[FFmpeg-user] Does converting to yuv444p by default make sense?

thljcl jiachielee at live.com
Wed Jul 31 11:02:56 CEST 2013


Earlier, I uploaded a slideshow I created to YouTube to demonstrate the way
to derive the inverse transformation matrix for YCbCr to RGB conversion from
RGB to YCbCr transformation matrix. While it’s fair to say that the method I
used is largely unchanged; apparently, I did make some mistakes during the
calculation process, resulting the wrong values for the transformation
matrix for YCbCr to RGB conversion. I’ve removed the earlier post and the
earlier version of slideshow video I uploaded to YouTube. Upon finishing the
revision to make the corrected version, I re-upload the slideshow video
again to YouTube.

<iframe width="640" height="390"
src="http://www.youtube.com/embed/PDVk-fRPzxU" frameborder="0"
allowfullscreen></iframe>


The reason that I made the derivation is to show that based on our
understanding of linear algebra, we know that how YCbCr can be used to fully
encode RGB color information. To be specific, the transformation being used
is actually affine transformation. Please watch the slideshow video and make
your own judgment. I don’t claim to be a know-it-all expert. I even admitted
that I made mistakes during my earlier derivation process. Still, it’s a
careless mistakes, rather than a misunderstanding of the algorithms behind
RGB to YCbCr conversion. There are different industry standards for defining
YCbCr color space model. I only used one to prove a basic concept. 
If you spotted any mistakes, please inform me. Thank you.




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