I just sent a potential client a hard drive containing 5400 High Def-size 
Targa files representing a 3 minute animation created in POV. I got a call 
saying that he had a service bureau load the frames into Final Cut and 
render them out (in a format I don't know - probably uncompressed QT Movie), 
then when they projected them they saw black horizontal lines appearing at 
the bottom of the screen and moving upward. My guess is that they either 
didn't use Fields and should have (or did and shoudn't have), or maybe they 
didn;t "interpret the footage as 29.97" and should have, or did and 
shouldn't have.
Does anyone know what would cause this? I have seen it myself when 
previewing work on an external RGB monitor after rendering individual Targa 
files into a video file.
Thanks much.
Dennis

-- 

dhm### [at] comcastnet
http://www.dennismiller.neu.edu

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Dennis Miller wrote:
> Does anyone know what would cause this? I have seen it myself when 
> previewing work on an external RGB monitor after rendering individual Targa 
> files into a video file.

It is most likely a data misinterpretation somewhere on their end, as you
already suggested. However, without seeing the actual problem, one can only
guess what is wrong, just like you currently have to guess. Here is my guess:

To see black horizontal lines in a digital production environment is rather
strange. They do appear in an analog environment when someone tries to film
video off a CRT or film projection with a camera (either digital or
film-based) and both are not in perfect sync, meaning they do not run with
the same frequency and vertical sync timing.

in a digital environment black lines sound more like corrupted data of some
sort, especially if running uncompressed video. Or their harddisks or CPUs
are just not fast enough to handle uncompressed video and start dropping
partial frames.

Either way, the problem clearly is at their end, so you need to find out
what is wrong and help them if they can't figure it out on their own. Of
course, if they can't, I am wondering if they really knew what they were
doing in the first place - expect a rough ride to get them to admit that
though :-(

	Thorsten

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Thanks much Thorsten. Focusing on the Fields issue for a moment, do you know 
if this might occur if their display is Progressive and they used Fields 
(upper or lower), or perhaps the other way round (their display is not 
Progressive and they neglected to use Fields in their render)... I think the 
29.97 issue would be more of a timing issue - a glitch every few second or 
so, but the Fields issue might be the area to examine for the horizontal 
black line that creeps up from the bottom of the screen.
 And unfortunately, I am several "layers" away from the actual production 
(they use a third part rendering service...), not to mention about 3000 
miles from their site.
Anyway, I'll look into the fields questions, as they might be the problem.
Thanks again.
Dennis
"Thorsten Froehlich" <tho### [at] trfde> wrote in message 
news:45b20eb4$1@news.povray.org...
> Dennis Miller wrote:
>> Does anyone know what would cause this? I have seen it myself when
>> previewing work on an external RGB monitor after rendering individual 
>> Targa
>> files into a video file.
>
> It is most likely a data misinterpretation somewhere on their end, as you
> already suggested. However, without seeing the actual problem, one can 
> only
> guess what is wrong, just like you currently have to guess. Here is my 
> guess:
>
> To see black horizontal lines in a digital production environment is 
> rather
> strange. They do appear in an analog environment when someone tries to 
> film
> video off a CRT or film projection with a camera (either digital or
> film-based) and both are not in perfect sync, meaning they do not run with
> the same frequency and vertical sync timing.
>
> in a digital environment black lines sound more like corrupted data of 
> some
> sort, especially if running uncompressed video. Or their harddisks or CPUs
> are just not fast enough to handle uncompressed video and start dropping
> partial frames.
>
> Either way, the problem clearly is at their end, so you need to find out
> what is wrong and help them if they can't figure it out on their own. Of
> course, if they can't, I am wondering if they really knew what they were
> doing in the first place - expect a rough ride to get them to admit that
> though :-(
>
> Thorsten

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Dennis Miller wrote:
> Thanks much Thorsten. Focusing on the Fields issue for a moment, do you know 
> if this might occur if their display is Progressive and they used Fields 
> (upper or lower), or perhaps the other way round (their display is not 
> Progressive and they neglected to use Fields in their render)...

It seems rather odd to see a single line moving. Maybe a misconfigured
interlace filter, but again the description of the problem seems far too
detailed for such a general configuration issue. They would be seeing
artifacts all over the place. If I wouldn't know better, I would check the
digital source material as well as the digital material they actually send
to the video output for a black line. They certainly can get you a copy of
at least a few frames of that digitally - it won't be all that big.

	Thorsten

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