In article , Dave Plowman
writes
In article ,
tony sayer wrote:
Certainly better than the general output on DAB, but still sounds very
"hard" and "metallic" even on the TV sound IHMO

I'd guess you're overloading something. Have you tried setting the output
of the STB lower - it's usually on the menu.


This is via the optical digi output Dave. Its a Sony box a few years
old. Sounds hard and harsh certainly not overloaded. The NICAM sound is
far better and pleasant. Suppose its the bit rates again:-((...

I'd defy *anyone* to tell the difference between DTTV and NICAM sound -
assuming no 'funnies'.


--
Tony Sayer

In article , tony sayer

wrote:
In article , Dave Plowman
writes

You also get the highest audio quality BBC radio services of any of
the alternatives, if you've got a half decent STB.


Certainly better than the general output on DAB, but still sounds very
"hard" and "metallic" even on the TV sound IHMO


Its a bit early for me to make comments on the sound quality of DTTV sound
as I've only had a receiver box for a few days! Also, I only linked it by
S/PDIF on Friday morning. (To a decent DAC - meridian 263.) In addition,
the input signal from the antenna is weak, so we get occasional periods of
breakup. To be fair I ought to give it longer and wait until I've been
using a better antenna feed. (Up to now, I've never taken TV very
seriously.)

However the sound seems quite good to me on the main channels. I
particularly have been enjoying BBC4 - for example the concert by James
Cullum (Jazz) and the masterclass by Barbara Bonney that was on last night.

Ignoring the occasional breakup, I have sometimes had the feeling that some
sibilance on voices has a slightly 'tuned' quality rather than being
broadband, but otherwise speech and music seem good.

However - possibly due to the weak signal - some of the radio channels seem
poorer at times. And on a couple of occasions the 'World Service' seemed to
have a lot of 'modulation noise' behind the voices. Are these services
transmitted with higher information losses than the main TV channels?

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

In article , tony sayer

wrote:
In article , Dave Plowman
writes

You also get the highest audio quality BBC radio services of any of
the alternatives, if you've got a half decent STB.


Certainly better than the general output on DAB, but still sounds very
"hard" and "metallic" even on the TV sound IHMO


Its a bit early for me to make comments on the sound quality of DTTV sound
as I've only had a receiver box for a few days! Also, I only linked it by
S/PDIF on Friday morning. (To a decent DAC - meridian 263.) In addition,
the input signal from the antenna is weak, so we get occasional periods of
breakup. To be fair I ought to give it longer and wait until I've been
using a better antenna feed. (Up to now, I've never taken TV very
seriously.)

However the sound seems quite good to me on the main channels. I
particularly have been enjoying BBC4 - for example the concert by James
Cullum (Jazz) and the masterclass by Barbara Bonney that was on last night.

Ignoring the occasional breakup, I have sometimes had the feeling that some
sibilance on voices has a slightly 'tuned' quality rather than being
broadband, but otherwise speech and music seem good.

However - possibly due to the weak signal - some of the radio channels seem
poorer at times. And on a couple of occasions the 'World Service' seemed to
have a lot of 'modulation noise' behind the voices. Are these services
transmitted with higher information losses than the main TV channels?

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 Sat, 15 Nov 2003 13:18:44 +0000 (GMT)
Jim Lesurf wrote:


When the receiver is picking up one multiplex, but then has the ability to
demodulate, symultaneously, more than one 'information channel' then how do
we best describe this? Should we be talking about 'dual demodulation' or
'de-multiplexing' or what?

From reading the linux-dvb lists, I believe the latter is the term in common use.

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

On Sat, 15 Nov 2003 13:18:44 +0000 (GMT)
Jim Lesurf wrote:


When the receiver is picking up one multiplex, but then has the ability to
demodulate, symultaneously, more than one 'information channel' then how do
we best describe this? Should we be talking about 'dual demodulation' or
'de-multiplexing' or what?

From reading the linux-dvb lists, I believe the latter is the term in common use.

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

In article ,
Jim Lesurf wrote:
It also seems very odd to me. I can't see that it saves them much money
as they are already employing switching, and the absence will deter
those who are aware of the problem from buying their unit! If I'd
realised this was not standard for pass through I'd have looked for an
alternative. Now I have the particular box I'll 'fix' the problem with
an external switch, but this is a measure I did not expect to be
required when I bought the receiver.

The main snag is that all Scarts are not alike. If you stick to stereo
audio and composite video, then they act as an in/out port. But once you
go to RGB or S-Video, they become an in *or* out. So a fully wired multi
socket adaptor unit can only be used for either ins or outs. And then
there's the problem with simply paralleling video circuits - they become
double terminated.

--
*Why is it that most nudists are people you don't want to see naked?*

Dave Plowman London SW 12
RIP Acorn

In article ,
Jim Lesurf wrote:
It also seems very odd to me. I can't see that it saves them much money
as they are already employing switching, and the absence will deter
those who are aware of the problem from buying their unit! If I'd
realised this was not standard for pass through I'd have looked for an
alternative. Now I have the particular box I'll 'fix' the problem with
an external switch, but this is a measure I did not expect to be
required when I bought the receiver.

The main snag is that all Scarts are not alike. If you stick to stereo
audio and composite video, then they act as an in/out port. But once you
go to RGB or S-Video, they become an in *or* out. So a fully wired multi
socket adaptor unit can only be used for either ins or outs. And then
there's the problem with simply paralleling video circuits - they become
double terminated.

