2009/7/28 Matthias Hopf
On Jul 28, 09 09:44:02 -0700, Yang Zhao wrote:
The autodetect is problematic - at least you should check for both width and height, as 4:3 images in 720p will be 960x720. Also note that 480p is a regular HD standard as well.
Or, you check out my suggestion for autodetect: - 640x480 gets Rec. 709 (this is HD 4:3) - Anything wider than 800 gets Rec. 709 (this includes HD 480p 16:9) - Everything else gets Rec. 601 (this includes 720/768x480/576)
My understanding is that Rec.709 only applies to content that is equal to or larger than 720p. 480p falls under something called "EDTV" which isn't technically HD. The definition of what is considered "HD" varies
Ok, still the 4:3 720p is an argument. So probably something like
width >= 1200 || height >= 700
would be reasonable (and account for some weird broken overscan possibilities).
I'm not sure 4:3 with 720 lines is an accepted common resolution. It's certainly not part of ATSC. My primary intention with checking only the width is to handle media that's been cropped from a 720p source to get rid of letter boxing. This is not uncommon for cinema in 1.85:1 and 2.39:1. To add to the confusion, I have media labelled as "HD" at 960x544 which is stretched to 1280x544 using Xv, which is then used as the effective resolution of the video. The sum of all this is that I implemented something which categorizes a video source as being encoded with Rec. 709 only when it is definitely fits the size requirement of being "HD", ignoring the grey area between HDTV and SDTV.
I also remember that there was a color space that used the full 0..255 range for Y, but I don't know its specification number.
xvYCC? http://en.wikipedia.org/wiki/XvYCC I'm not sure if it's actually in common use. Easy to add, if it has the same conversion constants as Rec.709. -- Yang Zhao http://yangman.ca -- To unsubscribe, e-mail: radeonhd+unsubscribe@opensuse.org For additional commands, e-mail: radeonhd+help@opensuse.org