Fixing a time delay between wto Freeview boxes

I have a freeview box and a freeview dongle (for my PC),
however they take different times to process the signals so
they are out of sync, this is most noticible on the sound when you
listen to both at the same time.

Is there anyway of fixing this time delay so they are in sync?

I was think a good idea would be to make the cable to the faster box
longer so the signal had to go futher, dunno how much cable I would need
though, the delay is only about 1/5 of a second. I have some spare cable but
I don't
know what lenght to cut it too :O)


TIA.

"Bazzer Smith" wrote in message
news
I have a freeview box and a freeview dongle (for my PC),
however they take different times to process the signals so
they are out of sync, this is most noticible on the sound when you
listen to both at the same time.

Is there anyway of fixing this time delay so they are in sync?

I was think a good idea would be to make the cable to the faster box
longer so the signal had to go futher, dunno how much cable I would need
though, the delay is only about 1/5 of a second. I have some spare cable
but I don't
know what lenght to cut it too :O)

Try 40,000km. Reduce it by 5,000km increments until it's right. It's OK to
coil it up. Signal losses will be about 8,000dB if you use CT100 so you
might need some compensating amplification.

Bill

"Bill Wright" wrote in message
...

"Bazzer Smith" wrote in message
news
I have a freeview box and a freeview dongle (for my PC),
however they take different times to process the signals so
they are out of sync, this is most noticible on the sound when you
listen to both at the same time.

Is there anyway of fixing this time delay so they are in sync?

I was think a good idea would be to make the cable to the faster box
longer so the signal had to go futher, dunno how much cable I would need
though, the delay is only about 1/5 of a second. I have some spare cable
but I don't
know what lenght to cut it too :O)

Try 40,000km. Reduce it by 5,000km increments until it's right. It's OK to
coil it up. Signal losses will be about 8,000dB if you use CT100 so you
might need some compensating amplification.


Hmmm.. any chance of a quote on the job, I'll just use bog standard cable if
it's cheaper :O)
I would expect a bulk buyers discount though :O|

And I want proper connectors too, not some twisted wires bodged job.

Bazzer Smith wrote:
I have a freeview box and a freeview dongle (for my PC),
however they take different times to process the signals so
they are out of sync, this is most noticible on the sound when you
listen to both at the same time.

Do you get good reception under your bridge?

--
Alex

Piece by piece the penguins have taken my sanity
www.drzoidberg.co.uk www.ebayfaq.co.uk

"Dr Zoidberg" wrote in message
...
Do you get good reception under your bridge?

Come now. The man asked an honest question and got an honest answer.

Bill

"Bazzer Smith" wrote in message
news
I have a freeview box and a freeview dongle (for my PC),
however they take different times to process the signals so
they are out of sync, this is most noticible on the sound when you
listen to both at the same time.

Is there anyway of fixing this time delay so they are in sync?

I was think a good idea would be to make the cable to the faster box
longer so the signal had to go futher, dunno how much cable I would need
though, the delay is only about 1/5 of a second. I have some spare cable
but I don't
know what lenght to cut it too :O)


As you've realised, its not something that us poor mortals can achieve. You
may be amused that DAB listeners have complained for sometime about the
"time pips", which sound like a peel of bells as every DAB radio in the
house goes off at a slightly different time, and all of them well behind any
analogue radios. Of course digital radio off Freeview or Satellite goes off
at a different time too!

Of course DAB is of such high quality that surely people won't care about
the fact that you can't listen around the house without all this bizarre
"echo" affects, he said with his tongue firmly in his cheek!

Paul DS

On Sun, 10 Sep 2006 21:50:27 GMT, "Bazzer Smith" wrote:

|I have a freeview box and a freeview dongle (for my PC),
|however they take different times to process the signals so
|they are out of sync, this is most noticible on the sound when you
|listen to both at the same time.
|
|Is there anyway of fixing this time delay so they are in sync?
|
|I was think a good idea would be to make the cable to the faster box
|longer so the signal had to go futher, dunno how much cable I would need
|though, the delay is only about 1/5 of a second. I have some spare cable but
|I don't
|know what lenght to cut it too :O)

I have seen a similar thing done, a long time ago, by a *commercial*
*professional* outfit, called IIRC Wigwam, in a long thin auditorium where
there were several TV monitors a long way from platform, and they
introduces a time delay for each ?video? stream to give lip sync with both
the natural speed of sound time delay and the audio out of the speakers.

Writing the above made me realise that I do not understand what they did,
but it worked very well.

Introducing time delays in audio and/or video streams is definitely
possible, and might now be down to a reasonable price now.
--
Dave Fawthrop dave hyphenologist co uk Google Groups is IME the *worst*
method of accessing usenet. GG subscribers would be well advised get a
newsreader, say Agent, and a newsserver, say news.individual.net. These
will allow them: to see only *new* posts, a killfile, and other goodies.

"Bazzer Smith" wrote in message
news
I have a freeview box and a freeview dongle (for my PC),
however they take different times to process the signals so
they are out of sync, this is most noticible on the sound when you
listen to both at the same time.

