Over compression used on Sky One Ireland

andrew3

Did anyone notice that Sky One Ireland suffers from over compression - its starting to look like an internet feed! - Ive started to use Sky One UK - in the other channels section - mostly to get rid of the crap news but now quality will be added to the list!

watty

Check your signal quality too...

To check it for a particular channel / transponder use Services 4 0 1 Select and Manual Tuning, put parmeters of desired transponder and unlike the "add channels" similar thing, it will show level and quality of THAT transponder befor doing the channel scan.

Round Cable

I think it had something with Sky Three being added to the same transponder, it really does look bad, for Sky's premium entertainment channel.

byte

Yup, this issue has been discussed some months back.

Some may even think it's deliberate, since SkyHD is around the corner!

Skyuser

It the quality not the same on Sky One UK?

Mossy Monk

no, seems to be better

Cantab.

watty wrote:

Check your signal quality too...

Sky use forward error correction so the signal to noise ratio (signal quality) does not affect picture quality above a certain threshold level. If you're below this threshold (e.g. hostile atmospheric conditions), you'll get very noticeable digital interference.

Sky use quite strong digital compression. In slow moving video (news reading, soap operas etc.) generally the image looks fine. However, for fast moving video (pop concerts, ice-skating with glittery costumes, soccer close-up action replays), there is much more colour/moving action to be transmitted which ups the real-time bandwidth requirement resulting in 'blocky' pictures - this is completely independant of your signal strength (above a threshold signal to noise ratio) and is wholely dependant on sky's aggresive video compression algorithms.

I've noticed this 'blocky' phenomenon before and was delighted to see a thread devoted to this topic. Sky really ought to reduce their compression levels - even 5% less compression would surely make a big difference to perceived image quality, particularly in fast-moving action shots.

I'm not sure if this is possible though becuase the sky set-top boxes might not be reconfigurable to allow varying bit-stream rates? Anyone know more about this? If they are not reconfigurable, I'd say there's a red-faced engineer or two! Anyway, sky's system is great technology despite this little problem.

Sponge Bob

The BBC looks fine, Sky are trying to shoehorn too many channels onto the one transponder more like.

Does anyone think sky 3 is a bit 'darker' than sky one UK ......maybe to hide somethin like missing picture data

watty

Yes there is FEC, but the "blockiness" or appearance of over compression can be and has been shown to relate to poorly aligned dishes. In such a case the picture freezes during rain.


I'd agree that if Sky1 ROI is noticabley worse than Sky1 UK, then the problem is too many channels on the Transponder.

Some channels do use Variable bit rate. Not a problem.

The only "Sky" technology involved is NDS encryption.