Don't buy a 1080p telly, warns consultant

Writing in his bog, Putman says that despite huge amounts of advertising for 1080p tellies and similar products people are not getting a true 1080p format.

Putman said that there is a 1080p/24 production format in wide use for prime time TV shows and some feature films. But these programs must be converted to 1080i/30 before airing on any terrestrial, satellite, or cable TV network.

While 1080p/24 could be broadcast as a digital signal, none of the consumer HDTV sets out there would support the non-standard horizontal scan rate required and it flickers too much anyway.

Live HDTV is captured, edited, and broadcast as 1080i/30 and there are no off-the-shelf broadcast cameras that can handle 1080p/60 with fast picture refresh rates, he added.

Putman said that Blu-ray and HD-DVD is also unlikely to manage 1080i either. Most HDTV sets run their horizontal scan at a constant 33.8 kHz, which is what's needed for 1080i (or 540p). 1080p scans pictures twice as fast at 67.6 kHz. But most of today's HDTVs don't even support external 720p signal sources, which requires a 44.9 kHz higher scan rate.

He said that you should not blame HDTV manufacturers for this oversight. They are only supporting the 1080 format in actual use, 1920x1080i. This is a legacy digital format that has its roots in the older Japanese MUSE analog HDTV format of the 1980s.

He said that as a result to show 1080i signals most consumer HDTVs convert the content by chucking most of the code into a dustbin. This is ok because the resulting 540p image is fine for CRT HDTV sets.

But if you stick a 540p signal on a 1080p display it looks awful. More here. µ