--
*Why is it that most nudists are people you don't want to see naked?*

Dave Plowman London SW 12
RIP Acorn

more from the 'Glenn Booth school' of uk.rec.audio-ism:

That depends. Decent resolution DV (uncompressed) would be *huge*,
mpeg2 about 5 gigs or mpeg4 about 1 with no lesser quality.

I normally encode MPEG2 at about 7.5 MBits/second, but that's high -
most of the Digital TV broadcasts are at less than half of that data
rate. You're right that perceptually, MPEG4 and its cousins can give
equivalent results at much lower data rates.

It's difficult to say what the file size ratio at the same perceptual
quality is between mpeg2 and 4, because mpeg2 is so dominant it's hard to
find digital video not already mpeg2 encoded. It depends on the encoder and
skill of the compressionist, but I think 4:1 might be a good guess for
fully automated compression.

It sometimes annoys me the number of devices stuck with mpeg2, given
the huge superiority of mpeg4. If DVD had used mpeg4, the disks could
be smaller, have massive data redudancy making them virtually
indestructable, have much better resolution AND hold more footage!

MPEG2 had the advantage of being a standard, when the world was still
farting about trying to ratify MPEG4.

True. There's a lot of very interesting stuff in the mpeg4 spec, real-time
3d for example, but most encoder implementaions don't even do subtitles!

There is also a whole bunch of
stuff in the MPEG4 standard that isn't used on most currently
available CODECs. The increase in quality per bit rate is at the
expense of more demands on CPU power for encoding and decoding, which
meant more money when DVD was brought to market. It's all a doddle
now, of course, because the world is stuffed with 2GHz CPUs with not
much to do apart from run Microsoft office.

This is where I think the biggest problem with the DVD format lies. CD is
an excellent example of a format which pushed the technology of the time,
making it was very expensive at launch but becoming mainstream over time. I
don't think it is beyond our capability now to create a video format that
gives a better picture than film on any cinema screen, and that should have
been the aim of DVD.

I would imagine DVD to be the last physical storage media for movies, after
DVD it'll be all streams and downloads.

I'm out of date with digital cinema systems, but I seem to recall that
the market demand (years ago) was for at least 2000 vertical lines of
video, which means a huge number of pixels. Qualcomm quoted figures of
around 35 - 55 megbits/second for compressed data, which is at least
five times the data rate of most DVDs. That's about 45 Gigabytes of
storage for a 2 hour movie including audio. Things might have changed
with recent codec advances - I don't get to play with anything above
1080 lines these days.

I don't think it's impossible that 45gigs of mpeg2 be squashed down to
maybe 10gigs of an mpeg4-ish format, especially given recent advances in
audio compression.

--
Jim H jh
@333
.org

more from the 'Glenn Booth school' of uk.rec.audio-ism:

That depends. Decent resolution DV (uncompressed) would be *huge*,
mpeg2 about 5 gigs or mpeg4 about 1 with no lesser quality.

I normally encode MPEG2 at about 7.5 MBits/second, but that's high -
most of the Digital TV broadcasts are at less than half of that data
rate. You're right that perceptually, MPEG4 and its cousins can give
equivalent results at much lower data rates.

It's difficult to say what the file size ratio at the same perceptual
quality is between mpeg2 and 4, because mpeg2 is so dominant it's hard to
find digital video not already mpeg2 encoded. It depends on the encoder and
skill of the compressionist, but I think 4:1 might be a good guess for
fully automated compression.

It sometimes annoys me the number of devices stuck with mpeg2, given
the huge superiority of mpeg4. If DVD had used mpeg4, the disks could
be smaller, have massive data redudancy making them virtually
indestructable, have much better resolution AND hold more footage!

MPEG2 had the advantage of being a standard, when the world was still
farting about trying to ratify MPEG4.

True. There's a lot of very interesting stuff in the mpeg4 spec, real-time
3d for example, but most encoder implementaions don't even do subtitles!

There is also a whole bunch of
stuff in the MPEG4 standard that isn't used on most currently
available CODECs. The increase in quality per bit rate is at the
expense of more demands on CPU power for encoding and decoding, which
meant more money when DVD was brought to market. It's all a doddle
now, of course, because the world is stuffed with 2GHz CPUs with not
much to do apart from run Microsoft office.

This is where I think the biggest problem with the DVD format lies. CD is
an excellent example of a format which pushed the technology of the time,
making it was very expensive at launch but becoming mainstream over time. I
don't think it is beyond our capability now to create a video format that
gives a better picture than film on any cinema screen, and that should have
been the aim of DVD.

I would imagine DVD to be the last physical storage media for movies, after
DVD it'll be all streams and downloads.

I'm out of date with digital cinema systems, but I seem to recall that
the market demand (years ago) was for at least 2000 vertical lines of
video, which means a huge number of pixels. Qualcomm quoted figures of
around 35 - 55 megbits/second for compressed data, which is at least
five times the data rate of most DVDs. That's about 45 Gigabytes of
storage for a 2 hour movie including audio. Things might have changed
with recent codec advances - I don't get to play with anything above
1080 lines these days.

I don't think it's impossible that 45gigs of mpeg2 be squashed down to
maybe 10gigs of an mpeg4-ish format, especially given recent advances in
audio compression.

--
Jim H jh
@333
.org

On Fri, 14 Nov 2003 13:44:13 -0000, "Keith G"
wrote:

Apparently the one to go for is the Sagem IDT602 (see
http://www.sagem.com/en/produits-en/...-itd602-en.htm) which
is currently available from Woolies and Safeway for £59.99 instead of the
'normal' £100.

I went to Woolies in Southampton intending to but one of these
devices, but they had none left. It must have been all of the people
who read this group having the same idea and buying them all up....
;-)


--
Chris Isbell
Southampton
UK