OT - Ofcom admits DAB sound quality isn't good enough

http://www.digitalradiotech.co.uk/ar...ood-enough.php

Ofcom's Director of Radio & Multimedia, Peter Davies, has said:

"I don't think the sound quality [on DAB] is good enough."

But he then goes on to say that they can't tell the broadcasters what bit
rate levels to use (err, of course they can, they're the bloody regulators),
and what he failed to mention was that under his leadership he's allowed the
bit rates to be reduced to 112 kbps (all of the stereo stations on the new
national DAB multiplex that will launch next summer will use 112 kbps,
whereas the current minimum bit rate used for stereo stations is 128 kbps)
and there were no music stations broadcasting in mono on DAB before Ofcom
came into being, but now there's loads of mono music stations on DAB.

Overall, the audio quality is as bad as it is BECAUSE of the regulation -
the BBC wouldn't have used lower bit rates than commercial radio - because
the Radio Authority, which regulated radio before Ofcom, set the minimum bit
rate for stereo stations to be 128 kbps in the first place, which is the
main problem with DAB's sound quality, and Ofcom has carried on allowing the
audio quality to be degraded further still.



--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

and what he failed to mention was that under his leadership he's allowed the
bit rates to be reduced to 112 kbps (all of the stereo stations on the new
national DAB multiplex that will launch next summer will use 112 kbps,
whereas the current minimum bit rate used for stereo stations is 128 kbps)
--
Steve -www.digitalradiotech.co.uk- Digital Radio News & Info

Surely there's not much audible difference between 112 and 128 kbps?

Dave W wrote:
and what he failed to mention was that under his leadership he's allowed the
bit rates to be reduced to 112 kbps (all of the stereo stations on the new
national DAB multiplex that will launch next summer will use 112 kbps,
whereas the current minimum bit rate used for stereo stations is 128 kbps)

--

Steve -www.digitalradiotech.co.uk- Digital Radio News & Info


Surely there's not much audible difference between 112 and 128 kbps?


Actually, they "think" that they can justify this reduction by using the
new coder from Coding Technologies.
The coder is actually better than what is in use now (Phillips).

However if services, in the future want to add MOT slide show (as I
think most will), this will steal bit-rate from what is available to the
audio.
We did some tests at 112k with MOT and it puts the quality back way
below that of the original 128k.

A sorry state for the future of UK DAB.

A

Dave W wrote:
and what he failed to mention was that under his leadership he's
allowed the bit rates to be reduced to 112 kbps (all of the stereo
stations on the new national DAB multiplex that will launch next
summer will use 112 kbps, whereas the current minimum bit rate used
for stereo stations is 128 kbps) Steve -www.digitalradiotech.co.uk-
Digital Radio News & Info

Surely there's not much audible difference between 112 and 128 kbps?


This is what Karlheinz Brandenberg has to say about bit rates vs quality in
a tutorial paper called "MP3 and AAC explained":

"Lower bit-rates will lead to
higher compression factors, but lower quality of the compressed
audio. Higher bit-rates lead to a lower probability
of signals with any audible artifacts. However, different
encoding algorithms do have "sweet spots" where
they work best. At bit-rates much larger than this target
bit-rate the audio quality improves only very slowly
with bit-rate, at much lower bit-rates the quality decreases
very fast."

The codec used on DAB is MP2, and its sweet spot is 192 kbps, so 128 kbps is
already waaaaaaay lower than its sweet spot, and the chumps at Ofcom are
allowing the commercial stations to go even lower to 112 kbps.



--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Andy Dee wrote:
Dave W wrote:
and what he failed to mention was that under his leadership he's
allowed the bit rates to be reduced to 112 kbps (all of the stereo
stations on the new national DAB multiplex that will launch next
summer will use 112 kbps, whereas the current minimum bit rate used
for stereo stations is 128 kbps)
--

Steve -www.digitalradiotech.co.uk- Digital Radio News & Info


Surely there's not much audible difference between 112 and 128 kbps?


Actually, they "think" that they can justify this reduction by using
the new coder from Coding Technologies.
The coder is actually better than what is in use now (Phillips).


