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Looks like the end is in sight for old DVB kit

everthewatcher

everthewatcher

Forum Supporter
Looks like Freeview are sounding out how many boxes and TVs are in use that don't support DVB-T2 with a view to using its codecs for SD transmissions in future.

Channel 71 is now using MPEG-4 AVC and HE-AAC codecs that until now have only been used for DVB-T2 (HD). Anything DVB-T2 capable will be fine but older boxes and TVs, like a bedroom TV here, won't be.

More info here: https://rxtvinfo.com/2025/freeview-technical-upgrade-could-make-older-screens-go-blank/
 
everthewatcher said:
Channel 71 is now using MPEG-4 AVC and HE-AAC codecs that until now have only been used for DVB-T2 (HD). Anything DVB-T2 capable will be fine but older boxes and TVs, like a bedroom TV here, won't be.
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They're not supposed to do that on DVB-T muxes. If they want to do that the correct way is to convert an entire mux to DVB-T2. We have standards for a reason.

As for "anything DVB-T2 capable will be fine" - not necessarily. Those codecs are not supposed to be used on DVB-T and I can easily see some DVB-T2 gear not handling that.
 
Linked article says:

"However, broadcasters may hope the change does remain unnoticed. That would indicate that there are sufficiently small numbers of incompatible TVs and set-top-boxes around to warrant considering switching other services across."

No, that would indicate very few people are watching "That's TV 3" and just shrug and watch something else if it doesn't work.
 
Black Hole said:
Might this explain the reboots some of us see, or is it not yet rolled out?
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Reads to me like it already rolled out. Audio set to multi channel should show it, AAC is converted to Dolby Digital for multi channel capability even if it is only actually in stereo eg ITV1 HD. MPEG audio used by std def is converted to LPCM.
 
Just retuned my HDR Fox T2 and on selecting channel 71 I get That's TV 3 and as expected my home cinema amp says the sound is Dolby Digital 2.0. Double checked and channel 3 ITV1 says LPCM 2.0 whereas channel 103 ITV1 HD says Dolby Digital 2.0. All as expected, That's TV 3 has AAC audio so I think we can assume it has AVC video as well.

The picture quality of That's TV 3 is dire even on my 32" TV, I couldn't stand to watch it regardless of what was on. The article points out the resolution has been reduced as well as the bit rate being reduced, so it's a Legovision channel now. I don't understand how market forces support that, surely no-one watches these channels?
 
Owen Smith said:
They're not supposed to do that on DVB-T muxes.
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Says who?
Those codecs are not supposed to be used on DVB-T
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Says who? Things move on even, if that was the old rule (yet to be proven). HD capable gear has now been around for over 15 years.
I can easily see some DVB-T2 gear not handling that.
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Demodulation and decoding are entirely separate processes. There is absolutely no reason why MPEG4 codecs can't be used with DVB-T on a suitable receiver, just as there is no problem using MPEG2 codecs with DVB-T2 (although there's not much point given its less efficient use of space).
 
prpr said:
Says who? Things move on even, if that was the old rule (yet to be proven). HD capable gear has now been around for over 15 years.
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I've changed job several times since the place I could have asked and got references to specs.
prpr said:
Demodulation and decoding are entirely separate processes. There is absolutely no reason why MPEG4 codecs can't be used with DVB-T on a suitable receiver, just as there is no problem using MPEG2 codecs with DVB-T2 (although there's not much point given its less efficient use of space).
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But why would you use DVB-T given its less efficient use of bandwidth? If they're going to start broadcasting channels that can't be played by DVB-T only equipment due to AVC/AAC, why not go the whole hog and switch to DVB-T2? Hopefully this is a soft trial on the road to getting there, putting increasingly important channels out in AVC/AAC until they convince themselves switching to DVB-T2 won't be an issue. Though it would mean everyone has to retune at the same time when the modulation changes.
 
Original Freeview / Ofcom licensing mandated MP4 via -T2 for HD although France (and others used it quite sucessfully on DVB-T).

Indeed there were reports from caravan/motorhome types that their TVs had audio but no pictures if memory serves me correctly.
Even today https://www.digitalbitrate.com/dtv.php?mux=R1,IDF&liste=1&live=1&lang=en there's one channel on that French mux using MP2 while the others are E-AC3 (DD+ ?) and is DVB-T modulation.

Now HE-AAC would be most unlikely to be included on older DVB-T only sets with MP4 codecs inside as that is a Freeview specific codec.

