Sports is higher because to do live encoding with a single pass you need a higher bit rate generally.

When you can analyse and multipass encode material you can use lower bit rates while in theory maintaining quality of picture.

In reply to a post by 4M2:

Apologies again for misunderstanding your post regarding the iPlayer and HD bit rates/file sizes.

No worries, thanks.

In reply to a post by MrSaffron:

Sports is higher because to do live encoding with a single pass you need a higher bit rate generally.

When you can analyse and multipass encode material you can use lower bit rates while in theory maintaining quality of picture.

Absolutely, goes without saying - and when deciding the output of a channel, I'm sure this is a major factor - combined with the fact sports/motion is less efficient/more difficult to encode with H.264

However, at the end of the day, the BBC have many live shows - and their output is still around the average of the channel, and Sky Sports (eg F1 HD) has many recorded shows and their output is still around the average of the channel.

Still, bitrates should only be used for comparisons with caution - it's a mug's game to assess quality by the easily obtainable number. It is interesting though that iPlayer on the Sky platform is near-broadcast bitrate with the same programmes. The hidden subtext is that these bitrates are all broadband-capable. The discussion may be arcane for some, but TV streaming is one of the biggest challenges and opportunities for the broadband market, and will be a game-changer in years to come.

For sports and any footage that includes fairly rapid movement then 50fps (50p) or 59.94fps (60p) will probably become the norm.

Are UK sports currently shot and transmitted interlaced (50i) in order that movement looks smoother allowing for the end user's monitor or LCD/plasma TV to de-interlace?

No salesman can tell you really what broadband speed your line will achieve, you will only find out the line capability when it is connected with FTTC (fibre to the cabinet).

Information from EE/Orange
If you join our 40 Mb service, you will typically receive up to 38 Mb/sec. Those joining our 80 Mb service will typically received up to 76 Mb/sec.

http://help.ee.co.uk/system/selfservice.controller?C...

https://broadband.ee.co.uk/home.do

In reply to a post by 4M2:

Are UK sports currently shot and transmitted interlaced (50i) in order that movement looks smoother allowing for the end user's monitor or LCD/plasma TV to de-interlace?

Sports HD broadcasts in the UK are 1080/25i (ie 50 interlaced fields) - just like pretty much all HD broadcasts. Temporally, this is just like SD has always been of course - and is natively the video look, ideal for sports. Programmes shot at 25p, or films converted to 25p, therefore rely on 2:2 pulldown by the de-interlacer to re-create the original frames. The exception is the Freeview HD platform which allows 1080/25p broadcast and frame-doubling by the receiver to output 50p - the BBC has used this since 2011 - the advantage being perfect 25p frames, and in theory near-instantaneous and perfect switching between mixed material within programmes - avoiding for example the juddery or tearing credits often otherwise seen while the de-interlacer locks on detecting what to do.

That is interesting - certainly iPlayer HD (viewed/downloaded from a browser) is 25p.

I use an Avisynth script using the "InterFrame" plugin for frame doubling 25p to 50p but that interpolates an intermediate frame from two adjacent frames. Also very useful for slo mo when shooting in 50p: the frame rate can be doubled to 100fps then slowed down to 25fps which results in pretty good 1/4 speed effects. Very dependant upon subject matter of course and I usually get better results with a certain degree of motion blur by using a 1/100 sec shutter.

Same thing can be done with 50i but that means half height frames are created when de-interlacing to 50p, e.g. 1080 reduced to 540, and obviously the quality is not as good as 1080 50p but it is almost as good compared to working from 720 50p

Edit: https://vimeo.com/44330932 example of one of my 720 50p clips slowed to 1/4 speed.

Edited by 4M2 (Wed 24-Apr-13 14:17:36)

In reply to a post by 4M2:

That is interesting - certainly iPlayer HD (viewed/downloaded from a browser) is 25p.

Indeed - 720/25p - and original interlaced content suffers as a result, sometimes too distracting to watch.

No such motion issues or significant compression artefacts on the Sky platform - which AFAIK is unique iPlayer content. In isolation, I really cannot tell if its iPlayer or broadcast and have even wondered if it is a direct mirror. We used to use iPlayer on the PS3 which is certainly nice and we are lucky to have it in the UK, but its performance and interface is a toy in comparison.