Whats the point of Freeview?

Mark Carver wrote:
wrote:
On Oct 24, 8:17 am, Stuart Clark wrote:

Technically though you _could_ use multi-pass encoding for non-live
programmes if you wanted (that would cover some channels completely and
some almost so).

Yep if they made all channels CBR, the same bitrate on all platforms,
and got rid of that silly re-encode arrangement for BBC1 English sub-
regions, then they easily could.

It would be difficult and messy to implement for a channel such as BBC1
where you're mixing pre-recorded programmes, with live content. There'd
be a big splat as you switched from the multipass encoded output, to the
'on the fly' encoded stuff. How would you mix and disolve from one to
another ? How would you plaster those annoying captions and voice overs
over the end credits etc. In this day and age of 'branding' it would be
very difficult to arrange, you'd essentially be trying to manipulate
your playout within the emission environment. Though personally I'd love
to see all that 'branding' ****e dumped forever, but it just ain't going
to happen.


That's why I put "technically" :-P

As for switching from live to non-live or between live/non-live
programmes, as long as you switch on a I frame you should be able to
switch completely seamlessly. I'd be quite worried if any of the
professional automation/playout systems can't handle that.

Paul Murray wrote:
On 2008-10-23, Andy Champ wrote:
So at 10MBit, MPEG2 is usually OK. For most purposes (not shoals of
fish, or the other favourite moving water) we can probably get away with
half that.

So what's Freeview?

Varies quite a bit by channel and time of day, but generally around
1.25-1.75 GB/hr, which if I've done the calculations right is about
3-4 Mbit/s. The main channels tend to get considerably more bandwidth
than the extra ones.


An interesting site is http://dtt.me.uk/ which gives the following rough
values (average figures):

BBC1 - 4.5Mbit/s
BBC2 - 3.2Mbit/s
C4 - 2.3Mbit/s
ITV1 - 2.2Mbit/s
Five - 1.9Mbit/s
Smile TV - 800Kbit/s

So quite a range!

Stuart Clark wrote:

That's why I put "technically" :-P

As for switching from live to non-live or between live/non-live
programmes, as long as you switch on a I frame you should be able to
switch completely seamlessly. I'd be quite worried if any of the
professional automation/playout systems can't handle that.

Most presentation depts demand frame accurate switching, and you still
wouldn't be able to do any dissolves or even audio voice overs between the two
modes. For production staff it would be like winding the clock back 25 years,
when you had to consider the PAL 8-Field sequence when editing.

--
Mark
Please replace invalid and invalid with gmx and net to reply.

Mark Carver wrote:

Most presentation depts demand frame accurate switching, and you still
wouldn't be able to do any dissolves or even audio voice overs between
the two modes. For production staff it would be like winding the clock
back 25 years, when you had to consider the PAL 8-Field sequence when
editing.


For audio, you can extract the audio stream and manipulate it on the
fly. For most voiceovers over the credits you just want to continue
playing the programme audio at a low level with the presenter on top -
should be doable for real time decompression of the audio stream, mixing
& recompression. Any slight loss in quality of the programme audio
through the second compression should be unnoticeable due to the low
volume level.

A similar technique could be possible for video too. Maybe to preserve
quality switching to the non-preencoded version just for the credits and
treating that as "live".

As mentioned though it would make statistical multiplexing harder - you
could still do it as long as there is one other channel in the group
which isn't pre-encoded, and that you don't mind its quality being
reduced quite harshly by the other pre-encoded channels.

Stuart Clark wrote:
Mark Carver wrote:

Most presentation depts demand frame accurate switching, and you still
wouldn't be able to do any dissolves or even audio voice overs between
the two modes. For production staff it would be like winding the clock
back 25 years, when you had to consider the PAL 8-Field sequence when
editing.


For audio, you can extract the audio stream and manipulate it on the
fly. For most voiceovers over the credits you just want to continue
playing the programme audio at a low level with the presenter on top -
should be doable for real time decompression of the audio stream, mixing
& recompression. Any slight loss in quality of the programme audio
through the second compression should be unnoticeable due to the low
volume level.

A similar technique could be possible for video too. Maybe to preserve
quality switching to the non-preencoded version just for the credits and
treating that as "live".

As mentioned though it would make statistical multiplexing harder - you
could still do it as long as there is one other channel in the group
which isn't pre-encoded, and that you don't mind its quality being
reduced quite harshly by the other pre-encoded channels.

That all sounds super, and the first question the playout centre's beancounter
will ask is, what's the cost/benefit analysis ? (for them).

TV playout is all about transmitting trailers, DOGs and the occasional
programme with a minimum of fuss, staff, and technical skill. (Regrettably)
As it is just look at the hamfisted mess Red Bee make of end credit 'push
backs' with the one frame jump when the DVE goes on line.


