What bothers me about 24F

[Bill Pryor]

Originally Posted by Raymond Toussaint

@ . The timing is similar as 24P 25P.

It's exactly the same.

[Chris Hurd]

Bill is right -- it is not "similar." Rather it is "identical."

[Raymond Toussaint]

My English.. I did a good job here.

It's for editing software like FCP identical like the same, if you look at the motion, it is as 24P 25P from an other system.

[Barry Green]

Originally Posted by Raymond Toussaint

In short: Frame mode writes one whole progressive frame, the V1 writes the progressive frame (say 25P) in an interlaced stream with two identical fields, like the panasonic dvx.

Not correct -- the fields are not identical. If they were, the resolution would be cut in half.

In progressive video (25p or 30p) a progressive frame is imaged all at once, and then split into fields for recording. The fields were created at the same instant in time, but contain different data -- each field contains half the progressive picture.

In interlaced video the fields are created in different instants in time. In progressive video (when recorded to an interlaced stream) the fields are created at the same instant in time.

[Raymond Toussaint]

Originally Posted by Raymond Toussaint
In short: Frame mode writes one whole progressive frame, the V1 writes the progressive frame (say 25P) in an interlaced stream with two identical fields, like the panasonic dvx.

Maybe short is too short.

with two -in time- identical fields,

If they were identical in data the resolution would be doubled, not cut in half I think. So the even/oneven lines vertical sync method remains, but is now filldup with in time unchanged data.

[David Ziegelheim]

Both A1 frame mode and V1 progressive mode are written to an interlaced 1080i HDV file. In both cases the entire 1440x1080 image is a single instant.

How does the recording differ?

[Barry Green]

Originally Posted by David Ziegelheim

How does the recording differ?

The A1 doesn't write to an interlaced data stream. It writes progressive frames to tape as progressive frames.

The V1 embeds its progressive frames into a 60i interlaced data stream, so it employs 2:3 pulldown to spread 24 frames across 60 fields.

The A1 doesn't do anything like that. It writes 24 progressive frames to the tape, progressively. Which is why A1 24F/30F footage won't play back on Sony equipment -- it's a totally different format.

[David Ziegelheim]

If 1080i HDV supports progressive frames directly, why would they need a 3:2 pulldown? It makes sense in DV, which doesn't support 24 frames/sec or progressive frames. But if HDV supports both, why use interlaced frames with a 3:2 pulldown?

Thanks,

David

[Raymond Toussaint]

Originally Posted by Barry Green

The A1 doesn't do anything like that. It writes 24 progressive frames to the tape, progressively. Which is why A1 24F/30F footage won't play back on Sony equipment -- it's a totally different format.

To make it almost poetical:
Canon A1 uses an interlaced sensor-->(reads it twice) --> to write it as one progressive frame
Sony V1 uses a progressive sensor--> (reads it once) --> to write it in two interlaced fields

But Barry:
If the two -in time- identical fields, were identical in data the resolution would be doubled, not cut in half. There is more data.

[Richard Hunter]

Originally Posted by Raymond Toussaint

To make it almost poetical:
Canon A1 uses an interlaced sensor-->(reads it twice) --> to write it as one progressive frame
Sony V1 uses a progressive sensor--> (reads it once) --> to write it in two interlaced fields

But Barry:
If the two -in time- identical fields, were identical in data the resolution would be doubled, not cut in half. There is more data.

Hi Raymond. I'm not Barry, but thought his meaning was clear. Each field contains data for half of the frame. If this data is identical then you do not have double the resolution, only redundant data so half of the vertical resolution is lost.

Richard

[Chris Suzor]

Originally Posted by Raymond Toussaint

To make it almost poetical:
Canon A1 uses an interlaced sensor-->(reads it twice) --> to write it as one progressive frame
Sony V1 uses a progressive sensor--> (reads it once) --> to write it in two interlaced fields

Has anyone done a comparison of 24F and 24P at high shutter speeds? Is 24F really merging 2 interlaced images taken at the same instant, or 2 different images taken separately (similar to deinterlacing)?

In the attached images, dvx100be @ 1/250s, there are no interlace artefacts, of course. These 2 images are 1/24s apart, but each is @ 1/250s so motion is relatively frozen. This is essential to me, for crisp slow motion playback of fast moving action. Does 24F enable this, or is it only similar to 24P at much slower shutter speeds?

Thanks
Christophe

[Pete Bauer]

Yes, see this post:
http://www.dvinfo.net/conf/showpost....1&postcount=53

[Barry Green]

Originally Posted by David Ziegelheim

If 1080i HDV supports progressive frames directly, why would they need a 3:2 pulldown? It makes sense in DV, which doesn't support 24 frames/sec or progressive frames. But if HDV supports both, why use interlaced frames with a 3:2 pulldown?

Well, now you come to the crux of the problem. What is "HDV"? What does it support? There are currently three manufacturers offering "HDV" gear, and all three are, to some degree, incompatible with each other. So you have JVC HDV, which won't play any Canon or Sony footage, and Canon won't play JVC footage, and Sony will display JVC 30P footage but not its 24P or 60P footage...

Then in the 1080 realm you have the original 1080 spec, which is what Sony is compliant with, which is 1080/60i and 1080/50i and that's it. Then Canon came along and invented their own recording format for 30F, 25F and 24F. So now the HDV specification has been extended to include those modes, but Sony doesn't support any of them. You can't play 24F, 25F, or 30F footage on any Sony equipment.

Yet it's all "HDV". Very confusing.

So, therein lies the crux of the matter. Sony gear doesn't support progressive recording, so when they made a progressive camcorder they chose to implement the progressive footage within an interlaced data transport stream. That gave them backwards compatibility with all their other HDV equipment; any Sony (or Canon) camera or deck can read any Sony HDV footage. JVC cameras and decks can't, but Sony cameras & decks, and Canon cameras, can.

Had they used progressive recording, they'd be in the same boat Canon is in, which is that no HDV deck can read Canon 24F, 25F, or 30F footage. But, Canon records progressively rather than embedded in an interlaced data stream, which should yield technically superior results. But at the expense of having made their own proprietary format which no deck can read (because Canon doesn't make decks).

To further confuse the issue, when the Canon outputs 24F over HD-SDI or analog component, it does add 2:3 pulldown into the signal. It's only the HDV tape itself where the footage is encoded as raw 24-frame progressive; on the analog or HD-SDI outputs it's treated as a 60i data stream.

[Raymond Toussaint]

Originally Posted by Richard Hunter

Hi Raymond. I'm not Barry, but thought his meaning was clear. Each field contains data for half of the frame. If this data is identical then you do not have double the resolution, only redundant data so half of the vertical resolution is lost.

Richard

Thanks.
Now I understand, I see the picture. I was on 99.5 % now I am on 99.8 %.


@ Barry Green
"Had they used progressive recording, they'd be in the same boat Canon is in, which is that no HDV deck can read Canon 24F, 25F, or 30F footage. But, Canon records progressively rather than embedded in an interlaced data stream, which should yield technically superior results. But at the expense of having made their own proprietary format which no deck can read (because Canon doesn't make decks)."


There is a growing behaviour to shoot (next to tape) on memory cards, harddisk, with laptop computers or portable drives. Doing so and in the future, gives Canon a system that is free from videodecks, 24F, 25F, 30F is technically a better format and shooting tapeless and editing on any system is possible.

Even Panasonic HVX200 users are in big numbers working with Firestore disks, and they can choose to go P2.

[Bill Pryor]

I think the reason HVX200 users are recording to Firestore is because of the tremendous cost and low capacity of P2 cards.