[FFmpeg-user] Mathematically lossless MotionJPEG2000 encoding possible?

[Christoph Gerstbauer]

> And you have shown convincingly that there is a better alternative
> to one existing jpeg2000 implementation. It will be no problem to
> write a faster one if you have the time (or the money), I am not sure
> if compression will be better than with current libopenjpeg.
How much (approx) would it cost to write a faster jpeg2000 encoder for 
ffmpeg?
>
> Note that the issues with jpeg2000 are of course nothing against the
> issues that mxf has, iirc you already know that there are as many
> interpretations of the standard as implementations, don't you?

The most solutions which are using JPEG2000 are encoding in lossy 
compression mode, as far as I know.
Additionally, I spoek last week with a very professional video guy, and 
he said to me how he checks the "losslessness" of jpeg2000.
He makes a difference picture of the original source and the encoded 
jpeg2000 -> and checks this just VISUALLY. (o.O)
He does not make frame md5s. So his (mathemtically) lossless checks are 
only visually checks.

And yes, I know that there are so mich implementations. Like Samma Solo 
(Front Porch) or OpenCube etc...
The most solutions which are using JPEG2000 are anyhow encoding in lossy 
compression mode, as far as I know.
>
> And regarding the "professional" solutions: Please ask them to show
> you how to get the original content back after encoding once;-)
>
> Please do not top-post here, Carl Eugen

Yesterday I tested to extract the original source from a libopenjpeg 
encoded file, and it worked (check was done with framemd5 checksums).
But i need to force ffmpeg to use the libopenjpeg decoder.
If I give the jpeg2000 MXF file (libopenjpeg) as source into a CARBON 
CODER, the picture looks exactly like the same I see in ffplay when I 
DONT use the libopenjpeg decoder. Officially Carbon Coder is able to 
READ jpeg2000.... but not to read correctly?

bg Christoph