What resolutions with S-video out?

S

shenwppd

Member
I would like to connect the S-video out from my DVX 100B to a Newtek Tricaster, which accepts S-video input sources, but records in D1 720 x 486 resolution on the built in DVR/hard disk. As we all know, the DVX 100 B records it's compressed DV output to 720 x 480 DV resolution. My question is this: is the S-video analog signal output by the DVX capable of being compressed to 720 x 486 D1 resolution by the downstream device without clipping of the top and bottom 3 lines? Would there be any problems or incompatibility. Can that analog signal be digitized to resolutions other than 720 by 480, in this case 720 x 486?

Thanks for any light anyone can shed on this, Steve
 
S-video is an analog standard, and it's really only good for maybe 400 lines of res anyway. Because it's analog, there's no inherent line clipping; the DVX will be converting its digital signal to analog in a standard NTSC analog stream, and the Tricaster will then digitize that back in.

You could digitize an analog signal into any size you want -- you could digitize it into 100x70, or you could digitize it into 1920x1080, or you could digitize it into 4096x3172. Usually you want at least 640x480 to hold as much information as the analog signal contains.
 
The FULL NTSC signal is actually 525 lines. And that is what the S-video (and Composite) signals are. Always.

D1, like DV, is just a codec. As you pass through analog, the source and destination codecs become (somewhat) irrelevant.


What it really boils down to in the end is the size of the picture area - or how many *visible* lines there are. NTSC has 486 visible lines. (The rest are lost in the "vertical interval" between frames.)

As the Live outputs on the DVX100 are pre-encoder, they are not limited by the DV codec (if you are shooting live, as I presume you are with a Tricaster), they *can* be the full 486 visible lines. If they actually are is something I don't know.

Note that even of those visible lines, the top and bottom ones are normally cropped off by the over-scan on most monitors. That's why those upper and lower lines are often used for stuff like Closed Captioning data. Still recorded in the signal, but not visible on the TV as they are cropped off on display.


I guess my point is that in most practical applications, those couple of lines at the top and bottom don't really matter.

As to if the DVX100 outputs 486 or 480 lines on it's live output, that's something that simply needs to be tested.



EDIT: I saw Barry perusing the board, I should have known that he was busy typing up a faster explanation than me. Beaten again. But mine has more confusing geeky numbers. :)

- Mikko
 
Two points of view directed at the same target is always a good thing:thumbsup:
 
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