Sound from TV.
 

Got an odd problem.

Sound from TV goes to an external setup via Toslink, and the volume can't
be adjusted on the TV - ie a proper line out. TV set speakers switched off.

Have a BT STB (Humax) fed to the TV by HDMI. The volume on that can be
adjusted by the remote in the normal way.

Set both to an SD channel - say BBC1 - and adjust the level from the STB
so it matches the TV when you switch between them. STB says 85 on the
screen.

Now change them both to the same HD channel, say BBC1 again. STB is now,
I'd guess, 6dB louder than the TV on the same channel - enough to annoy.
To make it match has to be reduced to 75.

And all that before any transmitted differences in level between SD and
HD. ;-)

Both TV and STB are set to stereo - and no strange balance from one which
would indicate it might be two channels from 5.1 or whatever.

Seems to exhibit the same behaviour between HD and SD on all channels.

--
*One tequila, two tequila, three tequila, floor.

Dave Plowman London SW
To e-mail, change noise into sound.

Sound from TV.
 

In article , Dave Plowman (News)
wrote:
Got an odd problem.

Sound from TV goes to an external setup via Toslink, and the volume
can't be adjusted on the TV - ie a proper line out. TV set speakers
switched off.

You don't say if the 'toslink' sends both stereo and surround as stereo
spdif, or sends the surround as 'bitstream'. I'll assume the former for
what I say below...


Have a BT STB (Humax) fed to the TV by HDMI. The volume on that can be
adjusted by the remote in the normal way.

Set both to an SD channel - say BBC1 - and adjust the level from the STB
so it matches the TV when you switch between them. STB says 85 on the
screen.

Now change them both to the same HD channel, say BBC1 again. STB is now,
I'd guess, 6dB louder than the TV on the same channel - enough to annoy.
To make it match has to be reduced to 75.

is it that the TV gets quieter or the STB gets louder?

And all that before any transmitted differences in level between SD and
HD. ;-)

Both TV and STB are set to stereo - and no strange balance from one
which would indicate it might be two channels from 5.1 or whatever.

Seems to exhibit the same behaviour between HD and SD on all channels.

I wonder if the TV/STB treat the *possibility* of surround on HD
differently. i.e. One mixs down to stereo when this happens by applying a
scaledown that is engaged when it detects surround. The other simply adds
the channels. So in effect is preset to give 'the same level' when the rear
and center are added. i.e. it scales down the L and R as if they were Lf
and Rf.

I don't know the current situation, but 1-2 years ago when I was first
looking into HDTV sound and the processing of surround in broadcasts I had
the impression that various parts of the industry weren't actually all
following the same rules for such matters. And that 'standards' were
evolving in a haphazard and 'do first and announce later' way that made it
almost impossible for them all to keep together.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Sound from TV.
 

I've also noticed that on a friends tv, a Samsung, that hd sound is
generally quieter than sd on all the channels that are duplicated.
Mind you I'm not very surprised having listened to the dogs dinner on their
I player output as far as level is concerned.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Dave Plowman (News)" wrote in message
...
Got an odd problem.

Sound from TV goes to an external setup via Toslink, and the volume can't
be adjusted on the TV - ie a proper line out. TV set speakers switched
off.

Have a BT STB (Humax) fed to the TV by HDMI. The volume on that can be
adjusted by the remote in the normal way.

Set both to an SD channel - say BBC1 - and adjust the level from the STB
so it matches the TV when you switch between them. STB says 85 on the
screen.

Now change them both to the same HD channel, say BBC1 again. STB is now,
I'd guess, 6dB louder than the TV on the same channel - enough to annoy.
To make it match has to be reduced to 75.

And all that before any transmitted differences in level between SD and
HD. ;-)

Both TV and STB are set to stereo - and no strange balance from one which
would indicate it might be two channels from 5.1 or whatever.

Seems to exhibit the same behaviour between HD and SD on all channels.

--
*One tequila, two tequila, three tequila, floor.

Dave Plowman London SW
To e-mail, change noise into sound.

Sound from TV.
 

In article ,
Brian Gaff wrote:
I've also noticed that on a friends tv, a Samsung, that hd sound is
generally quieter than sd on all the channels that are duplicated.
Mind you I'm not very surprised having listened to the dogs dinner on their
I player output as far as level is concerned.

Not really my question, Brian. It's why the two 'tuners' appear to give
different levels from HD, while adjusted for the same from SD.

The reason why the levels differ between SD and HD on a single tuner is
simple. The broadcasters don't care.

--
*Proofread carefully to see if you any words out or mispeld something *

Dave Plowman London SW
To e-mail, change noise into sound.

Sound from TV.
 

In article ,
Jim Lesurf wrote:
In article , Dave Plowman (News)
wrote:
Got an odd problem.

Sound from TV goes to an external setup via Toslink, and the volume
can't be adjusted on the TV - ie a proper line out. TV set speakers
switched off.

You don't say if the 'toslink' sends both stereo and surround as stereo
spdif, or sends the surround as 'bitstream'. I'll assume the former for
what I say below...

There are a number of options in the TV menu for the digital output. Most
of which I don't understand. It is set to PCM and stereo.

