On Mon, 21 Feb 2005, Steven Boswell II wrote: > >If you have a progressive frame in 4:2:0, then > >the first chroma line is the average from lines 1 > >and 2. The second chroma line is the average of > >3 and 4.
Right - for 4:2:0. The "average from lines 1 and 2" and 'lines 3 and 4' are the ":0" of 4:2:0. 4:1:1 is not subsampled vertically. > So, if I have a DV file of a 3-2 pulldown of a If you have a DV file you have 4:1:1 data and not 4:2:0 so there's no chroma line switching needed. > 24fps source, and I want to convert it back to > 24fps, I first have to swap lines 2 & 3 of every 4 > lines of the 4:1:1 color, in order to get the > progressive-frame color to come out right. With 4:1:1 all that I think is needed is to undo the 2:3 pulldown to get rid of the repeated fields. That will give you a 24 (well, 24000/1001 ;)) 4:1:1 progressive image. Then later on when you convert to 4:2:0 y4mscaler will do the right thing with respect to the chroma. > >Of course - but I got a headache the last time I > >looked at the sources :) > > Eeek...I hope the author responds & gives us an idea > of how feasible this is. It shouldn't be _too_ hard to use the chroma subsampling numbers from the stream in place of hardcoded divide by 2 and 4. Perhaps getting yuvkineco handling 4:1:1 data will be sufficient. Cheers, Steven Schultz ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users