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-   -   A1 at 24F or 30F compared to true progressive (https://www.dvinfo.net/forum/canon-xh-series-hdv-camcorders/102237-a1-24f-30f-compared-true-progressive.html)

Robert Petersen August 27th, 2007 02:32 PM

A1 at 24F or 30F compared to true progressive
I have not been able to find any "whitepapers" explaining how Canon does 24F or 30F. Since the A1 uses interlaced chips, how do they approximate 24P or 30P? Does anyone have information about how well they do in actual raw footage (not processsed)? In other words, if you shoot 24F and view the unedited footage in a player such as VLC without using any deinterlacing, will it still look like true progressive (no raster effect) on a computer monitor? Are there any noticeable differences between the Canon 24F or 30F and Sony's progressive scan on the V1? Any help would be appreciated.

Mats Frendahl August 27th, 2007 03:03 PM

Check out "Ultmately dumb question: What is 24f for?" - there is a discussion about this.

Robert Petersen August 27th, 2007 03:10 PM

Thanks, I already read that thread. It had a lot of good info in it, but I didn't feel that it answered my questions. I wasn't sure if it would be proper to "piggyback" my questions onto that thread. Thanks again.

Pete Bauer August 27th, 2007 03:37 PM

Canon's F Mode has been discussed over and over. Check out the numerous threads in both the XL H1 and XH forums. Here's one to get you started:


Mats Frendahl August 27th, 2007 03:44 PM

Robert, this is apparently a "sticky" question. I'm myself is trying to find out what it does for *me* personally as it seems, given info from very knowledge persons with detailed knowledge in this, that different frame rates are seen differently by persons and it *might* even depend on if you live in PAL or NTSC Land.

If you want a theoretical explanation of how Canon have solved it I cannot recall seeing such an "essay", but perhaps there is some.

Myself I'm not that interested in the pure image processing/mathematical aspects as getting a pleasing image. Let's see if there will be better answers to your question than mine. I'm sure there will be.

Bill Pryor August 27th, 2007 04:26 PM

I don't care how they do it--all I care about is that they manage to do it, and it's a true 24p image, and it looks that way on playback. You do not use any deinterlacing because it is not an interlaced image. I capture and edit in a 24p timeline, and when I export for web or DVD, there are no interlace artifacts like I get with 60i footage.

Steve Mydelski August 27th, 2007 06:51 PM

AE results
I'll chime in here with some recent work I've done on a very complicated After Effects composition using 24F footage from the A1.

Normally when dealing with interlaced footage in AE doing any type of keying is a super pain in the arse. You have to interpret your footage and pick which field to use. Then you get jagged edges from that field and have to work with pixel mapping or frame blending on which really slows AE down.

Why do I mention all this? Well, I had none of those problems using Canon's 24F footage. Adding on to what Bill stated, I don't care or need to know why or how they've implemented the 24F. It just plain works and looks great.

Robert Petersen August 28th, 2007 12:31 PM

Thanks to everyone for your feedback. My main concern was if the footage actually came out as progressive. Evidently Canon must process the image somehow in the camera. My big concern is being able to mix standard DV footage with HDV footage without having to worry about field order from the HDV footage. I've done some HDV tests (converting HDV to standard DVD) and got decent results with 60i by switching the field order, but found that some HDV footage had a "vertical jitter" when it was converted to an m2v file in Procoder. If I didn't switch the field order during encoding, then the frames were out of sequence causing double images during movement. I'm hoping that this is overcome by shooting in 30F.

Bill Pryor August 28th, 2007 12:36 PM

That should do it for you. No fields, since it's not interlaced. I get funkiness too when dealing with interlaced footage going to progressive, which is why I wanted to shoot 24F.

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