| Subject: Re: And what about BBC7? |
Author:
Outsider
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Date Posted: 06:19:27 01/10/04 Sat
In reply to:
mark1
's message, "Re: And what about BBC7?" on 00:47:24 01/10/04 Sat
>Yes, I agree.They should bring all national radio
>networks back including digital only (6Music,
>BBC7).I've noticed similar discussion going on at the
>BBC Messageboard Point Of View section.It seems some
>people are really trying to persuade us that the main
>obstacle for bringing back all radio channels to Astra
>2B is a technical one.Here is a post:
>"re: Radio 1 and Radio 3 back on Ast Kieren Walters -
>38th post - 9 Jan 2004 22:01
>The license fee is paid to watch TV in the UK, BBC
>Radio has no responsibility to broadcast outside of
>the UK, this is done by BBC World Service which is
>funded by the Foreign Office. Your right to say that
>BBCi services could move to 2D to make space for radio
>channels. The problem with this is that BBCi services
>are video streams so putting one BBCi video stream on
>2D would need more space than that created by removing
>all of the radio services from 2D (as video takes up
>more space than audio) It could also cause performance
>problems with BBCi as how the Sky box handles streams
>from different satellites within one interactive
>application is untested as far as I know."
Yes, it's not so straightforward but I would slighly disagree with that reply:
First, it's good to notice that a TP with SR=22000 and FEC=5/6 has exactly the same capacity as one with SR=27500 and FEC=2/3, i.e. appr. 16.9Mbits/s. BBC have put seven BBCi streams (in addition to the two radios) on Astra 2B TP38, giving each of them appr. 2.4Mbits/s (actually the allocation may not be static but continuously changes according to needs of individual streams by using a technique called "statistical multiplexing"). At the moment there are 15 radio stations on Astra 2D TP47, if I assume 192kbits/s for each of them (some are likely less and some are likely 256kbits/s) we would get 2.88Mbits/sec, in fact more than the 'share' of one BBCi stream!
This would suggest that moving some 12 radios would make sufficient space for one BBCi but I don't know the bitrates of each radio. Note, that there is also one data channel on TP47 to 'play with', I don't know how much it uses.
Also, as I already noted earlier, Astra 2D TP50 appears to have free capacity for one additional BBCi (it already has four) because BBC seems to put on a single transponder six 'ordinary' TV channels or as many as seven BBCi streams and this one only has one TV channel and four BBCi streams. After moving one BBCi from 2B to this TP would also mean all BBCi's are on two transponders, as they are now.
Things are not so simple but I would still maintain that it's more lack of will than technical issues preventing BBC from putting at least most of the radio channels on Astra 2B.
Comments are wellcome (especially from Bobben! ;-)
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