W dniu 2017-09-23 o 17:01, Michael Niedermayer pisze: > On Fri, Sep 22, 2017 at 02:10:01AM +0200, Mateusz wrote: >> To reduce bit depth in planar YUV or gray pixel formats ffmpeg uses >> DITHER_COPY macro. >> Now it makes images greener and with visible dither pattern. >> >> In my opinion there is no point to use dither tables for destination bit >> depth >= 9, >> we can use simple down-shift which is neutral in full and limited range -- >> result images >> are with the same brightness and with the same colors. > > Theres no reason why dither should mess up the average color tone.
In theory -- yes, I agree. In reality -- current version of DITHER_COPY mess up the average color tone. It's one of the reasons why I sending these patches. > And if the user asks for >= 9 bit depth and has >= 10 bit input the > user likely wants to get the best quality. > Thats more so in a world where computers get faster every few years, > this isnt 1995 where shaving off a add or a multiply per pixel was > actually making a difference in being able to play something in > realtime > More so coverting between bit depths might be memory speed limited and > not limited by arithmetic computations once its done in SIMD Yes, I agree. Now I can't write patches in NASM syntax, but I started reading and learning. I hope I'll back in a few months... Mateusz _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
