Video Broadcast help

[biferi]

I know the NTSC Digital SD Resolution is 720 X 480.

But when NTSC first came out it had a Resolution of 525 but we could only See 480 Line on the CRT TV.

So I know the 480 Lines are the Horizontal but how many Vertical Lines are in the CRT TV?

[DB83]

It is quite a common error (so no inference to you) which confuses horizontal with vertical. So your 480 lines are actually the vertical resolution since you look at them from bottom to top or top to bottom.


This article might be useful to clarify how many horizontal (read left to tight or right to left) 'lines' were displayed on a CRT. You will see that the actual number depended both on the quality of the actual tv and the broadcast so there is no exact number. But the article quotes 330 as the effective maximum.


http://lyberty.com/encyc/articles/tech/vid_horizontal_resolution.html

[Cornucopia]

To distill and summarize:

Both Digital TV and Analog TV have horizontal & vertical blanking areas (areas where there is no user content/image). This is designed to accommodate minor variations in timing.

Analog Has DISCREET vertical resolution (in the form of specific # of lines) but CONTINUOUS horizontal resolution (in the form of a constant scanning electron beam signal).
For NTSC analog, Vertical is 525, of which 486 (pro) or 480 (consumer) is captured to digital. The rest is thrown out, because digital will RE-CREATE it synthetically, much like a TBC does, which makes it rock-solid.
Even though the horizontal rez of analog systems is continuous, that doesn't mean it is infinite (though it could be considered so theoretically): it still has a bandwidth constraint and that gives the upper limit to horizontal resolution.
The horizontal scan is frame buffered and digitized based on the 13.5MHz scan frequency (common for both NTSC and PAL) in ITU-601 systems, which is where the user data visible pixels becomes 704/720 (PAL is usually 702/720).

Again, you do NOT need to worry about the additional lines in digital systems, as they are generated by the equipment automatically upon output, and they are stripped automatically upon input.

Scott

[dellsam34]

In case the OP is asking about the actual pixel structure of a CRT color TV (B&W TV had none) or an analog camcorder imaging sensor, Those numbers are dependent on the manufacturer of the equipment, CCD camcorders did publish a pixel count in the user manual and advertising brochures but for old tube camera's and CRT TVs had no mention of pixel count as far as I know, But all this doesn't matter now, doesn't it?

The 704 pixels (plus 16 black pixels as safety margins on the left and right) is good enough of a sampling rate for the horizontal bandwidth of broadcast TV and pro analog tape formats but overkill for consumer tape based video formats, Vertically 480 (576 PAL) lines still included head switch (about 6 lines), pro capture cards added an extra 6 lines on top of the frame for NTSC because some CRT camcorders had a slight shift of the frame towards the top so they added 6 lines to be safe, The true vertical active area is more of like 474 lines (570 PAL) but that will be an illegal resolution so the head switch is kept and just masked over.