JohnAd
Established Member
I've finally got round to reading the Snell and Wilcox Video Standards books I got from the Event last year and noticed something that I've been confused about for a while.
I wonder if one of the experts out there can help me out with this.
I was looking at the page covering what looks like the CCIR definition. This is what I think DVD's are decoded to and what passes along SDI. Anyway the S&W books says there are 720 digital pixels per line, OK no surprise there but there is also mention of 714 (702 for PAL) pixels in an analogue line. Now this is where I'm getting confused.
I'm just trying to add support for some new cards in DScaler and these allow you to set the decoding frequency, I have set this to 27Mhz in an attempt to get CCIR type output of I assumed 720 pixels. When I use 720 I get a lot of black space at the right of the picture off my set-top box or DVD player. If I only ask for 702 pixels I get no extra black at the sides.
Also when I recorded Star Wars using my Nova-t card I noticed that the MPEG stream was 702x576 rather than the 720x576 I was expecting.
So finally my question, when working out the aspect ratio for PAL CCIR/SDI should I use 720 or 702 and how are DVDs encoded for PAL, is the black space just stored as black or should this extra information be ignored?
Sorry if this is slightly confused...
John
I wonder if one of the experts out there can help me out with this.
I was looking at the page covering what looks like the CCIR definition. This is what I think DVD's are decoded to and what passes along SDI. Anyway the S&W books says there are 720 digital pixels per line, OK no surprise there but there is also mention of 714 (702 for PAL) pixels in an analogue line. Now this is where I'm getting confused.
I'm just trying to add support for some new cards in DScaler and these allow you to set the decoding frequency, I have set this to 27Mhz in an attempt to get CCIR type output of I assumed 720 pixels. When I use 720 I get a lot of black space at the right of the picture off my set-top box or DVD player. If I only ask for 702 pixels I get no extra black at the sides.
Also when I recorded Star Wars using my Nova-t card I noticed that the MPEG stream was 702x576 rather than the 720x576 I was expecting.
So finally my question, when working out the aspect ratio for PAL CCIR/SDI should I use 720 or 702 and how are DVDs encoded for PAL, is the black space just stored as black or should this extra information be ignored?
Sorry if this is slightly confused...
John