Adam M. Costello wrote: >Why is it 4 rather than 6? (1920 * 1080) / (720 * 480) = 6.0. > >And that's using the most generous DTV definition of SD. As part of the discussion is revolving around the BBC evaluations, i think the "most generous definition of SD" should be the european flavour which is 720x576. In that case the HD to SD ratio becomes 5. Now as higher resolution would seem to compress better, and given the elaborate arguments given by Craig, it doesn't seem to be such a strech to consider a more agressive compression , that would bring the ratio between the compressed HD and SD streams close to 4 ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.