Is there anyway of fixing this time delay so they are in sync?

I was think a good idea would be to make the cable to the faster box
longer so the signal had to go futher, dunno how much cable I would need
though, the delay is only about 1/5 of a second. I have some spare cable
but I don't
know what lenght to cut it too :O)

This won't be any help but.. did something like this many years ago.
However the frequency was 70 MHz rather than baseband video.
We used a couple of reels of cable, probably about 500m, and that gave
sufficeint delay.

Could TV delay line technology be of use?
A TV delay line has a delay of one line = 0.06 ms so you would only need
about 8000 of them ..or perhaps bigger capacitors ;-)

Roger

Dave Fawthrop wrote:

Introducing time delays in audio and/or video streams is definitely
possible, and might now be down to a reasonable price now.

There are numerous factors which are entirely hardware and firmware
dependent and vary from box to box which may influence how long it takes
each digital TV receiver to complete a prefill phase and begin to produce
visible and audible decoded results. A particular box may vary the length
of time from power cycle to power cycle because of additional external
environmental factors, including in particular the precise moment at
which the digital stream is joined (box A gets the start of an I-frame,
box B just misses it by a single byte - box B has to wait).

A system that actually sampled the (audio) output of two devices and
endeavoured to synchronise them based on the sampling result might be
dreamt up by somebody. Unfortunately, some boxes may be decoding faster
or slower than others at any particular instant due to internal clock
drift and lip sync correction. A synchronisation mechanism would have to
deal with such constant variations.

Attempting to slow down data delivery in the digital domain would be
disasterous as clocking assumptions built into the designs of accurate
data rate reception devices like Freeview boxes (as opposed to highly
error tolerant devices like IPTV receivers) could become invalidated.
This leaves us with having to delay the decoded output of digital receivers.

If a synchronisation system was already sampling receiver output it would
presumably do so by converting it to digital data for devices with
analogue output only. Buffering multiple inputs, even with standard
definition video bandwidths, for a 0-2 second (say) delay tolerance
should not be too expensive. An extra A-D-A cycle wouldn't do much for
quality, but if the receivers had digital outputs then things would be
better. I can't think of any digital TV receivers with digital *video*
outputs other than hidef products with HDMI, but for hidef the bandwidth
requirements become onerous again so costs may become prohibitive. The
wonderful world of HDCP means it may not be possible to record the
digital output anyway since the system is designed to prevent capture.

--
TTFN, Andrew Hodgkinson
Find some electronic music at: Photos, wallpaper, software and mo
http://pond.org.uk/music.html http://pond.org.uk/

On Mon, 11 Sep 2006 09:31:40 GMT, Andrew Hodgkinson
wrote:

|Dave Fawthrop wrote:
|
| Introducing time delays in audio and/or video streams is definitely
| possible, and might now be down to a reasonable price now.
|
|There are numerous factors which are entirely hardware and firmware
|dependent and vary from box to box which may influence how long it takes
|each digital TV receiver to complete a prefill phase and begin to produce
|visible and audible decoded results. A particular box may vary the length
|of time from power cycle to power cycle because of additional external
|environmental factors, including in particular the precise moment at
|which the digital stream is joined (box A gets the start of an I-frame,
|box B just misses it by a single byte - box B has to wait).
|
|A system that actually sampled the (audio) output of two devices and
|endeavoured to synchronise them based on the sampling result might be
|dreamt up by somebody. Unfortunately, some boxes may be decoding faster
|or slower than others at any particular instant due to internal clock
|drift and lip sync correction. A synchronisation mechanism would have to
|deal with such constant variations.
|
|Attempting to slow down data delivery in the digital domain would be
|disasterous as clocking assumptions built into the designs of accurate
|data rate reception devices like Freeview boxes (as opposed to highly
|error tolerant devices like IPTV receivers) could become invalidated.
|This leaves us with having to delay the decoded output of digital receivers.
|
|If a synchronisation system was already sampling receiver output it would
|presumably do so by converting it to digital data for devices with
|analogue output only. Buffering multiple inputs, even with standard
|definition video bandwidths, for a 0-2 second (say) delay tolerance
|should not be too expensive. An extra A-D-A cycle wouldn't do much for
|quality, but if the receivers had digital outputs then things would be
|better. I can't think of any digital TV receivers with digital *video*
|outputs other than hidef products with HDMI, but for hidef the bandwidth
|requirements become onerous again so costs may become prohibitive. The
|wonderful world of HDCP means it may not be possible to record the
|digital output anyway since the system is designed to prevent capture.

I have *myself* seen it working very well, not sure of the
electronics/mechanics/software..
--
Dave Fawthrop dave hyphenologist co uk Google Groups is IME the *worst*
method of accessing usenet. GG subscribers would be well advised get a
newsreader, say Agent, and a newsserver, say news.individual.net. These
will allow them: to see only *new* posts, a killfile, and other goodies.