Just asking, but does anyone have their programmes on Sky transmitting a few seconds later than terrestrial? (i.e. Watching ITV 1, then turn to Sky's ITV1, then you see a delay)
Also, does anyone experience an audio delay sometimes on GMTV etc on Sky?
One would assume that's to do with the satellite delay . . . the time it takes for the signal to be uplinked to the Astra
satellite, from the broadcaster (in this case, ITV1) then sent down to your Sky minidish, and into your Sky digibox.
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Every channel (bar News 24 I believe?) will do this. The difference is the time it takes for the feed to be compressed, maybe encrypted, then transmitted and decompressed and of course maybe decrypted by the set top boxes.
If broadcasters were nitpicky enough they could delay the analogue output by the 2-ish seconds it takes though, but there still might be a difference between digital satellite and digital terrestrial.
The delay between ITV1 on Sky Digital and Terrestrial ITV1 over here is about 5 seconds. But then again i live in the middle of nowhere.
The delay on ITV and S4C is about 3 or 4 seconds, but BBC1 is only about one or two.
The feed is a second later on BBC Wales mind you as it routes through Cardiff -- until the last local junction [if not at N24/ceefax handover] when you notice a click to network and you lose a second's worth of programme.
So the difference between BBC Wales analogue and BBC network digital is nothing really.
NTL has been doing this for years, I orginally thought it was an NTL problem but it is common on all platforms, but I think for us BBC One and BBC Two are only like 1 second behind, where as ITV1 is something like 2 or 3 seconds behind, Channel 4 I believe is a second, not sure about Five, probably the same as ITV1.
Though our Physics teacher told us this sometime ago about the delay and it was the case of the satellites and the fibre optics and the signals having to be decoded and what have you takes a couple of seconds compared to normal terrestrial TV.
Not strictly TV, but Classic FM don't appear to have a delay on any of their services - FM, DAB, Sky etc...
Not quite sure how they do it, but makes it very interesting when for example you're listening to your local Classic FM frequency on FM and then on Digital radio or TV, it has different commercials!
An artificial delay is introduced on BBC1, C4 and ITV because there are multiple versions of the same channel on the same transponder, ie all the regional variants. The delay is slight but is to do with the statmuxing (dynamically changing how much bandwidth each channel takes up) so that they're all slightly different.
It should be the case that 5Live on DSat is the same as MW - the MW transmission goes through a delay stage so that it's in synch with the satellite transmission so that if a transmitter loses its feed it can fail to the digibox backup without causing problems in the overlap areas where there are two transmitters on the same frequency.
