Tv picture quality -Analogue (aerial) vs Digital (cable)

peter999

Watching Tv I noticed the picture quality of my channels tuned to Analogue via the Aerial are noticably better than same channels through Digital Cable.

In the analogue picture I can see more detail, it's a crisper sharper picture.

Does anyone know why that is & how they compare in their resolution ??

peter999

fwor

It's hard to say why.

Analogue TV is roughly the same resolution as SD Digital. In theory analogue has greater vertical resolution at 625 lines (compared to 576 for digital SD), but IIRC some of those are taken up for things other than the picture, so I doubt the eye could resolve much difference there.

It's a bit academic anyway, given that analogue only has a few months left to live...

peter999

fwor wrote: »

It's hard to say why.

Analogue TV is roughly the same resolution as SD Digital. In theory analogue has greater vertical resolution at 625 lines (compared to 576 for digital SD), but IIRC some of those are taken up for things other than the picture, so I doubt the eye could resolve much difference there.

It's a bit academic anyway, given that analogue only has a few months left to live...

I can see the difference, it's just that little bit more detail through whole picture. You can see it.

It's the same with Digital Freeview via Aerial, the analogue is better detail.

I'm curious as my area switches over to digital this month.

It's useful to switch between analogue/digital channel, if I record one & want to watch other at same time using Tv tuner.

peter999

debitcardmayhem

Have you got digital via SCART and also the same for Freeview then it just may be bad scart sockets / cables or up/down scalers .... just my thoughts really.

peter999

debitcardmayhem wrote: »

Have you got digital via SCART and also the same for Freeview then it just may be bad scart sockets / cables or up/down scalers .... just my thoughts really.

Yes, digital cable/freeview is via SCART.

Can that make difference in picture quality ?

BlueC

Cable TV (Virgin I presume?) is often horribly compressed so the picture looks really crappy. Same goes for digital freeview - especially the non-BBC channels. I have found freesat/sky/satellite gives by far the best picture.

debitcardmayhem

Can't say about cable but ^^ BlueC seems to think it could be a "feature" , as for the Freeview over scart it should be fair to better than analogue unless there are signal problems (pre switchover) or if there are problems in the scart connection. Perhaps you may have more luck if you say which TV and Freeview box you have , and maybe AVForums may help if nothing fortcoming from here. Sorry not much help but good luck

It may be useful if your set-top box has the option of finding out the signal strength too, and also which transmitter you are on.

fwor

One other possibility is that the pixels in a digital signal have more accurately defined limits, while analogue is more likely to "smooth over" the edges between pixels - particularly horizontally.

On a big screen it's also quite easy to see pixellation on a digital medium if the signal is not quite up to standard, because of the way that the compression algorithms work.

In my area (not yet switched) the picture looks better to me with digital than analogue, except for things like motor racing, where there's a fast moving object in a panning shot. It appears that the compression cannot cope well with that combination, but perhaps I'll see an improvement when they up the transmitter power here.

A.Penny.Saved

Freeview has had the bitrate repeatedly lowered which has affected the quality. Also some channels are only 544x576 rather than 720x576 so the low resolution would not compare well with 720x576 Analogue and would also lose detail. The bitrate is the biggest problem, the more movement the worse the picture becomes and with some channels the bitrate is so low that the picture becomes a mass of blocks whenever there is some fast movement. That is an extreme example of how the detail suffers, however, it's much the same with the higher bitrate channels such as BBC1, some detail is lost.

You could try encoding some video with different bitrates and check how much detail is retained as the bitrate lowers. Some will always be lost, that's what compression does.

jamesd

Yes, SCART can reduce signal quality and it'll prevent a digital signal from being sent directly to your TV. If your TV has a digital input of some sort you should prefer using that for your digital watching. HDMI is the best available to consumers and you should use that if you can, any cheap HDMI cable will do.

If your TV set has Freeview decoding built in try an experiment with the aerial connected directly to the TV to see whether that improves things or not.

If the type of loss of detail is the same for both Freeview and cable then it may be due to the compression used in digital signals. Packing more channels into the same broadcast space does reduce quality even with the fairly old compression method used to make it easier.

InsideInsurance

The issue is predominately due to do with the compression used in digital broadcasting.

With digital, you predominately get a signal or you dont. If you get it you will get the picture and sound at the quality intended. This is predominately defined by the bitrate they are using and broadcasters do vary the bitrate between channels giving the feature channels a better quality than the secondary.

With analogue things are not that simple, you have good, average and poor reception and so rather than it being a binary (aka digital) there or not you will have a standard of picture that is related to the standard of your reception. If you live in a formally good reception are you simply will have a better SD picture on analogue. If you live in a formally ok area the quality is probably about the same, if your in an average area the digital picture is probably better and if you live in a poor analogue area, well you probably cant get digital.

There is little you can do other than compare the bitrates of the channels you watch most frequently across the different providers and see which are giving the best focus on those channels. From others research it tends to be virgin the worst, then freeview and then Sky as the best but I havent confirmed it with my own checking and dont know where the newer services like BT Vision fit on the scale.