Peter Moretti

And how about with the Sony HDR-FX1? Would recommend shooting in CineFrame (Sony's verson of 24p simulation) and running the footage through Cinefom? Thanks A LOT!

I that is less obvious, we do remove pulldown for Sony CineFrame 24, but you get more resolution using 60i and converting that to 24p.

Try it out and see which mode you prefer -- all our software has a 15-day trial.

Matt Buys · July 27th, 2007, 10:24 AM

Mr. Newman, using neo, is my HV20 footage going to have more resolution if I shoot in 60i and then convert to 24p? than if I shot in 24p and then did the pulldown and kept it at 24P?

David Newman · July 27th, 2007, 10:37 AM

The reverse is true. Shoot 24p.

Matt Buys · July 27th, 2007, 01:03 PM

That's what I thought and then saw your post above. Just temporarily confused by the fact the sony process for the FX7 is different than the HV20's. Thanks for replying. BTW. Very impressed with the trial download of Neo. Thanks for allowing the trial over the net, I'll bet I'll be purchasing it in two weeks.

Robert Ducon · August 28th, 2007, 02:51 PM

Hi all. I've shot scenes with a 35mm adapter and an HV20 in 24P mode (which records 24P in a 60i stream in HDV). Then I've imported into FCP6, rotated the image 180degrees (to get it upright) and then used the new Compressor to Reverse Telecine the footage to get it into 24P (Apple Prores 422). Looks great, except...

The Chroma lags behind the luma! Two frames it's correct (and on the luma) then the next two frames it lags behind the luma, then repeats. It's noticable when there's big movement with contrasting colours in the image (red really stands out).

It's not just every 4th frame - it's 2 'bad frames' frames every 2 good frames! About 12 frames every second are off ... i.e. half! 50%!

Did I miss a step, or is it just this bad?

David Newman · August 28th, 2007, 03:08 PM

24p from the HV20 is fine, the error always in the pulldown removal. Here is my blog entry on the subject : http://cineform.blogspot.com/2007/07...4p-or-not.html

You might try removing the pulldown before rotating the image, as a bad (frame based) rotate will mess with the field ordering.

Robert Ducon · August 28th, 2007, 03:39 PM

I think you're right - remove the pulldown, THEN rotate the image. *sigh* Because I use a 35mm adapter, that'll add a lot more time to my renders.. they'll take twice as long now. But hey, it's the price of a good value camera. Thanks David.

EIDT: Did a test - David's correct - when shooting 24P with the HV20, do not reverse telecine and flip in FCP6/Compressor in one step.. make it two steps (two full renders, unfortunately). Good news: more confident than ever in the HV20's 24P ability.

EDIT: I was off, again.. there was a filter that was messing the colour up - I was applying in the process to fix 4:2:0 to 4:2:2.. so, yes, the footage can be flipped and deinterlaced in one step, however, the G Film plugin has to be done after, in a second step. So it's even better than I thought!

David Newman · August 28th, 2007, 04:12 PM

Quote:

Originally Posted by Robert Ducon

EIDT: Did a test - David's correct - when shooting 24P with the HV20, do not reverse telecine and flip in FCP6/Compressor in one step.. make it two steps (two full renders, unfortunately). Good news: more confident than ever in the HV20's 24P ability.

If you have an Intel Mac, you could purchase NEO HD and run it under Boot Camp, it will flip the image, remove the pulldown, bump the image to 4:2:2, and encode to CineForm MOV which will work on a FCP6 timeline, all in one step (real-time during ingest.) :)

July 27th, 2007, 10:37 AM	#40
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	The reverse is true. Shoot 24p. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

August 28th, 2007, 02:51 PM	#42
Robert Ducon Major Player Join Date: Nov 2006 Location: Victoria BC Posts: 400	More than just Chroma crosstalk? 50% frames are off... Hi all. I've shot scenes with a 35mm adapter and an HV20 in 24P mode (which records 24P in a 60i stream in HDV). Then I've imported into FCP6, rotated the image 180degrees (to get it upright) and then used the new Compressor to Reverse Telecine the footage to get it into 24P (Apple Prores 422). Looks great, except... The Chroma lags behind the luma! Two frames it's correct (and on the luma) then the next two frames it lags behind the luma, then repeats. It's noticable when there's big movement with contrasting colours in the image (red really stands out). It's not just every 4th frame - it's 2 'bad frames' frames every 2 good frames! About 12 frames every second are off ... i.e. half! 50%! Did I miss a step, or is it just this bad? __________________ Mac + Canon HV20

