In article , Dickie mint
wrote:
DAB sounds worse than FM wrote:
Jim Lesurf wrote:

Who does one contact at the BBC these days for reports/complaints
about technical matters like this?


. Be prepared for a very, very long wait before
they bother to sort it out.


There are only a handful of engineers in RA, but most of them read the
newsgroups as do the engineers looking after DTT & DSAT.

If any are reading this (or anyone else who can help)...

One of the things I wish to discover is the details of the 'chain' which
sends the audio data from a prom to FM R3, DTTV R3, and DTTV BBC4 (also
DAB), both 'live' and when rebroadcast a few days later. I'm trying to
determine where any 'differences' might arise for defined reasons like use
of convertors, different data rates, etc. Is there a detailed description
of this anywhere, or someone who can say?

IIUC DTTV R3 is on a different mux to BBCTV4, and I am also wondering if
the audio data for R3 is altered at some point outwith the direct control
of the BBC...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

On 2005-07-28, Jim Lesurf wrote:
In article , John Phillips
wrote:
On 2005-07-27, Jim Lesurf wrote:
I had been intending to record the entire 'Sea Symphony' onto DVD-R as
that is connected to the DTTV RX. I'm collecting comparison recordings
for doing an analysis at a later date. With some of the previous proms
I felt I'd been hearing artefacts/problems on the DTTV R3 rebroadcasts
that I wasn't hearing on the BBCTV 'live' sic broadcasts of the same
proms, so have been 'collecting data' for closer examination in due
course.

If you like I can send you a 48 ksample/s .wav on CD or DVD of today's
Prom re-broadcast, captured from R3 DAB, which may well be nominally
the same bitstream as R3 DTTV.

Yes please! :-) ...and many thanks for the battery. :-)

Will do.

Although isn't DAB at 32 ksamples/sec?...

Not as far as I am aware. Extract from the DAB standard: "The DAB system
uses MPEG Audio Layer II, suitably formatted for DAB transmission. For
48 kHz sampling frequency it uses the ISO/IEC 11172-3 standard [3] and
for 24 kHz sampling frequency it uses the ISO/IEC 13818-3 standard [14]."

Certainly, the optical S/PDIF output from my DAB tuner comes out at 48
kHz according to the display on the DAC.

I think DAB audio coding is the same as audio on DVB-T, and I think R3
DAB and R3 DVB-T both encode to 192 kbit/s these days. That's why I
think the R3 DAB and R3 DVB-T digital audio should be exactly the same
(if the TX chain is working well).

--
John Phillips

Jim Lesurf wrote:
In article , Dickie mint
wrote:
DAB sounds worse than FM wrote:
Jim Lesurf wrote:

Who does one contact at the BBC these days for reports/complaints
about technical matters like this?


. Be prepared for a very, very long wait before
they bother to sort it out.


There are only a handful of engineers in RA, but most of them read
the newsgroups as do the engineers looking after DTT & DSAT.

If any are reading this (or anyone else who can help)...

One of the things I wish to discover is the details of the 'chain'
which sends the audio data from a prom to FM R3, DTTV R3, and DTTV
BBC4 (also DAB), both 'live' and when rebroadcast a few days later.
I'm trying to determine where any 'differences' might arise for
defined reasons like use of convertors, different data rates, etc. Is
there a detailed description of this anywhere, or someone who can say?


You won't find a description of this on the net, but Mark Carver (who
posts on here) heard that Radios 1-4 on DTT "take a rather circuitous
route", which is obviously not best practice, and probably involves one
or more transcodes en route thus degrading the audio quality from what
it could be.


IIUC DTTV R3 is on a different mux to BBCTV4,


Correct.


and I am also wondering
if the audio data for R3 is altered at some point outwith the direct
control of the BBC...


R3 is on the SDN commercial multiplex, and there's a thread about how
this is distributed he

http://groups.google.co.uk/group/uk....b51f5b111c720b

But I think the problem is at the BBC's end of the chain, and they don't
seem to care less about R1-4 on DTT.


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

Find the cheapest Freeview, DAB & MP3 Player Prices:
http://www.digitalradiotech.co.uk/fr..._receivers.htm
http://www.digitalradiotech.co.uk/da...tal_radios.htm
http://www.digitalradiotech.co.uk/mp...rs_1GB-5GB.htm
http://www.digitalradiotech.co.uk/mp...e_capacity.htm

John Phillips wrote:
On 2005-07-28, Jim Lesurf wrote:
In article , John
Phillips wrote:
On 2005-07-27, Jim Lesurf wrote:
I had been intending to record the entire 'Sea Symphony' onto
DVD-R as that is connected to the DTTV RX. I'm collecting
comparison recordings for doing an analysis at a later date. With
some of the previous proms I felt I'd been hearing
artefacts/problems on the DTTV R3 rebroadcasts that I wasn't
hearing on the BBCTV 'live' sic broadcasts of the same proms, so
have been 'collecting data' for closer examination in due course.

