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noggin14,455 posts since 26 Jun 2001
There are two generally accepted, but different, ways of defining scanning standards ...

If the letter comes first the following number is always the frame rate : i25, p25, p50 (And NOT the image rate when it comes to interlaced systems)

If the number comes first then the following number is the image rate (field rate for interlaced, frame rate for progressive) : 50i, 25p, 50p.

i25=50i (Though lots of people will assume the former is defining a standard with half the image rate of the latter...)
i29.97=59.94i
p25=25p
p50=50p

Both are in widespread use in the industry - and some people get them wrong when describing interlaced content (and commonly describe video as i50 or 25i - when they mean i25 or 50i...)

The EBU would define the UK HD system as 1080/i25. Many manufacturers would define it as 1080/50i (and use that nomenclature in their camera settings)...

Personally I think the image rate is a better number as it instantly tells you the temporal resolution.

Lots of people will think i25 and p25 will have the same number of images per second (i.e. the same temporal resolution) whereas it's much clearer that 50i has twice the temporal resolution of 25p. (Even though 50i and i25 are two ways of describing the same, identical, system)
Last edited by noggin on 7 February 2019 1:38am - 2 times in total
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London Lite gave kudos
noggin14,455 posts since 26 Jun 2001
Live ... understand it's escaped the tvOS store a tad early too.

Given the HD channels are originated as 1080i25, there must be some heavy-duty deinterlacing going in the encoders.


I'd guess so. The BBC deinterlace 1080i25 to 720p50 for iPlayer. (NRK hang two Alchemists off their 1080i25 Playout systems to cross-convert to 720p50 for DVB transmission too I believe - working entirely 1080i internally? Or they used to...)
DVB Cornwall8,400 posts since 4 Dec 2003
Westcountry Spotlight
Interesting handover on the 4K channel tonight. Arsenal's game being carried on BTS3 and the 4K channel, switching across to an already in progress Chelsea build up being carried on BTS2, using an extended commercial break to do the switch of 4K feed.
thegeek4,967 posts since 1 Jan 2002
London London
It's a semi-regular occurrence for 4K on a Saturday - lunchtime football, 3pm rugby, then teatime football - with the football being a BTS1 simulcast and rugby from BTS2. Often the first two will lose their last part in 4K (because they overlap in the schedule), and it's usually done quite smoothly via a natural break point, but sometimes pres just crash out of one and into the next.
Hatton Cross3,266 posts since 4 Jan 2003
Central (West) Midlands Today
Good to see Glenn is making a good recovery - thanks to Simon, London Ambulance Service and the NHS.

You know something good could come from this. Maybe BT Sport could consider sponsoring the placement of CPR machines in a few sports stadia where they don't currently have them.
My user name might look like Hatton Cross, but it's pronounced Throatwobbler Mangrove.
thegeek4,967 posts since 1 Jan 2002
London London
That segment will be getting a few repeats during the week, including after Wednesday night's Spurs match.

Due to the Continental Cup final going to ET, Score will now start and be simulcast on BT Sport 2.
dvboy9,850 posts since 11 Jan 2003
Central (West) Midlands Today
Last night BT Sport used the red button to show the start of Venus Williams's match in Indian Wells while another was still underway.

No such consideration for Johanna Konta's match tonight though despite BT Sport Extra 5 currently showing on the red button but not being used.
Last edited by dvboy on 8 March 2019 8:43pm
Watch it and find out.