On Sat, 27 Apr 2002 15:20:00 GMT, "Gunnar Thalin"
>"Neuman - Ruether"
>news:3ccab10f.1110709@newsstand.cit.cornell.edu...
>> On Sat, 27 Apr 2002 08:27:46 GMT, "Gunnar Thalin"
>>
>> >"Neuman - Ruether"
>> >news:3cc95089.1696897@newsstand.cit.cornell.edu...
>> >> - PS-mode/"frame-mode" operates at 30fps for Canon cameras,
>> >> 15fps for Sony, but the Canon interpolates fields to get
>> >> the higher frame rate, reducing spatial resolution (which
>> >> in any case cannot be greater than it is for interlaced
>> >> video...)
>> >Slightly incorrect. Motion is recorded at higher spatial
>> >(but lower temporal) resolution in progressive mode than in
>> >interlaced mode. Static video is the same for both modes.
>> And where does that extra spatial resolution come from...?
>> Sorry, you cannot exceed within a frame the resolution
>> provided by the interlaced video, unless you are talking
>> about stills and proper time alignment of the fields for
>> these - but for motion, as I said, there cannot be increased
>> spatial resolution with PS mode...
>In interlaced mode we have (in NTSC) 60 fields per second
>with each 240 lines. In progressive mode we have 30 frames
>per second with each 480 lines.
>Let's say we have a video clip with a moving object. The object
>will always only have half the vertical resolution in interlaced mode
>since only every other line in a full frame is used to represent the
>object a a certain moment in time. And you can't combine the two
>fields and increase the resolution either as you can for static video.
>Maybe we're just misunderstanding each other. You're talking
>about spatial resolution for motion. Define exactly what do you
>mean by that? Sounds very fuzzy to me.
OK, I think you are right - we are looking at the same thing
in different ways. To state it a different way: the spatial
resolution of a single frame with no motion in it will be
the same for both PS-mode and interlaced mode, *all else
being equal*; the spatial resolution for a single frame with
motion in it will be somewhat lower for interlaced vs
PS-mode (but with the attendant worsening of the temporal
resolution with multiple frames); in all cases I know of,
all else is *not* equal, since true 25/30fps at full
resolution has not been possible in consumer gear, so the
spatial resolution is also lower in PS-mode compared with
interlaced in a single frame without motion...
>> >And where on earth did you hear that Canon cameras interpolate
>> >the fields? I just got my Canon MV30i (European version of Optura Pi)
>> >yesterday, and you really scared me for a while.
>> >But I just made some tests, and I can assure you you're wrong;
>> >it does NOT interpolate the fields. Not spatially and not
>> >temporally.
>> Check out www.adamwilt.com for more on this - the Canons
>> do reduce spatial resolution to provide full 30fps (NTSC)
>> frame rate in PS-mode. So far, they cannot give full
>> 30fps (or 25fps PAL) and maintain full frame resolution
>> (relatively poor as that is, in any case...;-). Which is why
>> Sony PS-mode is at 1/2 the normal frame rate, to maintain
>> full resolution for stills...
>Well, I didn't find anything on that site, but it really doesn't
>matter. My Canon clearly doesn't interpolate the fields.
>It's so easy to test, it's ridiculous we're having this debate.
>Maybe other Canon models do this but not mine.
Try a simple test: shoot a detailed still subject with the
camera on a tripod in both PS and interlaced mode (a distant
street scene with lots of siding, roof, tree, etc. detail
works well for this. Bring the footage into the computer and
grab a best frame from each. Compare them carefully...
The drop in resolution in PS-mode is not great, but it
should be just noticeable...
I don't have the URL for the specific article on the Canon
process for deriving 25/30fps PS-mode, but Adam Wilt was
quite thorough in the description, as I recall...
>> >> - Since most TVs are interlaced displays, using PS-mode for
>> >> these is generally inappropriate, though some people
>> >> appear to like the resultant "flicker" for reasons totally
>> >> mysterious to me...;-)
>> >Not all people watch their video on 50/60Hz TV's.
>> >On a computer monitor, for example, I definitely prefer
>> >progressive scan video.
>> Yes - but this is the "minority" mode for video-watching...
>Maybe. But for those of us who have left 50/60Hz TV's behind,
>progressive mode is a good thing.
Yes, of course... But if you produce video for most users,
PS-mode video will not be acceptable...