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Old September 24th, 2007, 04:55 PM   #1
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Question regarding AVCHD's kind of 24p

I was reading at the AVCHD site their specs:
http://www.avchd-info.org/format/index.html
and I saw that they have a 24p standard among their formats.

However, my question is this: is their 24p standard a REAL 24p (all frames being progressive), or it's like Canon's 24f format (3 progressive, 2 interlaced)? You see, while Canon implemented AVCHD on some of their camcorders, they still use that bastardized 24f-inside-a-60i-stream format instead of real 24p.

Note from Admin: The above is incorrect -- this is NOT how
Canon works! See the clarification by Barry Green below


So this begs the question: what does the AVCHD standard actually say about 24p?
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Old September 25th, 2007, 09:27 AM   #2
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I can't speak of an expert on AVCHD as I'm not one, but 24p that is recorded on DV is also recorded inside a 60i stream, even when it is TRUE 24p (such as with the DVX100 or XL-2). It has to go through the pulldown process to get the actual true frames, but that doesn't mean it isn't true 24p. I'd suspect that the AVCHD standard does have true 24p, even if there is pulldown involved. The frames are still individual frames, it's just a matter of how they are packaged within the stream.
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Old September 25th, 2007, 12:40 PM   #3
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But that's my point. I want to know if it is the kind of 24p that does not require pulldown. I don't see WHY it should require pulldown and not save it as true 24p. I mean, AVCHD usually writes its files on an HDD, so it has not the limitations of DV tapes and surrounded standards. I just don't see why that should not be true 24p without extra frames.
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Old September 25th, 2007, 02:01 PM   #4
 
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Because native 24p is not a consumer-friendly shooting nor editing format.
Consumers that _do_ choose to shoot 24p most likely won't have a clue what to do with it, and even if they do, they likely won't have an NLE that supports it.
It's a consumer cam, ergo; consumer features.
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Old September 25th, 2007, 03:19 PM   #5
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Douglas, thanks for the reply (I bought your Vegas 6 book btw, thanks for writing it).

However, what you say for the specific thing is not really what's going on. I mean, it's the standards that will have to push NLEs to support 24p. For example, once upon a time NLEs didn't support HD. Now they do. It is in fact more work to add pulldown support on an NLE rather than add IVTC timeline support. I mean, from the engineering point of view, that would be just bad...
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Old September 25th, 2007, 05:40 PM   #6
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Quote:
Originally Posted by Eugenia Loli-Queru View Post
or it's like Canon's 24f format (3 progressive, 2 interlaced)?
Canon's 24F is not like that. Canon's 24F is true 24 frame recording with no pulldown and no interlacing. It's only available on the XHA1, XLH1, and XHG1.

Canon's 24P mode records the way you described: using 3:2 pulldown.

Quote:
So this begs the question: what does the AVCHD standard actually say about 24p?
It is my understanding that it is genuine 24 fps, and only 24fps, with no pulldown.
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Old September 25th, 2007, 06:36 PM   #7
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>Canon's 24F is true 24 frame recording with no pulldown and no interlacing.

That's 24p. Why don't they just call it 24p? :P
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Old September 26th, 2007, 11:39 AM   #8
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It's confusing, but it's the way it is.

Canon 24F = footage sourced from interlaced chips, but recorded on an HDV tape in pure progressive format.

Canon 24P = footage sourced from progressive chips, but recorded on an HDV tape or AVC-HD disc as 1080i using 2:3 pulldown.
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Old September 26th, 2007, 12:40 PM   #9
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Quote:
Originally Posted by Barry Green View Post
Quote:
So this begs the question: what does the AVCHD standard actually say about 24p?
It is my understanding that it is genuine 24 fps, and only 24fps, with no pulldown.
If the HG10, like the HV20, records 24p within a 60i stream, why the divergence from the AVCHD spec, which, from what I'm hearing, says 24 fps should be recorded as such, not as 2:3? I guess, from a practical point of view, Canon's decision makes sense because no consumer would be able to do anything with it otherwise.
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Old September 27th, 2007, 10:40 AM   #10
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That's right, Lawrence... 24p in the Canon HG10 AVCHD camcorder is identical to 24p in the Canon HV20 HDV camcorder. If it was any different, the vast majority of consumers wouldn't be able to use it.
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Old September 27th, 2007, 10:58 AM   #11
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If it was any different, the vast majority of consumers wouldn't be able to use it.
Why?

I mean, for HDV there was some reasoning there -- tape decks. But with AVC-HD being tapeless, compatibility is not an issue. So why would anyone not be able to use it?
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Old September 27th, 2007, 11:02 AM   #12
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I am also a little mystified by Chris's comments that 24p from the HG-10 would not be able to be used by a vast majority of consumers?

Is that NLE related, or some other basis?
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Old September 27th, 2007, 11:30 AM   #13
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I was merely echoing Lawrence's observation:

Quote:
Originally Posted by Lawrence Bansbach View Post
I guess, from a practical point of view, Canon's decision makes sense because no consumer would be able to do anything with it otherwise.
And yes, it's a matter of consumer NLE compatibilty. Unless I'm missing something blatantly obvious, I didn't see any mention of *native* 24p compatibility within Ulead VideoStudio, Nero Digital or any other consumer-level PC-based editing app in the $100 price range.
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Old September 27th, 2007, 11:49 AM   #14
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Originally Posted by David Saraceno View Post
I am also a little mystified by Chris's comments that 24p from the HG-10 would not be able to be used by a vast majority of consumers?
I did not say that. In fact I've gone out of my way to say that despite some unfortunate misinformation communicated by another source elsewhere on the web, it is indeed *identical* to the HV20.

What I said that if it was any different than what it is, it couldn't be used by a vast majority of consumers.

By the way... can someone name a currently shipping consumer-level AVCHD camcorder that records native 24p (that is, without 2:3 pulldown in a 60i stream)? Because I'm not aware of one. How about the same thing in a currently shipping consumer-level HDV camcorder? I'm not aware of that either.

If there is no such thing, then it's not a Canon-specific issue but an industry-wide issue, as to why no manufacturer yet offers it.
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Old September 27th, 2007, 03:00 PM   #15
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Chris, both Sony Vegas Movie Studio and Premiere LE support 24p (even if, unofficially). The rest consumer NLEs don't, but I would think that whoever switches his AVCHD camcorder to 24p, he knows what he's doing, and he has already bought the right $100 NLE. For the rest who use iMovie or Ulead, well, leave them in their fate. They won't care about 24p anyway.

I think it's a mistake for Canon (and whoever else) to advertise 24p and yet not giving us the real 24p. And while I do understand the HDV tape excuse, they have no excuse to do that for AVCHD camcorders. Heck, at least they could make it a option to let the user decide if he wants real 24p or 24p-in-60i (which could still be left as the default).

EDIT: I will call Canon on the phone and ask just that.
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