--
Mark
Please replace invalid and invalid with gmx and net to reply.

Mark Carver wrote:

That all sounds super, and the first question the playout centre's
beancounter will ask is, what's the cost/benefit analysis ? (for them).


Absolutely nothing!

Few people these days are prepared to pay for a higher quality product. :-(

On Friday, 24 Oct 2008 19:50:27 +0100, Mark Carver wrote:

TV playout is all about transmitting trailers, DOGs and the occasional
programme with a minimum of fuss, staff, and technical skill.
(Regrettably) As it is just look at the hamfisted mess Red Bee make of
end credit 'push backs' with the one frame jump when the DVE goes on
line.

For those of us who do not work in broadcasting, perhaps you could explain
the technical relationship in the playout process between what Red Bee
does and the BBC continuity, and especially how this applies in the
national regions.

J G Miller wrote:
On Friday, 24 Oct 2008 19:50:27 +0100, Mark Carver wrote:

TV playout is all about transmitting trailers, DOGs and the occasional
programme with a minimum of fuss, staff, and technical skill.
(Regrettably) As it is just look at the hamfisted mess Red Bee make of
end credit 'push backs' with the one frame jump when the DVE goes on
line.

For those of us who do not work in broadcasting, perhaps you could explain
the technical relationship in the playout process between what Red Bee
does and the BBC continuity, and especially how this applies in the
national regions.

Red Bee are the privatised incarnation of what was the BBC's continuity dept
in London. The parent company is Macquarie (also owners of Arqiva).
They hold the contract for the playout of all BBC TV services from London, as
well as the UK** channels, Dave, Virgin, Fiver, Five US, (but not Five itself).
From next Summer they will also playout all of C4's family of channels.

As far as BBC Nations go, Red Bee provide clean feeds of network programmes on
BBC 1 and 2, so that BBC Continuity in Belfast, Cardiff, and Glasgow can
provide their own local continuity. In other words (AIUI for the time being)
BBC Nations continuity is still in house.

http://www.redbeemedia.com/html/allabout.html

--
Mark
Please replace invalid and invalid with gmx and net to reply.

On Friday, 24 Oct 2008 22:52:30 +0100, Mark Carver wrote:
Red Bee are the privatised incarnation of what was the BBC's
continuity dept in London. The parent company is Macquarie (also
owners of Arqiva).

Soooo ...

The network continuity announcers on BBC 1,2,3,4 are not BBC employees
but Red Bee contractors?

As far as BBC Nations go, Red Bee provide clean feeds of network
programmes on BBC 1 and 2, so that BBC Continuity in Belfast, Cardiff,
and Glasgow can provide their own local continuity. In other words
(AIUI for the time being) BBC Nations continuity is still in house.

Aha, this is what I was wondering.

So if you want to hear a "real BBC" continuity announcer on TV, one
needs to watch BBC 1,2 {NI, Scotland, Wales}.

Presumably, continuity on BBC Radio is still done for the domestic English
networks by BBC contractors in Langham Place? Or will this soon
be contracted out to some private company?

And has anybody noticed but the continuity announcer from BBC 7,
Joanna PinnockI think, is doing some of the continuity on BBC HD?

So presumably she is contracting to both BBC and Red Bee?

On Oct 24, 2:44*pm, Mark Carver wrote:

It would be difficult and messy to implement for a channel such as BBC1
where you're mixing pre-recorded programmes, with live content. There'd
be a big splat as you switched from the multipass encoded output, to the
* *'on the fly' encoded stuff. How would you mix and disolve from one to
another ?

well... years ago, the BBC were developing something called the
"atlantic project" - the plan was to add an extra data channel
alongside each MPEG2 stream, which contained detailed information
about how the stream had been encoded - eg. which bits of the
original had been thrown away during the compression sequence, so that
the exact same encode process could be duplicated again and again. The
idea was that they'd be able to transcode many times without degrading
the picture quality. During feed switches, when this data channel was
interrupted, the chain of encoders would revert to 'normal' lossy
encoding until it was reinstated, or replaced with another.
This system, if they ever finished it, could potentially be used to
allow 2-pass encoded CBR content to be broadcast directly to viewers.

As for the re-code of BBC 1 English regions, that's being phased out as
each region has DSO. The post DSO BBC Muxes are being centrally (with
geographical redundancy) coded and muxed, so starting with BBC 1 SW in
April that practice will vanish.

So how will they insert the local junk programming for each region?
and why wait for DSO - there are still two independent feeds for the
"analogue" and digital networks, so I don't see why they'd have to
wait?