What about using the CI slot on a digital TV?
It’s not very practical. A French company called Neotion has made modules that can convert H.264 to MPEG 2 in a CAM (Common Access Module) but the use of DVB-T2 means you’d need almost a whole set-top box in the CAM. Controlling a CAM through your TV’s menus isn’t very straightforward, and may not be possible without an upgrade to the TV’s firmware anyway, as most sets only expect to use the CAM for encrypted channels. Some older sets will only have an SD MPEG 2 decoder, so still wouldn’t be able to show H.264 HD pictures this way.
Why not use the same standard as everywhere else?
To make HD practical on terrestrial television, using H.264 is essential, unless lots of other channels are turned off to make room. Lots of existing sets made for the European market would work if we used H.264 with DVB-T, but even more wouldn’t, as they lack any HD tuner or decoder at all – only some sets made in the last couple of years would cope, so many people would need to upgrade anyway.
With DVB-T2 providing much more bandwidth, in the longer term it’s likely that a change to that standard would happen anyway. Launching HD now, and then using the new transmission technology later would force many people to upgrade twice in a short time, once for H.264 and then again for DVB-T2. By linking the two upgrades together, the intention is to ensure that once you do buy into Freeview HD, you won’t have to upgrade again for a long time as we should have the most technically advanced terrestrial TV system in the world.
What’s so special about DVB-T2?
DVB-T2 can provide more capacity for programmes than DVB-T. Tests suggest around 60 per cent more capacity for the same robustness of signal. With DVB-T, it’s often been a much harsher trade-off, for example with the main BBC multiplex being more robust, but carrying fewer channels than the ITV/Channel 4 one, and some multiplexes being more susceptible to interference.
You can read up on the maths behind T2 here (PDF).
Does this mean my existing equipment is obsolete?
No. Only one of the six multiplexes - the digital TV transmission frequencies, essentially - in the UK is converting to DVB-T2. All the others will continue broadcasting DVB-T with MPEG 2 pictures for the foreseeable future. You will be able to continue watching the existing Freeview channels, and you only need to invest in new equipment if you want to watch HD services.
Will more channels move to the new technologies in future?
It’s possible, and during the downtime of the HD channels, they may sublet capacity to other channels, perhaps SD ones using H.264 video. But we’d consider it very unlikely that all the current DVB-T/MPEG 2 transmissions will cease much before the 2020s - the BBC won’t be in a rush to disenfranchise viewers, and the operators of the commercial multiplexes won’t switch over until they can convince their customers (the channels they carry) that they won’t lose out on audiences by switching to DVB-T2/H.264. Yes, in the long term, all the multiplexes will probably move to DVB-T2 and H.264, even for SD. But like we said, don’t expect it any time soon. ®
Freeview HD - your questions answered
COMMENTS
I'll get back to you...
For the full technical details of the change, since I don't have them in my notes, I shall have to go back to one of my BBC engineering sources again - I'd rather be completely right than attempt to paraphrase from memory and make a hash of it, if we're going to get into real technical nitty gritty, but my recollection is that it's something to do with PAFF/MBAFF that caused issues with some PC codecs.
It's not, of course, the first time that software developers have skimped: look at the split NIT problem, which, in essence, could have been avoided by coding to the specs, which always allowed for multi-part tables. It crashed quite a few boxes because they were coded instead on the assumption that the single part NIT in use at the time was how it would remain.
DVB-T2 will provide 67% higher bitrate in the UK.
@Mage "The Neotion is a stop-gap solution for Countries with some DVB-T TVs that do MPEG2 and have launched DVB-T MPEG4 SD TV, New Zealand, Estonia, Ireland, France. About 20 countries."
"The Neotion "CAM" does however work with Irish test transmissions, but not on all models of TVs."
Neotion does not support HE-AAC audio that is used in Denmark, Norway and will be used in Sweden, Finland shortly.
HE-AAC audio is part of the Irish spec. too. The Irish tests are, however, currently being broadcast using MP2 audio.
@Mage"Frankly I'm sceptical about the claimed 60% saving of DVB-T2 compared with DVB-T"
But the PSB-3 DVB-T2 HD multiplex will broadcast with 40.2 Mbit/sec from December 2. The other DVB-T muxes will have a bitrate of 24.1 Mbit/sec. 40.2/24.1 = 1.67 = +67%.
This is not just theory - its a proven fact.
The 30% was known to be to low right from the start of the DVB-T2-TM (the technical workgroup) - just not by how much.
Lars :)
one more day and counting
just a reminder incase you forgot
one more day before winterhill goes live, and counting
still no kit to buy or play with, sad.
PR disaster
Incompetent regulators with no feeling for consumer sentiment and complicit cynical manufacturers of unupgradable hardware (some of which they even have the audacity to market as "green" technology) have contrived to create a PR disaster. Millions of recently upgraded licence payers are going to feel hoodwinked and will say "screw Freeview HD - I'm not pissing more money up the wall, I'm going to wait till Freeview XH3D comes out". And that will probably happen within 5 years.
For now all the looser-vision shopping channels and unnecessary "+1" channels should be switched off to make enough space for proper channels to be broadcast in HD using the DVB-T standard.
EPG encoding
The video will be unencrypted; non-compliant receivers will still be able to tune into it. Yes, they'll have no broadcast EPG - but then, plenty of PVRs and PVR software manage to work without one anyway, retrieving information from various online sources.
Personally, I would have imagined that most of the people capable of making something like Myth work would find it simple enough to set up an online EPG feed. With programmes in the clear, and only the EPG data encrypted, you'll be able to tune in, add net-sourced EPG and you'll have everything you need to record - just as Windows Media Centre and many other programs (and even the sacred Tivo) have managed for year, without an OTA EPG.
And as it's the OTA EPG that will contain the meta-data, rather than some artefact of the video streams themselves, what exactly is the problem? Other than the fact that you won't pick up last minute schedule changes or over-runs, you'll have a functioning PVR.
It seems to me that the merest whiff of the word "encryption" has made a lot of people panic and assume they won't be able to do this - but it should be perfectly possible.
Yes, only approved PVRs, get the EPG, and there may be content restrictions (just as there already are on Freesat - one copy of an HD show to Bluray, for example, unlimited copies in SD), but those don't seem to be causing major hassles for Freesat, frankly.
There is no encryption planned or proposed on Freeview HD. And nothing that's been proposed will stop users of non-approved equipment with an alternatively sourced EPG from recording what they want, when they want.
