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Matrox rtx10 and analog to digital

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Tejano Guy
Matrox rtx10 and analog to digital
on May 15, 2004 at 2:49:39 am

I have a matrox rtx10 and the resolution from analog to digital isnt exactly what i expected or wanted.Im using of course adobe premiere pro and encore.Listen I barely started doing this so Im kinda a begginer any help I would appreciate Thanx.


Jorge


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John Q
Re: Matrox rtx10 and analog to digital
on May 15, 2004 at 3:29:53 am

GIGO. Garbage in, garbage out. What was your video source? Even at the 2 hour speed, VHS is only about 230 lines of horizontal resolution, which is less than half the typical 500 line resolution that you get with DV.


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Tejano Guy
Re: Matrox rtx10 and analog to digital
on May 17, 2004 at 11:48:13 pm

Well let me give you some insight.Im using s-vhs tapes on a proffesional Panasonic player but Im coming out on the s-video cuz it doesnt have any firewire.Despite that some people have said it should come out pretty good. Im still Kinda confused.
Hey thanx for the reply!!


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John Q
Re: Matrox rtx10 and analog to digital
on May 18, 2004 at 4:21:08 am

Okay. I've done s-video captures of powerpoint presentations from my Thinkpad with no problems. I assume you selected the Matrox DV analog input default settings and then set/checked the Video Source setting to "S-video".


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Alan C
Re: Matrox rtx10 and analog to digital
on May 19, 2004 at 10:45:26 pm

Sorry to break in, but you said 500 lines? Shouldn't DV be 720? Or does it depend on what you are capturing? Thanks from another rookie.


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John Q
Re: Matrox rtx10 and analog to digital
on May 20, 2004 at 2:45:19 am

NTSC video is an analog video signal tracing 525 horizontal lines sweeping down vertically with half the lines displayed on the first pass and the other half following. The two fields combine to make a video frame. The frames are displayed at 29.97 frames per second.

The key element is that the video is composed of horizontal analog video lines. There's a limit on how fast you can turn this raster signal on and off, although it's a little more complicated than this. The luminance and chrominance signals are processed separately. The luminance signal is given priority and more bandwidth, because the human eye is more sensitive to seeing detail in the luminance data than the chrominance. The key point is that you really have a black and white video signal with a color overlay.

For VHS, which is recorded in analog formst on tape, this typically results in about 230 lines of resolution, referring to how quickly the raster can be switched on and off in a horizontal line. The vertical resolution is fixed by the raster format, 525 lines. 8mm and Hi8 tapes were better, reaching about 400 lines.

DV is digitized as series of 720x480 frames. It's about equivalent to 16-bit color. (That's where you get your extra 8 bits in video editing to do alpha channel overlays.) At 29.97 frames per second, that works out to about 166 megabits per second. Well, DV compresses this down to 25 megabits per second to fit on the tape. The compression reduces the theoretical horizontal resolution from the maximum 720 lines down to about 500.

Someday we'll be watching High Definition television and recording our video on a new HD digital recorder, but for now, this is as good as it gets.


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