About 2 months ago we switched from cable t.v. to digital cable t.v… More channels, better piture and sound.
Also, now we have to use a converter box to descramble the signal, as a cable ready television can’t do it. Man, that converter box is huge, bigger than a large VCR.
Anyway, I’ve noticed that sometimes when I flip to a channel, it takes a moment or two for the picture to descramble. Sometimes the picture will flicker a bit as though the box is having a hard time descrambling it. This doesn’t happen often, but it does happen. And when it happens, it’s anoying as hell. All of my friends who have digital cable report the same thing. Why does it do that? Is the picture encoded so well that even the appropiate descramble box has a hard time decoding it?
It’s not the descrambling, it’s decompressing. It takes a bit of time to process the incoming signal. The same thing happens with DSS systems, they are encoded just like digital cable.
Your DSS or Digital Cable signal will always be slightly delayed relative to the live uncompressed signal. I’ve verified this by using picture-in-picture, and watching CNN via cable (plain old analog cable, not digital) on one picture and on DSS in the other. DSS is always about a second behind Cable.
What this means is, when you switch to a new channel, the processor has to fill its cache with data and it takes a second to start decompressing the incoming stream. So you always get a bit of dead air before the new channel is visible. It takes some getting used to, but before long, you won’t even notice it.
But it’s not just dead air, its a totally scrambled picture. This morning CNN was scrambled for 5 seconds. It looks like the smut channel does when you don’t pay for it.
Then it blinks a couple times and poof, it’s desrambled.
I live in houston now where we all have to leave praise to the mightly time warner giant that basically owns a monopoly over cable in my region. Their digital cable sucks. I watched the movie go for about two minutes then I suddenly saw the boxed image shift around the screen, it was kind of annoying after the first hour but I enjoyed watching the brilliant special effects going on with the box. This has made me a critic of the new tech of digital cable. I hate it.
Digital TV uses MPEG-2 encoding to squeeze full motion video into a narrow channel. MPEG works by sending what is in effect a single JPEG image (like a photograph on a web page) and then, for each successive frame, sending just the differences between that that and its predecessor. Periodically it will send another complete frame for synchronization. Perhaps what you are seeing is from the period before your decoder gets it’s first full frame?