As I got some questions about progress I decided to post some updates and clarifications:

1. I succeeded to improve performance so now encoder a bit faster of Apple implementation with identical output (and I still see room for improvements)
2. I fixed some minor issues and fully implemented XQ profile
3. About 12 bit support: there was a thread in ffmpeg dev list where some core developers were claiming 12-bit Prores is a myth so you know Apple encoder encode all data as 12 bit even if you pass 8-bit uyvy it first converted to 12 bits and encoded after that
4. Based on statement (3) I can expose big mistake I made in Cinedeck Prores Insert-Edit. Basically Cinedeck checks some stream parameters to make the decision if input stream should be re-encoded or not before insert. One of them is src pixel format and if input and output has different src pixel formats video gets re-encoded before insert which now i can say is wrong behavior as basically on encoder side its always 12 bit and not src pixel format but chroma subsampling had to be checked
5. There is one more util I work on. Its Prores smart transcoder:
   Lets say we need to transcode Prores HQ to Prores Proxy, thats how any transcoding app will do it:
   1) Decode frame (vlc decode -> dequantize -> inverse dct -> assemble slices to frame buffer
   2) Encode (disassemble frame to slices, -> forward dct -> rate control -> quantize -> vlc encode)
   
   From first point of view it looks ok, but from my point of view it should be:
   1) vlc decode -> dequantize -> rate control -> quantize -> vlc encode
   so basically I got rid of some heavy but useless steps which make transcode almost x2 faster comparing to the classical way
   Obviously, it works only if you transcode from Prores to Prores

I`m still quite far to show demo (except some command line applications), but here is priority list:

1. Make user friendly UI so it easy to show and use
2. Finish MOV parser/muxer (as im not a fan to use FFMPEG for demo)