Tech Support > Computer Hardware > Desktops > Scan converter PC Video to NTSC progressive?
Scan converter PC Video to NTSC progressive?
Posted by Ken Broomfield on June 9th, 2004


I'm looking for a good scan converter that can convert PC video
(1024x768, 60-75Hz) to NTSC standard def video, and I'd like the NTSC
output to be effectively progressive, i.e., each field sampled at the
same time, 29.97 fps, just like a progressive scan video camera (such
as my Canon Optura Pi).

I know of a couple of high-end scan converters that do this, but it'd
be nice to just buy one for under $10K (preferably under $1000) that
could.

Does anyone know of such a box? Many thanks to anyone who can point me to one!

Thanks!

Posted by Tom Ellliott on June 10th, 2004


hmm,
When I first got started in video editing, the old linier way, I used a
$99.00 VGA to NTSC converter attached to my pc. What ever showed on my
computer moniter could also be seen on my NTSC monitor thus recorded on a
tape deck. I used Power Point for my first credit titles. I mean in the days
of the silents, they used "Title Cards" not only for the normal screen
credits but also for dialogue. Now I do not know if these converters are up
to the standards you need but it sure worked for me on the pro-sumer level.
Yours,
Tom
"Ken Broomfield" <news@irider.com> wrote in message
news:7643ed51.0406091407.52264654@posting.google.c om...


Posted by FLY135 on June 10th, 2004



"Ken Broomfield" <news@irider.com> wrote in message
news:7643ed51.0406091407.52264654@posting.google.c om...

Why not just buy any one of a number of current video cards that have NTSC
(TV) out. Most if not all will scale a 1024x768 screen to output on the TV
connector as NTSC video. PC displays are inherently progressive and most
video decoders will deinterlace any interlaced video, so that should do the
job.



Posted by Ken Broomfield on June 10th, 2004


Yes, I have a video card with NTSC out, and I know there are scan
converter boxes. The main trick is this: both the video cards I've
seen and most scan converters generate interlaced output, sampling
each field at a different time, at 59.97 Hz. So, any motion,
especially mouse cursor motion, causes interlace artifacts when the
video is played on a computer. Sampling each field at the same time,
like a progressive camera, would eliminate this. Some high-end scan
converters do this.

Basically, we want to record a demo of some software and have it look
good when played back on a computer. www.totaltraining.com does demos
like this. (Many people play their DVDs on a computer, so they capture
everything progressive.) Software screen recorders don't work for us
because the CPU and disk overhead interferes with the software we're
demoing (which we'd like to show at full speed).

I almost wonder if a software/firmware hack to a video card with NTSC
out could do the trick.

Posted by FLY135 on June 10th, 2004



"Ken Broomfield" <news@irider.com> wrote in message
news:7643ed51.0406101058.785ddae5@posting.google.c om...
I see the point you are making. But on my $70 (from NewEgg) generic Radeon
9600 card, when I send my desktop out to the TV I don't see any interlacing
artifacts at all. It appears to be that the screen image is captured in a
single instance of time and then scaled for output to the NTSC port. No
mater how fast I move the mouse cursor or windows on the screen, I don't see
any combing (interlace) effects on the TV.

I'm guessing that you've tried this with your current card and had
distracting interlace artifacts. What kind of VGA card are you using?



Posted by FLY135 on June 10th, 2004



"Ken Broomfield" <news@irider.com> wrote in message
news:7643ed51.0406101058.785ddae5@posting.google.c om...
I forgot to mention that it's a requirement of NTSC that the output be
interlaced. The problem lies in the second half of your statement regarding
the time each field is sampled. The point is that you'd like a scan
converter that captures the whole frame at once, scales the image, then
feeds it out as interlaced NTSC. It seems like my Radeon card is doing
this, as I haven't seen any effects that indicates otherwise.



Posted by Ken Broomfield on June 12th, 2004


"FLY135" <fly_135(@ hot not not)notmail.com> wrote in message news:<ry2yc.5023$Y3.4173@newsread2.news.atl.earthl ink.net>...
Thanks, but you won't see interlace artifacts (aside from flicker) on
a TV, since it's an interlaced device.


Right. There are progressive cameras, like my Canon Optura Pi, that do
this, as well as scan converters.


I'd be curious whether the Radeon is doing this, but the only way to
test would be to capture the video to a computer and check. Here's
what I get on an nVidia card with TV-out (the large arrow points to a
moving cursor):
http://www.irider.com/ScanConvInterlace1.jpg

Thanks for thinking about this.


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