The BBC use Coding Technologies' new encoders already (as do a lot of other
DAB stations), and the BBC stations sound crap at 128 kbps, so I dread to
think what 112 kbps will sound like.


However if services, in the future want to add MOT slide show (as I
think most will), this will steal bit-rate from what is available to
the audio.
We did some tests at 112k with MOT and it puts the quality back way
below that of the original 128k.


Who is "we"?


A sorry state for the future of UK DAB.


Indeed.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

DAB sounds worse than FM wrote:
Dave W wrote:
and what he failed to mention was that under his leadership he's
allowed the bit rates to be reduced to 112 kbps (all of the stereo
stations on the new national DAB multiplex that will launch next
summer will use 112 kbps, whereas the current minimum bit rate used
for stereo stations is 128 kbps) Steve -www.digitalradiotech.co.uk-
Digital Radio News & Info

Surely there's not much audible difference between 112 and 128 kbps?


This is what Karlheinz Brandenberg


Forgot to mention: he's one of the two main people that invented MP3.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

DAB sounds worse than FM wrote:
Dave W wrote:
and what he failed to mention was that under his leadership he's
allowed the bit rates to be reduced to 112 kbps (all of the stereo
stations on the new national DAB multiplex that will launch next
summer will use 112 kbps, whereas the current minimum bit rate used
for stereo stations is 128 kbps) Steve -www.digitalradiotech.co.uk-
Digital Radio News & Info
Surely there's not much audible difference between 112 and 128 kbps?


This is what Karlheinz Brandenberg has to say about bit rates vs quality in
a tutorial paper called "MP3 and AAC explained":

"Lower bit-rates will lead to
higher compression factors, but lower quality of the compressed
audio. Higher bit-rates lead to a lower probability
of signals with any audible artifacts. However, different
encoding algorithms do have "sweet spots" where
they work best. At bit-rates much larger than this target
bit-rate the audio quality improves only very slowly
with bit-rate, at much lower bit-rates the quality decreases
very fast."

The codec used on DAB is MP2, and its sweet spot is 192 kbps, so 128 kbps is
already waaaaaaay lower than its sweet spot, and the chumps at Ofcom are
allowing the commercial stations to go even lower to 112 kbps.



Yes, typical of just about everything in this country now - do it on the
cheap/bodge it for now/come back to it later if anyone complains, but
let's hope that they forget. Someone correct if I'm wrong, but isn't the
DAB standard that we use in the UK a poorer implementation - other
countries are using something more robust?

IMO, DAB has a lot of potential but I can hear marked differences in
quality between DAB and FM on many stations, FM sounding a lot better
generally. It leaves me preferring FM. It reminds of the "pile 'em high,
sell 'em cheap" saying. The same can be said for HDDTV too - rather than
ensure that come the analogue switch off in 2012 we get access to a
sensible number of HD transmissions on Freeview Ofcom want to sell-off
the spectrum to mobile 'phone operators and the like, forcing us into
the arms of Murdoch if we want to watch any HDTV. Great - not.

There are parallels here too outside of broadcasting - good old HMG did
flood defences on the cheap, slashing the budget last year, hoping that
they'd get away with it. It's obvious to those poor people that who are
flooded out that yet again, it's a case of false economy.

When will we do things right in this country, FFS?


Clem

Clem Dye wrote:
DAB sounds worse than FM wrote:
Dave W wrote:
and what he failed to mention was that under his leadership he's
allowed the bit rates to be reduced to 112 kbps (all of the stereo
stations on the new national DAB multiplex that will launch next
summer will use 112 kbps, whereas the current minimum bit rate used
for stereo stations is 128 kbps) Steve -www.digitalradiotech.co.uk-
Digital Radio News & Info
Surely there's not much audible difference between 112 and 128 kbps?


