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Why is Frame Mode so horrible???

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Timelord13
Why is Frame Mode so horrible???
on Apr 12, 2006 at 7:20:30 pm

I was wondering if you could help me to understand something. I have a Canon GL2 and I have just tried the Frame Mode. It looks awful! Everyone says it mimics the look of film to a small degree. However, I really don't have a clue as to what people are talking about. When I pan the camera around the image jitters like crazy. In fact, regular 30i looks far better than the 30p. Perhaps I'm doing something wrong here? I have the camera in Frame Mode, Manual mode, Manual focus, Optical image stabilization turned OFF (the camera is mounted on a head unit that can pan and tilt very smoothly so image stabilization is not necessary. In addition, since I am shooting multiple video passes for effects shots I must have everything as "manual" as possible). When I do all of this in regular "Normal Mode" (obviously 30i), then it all looks great, but this progressive "Frame Mode" jitters horribly.

I have seen this exact kind of "jitter" before so I don't really believe that it is an issue with my camera, but I'm not sure just what is going on. By default, my Avid editor interpolates DV as the lower (or odd) field first, and then the upper (or even) field. When I then imported the Avid footage into After Effects it interpreted it as even and then odd. Once I applied effects and then imported it back into Avid I saw this exact same kind of jitter that I see with Canon's Frame Mode. Of course, once I imported the footage into After Effects and specified Odd first and then Even (like Avid exported it), then when I brought it back into Avid everything looked totally fine and the jitter was gone. This was all with video that was originally shot in 30i.

So when I shoot in Frame Mode and then just output the signal from my GL2 to a broadcast monitor through a Y/C cable, it is attempting to show it as 30i. However, since the camera is shooting the full frame in 1/30th of a second shouldn't the output on the monitor look fine anyway, even if it IS now interlaced?

If I import the video through fire-wire to my Avid editor and play it out of my Avid Mojo in real-time I see the same horrible jitter. Again, am I missing something here? Do I really need a progressive monitor to display this? Canon doesn't seem to state that this is necessary. I would assume that I could just output it to a regular TV and have a slightly different look but a very usable image. I can't imagine why everyone would say that all of this looks good and is similar to film. Film doesn't look this bad!

Thanks!

Brendan.


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thewanggao
Re: Why is Frame Mode so horrible???
on Apr 12, 2006 at 10:08:24 pm

It's because frame mode is not true progressive scanning, it's just adding 2 fields together. Also, i believe you are losing some noticable resolution. Further, it's all about what you need to achieve. If it's alright for your footage to have that video quality to it, then there's no reason not to just shoot it interlaced.

Alexander Gao

"When the revolution happens, I'll be leading it."


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Relaxman
Re: Why is Frame Mode so horrible???
on Apr 13, 2006 at 2:38:25 pm

Shoot in interlaced, and do deinterlace in post.
When this doesn't look good enough to you, buy a real progressive cam,
like dvx100.

Relaxing videos, 3D-photos:
http://www.relaxvideo.hu


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Timelord13
Re: Why is Frame Mode so horrible???
on Apr 13, 2006 at 2:48:20 pm

Thanks! I will do that. I just somehow thought I was losing my mind and Frame Mode was supposed to look much better!

Brendan.


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Timelord13
Re: Why is Frame Mode so horrible???
on Apr 13, 2006 at 2:50:32 pm

Thanks. I am now convinced that something other than true progressive scanning is going on here! Hence the reason Canon doesn't refer to it as 30p or Progressive, but just Frame mode, their own version...

Brendan.


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Stephen Downes
Re: Why is Frame Mode so horrible???
on Apr 14, 2006 at 8:45:44 am

Timelord 13,

Canon's F mode certainly is not true progressive scan - the camera's chips are interlaced and then the camera uses either pixel shift technology, reading the two fields at the same moment in time or field doubling (I don't think Canon have released the details of how they do it) to gain a frame that is essentially equivalent to a progressive frame but is probably of lower resolution than what would be recorded if it was truly progressive. Maybe the Canon F mode frame would more accurately be called a psf frame? Having said this, unfortunately what you are seeing with regard to motion judder is not a result of Canon's methods, it is in fact a natural result of progressive scan at low frame rates. This was part of the reason interlaced video was invented, because the low temporal data rates of 24 fps, 25 fps and 30 fps produces horrible motion judder at certain pan speeds. This judder disappears at around 60 fps and if you shoot 60 fps progressive the motion is smooth and the images very sharp. 30 fps interlaced is effectively 60 fps but instead of recording full frames it records half frames of alternate television lines, called fields. Two fields make up a frame and give you 30 fps but you're still getting the equivalent motion smoothing of 60 fps because each field is recorded at a different point in time. I can tell you I've shot a huge amount of material progressively on VariCam and even these most expensive of cameras suffer from the same motion judder. If you shoot at 60 fps on VariCam the motion is smooth. If you shoot 24 fps or 25 fps the motion judder is terrible at certain pan speeds, particularly with strong hard-edged verticals in your shot. This has always been known to be a problem shooting 24 fps film for theatrical release and techniques have been employed to reduce motion judder - pan speeds are kept low, the camera is often moved with the subject (dolly and crane shots) which reduces the appearance of judder, the shallow depth-of-field of 35mm helps to reduce background judder and theatrical projectors employ a double shutter system showing every frame twice also helping to reduce judder (effectively giving 48 fps reminiscent of what interlacing does in television). I myself hate the look of 24, 25 and 30 fps progressive video on an interlaced CRT monitor/television. Having said this, these progressive frame rates look fine on an LCD or video projector which has a bit of latency and seems to smooth the motion.

Hope this helps,

Stephen Downes


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Relaxman
Re: Why is Frame Mode so horrible???
on Apr 16, 2006 at 8:24:23 pm

Finally a man, who HATE 24-30 fps progressive video on interlaced CRT TV :)
IMHO life begins at 50 fps :)
My dream is watching video in HD 1920x1080 at 50/60i with a good hd projector! (or maybe two, for 3d stereoscopy effect..) i can't wait.

Relaxing videos, 3D-photos:
http://www.relaxvideo.hu


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Relaxman
Re: Why is Frame Mode so horrible???
on Apr 20, 2006 at 5:36:05 am

Sorry, i mean 50/60p.

Relaxing videos, 3D-photos:
http://www.relaxvideo.hu


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Timelord13
Re: Why is Frame Mode so horrible???
on Apr 18, 2006 at 1:01:00 pm

Thanks Stephen, that was very informative. When you say that you hate the look of 24, 25 or 30 fps progressive video on an interlaced monitor, what about this same video on a progressive monitor? I assume that it looks fine just like the LCD or video projector?

At some point I'll have to get a hold of a camera that shoots true progressive video at these rates and compare the output on an interlaced monitor and a progressive monitor.

Thanks,

Brendan.


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steph
Re: Why is Frame Mode so horrible???
on May 7, 2006 at 3:49:46 am

I shoot in frame on every production I do and it looks great. Perhaps you've got a problem specific to your unit? I haven't noticed the problems you've talked about. I like it a lot more than the 30i.

s.


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