Sound break up

OK I can understand that with a digital signal it's either there or not
hence the artifacts on vision where the delta is missing and the set
plays catch up. And this is usually due to low quality signal. I
suppose the sound could drop out in much the same way.

So how come the sound from my Daewoo, on the BBC1 mux mostly, seems to
change its stereo characteristics? - that's the closest I can come to
describing it - There does not seem to be any picture disruption and
the signal strengths etc seem the same in either case.

--

Regards

Dave Saville

NB Remove no-spam- for good email address

Dave Saville wrote:

OK I can understand that with a digital signal it's either there or not
hence the artifacts on vision where the delta is missing and the set
plays catch up. And this is usually due to low quality signal. I
suppose the sound could drop out in much the same way.

So how come the sound from my Daewoo, on the BBC1 mux mostly, seems to
change its stereo characteristics? - that's the closest I can come to
describing it - There does not seem to be any picture disruption and
the signal strengths etc seem the same in either case.


I've got total audio drop outs which last less than half a second.
Picture is undisturbed, and being sort of lazy I'm waiting with patience
for the next update (October). If not that, then I've got a fault with
the box - it will going back if that's the case...

How'd you mean "change its stereo characteristics". Does one (or both)
channel(s) drop out totally, drop in level, lose high/low frequencies or
suffer a phase shifting change in stereo separation? I know you think
it's related to a mux (does a channel's audio bit rate change during the
day?) - but could it be maybe your scart plug is trying to jump out from
the TV/Video socket when a BBC promo's bass notes wobble the cabinet? I
did have this once...

--

Adrian C

On Thu, 23 Sep 2004 16:13:56 +0100, Adrian C wrote:

How'd you mean "change its stereo characteristics". Does one (or both)
channel(s) drop out totally, drop in level, lose high/low frequencies or
suffer a phase shifting change in stereo separation? I know you think
it's related to a mux (does a channel's audio bit rate change during the
day?) - but could it be maybe your scart plug is trying to jump out from
the TV/Video socket when a BBC promo's bass notes wobble the cabinet? I
did have this once...

Oh I like that one :-)

I am not sure really how to describe it I would guess a combination of
frequency loss and separation - It sounds "harsh" and somewhat
"hollow". I doubt anything is loose; It has happened, for example, with
just a reporters voice on the news. I switched to analogue to check and
it was not the outside feed.

--

Regards

Dave Saville

NB Remove no-spam- for good email address

I am not sure really how to describe it I would guess a combination of
frequency loss and separation - It sounds "harsh" and somewhat
"hollow". I doubt anything is loose; It has happened, for example, with
just a reporters voice on the news. I switched to analogue to check and
it was not the outside feed.

Welcome to the world of MPEG. It sounds like what you're hearing is the
effect of tandem coding. It's likely that the feed into the news was being
fed via an MPEG feed. On analogue, you would have heard the feed after only
the one MPEG encode-decode process. Listening on DTT or DSAT you would then
hear the effects of at least two encode-decode processes (depending on where
you are). Each time it goes though an MPEG encode-decode process, bits of
the audio are thrown away, and the more processes it goes through, the more
audible are the artifacts as it starts throwing away crucial parts of the
audio.