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

Dave_C_2

This is because the digital signal is sampled and compressed from a good quality analogue signal. As with any sampled signal, some loss of quality occurs.
However when broadcast, the digital signal does not lose its quality as it's error corrected and so forth.

So if you live in an area with a good analogue signal, the quality will be noticeably better than digital. On the flip side if you live in a poor analogue reception area then the digital signal will be better. Obviously there is somewhere in the middle where there is no difference.

Dave

peter999

BlueC wrote: »

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.

The picture quality of my digital Cable & Freeview are about the same.

peter999

Dave_C wrote: »

This is because the digital signal is sampled and compressed from a good quality analogue signal. As with any sampled signal, some loss of quality occurs.
However when broadcast, the digital signal does not lose its quality as it's error corrected and so forth.

So if you live in an area with a good analogue signal, the quality will be noticeably better than digital. On the flip side if you live in a poor analogue reception area then the digital signal will be better. Obviously there is somewhere in the middle where there is no difference.

Dave

Yes, I have a local transmitter nearby & had replacement aerial installed last year pointing at it.

I haven't noticed the difference in picture quality until now. Haven't looked that closely until I realised digital switchover & analogue switch off is happening in my area this month.

I'll need to reconfigure my setup to record one channel & watch another channel at same time, as no analogue signal for Tv tuner. I have just replaced my Tv with an old analogue CRT Panasonic Tv after previous Tv packed up before Xmas.

peter999

almillar

Eh? Your analogue signal is in the wrong aspect ratio, and will be really mushy on a nice big screen. Compare BBC1 digital to BBC1 analogue (since the bitrate is usually good), the colours and sharpness should be much better on digital. You've got a poor quality digibox or SCART cable. Are you using an RGB signal over SCART? You should be rather than Composite.

Notmyrealname

peter999 wrote: »

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

You are correct. Digital TV is a far poorer quality. Digital TV does not do gradients in shade or colour change well. It also doesn't do waterfalls well.

It gets worse.

There is a thing called bitrate. The higher the bitrate the better the quality. Now here is where it falls down. Each transponder has a limited bandwidth to broadcast all the channels. On the transponder the BBC channels broadcast on, there's 8 TV channels and a dozen radio channels so they can have the bitrate quite high. On one transponder there are over 20 TV channels. To fit them in the same bandwidth they drop the bitrate which drops the quality.

You can see how this affects a picture yourself. Take a photo on a digital camera. Save it to the computer. Scale it up and look closely at it. Save a copy but lower the filesize by 50%. Check the quality again. You'll see its more blocky, the gradients are worse. The same happens with digital TV.

peter999

almillar wrote: »

Eh? Your analogue signal is in the wrong aspect ratio, and will be really mushy on a nice big screen. Compare BBC1 digital to BBC1 analogue (since the bitrate is usually good), the colours and sharpness should be much better on digital. You've got a poor quality digibox or SCART cable. Are you using an RGB signal over SCART? You should be rather than Composite.

The analogue picture is (slightly) better quality than both the digital cable/freeview, more detail in picture.

This isn't something I've noticed until now, when I've looked a bit more closely.

It's not obvious until you look more closely at detail within picture, like a face, switching back & forth between analogue/digital using AV button.

peter999