Monthly Archives: May 2019

ffmpeg, Prores

Prores QUALITY

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UPD: ffmpeg builds I shared were added just to show encoder is no a myth, but as FFmpeg (or at least some guys from the community) has something against I had to remove repo…s o all github links below invalid, sorry

In the previous post I forgot to mention the problem I mentioned couple times before – Quality. Its not always easy to detect by eye big difference, but I have some test files where any of ffmpeg prores encoders really fails.

I uploaded one to github if you want to check:

https://github.com/da8eat/ffmpeg_prores_encoder/blob/master/1.bmp

and you can see how badly ffmpeg encodes it if you want Proxy profile:

ffmpeg -i 1.bmp -c:v prores_aw -profile:v -pix_fmt yuv422p10le aw.mov

ffmpeg -i 1.bmp -c:v prores_ks -profile:v -pix_fmt yuv422p10le ks.mov

as you see both looks quite blury (aw looks better but as I said before there is nothing about rate control and aw guarantees nothing except correct bitstream)

Thats how looks same frame encoded with encoder I made:


ffmpeg -i 1.bmp -c:v prores_amcdx -profile:v -pix_fmt yuv422p10le amcdx.mov

I uploaded all 3 mov files so you can compare results by yourself:
https://github.com/da8eat/ffmpeg_prores_encoder/blob/master/aw.mov
https://github.com/da8eat/ffmpeg_prores_encoder/blob/master/ks.mov
https://github.com/da8eat/ffmpeg_prores_encoder/blob/master/amcdx.mov

I also do believe you have your own test footage which you want to try encoder with, so I built ffmpeg master branch and added one more Prores Encoder, so you can test and check results . Usage:
https://github.com/da8eat/ffmpeg_prores_encoder/blob/master/build/ffmpeg_win_MSVS2015.7z
https://github.com/da8eat/ffmpeg_prores_encoder/blob/master/build/ffmpeg_osx_clang.7z

ffmpeg.exe -i 1.bmp -c:v prores_amcdx -profile:v 5 -pix_fmt yuv444p12le xq.mov

profiles same as others ffmpeg Prores encoders: 0 – Proxy, 1 – LT, 2 – Standard, 3 – HQ, 4 – 4444, 5 – XQ

supported pixel formats: uyvy422, yuv422p10le, yuv422p12le, yuv444p12le

I do believe my encoder still have some bugs, so If you face any do not hesitate to message me

ffmpeg, Prores

Prores progress updates

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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)