If you like I can send you a 48 ksample/s .wav on CD or DVD of
today's Prom re-broadcast, captured from R3 DAB, which may well be
nominally the same bitstream as R3 DTTV.

Yes please! :-) ...and many thanks for the battery. :-)

Will do.

Although isn't DAB at 32 ksamples/sec?...

Not as far as I am aware. Extract from the DAB standard: "The DAB
system uses MPEG Audio Layer II, suitably formatted for DAB
transmission. For 48 kHz sampling frequency it uses the ISO/IEC
11172-3 standard [3] and for 24 kHz sampling frequency it uses the
ISO/IEC 13818-3 standard [14]."


Yes, R3 is 48kHz on DAB.


Certainly, the optical S/PDIF output from my DAB tuner comes out at 48
kHz according to the display on the DAC.

I think DAB audio coding is the same as audio on DVB-T,


Yes, both MPEG-1 Layer 2 (MP2).


and I think R3
DAB and R3 DVB-T both encode to 192 kbit/s these days.


Correct, apart from when Radio 5 Sports Extra is on during the day
(before 5 p.m.), in which case R3 is 160kbps on DAB but 192kbps on DTT.



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

Find the cheapest Freeview, DAB & MP3 Player Prices:
http://www.digitalradiotech.co.uk/fr..._receivers.htm
http://www.digitalradiotech.co.uk/da...tal_radios.htm
http://www.digitalradiotech.co.uk/mp...rs_1GB-5GB.htm
http://www.digitalradiotech.co.uk/mp...e_capacity.htm

"Jim Lesurf" wrote in message
...
If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late by
the
time you read this, but I have been listeing and am finding the sound
quite
awful. [1]Yet other BBC radio stations on the same mux seem fine, and the
UHF carrier level here seems OK...

The sound on DTT has always been awful and the Proms on the digital version
R3 is like listening through mud. In fact everything on the digital version
of R3 is like listening through mud so I listen on FM.

Further more the sound on BBC1 and is now actual WORSE than that of BBC3 and
BBC4 even though it uses a fixed bit rate.


Who does one contact at the BBC these days for reports/complaints about
technical matters like this?

Slainte,

Jim



[1] Effect something like dire levels of flutter multipath distortion on
*AM*. Makes massed strings sound more like a band of balalaikas!

--
Electronics
http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"spiney" wrote in message
oups.com...
All sound on DTT is mp3 format, which employs psycho-acoustic "tricks"
for bit rate reduction, yes it can sound awful.

Its in mp2 MUSICAM formant which is ****. They can't even be bothered to use
a decent codec like AT&T so they use the basic Fraunhoffer codec instead
which is useless even at very high bit rates.


Might be better to use fm sound and DTT picture, although then they're
not syncronised.

They are several minutes out of sync.


Sometimes, technicians put limiters, noise gates, etc, into sound
channel, which can muck things up even further.

In article ,
Agamemnon writes

"Jim Lesurf" wrote in message
...
If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late by
the
time you read this, but I have been listeing and am finding the sound
quite
awful. [1]Yet other BBC radio stations on the same mux seem fine, and the
UHF carrier level here seems OK...

The sound on DTT has always been awful and the Proms on the digital version
R3 is like listening through mud. In fact everything on the digital version
of R3 is like listening through mud so I listen on FM.



Further more the sound on BBC1 and is now actual WORSE than that of BBC3 and
BBC4 even though it uses a fixed bit rate.


Perhaps we're being "softened up" for things to come;(......

--
Tony Sayer

Mark Carver is wrong, both DTT and DAB use identical MP3 sound coding
(MP3 is the audio subset standard of MPEG2!).

"spiney" wrote in message
oups.com...
Mark Carver is wrong, both DTT and DAB use identical MP3 sound coding
(MP3 is the audio subset standard of MPEG2!).

No, you're wrong. DTT and DAB use MPEG1 layer 2 (aka MP2), which is a
broadcast standard. MP3 is correctly known as MPEG1 layer 3.

spiney wrote:
Mark Carver is wrong, both DTT and DAB use identical MP3 sound coding
(MP3 is the audio subset standard of MPEG2!).

You are the one that's wrong! You've shown what an ignorant fool you are
on more than one occasion,