Please note that the YCoCg video codec has been superseded on the 12th of January 2019 by its generalisation MovIm.


It’s the story of a video codec, built on the Y′COCG colour space and specifically designed for restoration purposes. This video codec is developed since early 2014 by Reto Kromer, who first presented it publicly in 2015, but it was called YCoCg only two years later.1 We use the unofficial FourCC “YCOG” for this video codec.

The openYCoCg package contains the libycocg C library, implementing the YCoCg video codec, and the openycocg Bash command−line interface to libycocg, allowing to encode, decode, play and analyse Y′COCG video files. The package is released under a 3-Clause BSD License and is provided “as is” without warranty or support of any kind.

A PDF of the current man page is available.

The source code will become freely available, as soon as a public beta not requiring special user’s skills will be released.

A Little Context

  • When working with old colour processes, like the additive ones used during the first half century of cinema, it’s often more effective to handle independently, on one hand, the luma Y′ and, on the other hand, the chroma C1 and C2 components.
  • Working with CO and CG is easier than working with the common CB and CR, because the de-correlation of the colour planes is better and the transcoding from and to R′G′B′ is faster. Therefore one can check quicker the results on modern monitors.

Alpha Release

An alpha release is currently tested by some restoration facilities and archives located in Asia, Europe and North America (often by using a plug-in for the Diamant-Film restoration suite). At present, it supports four different bit-depths:

  • 10-bit, 12-bit and 16-bit per channel Y′COCG for actual work
  • 24-bit per channel Y′COCG primarily for research purposes on file formats for the future

and it handles both the big-endian format and the little-endian format, as well as lossless wavelet compression. Only 4:4:4 sampling is supported.

Our clients can currently install and test an alpha by running the following command:

brew install avpres/formulae/openycocg

The Homebrew/Linuxbrew formula has been successfully tested on x86_64 architectures running on the following operating systems:

  • Linux: Ubuntu 18.04.1 LTS, 16.04.5 LTS and 14.04.5 LTS, and Slackware 14.2
  • Macintosh: macOS 10.13.6 and 10.12.6, and OS X 10.11.6
  • Windows 10 (Pro and Home) running Debian 9.5 or Ubuntu 18.04.1 LTS


Older names include YOG1, YOG2 and YOG3 and have been used also as unofficial FourCC – in case one should come across those files in the wild …