Confused about 24p

[Joseph H. Moore]

The camera encodes the 24p sequence into a 60i data stream ... an incredibly common practice. Are you trying to claim that any method that uses reverse telecine is not 24p?

I undertstand your frustration that there are some undesirable artifacts, but the manner in which you are presenting your argument makes it difficult to see past your "sky-is-falling" tone.

P.S. I've seen some very clean keys from the HV20 when a good chroma smoothing filter was used first (Nattress, etc.)

[Ian G. Thompson]

Besides the flags....It's no different from the DVX in how it implements 24P.... so what's the problem. How is it not real????.....then you are saying the DVX is a fake. Also the Hollywood movies you watch on DVD must also be fake.

[David Ridlen]

Originally Posted by Joseph H. Moore

The camera encodes the 24p sequence into a 60i data stream ... an incredibly common practice. Are you trying to claim that any method that uses reverse telecine is not 24p?

I'll try to make this as clear as possible. 60i is not 24p. 'i' is for interlacing, 'p' is for progressive, meaning no interlacing. 'Progressive' and 'interlacing' do not exist simultaneously within the same signal. The HV20 either records with 2:3 interlacing, which is in no way 24 progressive, or it records 24 progressive, which is in no way interlaced. It does not somehow simultaneously record both progressive and interlaced contained in one magic signal. Sort of like how a specific volume of water may exist as liquid, solid ice, or a gas and may be converted from one to the other. But the water does not exist as all three simultaneously. The same applies to how dvds are burned. But there seems to be an odd interpretation that there is a 24p signal somehow simultaneously mixed in along side the interlaced signal (?). The signal exists only as one or the other at any given moment. Canon support, the HV20 spec sheet, Cineform and elsewhere in this forum clearly explain how the HV20 records only with interlacing, not progressively. The Hv20 does not record 24 progressive, and it does not playback 24 progressive. It only records and plays back with interlacing.

Curiously, what Canon's site and pro reviewers fail to mention is that you will have to own or buy a separate, third party piece of hardware/software to interpret the 24p out of the HV20 since it does not independently record or playback 24p on it's own. I equate this with an 'HD ready' TV which is capable of dealing with HD television, but you have to purchase a separate HD tuner to interpret the HD signal. I consider the HV20 '24p ready' but not 24p on its own since it requires more parts to deliver 24p.

Most of us are prepared to overlook this situation given the relatively simple conversion process provided by Cineform, Black Magic and the like. But everything I capture, and convert to 24p is playing back strobey because of another unmentioned problem with every 4th frame hanging onto the interlacing. What frustrates me is that Canon support entirely denies the problem. They blame Cineform, or whatever app you use to convert to 24p as 'doing it wrong.' We all know that is not the case. The problem is in the HV20s recorded signal. And if every 4th frame still contains interlacing after proper 24p extraction, then it is not true progressive. The HV20 records interlaced, it plays interlaced, and it remains partially interlaced after the 24p conversion that everyone says is suppose to do the trick. So as a portable camcorder (for me, the whole reason for buying it), the HV20 is never true 24p.

You may only get 24p while capturing live, hooked to a computer with an HDMI capture card. Where is that explained by Canon?

You say, 'You get what you pay for?' Always with video gear. But that doesnt make the claims of 24p any less misleading by Canon.

[David Newman]

Ian,

The issue 4:2:0 encoding, DVX100 using 4:1:1 encoding which doesn't mix chroma encoding between scanlines.

Peter,

>Does Cineform NEO HD deinterlace 60i (I'll probably be using a combination of a Sony FX-1 and a Canon HV-20) to 24 progressive frames per second? And if so, how does it handle motion and how much vertical resolution is lost?

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 Ridlen,

You are complaining as much as you are because you are removing the pulldown incorrectly -- and that will look bad (not a camera fault.) The lumanence is completely separatable, yet you are showing images with luma crosstalk. You should not see any interlacing artifacts. The problem is only in chroma and that is much more subtle. So while you have been quoting me, you have miss-understood the issue. Yes there is a issue, but not what you are showing. Please send me a link to those M2T files and I will show you how they look when the pulldown is removed correctly.

[Joseph H. Moore]

David Ridlen,

Dude, brother, the more you try to "make it clear" the more you dance around a dead horse, and obfusicate the real issue.

The point is, the camera has a progressive sensor, it "captures" a true progressive frame, it just happens to encode those frames in a 60i stream in order to record them to tape.

Yes, yes, yes, you can encode a progressive frame inside of a sequence of interlaced fields, and then extract those frames back out.

Hell, one can encode a picture into an audio signal, or encode a recipe into a still photo ... IT'S DATA!

Just because current software makes it difficult to do, doesn't mean it can't be done. This morning, I used both Compressor and JES Deinterlacer (free) to properly deinterlace. Sure I wish Canon had included flags and I didn't have to take an extra step, sure I hope FCP and other editors get smarter about injesting unflagged footage, but to imply that we're all suckers to Canon's misleading marketing is off mark.

[Ian G. Thompson]

Canon can make the claim that its progressive because it has a progressive sensor. It only lays it down on tape (like the DVX) with pulldown added. Since you used your own analogy I'll try my own. To me what you are stating is like saying, even though Hollywood movies are known to be shot at 24fps but telecined when put on DVD, that it's not real 24p. That does not make any sense to me. Canon can also make the claim that the cam shoots at 1920x1080 even though it lays it down to tape as 1440x1080. All they are doing is meeting industry standards when they implement these steps.

