News coming from EOS HD, Canon working on a new codec for the 5D Mark 3 based on the MPEG format. It will feature a 4-2-2 colour space and a variable bit rate, up to 50mbit. It is the DSLR version of the codec used in the XF305 (The Canon XF305 and XF300 PRO Camcorder models, both come in under $8,000 also use the same MPEG-2 4:2:2 50Mbps codec.)
The 4-2-2 colour sampling and the 14bit A/D converters on the sensor will deliver more lifelike color and smooth gradated tones like high quality still images.
src – eoshd.com