[FFmpeg-user] x265 lossless from 10-bit RGB sequences

Joakim Ziegler joakim at terminalmx.com
Sat Mar 12 03:01:10 CET 2016

I'm playing around with x265's lossless mode, which has pretty interesting 
performance. However, I'm compressing from 10-bit per channel RGB DPX files, and 
my compression doesn't seem to be totally lossless, probably because my RGB data 
is converted to yuv444p10le for compression with x265.

I understand that using the YCgCo colorspace might be a solution to this 
problem, since it's losslessly convertible to and from RGB. From what I'm 
reading, there might also be a range problem with RGB vs YCbCr...

Can I make ffmpeg convert the full range 10-bit RGB values from the DPX files to 
full-range YCgCo values, and pass those into x265 as if they were YCbCr values? 
Does anyone have an example commandline?

And, just to ask right away, what would be the right way to decode the resulting 
x265 stream and convert it back to RGB DPX files?

What I'm basically asking for, obviously, is a way to make the whole DPX to x265 
lossless to DPX pipeline using ffmpeg be mathematically lossless.

Joakim Ziegler  -  Supervisor de postproducci├│n  -  Terminal
joakim at terminalmx.com   -   044 55 2971 8514   -   5264 0864

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