[FFmpeg-user] Questions about readout important metadata from DPX files ("logarthmic/linear") and recreate DPX with same metadata

Christoph Gerstbauer christophgerstbauer at gmail.com
Tue Mar 10 11:23:46 CET 2015

> We've encountered something similar when transcoding FFV1 over the
> network. So we used framemd5 not to verify FFV1's losslessness, but to
> validate that the transcoding goes error-free :)
> FFmpeg's framemd5 became *the* feature for professional video preservation.
> So, thanks again for all your great work here!
> Regards,
> Pb
Indeed, ffmpeg framemd5 is my only possibility to check lossless 
transcodings. A BIG THANK YOU FOR THAT!
Otherwise I could only test it to make it visually with e.g After 
effects overlay the transcoded video to the original and make a 
DIFFERENCE/DELTA video... (btw: some videotechnicians do that, because 
they dont know about ffmpeg or framemd5 ;)
With the framemd5 checksum I can check many "Lossless" transcoders if 
they do their job correct when using lossless codecs, and I was 
wondering how many "professional" transcoders are destroying the video 
when transcoding from lossless formats like uncompressed 4:2:2 10bit 
(v210) to the same output format (v210) (because of an internal 
YUV422->RGB blowup I guess).

Best Regards

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