Originally Posted by rdgrimes
The DVD and BD box sets are released in the UK right after the season ends,(November) and thus do not include Christmas specials. The US box sets are released in Jan and DO include the Christmas specials. Bonus content is the same in both sets, however the US sets have "sped up" audio due to frame rate conversion and sometimes are edited for time. The show is produced in 1080/50i. Season 4 is available now for pre-order from Amazon.uk.
Surely the US sets have slowed down audio if anything?
The show is shot 25p (like most European TV drama). This will be shown 50i in the UK with 2:2 pull-down. Historically US versions would have been a straight 50i to 60i conversion, in real time, with no speed change, but interpolated frames would have been used, reducing picture quality. Some US releases of UK shows have instead converted the 25p to 24p using slow-down, so there is no frame interpolation (and no quality loss in picture terms) but there is a speed change.
In the UK the first series of Downton was released 24p as a 25p to 24p slow-down - and presumably the US release was similar. No idea if the PBS broadcast was a 24p to 60i conversion from the 24p slowed down master, or a separate 50i to 60i conversion (with no speed change)