This is what Karlheinz Brandenberg has to say about bit rates vs
quality in a tutorial paper called "MP3 and AAC explained":

"Lower bit-rates will lead to
higher compression factors, but lower quality of the compressed
audio. Higher bit-rates lead to a lower probability
of signals with any audible artifacts. However, different
encoding algorithms do have "sweet spots" where
they work best. At bit-rates much larger than this target
bit-rate the audio quality improves only very slowly
with bit-rate, at much lower bit-rates the quality decreases
very fast."

The codec used on DAB is MP2, and its sweet spot is 192 kbps, so 128
kbps is already waaaaaaay lower than its sweet spot, and the chumps
at Ofcom are allowing the commercial stations to go even lower to
112 kbps.
Yes, typical of just about everything in this country now - do it on
the cheap/bodge it for now/come back to it later if anyone complains,
but let's hope that they forget. Someone correct if I'm wrong, but
isn't the DAB standard that we use in the UK a poorer implementation
- other countries are using something more robust?


Yes, that's basically it. The UK, Denmark and Norway are using DAB, but
because so many countries refused to use DAB because it is too inefficient
and out of date, WorldDAB was forced to design DAB+ (which is DAB but with
the AAC+ audio codec and stronger error correction, so reception quality
will be more robust), so pretty much everybody will use DAB+, whereas we're
stuck with DAB for a few more years before we can also switch to DAB+, but
the problem is that there's 5 million legacy DAB receivers sold so far which
will all be made obsolete by the switch.

Basically, DAB is being scrapped (albeit slowly), and it will be replaced by
DAB+.


IMO, DAB has a lot of potential but I can hear marked differences in
quality between DAB and FM on many stations, FM sounding a lot better
generally. It leaves me preferring FM.


Absolutely.


It reminds of the "pile 'em
high, sell 'em cheap" saying.


That's exactly what it is. The scandalous thing though is that all of the
technologies that are being used for DAB+ (apart from one) were already
available in the mid 1990s, so they could have re-designed DAB and there
wouldn't have been the current audio quality problems.

The people to blame are primarily the BBC executives, because the BBC R&D
department published documents extolling the virtues of using AAC (whcih
would have solved the audio quality problems alone), but the BBC executives
must have just ignored what they were saying.


The same can be said for HDDTV too -
rather than ensure that come the analogue switch off in 2012 we get
access to a sensible number of HD transmissions on Freeview Ofcom
want to sell-off the spectrum to mobile 'phone operators and the
like, forcing us into the arms of Murdoch if we want to watch any
HDTV. Great - not.


Freesat will carry a few free-to-air HDTV channels, and that will have
nothing to do with Murdoch, and we'll all have ADSL2+ within the next 2-3
years, so we'll be able to receive HDTV via broadband as well.

Also, the broadcasters will be able to use DVB-T2 to provide more HDTV
channels on Freeview than the broadcasters are letting on - they're just
making a land-grab for the spectrum, and I actually agree with Ofcom on
this, because it's just bad long-term policy to gift this spectrum to the
broadcasters.


There are parallels here too outside of broadcasting - good old HMG
did flood defences on the cheap, slashing the budget last year,
hoping that they'd get away with it.


Hmm, this all sounded far too much like 24-hour rolling news channels trying
to think up new stories to fill the time rather (a bit like how they started
blaming the Portuguese police for being incompetent just because they
weren't doing things the way British police were doing things, i.e. briefing
the media every 2 seconds) than there being any proof that the flood
defences have actually been done on the cheap, which was the case in New
Orleans.


It's obvious to those poor
people that who are flooded out that yet again, it's a case of false
economy.


I'd agree with you if they did cut budgets for flood defences, but as I say
above, I'm sceptical that they actually have cut budgets.


When will we do things right in this country, FFS?


On the subject of broadcast quality only: when they disband Ofcom...


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Clem Dye wrote:

There are parallels here too outside of broadcasting - good old HMG
did flood defences on the cheap, slashing the budget last year,
hoping that they'd get away with it. It's obvious to those poor
people that who are flooded out that yet again, it's a case of false
economy.


I've just heard that they're going to cover this on BBC1 at 7.30, so maybe
they have more evidence than they previously had, so I might be proved wrong
on this.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

What has this got to do with digital TV, the subject of the newsgroup?