[Libav-user] Lossless encoding - red color sharpness defect

Carl Eugen Hoyos cehoyos at ag.or.at
Mon May 28 14:45:49 CEST 2012

 <koli at ...> writes:

> I was trying to use ffmpeg for screen capture and come to 
> this problem.

(Note that ffmpeg natively supports screen capture input, 
no need to use png's.)

> ffmpeg -r 5 -i ./GrabedPictures/Pic%d.png -r 5 -vcodec libx264 
> TestX264.avi

Complete, uncut console output missing.
Your resulting file has colourspace yuv420p, that means it cannot 
look better / store all colour information;-)
Either you are using an ancient or broken version of FFmpeg, or 
your version of x264 only supports yuv420p (current x264 also 
supports yuv444p which does not loose chroma information, 
current FFmpeg with current x264 automatically chooses yuv444p).


> ffmpeg -r 5 -i ./GrabedPictures/Pic%d.png -r 5 -vcodec huffyuv 
> OutHuff.avi
> ffmpeg -r 5 -i ./GrabedPictures/Pic%d.png -r 5 -vcodec ffv1 
> -sameq TestFfv1.avi

-sameq does not do what you believe and it has no effect in this 
command line (ffv1 is always lossless).


> What is more interesting when I was trying to play huff or ffv1 
> video with mplayer or ffplay the red text was still fuzzy.

(Complete, uncut MPlayer console output missing.)
ffplay only supports yuv420p output and you started mplayer 
with the wrong -vo, try -vo gl which supports yuv444p output.

> It seems that ffmpeg has not 
> correct decoding of "lossless" video codecs.

Please understand that this is not a very useful comment, 
the lossless codecs are tested quite extensibly (which does 
not mean they cannot have bugs, but they should be 
reported differently).

Carl Eugen

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