August 28th, 2007, 03:08 PM	#43
David Newman CTO, CineForm Inc. Join Date: Jul 2003 Location: Cardiff-by-the-Sea, California Posts: 8,095	24p from the HV20 is fine, the error always in the pulldown removal. Here is my blog entry on the subject : http://cineform.blogspot.com/2007/07...4p-or-not.html You might try removing the pulldown before rotating the image, as a bad (frame based) rotate will mess with the field ordering. __________________ David Newman -- web: www.gopro.com blog: cineform.blogspot.com -- twitter: twitter.com/David_Newman

August 28th, 2007, 03:39 PM	#44
Robert Ducon Major Player Join Date: Nov 2006 Location: Victoria BC Posts: 400	I think you're right - remove the pulldown, THEN rotate the image. sigh Because I use a 35mm adapter, that'll add a lot more time to my renders.. they'll take twice as long now. But hey, it's the price of a good value camera. Thanks David. EIDT: Did a test - David's correct - when shooting 24P with the HV20, do not reverse telecine and flip in FCP6/Compressor in one step.. make it two steps (two full renders, unfortunately). Good news: more confident than ever in the HV20's 24P ability. EDIT: I was off, again.. there was a filter that was messing the colour up - I was applying in the process to fix 4:2:0 to 4:2:2.. so, yes, the footage can be flipped and deinterlaced in one step, however, the G Film plugin has to be done after, in a second step. So it's even better than I thought! __________________ Mac + Canon HV20 Last edited by Robert Ducon; August 28th, 2007 at 04:42 PM.

July 26th, 2007, 04:19 PM	#33
Paul V Doherty Regular Crew Join Date: Aug 2006 Location: USA Posts: 64	The author of this thread clearly does not understand the industry-standard practise of embedding progressive material in an interlaced stream by using Progressive Segmented Frames (PsF). The HV20 records true 24p material from the camera head into a 60i stream by implementing the 60 year old technique of 2:3 pulldown and embedding PsF in the 60i stream. This is the EXACT same recording process as used in the HIGHEST-end HDCAMSR cameras and no-one but the author of this thread would try to make the futile argument that those camera are not 24p either. The author of this thread loses all credibility by the aggressive and ignorant nature of his approach, and his inability to comprehend basic concepts of decades-old telecine methods is simply mind boggling. The HV20 contains an ingenious and economical true 24p camera head coupled with a robust and industry standard telecine engine to deliver the 24p material in a 60i HDV stream. Users who want true 24p performance can extract full HD 24p via HDMI from the HV20, or they can fork out 3 times the price for the A1.

July 26th, 2007, 07:44 PM	#36
Joseph H. Moore Major Player Join Date: Oct 2005 Posts: 362	Nathan, Not only does HD offer a big jump in spacial resolution from standard definition, but it offers a big jump in temporal resolution from film. 60 FPS is a lot more visual information per second than 24, so it's much smoother and more lifelike. For content like nature documentaries, that temporal resolution really helps sell the image as "real." But for some uses, it's too real. Huh? Explain? Well, film, which has traditionally been a more narrative medium ... storytelling ... has always been at 24 FPS. That stacato motion is one of several cues (motion blur, controlled depth of field, etc.) from film that tell our brains "sit back, enjoy, this is fine storytelling, this isn't real, this is something different." That's why you'll find HD dramas and comedies, etc. on network TV shooting at 24p, but HD sports and a specials about sharks shooting at 60i/p.

July 27th, 2007, 10:24 AM	#39
Matt Buys Major Player Join Date: Aug 2006 Location: Asheville NC Posts: 426	Mr. Newman, using neo, is my HV20 footage going to have more resolution if I shoot in 60i and then convert to 24p? than if I shot in 24p and then did the pulldown and kept it at 24P?

July 27th, 2007, 01:03 PM	#41
Matt Buys Major Player Join Date: Aug 2006 Location: Asheville NC Posts: 426	That's what I thought and then saw your post above. Just temporarily confused by the fact the sony process for the FX7 is different than the HV20's. Thanks for replying. BTW. Very impressed with the trial download of Neo. Thanks for allowing the trial over the net, I'll bet I'll be purchasing it in two weeks.