> Is my calculation right ?
Nope. :) The answer for your PAL CVD is 59/54 * 2/1 = 59/27. (i.e. 59:27) For an NTSC CVD it would be 10/11 * 2/1 = 20/11. (i.e. 20:11) It's just the plain old PAL or NTSC pixel aspect ratio scaled by 2, since the horizontal resolution is reduced by 1/2. > I've calculated myself and found 295/132 : > > (59/54)*(720/576)*(576/352) = 295/132 The mistake here is that the unencoded "720x576" frame and the CVD "352x576" frame correspond to *different sizes of physical image*. The 352x576 frame is actually subsampled from a 704x576 frame (which is cropped out of a 720x576 frame). > But, also found a pixel aspect ratio value of 256/117 at > http://www.uwasa.fi/~f76998/video/conversion/ Well, the problem with Aho's page is that it is *too* correct. ;^) That's to say, he works out all the numbers exactly --- which is refreshing, no doubt --- and points out that the "Industry Standard square-pixel" aspect ratio is actually 768/767, not 1:1! In our Industry Standard world, we pretend that square-pixels are 1:1, so all of Aho's numbers need a 767/768 correction factor: 256 767 2^8 * 13 * 59 59 --- * --- = -------------- = -- 117 768 2^8 * 3^3 * 13 27 Quoting Aho from his "Related Links" section: "This is mostly because the author [Pirazzi] of the article [Square and Non-Square Pixels] chose to consider the "industry standard" square pixels the same as real square pixels, whereas I wanted to make a pedantic distinction between the two. (Yes, I am an impractical fool, so shoot me.)" I'll add a note about the "square is not *really* square" issue to the mir.com page. And, a CVD preset is now on the TODO list. -matt m. ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. SourceForge.net hosts over 70,000 Open Source Projects. See the people who have HELPED US provide better services: Click here: http://sourceforge.net/supporters.php _______________________________________________ Mjpeg-users mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/mjpeg-users