If you're interested, I'll wright them all down. The STB seems to have
less options - although I'm using HDMI via the TV for it rather than its
Toslink to the external sound system.

Which is actually more convenient as the mute button still works which is
doesn't on the TV when sending digital. Which seems silly to me.


Have a BT STB (Humax) fed to the TV by HDMI. The volume on that can be
adjusted by the remote in the normal way.

Set both to an SD channel - say BBC1 - and adjust the level from the
STB so it matches the TV when you switch between them. STB says 85 on
the screen.

Now change them both to the same HD channel, say BBC1 again. STB is
now, I'd guess, 6dB louder than the TV on the same channel - enough to
annoy. To make it match has to be reduced to 75.

is it that the TV gets quieter or the STB gets louder?

And all that before any transmitted differences in level between SD
and HD. ;-)

Both TV and STB are set to stereo - and no strange balance from one
which would indicate it might be two channels from 5.1 or whatever.

Seems to exhibit the same behaviour between HD and SD on all channels.

I wonder if the TV/STB treat the *possibility* of surround on HD
differently. i.e. One mixs down to stereo when this happens by applying
a scaledown that is engaged when it detects surround. The other simply
adds the channels. So in effect is preset to give 'the same level' when
the rear and center are added. i.e. it scales down the L and R as if
they were Lf and Rf.

I don't know the current situation, but 1-2 years ago when I was first
looking into HDTV sound and the processing of surround in broadcasts I
had the impression that various parts of the industry weren't actually
all following the same rules for such matters. And that 'standards' were
evolving in a haphazard and 'do first and announce later' way that made
it almost impossible for them all to keep together.

Thanks Jim. That does sound a logical explanation.

--
*I'm reading a book about anti-gravity. I just can't put it down.*

Dave Plowman London SW
To e-mail, change noise into sound.

Sound from TV.
 

Oh, I see, but surely if you are correct, then each tuner has a different
idea of the difference, or your example would b be the same on all tuners.
Some time ago, I read that in DAB it was possible to get the sound of all
stations equal, but very few radios impliment this. I wonder as this is
after all digital whether some very basic processing on the audio side might
make this problem go away. After all we are always being told that Sony or
Panasonic have video processing to get better looking bpictures, what about
better matched sound as well, or are they all assuming we are interested in
silence?
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Dave Plowman (News)" wrote in message
...
In article ,
Brian Gaff wrote:
I've also noticed that on a friends tv, a Samsung, that hd sound is
generally quieter than sd on all the channels that are duplicated.
Mind you I'm not very surprised having listened to the dogs dinner on
their
I player output as far as level is concerned.

Not really my question, Brian. It's why the two 'tuners' appear to give
different levels from HD, while adjusted for the same from SD.

The reason why the levels differ between SD and HD on a single tuner is
simple. The broadcasters don't care.

--
*Proofread carefully to see if you any words out or mispeld something *

Dave Plowman London SW
To e-mail, change noise into sound.

Sound from TV.
 

In article , Brian Gaff
wrote:
Oh, I see, but surely if you are correct, then each tuner has a
different idea of the difference, or your example would b be the same on
all tuners.

"Tuner" is probably too wide a term here. What probably matters is the way
the audio part of the stream is handled at a relatively late stage of the
process. e.g. where the mpeg/dolby/aac is converted to LPCM or mixed down
from surround, etc.


Some time ago, I read that in DAB it was possible to get the
sound of all stations equal, but very few radios impliment this. I
wonder as this is after all digital whether some very basic processing
on the audio side might make this problem go away.

I guess the problem at root is the same as Dave has found with TV. That the
broadcasts and receivers aren't all following exactly the same 'standards'.

To get levels to match across broadcasters they'd either have to do that at
source or use a common mode way of flagging what correction a receiver
needed to make. *And* have all the makers of recievers adopt it in exactly
the same way. Given the way the industry behaves I suspect being successful
at herding cats is more likely! :-/

After all we are
always being told that Sony or Panasonic have video processing to get
better looking bpictures, what about better matched sound as well, or
are they all assuming we are interested in silence? Brian

Then there's the question of what 'matched sound' would mean when you
include R1 and R3 with Karsk FM. *And* on items from small bedside radios
to large high-quality hifi/AV systems. Even ignoring the differences
between stereo and surround.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Sound from TV.
 

In article , Dave Plowman (News)
wrote:
In article , Jim Lesurf
wrote:

You don't say if the 'toslink' sends both stereo and surround as
stereo spdif, or sends the surround as 'bitstream'. I'll assume the
former for what I say below...

There are a number of options in the TV menu for the digital output.
Most of which I don't understand. It is set to PCM and stereo.

OK. In theory that should be fine. But as you see, in practice... :-/

If you're interested, I'll wright them all down.

Ahem. You may have Bill in mind, there. ;-

The STB seems to have less options - although I'm using HDMI via the TV
for it rather than its Toslink to the external sound system.

It depends how the options are described. Not sure I'll know what some
would do!

It may be that some other option fixes the behaviour. The difficulty is
that the descriptions may not really explain anything that would give a
clear clue. But if there aren't too many, if you list them I or someone
else may spot a likely candidate.

Are there any options wrt surround-stereo mixdown or reprocessing?

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html