HPA Retreate Notes

There was an interesting session at the HPA (Hollywood Post Alliance) retreat last week where many studios as well as a representative of the EBU (European Broadcasting Union) talked about their real world experiences with video encoding and distribution.
Here are my notes.

The EBU has published their recommendations for HDTV video compression for acquisition, production and distribution in this document: http://tech.ebu.ch/docs/r/r124.pdf
The full report is only available to EBU members, but we can take note that:

1. Progressive pictures look better than interlaced.
2. Acquisition is recommended at 4:2:2 where 8bit is sufficient.
3. To manintain quality after 7 cycles of encoding, Long GOP, CBR, MPEG-2 at 50Mbit/sec at the least is recommended (post and production).
4. Distribution using H.264/AVC, CBR encoding requires 50% less bit rate than MPEG-2.
5. Interlaced video requires 20% more bit rate than progressive video for the same quality.
6. The dominant image quality impairments are determined by the distribution codec.

In that panel, there were engineers form three mayor broadcast studios who revealed their own conclusions:

MPEG-4 @ 20Mbits/sec, MPEG-4 @25Mbits/sec and MPEG-2 @45Mbits/sec are used in their facilities to maintain reasonably constant quality.