How much colour banding should I expect from Sky+ ?

[AndyH]

Hi,

Panny PV500 with Sky+ RGB via Ixos Scart - Approx 100 hours of run in, need to re-do DVE calibration.


So how much colour banding should I expect from Sky, and what can be done to minimse it? I hardly see any from DVD via my 868 and HDMI, so I'm thinking this is mainly a low bit rate issue.


At its worst, I'd describe walls of solid colour, circles of light cast onto walls, solid blue skies etc. like watching a PC running in 16 bit colour.


This is all slightly more distracting than I was hoping, and my gut says I have some tweaking still to do. Any top tips?

Currently I have my brightness and contrast around the 20% mark, with colour more like 60-70%. Sharpness up one notch.

 

[StrongSilent]

Has the banding issue improved for you at all? I'm seeing exactly what you describe on my new PWD8 on freeview and digi. sat. I'm wondering whether its bitrate as you say or a combination of other factors such as choice of s-vid/component, prog-scan, and even choice of cable.
Do any of the experts have any tips on how to minimise the appearance of this banding?
Cheers.

 

[mal60908]

I think it is the low bitrate on sky, it really shows up when you get a decent plasma.

 

[StrongSilent]

Thanks mal, I think you;re right. I guess the same would apply to Freeview and some satellite channels too in that case.

With the advanced configurability of just about every detail of the PWD8's picture I'm hoping I can tweak it out, at least partially.
Would an ISF makeover improve this? I'm afraid I'm noticing it more and more now.

 

[AndyH]

Hi,

I've had another bash at self calibrating since the 100 hour run in, and now I'm at (very roughly) 10% contrast, 30% brightness and 75% colour.


Slight improvement in banding (more of an improvement in posterisation on peoples faces - they don't look so ill anymore! But that's another thread..).

I suspect I'm possibly psycho-visually blanking it out within my brain as I get more used to the plasma experience.

But I think mal is right too - bitrate has more to do with it than anything. I'm using top notch IXOS Scart for RGB from Sky+, so I'd be surprised if cabling would improve anything.

Roll on HD...

 

[StrongSilent]

Nice to hear it's improving a little.
I'll have to wait till I've run mine in a bit longer before calibrating

 

[David PluggedIn]

I think it is the low bitrate on sky, it really shows up when you get a decent plasma.

no - this is the oft quoted myth I'm afraid...The output from Sky is fine, it is the video processing of video signals in most large panels that is truly hopeless. Yes, you can do some tricks with the panels to try and hide the problem, but ultimately the only way you will resolve the problem is to feed the panel video that has already been processed externally, so that means a video processor...

 

[StrongSilent]

no - this is the oft quoted myth I'm afraid...The output from Sky is fine, it is the video processing of video signals in most large panels that is truly hopeless. Yes, you can do some tricks with the panels to try and hide the problem, but ultimately the only way you will resolve the problem is to feed the panel video that has already been processed externally, so that means a video processor...

You could be right.
Wouldn't happen to know anyone that sells them would you?

 

[David PluggedIn]

LOL

there are plenty of suppliers of video processing, not just us

but really just trying to get people to realise that despite what their retailer that just sold then a £2k display is saying, it isnt Sky that is the problem.

 

[ROBERTT]

Sorry David, but I cant agree with you

How can it be the panels video processing when the PQ from DVD is excellent! It can only be down to the bit rate of certain channels as well as the source material itself. Some channels look good some look rubbish but this is directly down to the bandwidth allocated (payed for) by that channel.

Using an external scaler will improve things but still some channels will look better than others.......

 

[David PluggedIn]

Sorry David, but I cant agree with you

but you just have

How can it be the panels video processing when the PQ from DVD is excellent!

Because in many cases people use the better connectins for the DVD, either prog scan inputs or in this case HDMI

It can only be down to the bit rate of certain channels as well as the source material itself. Some channels look good some look rubbish but this is directly down to the bandwidth allocated (payed for) by that channel.

Again I wouldnt disagree with this. Just like DVD, if you watch a poorly mastered DVD then it doesnt look as good as a well done one.

The point that I am making though is the blanket statements of 'its Sky' , when it isnt that at all. Colour banding is a classic symptom of poor A-D conversion, and with an external scaler going in to high quality inputs on the panel, then you bypass this.

Using an external scaler will improve things but still some channels will look better than others.......

yes, of course, again, poker-quiz-bidup shows will always have poor production values and arent going to care about a pristene looking image. A poor quality DVD disc will look poor on a great DVD player - the difference is that people wouldnt say 'DVD looks rubbush on large screens' as a result of that.

The poor quality on the fringe channels is not important unless you spend your time watching this stuff. Most people dont, they watch the main channels.
honestly, I am not trying to be antagonistic or controversial, just really trying to debunk myths..

I will have to get a screenshot from Sky on to our website to really illustrate this I think..

 

[AndyH]

So one thing I've been wondering..

Is it likely that a Sky HD box connected via Component / HDMI would offer any improvement on SD material when compared to a today Sky+ box via RGB SCART?

I'm sure that doesn't make sense, I'm full of man cold..

 

[martinthorn]

I have to disagree too! I view DVDs through the same connections as SKY (RGB Scart). Some Sky channels show noticeable colour banding, but with the main channels (BBC1 etc) it is harder to see and on DVDs can't be seen. (Freeview also seems a little better than Sky in this respect)

I think it is low bit rates on the mpeg transmissions that are to blame (IMHO !) otherwise DVDs would show banding on my tv..

Martin

 

[David PluggedIn]

Hi Andy

thats a good question. It would seem likely that it will do. It may of course bring all sorts of other issues but time will tell of course.

Martin, that is a more valid comparison, same connections etc.
However
There are lots of things going on here..
1] the A-D conversion of standard def signals varies widely on different models of digital display. Some are truly horrible, full of block artefacts, smearing, false contours etc. some are ok, some are pretty good. It sounds like yours is good.
2] the broadcasts can vary in quality. Watching BBC news switch from national to the local news you see an incredible change in picture quality, it suddenly goes very, very soft. We have sold a number of SDI Sky boxes to major broadcasters that have used them to replace analogue to digital solutions that they were previously running..so sure, those guys have a role to play in delivering a a good/bad/indifferent picture.

The point is though, you hear far less complaints about these type of issues from CRT users, which while of course they are typically smaller than digital panels (making the issues harder to spot) , they usually dont have video processing in them introducing these nasties.

honestly guys, I am not saying Sky is a perfect platform. it isnt. I am not saying that video processing will solve all your problems, or that all digital panels are bad.

What i am saying is that (back to the original poster) that if you are seeing continual colour banding, and you are running a digital panel with straight standard def video, then unless you are watching the duff channels all the time, you have a problem.

 

[David PluggedIn]

Just an update to this thread - have a look at 'TheDoctor' comments on driving his plasma with a video processor etc through Sky.

http://www.avforums.com/forums/showthread.php?t=258733

cheers