Do us a favor and show us an example of your intelaced fourth frame shot. (EDIT: Ok I took a look at your pictures on the first page...seems like you must be doing something wrong) I have stepped through, frame by frame, many of my reverse telecined footage and I witness no interlaced frames. The extra frames that were there at first (which caused the ghosting effect) were all gone. So I am confused by your statements.

This statement you make here is very funny:

Originally Posted by David Ridlen

I equate this with an 'HD ready' TV which is capable of dealing with HD television, but you have to purchase a separate HD tuner to interpret the HD signal. I consider the HV20 '24p ready' but not 24p on its own since it requires more parts to deliver 24p. .

You are contradicting your own previous statement.

Originally Posted by David Ridlen

'Progressive' and 'interlacing' do not exist simultaneously within the same signal. The HV20 either records with 2:3 interlacing, which is in no way 24 progressive, or it records 24 progressive, which is in no way interlaced. It does not somehow simultaneously record both progressive and interlaced contained in one magic signal. .

It might be true that it needs more parts to "deliver" the 24P footage but it's there...even in your own previous admission.

It's one thing to be upset about the 24p being wrapped in a 60i timeline but to say that it's not 24p is too much of a stretch and misleading to me.

[Ian G. Thompson]

I was really addressing the other David's original statement at the top of this thread about it not being real 24p. I think his issues are really with the HDV standard and how it's recorded to tape. I guess if we were talking about HDMI capture then the croma bleeding issue would be a different story (as you suggested earlier).

[Thomas Barthle Jr.]

I don't plan on making this lengthy, because I have better things to do, but there is nothing that uses magnetic tape as its medium that embeds a progressive image. IT IS IMPOSSIBLE due to the helical scan head. Look THAT on Wiki. The sensor, where it matters, is progressive. It processes in progressive, but records to tape in interlaced, THE ONLY WAY IT CAN! I love the image it produces and have not seen this problem when I reverse telecine. Even your images zoomed in and paused at one particular frame is hard to see, especially in the green and blue examples. All my distribution will be on DVD and viewed interlaced anyway. See Ya.

[Matt Buys]

Could the strobing David's talking about be exacerbated by not shooting in 1/48 or 1/24. Even though I just downloaded a trial version of Neo I'm getting some strobing and I'm worried it's because I did not set the camera up properly? Ie I was using a higher shutter speed. Or is there something I'm missing in regards to the pulldown with neo?

[Joseph H. Moore]

Getting the interlacing artifact on every x frame is not because of the shutter speed, but rather that the inverse telecine process is not detecting the proper "cadence" that the 24P frames have been encoded into. With HV20 clips, you never really know where the sequence starts unless you actually analyze the footage to determine the duplicates. My first attempt at de-interlacing was with a tool that expected the sequence of A-B frames a certain way, and it gave me the same nasty interlacing. Then I switched to a tool that actually analyzed the footage and than I got the expected clean results.

If you're capturing a bunch of takes as one big stream, then you need to be double sure that your tool looks for all of the breaks and cadence changes, not just the first. I got bit by this, too. My first clip looked great, but all of the rest had interlacing. I had to instruct the tool to look at the entire stream.

Now, as far as capturing a "look" to the motion that people will subliminally associate with film, yeah, then using a 1/48 shutter speed really does make a nice difference.

[Joe Busch]

Shoot 60i, Using motion bob convert to 60p



Why is everyone obsessed with that "film" look?

You have a video camera... you are shooting videos...

If you wanted to shoot a film... you would buy a film camera...

I never understood that... meh... Film isn't 1920 x 1080... ? You're trying to copy the "film" look... I guess I'll never understand... haha...

[Joseph H. Moore]

1) You'll get more spacial resolution than by deinterlacing a 60i capture. (Of course, you lose a lot of temporal resolution.)

2) Editing in 24P uses less resources.

3) But most importantly, the average consumer associates the 24p "feel" with "quality" narrative work. HD can't undo 100 years of ingrained perception overnight. 24p/48th sec. motion rendering just feels "cinematic."

I only have a "video" camera because I can't afford to buy a Panaflex rig and pay for the processing of miles of 35mm film. ;-)

[Joe Busch]

I doubt the average consumer could tell the difference between 24p and 30p...

60i to 30p is simple...

[Ian G. Thompson]

Ha..I think most of us would shoot film if it was affordable. I know you can't see the obsession....neither did I until I got more and more into these forums. But Joe....you shoot some amazing videos with your HV10 (and FX7 now???). If I were a major film studio interested in your stuff to put on the big screen for some sort of say.....paintball documentary....then.....I bet you would become "obsessed" with what's being talked about here also. Maybe most of us have delusions of grandeur hoping one day our stuff will end up on the big screen....(ok maybe its just me) but it's great to know there are tools out there that can help us along the way.

Plus there are entities in Hollywood doing the same thing (with more expensive cams maybe but....think Michael Mann) and I think think it's only going to keep growing and going in that direction for a long time to come. Digital cams are getting better and better these days.

[Joseph H. Moore]

A 60i capture, de-interlaced to 30p has the exact same issue: The image changes between fields, you can't reconstruct one solid frame without sacrificing some spacial resolution. (Inconsequential if the subject hasn't moved much, as much as half the resolution if it is fast moving.)

Now, if you captured 30p, yes, it has most of the same feel as 24p. The key is a progressive sensor. Interlacing is an NTSC hack whose time is up.