Bit rates for Sky vs FreeView

[TheSeer]

Hello everyone,

Quick question:

Are the picture-stream & sound-stream bit rates higher on Sky than FreeView? Does anyone have the actual numbers available?

And, if the Sky rates are higher, then does this mean, that all other things being equal, that the the Sky picture & sound quality will be higher than Freeview?

The Freeview picture quality can be pretty poor at times with severe blocking on scenes which have lots of changing detail (eg swirling streams of water etc).

Thanks

 

[Starburst]

Some channels on SKY are broadcast at a higher bitrate than any of DTT however some channels on SKY are broadcast at a lower bitrates than any on DTT.
Bitrates are variable, they differ from program to program, channel to channel and platform to platform.

Taken as a whole the channels that are on both platfroms tend to look better on DTT as the big two (BBC and ITV) are not willing to spend the required money to buy enough capacity to ensure the best practical picture on dsat while they have direct access to the DTT platform. Although it has to be said that DTT can often be lacking as well when showing programming which requires less compression and the capacity simply isn't there.

Simple equation is that the less compression/higher bitrates are the better the picture will be although the encoding of data into the mpegII format can have a huge impact on the final results.

 

[TheSeer]

Hello Starburst,

Thanks for that - it would seem to explain the very variable Freeview picture quality that I get even on the same channel. From what you are saying Sky doesn't look as appealing as I originally thought it might. Its just sad that the progression to digital Tv hasn't really delivered on the image/sound quality front for the majority of people. I remember getting much better analogue pictures than I do digital ones.

Do you know if the quality of the Freeview sigal has a direct effect on the quality of the image? For example. if I am receiving a signal that is 50% in terms of quality, then will this deliver a picture that is noticeably inferior than if I had a 75% signal quality? Or does it make no difference so long as the signal strength/quality is sufficient for the STB to decode adequately? Surely, the STB has to do far more error correction etc when the signal is weak and/or poor quality?

thanks.

 

[Starburst]

Analogue broadcasting has decades of development combined with regulated quality/service levels both of which digital TV in the UK does not have. Digital TV by it's very nature is open to much more manipulation (cost savings) than analogue which doesn't help either and the viewers including myself do not complain enough for the situation to change. Digital TV is the future and is far more versatile than analogue but it has it's weak points as we all know
The goverment and it's regulators should be ashamed of themselves for allowing digital broadcasters to get away with sub standard images.

As I understand it the actual picture quality should not be affected by less than perfect reception, 50% is as good as 75% if the receive data is clean. However once the signal reception starts to drop below which the error correction can compensate for then that's when you get audio and video breakup.
That I assume is the major difference between analogue and digital, the analogue picture quality can be noticeably affected by a drop in signal quality while digital can tolerate a drop in stength since it's dealing with zeros and ones but eventually missing data can't be recovered and then you get the catastrophic break up.

 

[MartinImber]

Tuner quality does come into it - my IDTV is better than an old Ondigital Nokia box

 

[TheSeer]

Yes, I get the impression that the DTT tuners in IDTV's are definitely better than stand-alone DTT set-top boxes. Surprising really, as I would have expected it to be the other way round. Makes you wonder why the DTT STB manufacturers can't (or won't) match the IDTV's.....................

 

[StooMonster]

At The Event II, Richard Ansell of Snell & Wilcox (famous for highlight the infamous chroma bug amoungst other things) did an excellent piece about video formats and MPEG-2 and broadcasting.

He said that Sky Digital was typically 4Mb/s and Freeview was typically 2Mb/s -- and he's the best industry source I've heard on the matter.

However, many channels on the Sky platform vary their bit-rates; and have them low for programmes and high for paying advertisers. Not only are adverts louder, but also clearer.

Contrary to what Starburst says, I find BBC to have some of the best bit-rates and give a stunning picture, some of the BBC TWO and BBC FOUR programmes recently have been really excellent; however, don't watch ITV so have no idea about them.

Also bear in mind the iTV part of channels, interactive TV can take up to half a megabit. Also that Sky's platform can top out at 8Mb/s (near top DVD quality) but no broadcasters are prepared to pay for that much bandwidth -- they'd rather have two or three (at a squeeze) channels instead.

StooMonster

 

[Starburst]

Originally posted by StooMonster


Contrary to what Starburst says, I find BBC to have some of the best bit-rates and give a stunning picture, some of the BBC TWO and BBC FOUR programmes recently have been really excellent; however, don't watch ITV so have no idea about them.

My overall experience of BBC dsat PQ is based on examples over the last few years, I've been shocked at the quality of some US imports on BBC2 in particular but that could be down to encoding and not overall bitrates.
The big factor for me was when I switched back to BBC1 analogue to watch a football game since the dsat PQ was very very poor.
On the other hand, Auf Wiedersehen Pet and Clarksons new show have been perfectly acceptable in regards to PQ.

 

[Dean]

FWIW I think Freeview quality very much depends on your location in order to get a quality signal. For me pictures on my Nokia Freeview have made a step forward in image quality from analogue, especially on the BBC/Sky channels. It also allows better quality digital radio than a seperate DAB tuner.