OT Newer technology not as good as old -new-technology! <rant'ish>

[The Natural Philosopher]

they are. Its called multi-tasking. Processors do it even better than women claim they do ;-)

It is also necessary for the processor to wait until it receives and

which is far more pertinent.

How do you think that they manage

No, but its a very quick one.

They also don't broadcast individual frames, as they did

That is far more the issue at hand. The encoding standard and compression mandates a time lag between what is received and what is displayed.

Beter STB's like my sonys, at least show a response to user input and blank the screen whilst waiting for the new channel streams to establish.

Amusingly, my set-up on this computer, leaves the last frame frozen, whilst it assembles a new one. If moving to radio with no picture,I get the average actor/actress with absolutely ghastly expressions frozen in place, and have to minimise to avoid throwing up ;-)

Well the cheaper DTVS and set top boxes are truly bad. No sign of a button press on-screen, and that's just poor software.

At the very least a channel change should freeze or blank the video display, it is helpful if it displays what has been selected at the screen top, and it should throw the audio and video on as soon as it has a valid stream of either.

get a better STB. you cant change instantly, but you can at least give a perceptible response to user input..

[Man at B&Q]

Not quite. On one of our DTVs, when navigating the freeview programme guide the TV *does not* always respond instantly. It sometimes queues the commands and then performs 3 or 4 operations quickly after a very noticeable delay. It's clearly because some half wit specified a processor that cannot handle the load under all circumstances and did not test their design properly.

MBQ

[Man at B&Q]

All fine and dandy, but you obviously missed the bit where the OP said that the channel change isn't recognised at all, not that it takes a long time.

MBQ

[Jules]

Ahh, "progress" :-)

For a society that likes everything to be instant, it is funny how many tasks are actually made slower than they used to be.

No, you're not. That's often the problem with anything "digital" - it doesn't handle poor conditions very well at all, whereas with analogue you still get something meaningful through, even if it is of poor quality - but the human brain's very good at making sense of poor analogue data, and in normal conditions a good analogue TV setup's very good indeed.

(My experience of digital TV has not been good - just seems like an excuse for extra crap channels and with typical picture quality that's worse than the old analogue setups, presumably because they're pumping so much data down the line with digital).

cheers

Jules

[Jules]

:-) I grew up with three, and then for the last 7 years before I hopped across the Atlantic I was around Cambridge, which didn't get C5 reception at all.

Yep. That or they simply get the details wrong - seems to happen with ours on a regular basis (and I wish it had some intelligence so I could tell it to only show me channels I was interested in - and that it'd let me scroll back past "now" as once in a while I want to check to see if I missed something that I thought was going to be on)

I'm in the land of NTSC now, so it's all crap ;)

cheers

Jules

[Clive George]

Toshiba, and yes, it's a combo with a DVD.

[Dave Plowman (News)]

Right. PVRs work entirely in the digital domain and would need an A/D convertor to record analogue. Something most wouldn't ever use. A DVD recorder is likely to be used to copy VHS etc so has this facility. And of course if you combine them it makes sense to give you the choice of inputs.

[The Natural Philosopher]

Never The Same Color

Cable or satellite. Analog terrestrial in the USA is unwatchable.

[Clive George]

This one doesn't have a digital tuner :-)

[John Rumm]

Channel changing performance does vary with decoder - some like the Topfield PVRs are pretty quick when jumping to a channel on the same mux or an channel on another mux but with the same encoding. The longest delay is usually jumping to or from a channel on 16QAM mux and and 64QAM mux.

Most digiboxes seem to give instant feedback on screen that a channel change has been requested (typically pop up channel indicator) even if the actual program takes a little time longer.

However the fastest way to see what is on is call up the EPG or the now and next pages...

Having more than 9 channels makes a difference - you can't simply take the first digit hit as the channel number. I presume they also worked out that people had trouble using the -/-- buttons that older remotes had, and instead simply go for a keystroke delay instead.

no change there then

I suspect that in the presence of interference, everyone would prefer analogue. The only acceptable solution with digital is to ensure the reception is "perfect" as near as damn it all the time!

[John Rumm]

The GOP length varies IIUC. BBC use fixed lengths on most channels, and the commercial broadcasters use a variable length. I think 12 frames (i.e. 24 fields) is a common length for BBC.

In fact:

Fiver looks about the longest for something you might actually want to watch at 48 - so potentially nearly 2 seconds worst case.

[Jules]

Yep. Actually I don't notice the colour being too bad - I suppose a lot of what I do watch on TV are old movies, so the colour's probably questionable by now anyway. But the picture quality seems to just be awful, and as it seems to be like that on any US TV regardless of age or reception mechanism I think it must just be down to NTSC itself.

They are running fibre up to the house next Monday (the last 50' or so is copper right now), so it'll be interesting to see if it gets any better after that.

Cable here. Something like 300 channels of s**te. Well, there are some good music stations via cable, but running a power-hungry TV just to listen to audio grates somewhat :-)

cheers

Jules

[fred]

In article , Arfa Daily writes

The actions you describe are all back end tasks, packet headers contain all the information required to set up the decoding engine for a particular programme stream and these are extracted in hardware. All that software has to do is read these parameters and set up the decoder.

The interleaving and error correction scheme for digital transports was chosen specifically to reduce the time taken to recover from breaks in reception so there is no excuse for a decoder taking to an excessive time to produce a valid output after receiving a valid input and changing channel is just a special case of signal change/loss.

If you look at the time taken for a decoder (STB) to recover from a break in reception then you should expect a channel change in only tens to hundreds of milliseconds longer.

3s is just a joke.

[John Rumm]

As with all design issues its a trade off. The more complicated coding and the higher compression ratios give more channels (more "choice" in marketing speak - even if it is a choice between variations of dross!). Its also a cost issue. Buy low price decoders with the minimal processing power required to just do the job and you will get less performance than if you go for one with more power at a (usually) higher price. Same as with cars or computers and many other things.

The have been "chosen" by the need to maintain dual system operation. The panning for this exercise is in no way trivial or simple. You are never going to mak all the people happy either!

Indeed - many places will be seeing at least 9 - 12dB improvement in signal strength, which will take many a marginal install well into "rock solid"

[John Rumm]

That's possibly being harsh on technical authors. The reality is that many companies will have marketing bods re-hash technical infor produced by the engineers, and miss out any pass through a proper technical author at all!

[John Rumm]

That might be your problem. IIRC CH5 is not actually transmitted from the main CP mast, but from one a few miles away. You might be close enough for the CH5 one to be well off axis.

[R D S]

TBH I have fixed a couple with cellotape in my time, only tapes where certain parts got watched a lot and were worth fixing though.

[The Natural Philosopher]

I THINK you can get a TV USB or card that works on US cable.

or something like this

cheers

[Tim S]

John Rumm coughed up some electrons that declared:

That adds up. My TVs can change pretty fast, but 2 seconds seems to ring a bell as worst case scenario.

What I hate about DTV is:

a) Some fool thinks more is more - endless tripe and wibbly "ChannelX+1" channels (what a waste of bandwidth).

b) The quality is definately poorer than analogue. I can see the artifacts on most channels.

What I like:

a) Virtually continuous Star Trek on Virgin. Pity I don't have time to watch it!

And on the odd occasion I take a daytime break and turn on for a bit, WTF are CPC doing advertising (well sponsoring) stuff on daytime TV?!! Are bored housewives and the unemployed really their target audience?

Cheers

Tim

[Dave Plowman (News)]

CP and Croydon are near enough in line to make no difference here.