So Ofcom almost certainly must have agreed to a change to that original mandate to allow this to happen (HE-AAC, if not MP4). {Not that I can find any reference to it so far by searching their site}

It's not really a lot different to the DAB / DAB+ changes that have happened where the DAB+ services have encouraged people to get new gear, when needed.
 
prpr said:
Demodulation and decoding are entirely separate processes. There is absolutely no reason why MPEG4 codecs can't be used with DVB-T on a suitable receiver, just as there is no problem using MPEG2 codecs with DVB-T2 (although there's not much point given its less efficient use of space).
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Perhaps not, from theoretical point of view, but unless receivers have been programmed to expect that...
 
Has anyone been able to test an HD Fox T2 with this change? Mine is in Yorkshire in use by my parents on their bedroom TV. Annoyingly that TV is a 1080p 24" Sony made long after DVB-T2 existed but it doesn't support it, hence the HD Fox T2. Ofcom mandating DVB-T2 in TVs would also have prevented this stupidity, but they were spineless at the time.
 
Black Hole said:
Perhaps not, from theoretical point of view, but unless receivers have been programmed to expect that...
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The transport stream is presented to the decoding hardware. It doesn't know or care how it got there, whether it came off air (via T or T2 modulation) or off disk (for a recorder).
 
prpr said:
There is absolutely no reason why MPEG4 codecs can't be used with DVB-T on a suitable receiver, just as there is no problem using MPEG2 codecs with DVB-T2 (although there's not much point given its less efficient use of space).
Click to expand...
Ages ago I looked through some of the sites listed on www.digitalbitrate.com and I remember seeing MPEG4 on DVB-T. I've just had a quick look and there are still some there. If I'm to believe it all the multiplexes in Rome use DVB-T but all the transmission are MPEG4. What I find confusing is that in Germany they are using DVB-T2 and HEVC but, unlike our DVB-T2, the mux's capacity is approximately the same as our DVB-T. I must be missing something (256 QAM UK vs 64 QAM Germany?)
 
prpr said:
The transport stream is presented to the decoding hardware.
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In some designs. I can believe there are designs where firmware gets in the way and screws up in some situations, for example unexpected codecs in a DVB-T multiplex.
prpr said:
It doesn't know or care how it got there, whether it came off air (via T or T2 modulation) or off disk (for a recorder).
Click to expand...
Again in some designs.
 
My crappy Bush HD ready (but no ability to scan for or store HD mux) can find That's TV 3.
I've just fired up my old 9150T (no ability to use DVB-T2 multiplex and so might not have mpeg4/aac on board) and it can't find That's TV 3. So that's one old design that can't cope with an unexpected codec.
Owen Smith said:
Again in some designs.
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Probably older devices.
 
Owen Smith said:
Has anyone been able to test an HD Fox T2 with this change? Mine is in Yorkshire in use by my parents on their bedroom TV. Annoyingly that TV is a 1080p 24" Sony made long after DVB-T2 existed but it doesn't support it, hence the HD Fox T2. Ofcom mandating DVB-T2 in TVs would also have prevented this stupidity, but they were spineless at the time.
Click to expand...
Mandated in Freeview HD spec. After ETSI ratification of DVB-T2 as a Standard in September 2009. All new Freeview HD product designs launched after April 2011 in UK had to also include HE-AAC transcoding to DD (Phil Layton, BBC R&D blog).

UK Freeview HD had a technical launch broadcast from 2nd December 2009. Official launch was 30th March 2010.

Note that the Freeview spec changes always applied to "new Freeview product designs" and makers were permitted to keep selling old stock (whether complete sets or component form to build more). In a Free Market.

Sadly the marketing-speak was all too keen to exploit the unwary - "HD Ready" anyone?

FWIW my HDR Fox-T2 found the new MP4 lcn 71 without a retune. (It was last retuned on 20th May). My Panny oled needed retuning as I have auto channel update off due to the silly lcn 101->1 not working for all HD channels (looking at you ITV in particular). I'd expect the HD Fox to be fine without retuning (@Black Hole to confirm, possibly).
{Note I don't run the CF's tunefix packages, should that make any difference.)
 
EEPhil said:
My crappy Bush HD ready (but no ability to scan for or store HD mux) can find That's TV 3.
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Yes but can it display the video and play the audio?
EEPhil said:
I've just fired up my old 9150T (no ability to use DVB-T2 multiplex and so might not have mpeg4/aac on board) and it can't find That's TV 3. So that's one old design that can't cope with an unexpected codec.
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But can it still play all the other channels on the multiplex? If so I suspect the powers that be will be happy with that. What they don't want is to prevent a load of people watching ITV1 SD and C4 SD.
 
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