which is line 1 in smpte numbering?

[jmac698]

In a 480 active line digital system, where is line 1, in terms of SMPTE analog numbering? Maybe line22 or line 284?

[Ebobtron]

I might say yes if I understood your question.

"SMPTE analog numbering" is not a term I have seen used.

The data I think you seek would be defined by the NTSC.

lots of info here.
http://www.paradiso-design.net/videostandards_en.html

search using NTSC and SMPTE at below can really pay off.
http://en.wikipedia.org/wiki/Main_Page

The real answer is inside the DVD player. I am sure that there is a predictable standard for how the hardware merges the digital ones and zeros with the horizontal and vertical sync pulses. The slight skewing about the screen between different brand players suggests that not all do the job exactly the same way.

[foxyshadis]

SMPTE 170M defines a set of lines for NTSC, numbering them so that when others talk about VBI data they have a standard definition. (Such as widescreen switching transmitted on "line 22", or whatever it is.) However, I don't know which line starts the active picture area, and I can't actually find 170M online.

[Wilbert]

In a 480 active line digital system, where is line 1, in terms of SMPTE analog numbering? Maybe line22 or line 284?
Figure 5c from ITU-R_BT.470-6.pdf: for NTSC the active lines are 20-262 and 283-525 (486 lines). I thought it had actually 483 active scanlines, but i can't read that from that figure though. I also thought that line 21 is teletext, so it can't be all video ...

[jmac698]

wilbert: thanks. WSS is line23 in pal, cc is line21/284 in ntsc, I believe. However I'm still missing one piece of info: what is the first digital line as per rec.601, that is 720x480 is which 480 lines of the 486??
I can define the middle now, it's between the 262 and 263th line..

0 283
1 20
2 284 cc
3 21 cc
4 285
5 22 video
484 525
485 262

The digital 480 lines might start on line 21 then, so a proper upconversion should show some cc data...

[Wilbert]

The digital 480 lines might start on line 21 then, so a proper upconversion should show some cc data...
I'm not aware of a prescribed starting line. I always assumed that the capture device has to decide this.

[jmac698]

That's crazy, it would mean everyone's TV captures are starting at some random, unknown line! Since everyone sees letterbox starting at line 58, it shows me that all TV cards are starting on the same line. I think it starts somewhere in 22 or below. I'll think about it..
thanks for your help.

[jmac698]

"For video decoding, VDELAY is programmed with the number of half lines
between the end of the serration pulses and the first line to be displayed or
captured.
For GPIO SPIOUT, VDELAY is programmed with the number of half lines
between the rising edge of VRESET and the rising edge of VACTIVE.
The register value is programmed with respect to the unscaled input signal.
VDELAY must be programmed to an even number to avoid apparent field
reversal."
Fusion(TM) 878A PCI Video Decoder, 2-19

"Vertical Delay Register...Upon reset this register is initialized to 0x16."
5-11

Also, the VACTIVE register defaults to 0xE0. This means 240 lines per field are captured, or 480 lines total.
To know which is the first line, you need to decode the first statement.

[jmac698]

The term serration pulses would mean the equalization and broad pulses of the vertical sync, which end at line 10. Therefore I take the final answer as 10+(0x16/2)=line 21, which is also the first video active line, therefore CC appears in the picture! Also it's the last 6 lines of video which are cutoff by capture cards.

Centre
The scripts for letterboxing imply that centre is 360/2+58=238. Ok, I can't figure out the centre vertical right now, but what's very interesting is..

How film is converted to video
SMPTE 96M-2004 defines how film is digitized for video. For recent Super35 films, the full frame version should contain all of the film, and widescreen contains vertical cropping of the 4x3 image.
When filming, there is a "ground glass" which contains markings for the various aspect ratios, so that you can protect the action area. Protect means literally protect that area from microphones appearing and so on.