Dvb-s / dvb-t /analogue / sky quality comparison

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Asmodeus

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Topic # 27105 14-Oct-2008 17:04

Right, I was wondering about the quality difference for the FTA channels over the currently 4 different methods you can receive them. Lets discuss the ones available on all 4 methods, C4 will do.

How would you rate the quality of SD transmissions over these 4. I know analogue would be the worst, then I assume sky. How does dvb-s and dvb-t compare when both are transmitting SD content? Is there much difference?

Is DVB-s freeview C4 much better than sky C4 (through component cables)? IS DVB-T C4 much better than DVB-s C4?

Is dvb-s freeview just as good as dvb-t if one excludes the certain programmes that are broadcast in HD?

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eXDee

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Reply # 171110 14-Oct-2008 17:47

DVB-S and DVB-T C4 are effectively the same because both transmissions are 576i, though the DVB-T feed might be a slighly higher bitrate. Can't comment on sky bitrate apart from that Freeview's version looks better.

openmedia

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Reply # 171112 14-Oct-2008 17:50

Now this is based on a number of factors, including the technology involved and typical conditions

From worst -> Best

Typical analogue NZ TV UHF
Typical analogue NZ TV VHG
Sky
freeview DVB-S
Very good analogue UHF/VHF
freeview|HD DVB-T

The surprise is that analogue can beat digital if you have a really really good picture.

For example my own TV2 and TV3 analogue reception is excellent and for a lot of content looks better than DVB-S. If the weather is bad I get a lot of ghosting and then DVB-S looks better.

Comparing an SD channel such as C4 my analogue isn't quite as good as freeview on DVB-S, but often looks better than Sky's signal. The DVB-T version of C4 does look a little bit better thanks to the higher bitrate H.264 encoder they use.

Another good example is TVNZ6. The DVB-T and DVB-S pictures are similar, but the DVB-T H.264 encoded one looks slightly better.

Now let the flames begin..

Generally known online as OpenMedia, now working for Red Hat New Zealand as a Solution Architect for all things Linux, Virtual and of course Cloud. Still playing with MythTV and digital media on the side.

Regs

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Reply # 171180 14-Oct-2008 22:56

openmedia: Now this is based on a number of factors, including the technology involved and typical conditions

From worst -> Best

Typical analogue NZ TV UHF
Typical analogue NZ TV VHG
Sky
freeview DVB-S
Very good analogue UHF/VHF
freeview|HD DVB-T

The surprise is that analogue can beat digital if you have a really really good picture.

isnt DVB-S broadcast with a higher resolution than the standard analog broadcasts? I cant recall the technical details but i'm certain i've never seen an analog broadcast look better than a freeview dvb-s broadcast on my 40" SD plasma screen.

I've definately seen some crappy SKY dvb-s broadcasts though - some of their channels were using such low bitrates they would have looked worse than an analog broadcast of the same content....

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openmedia

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Reply # 171218 15-Oct-2008 09:05

Regs:
openmedia: Now this is based on a number of factors, including the technology involved and typical conditions

From worst -> Best

Typical analogue NZ TV UHF
Typical analogue NZ TV VHG
Sky
freeview DVB-S
Very good analogue UHF/VHF
freeview|HD DVB-T

The surprise is that analogue can beat digital if you have a really really good picture.

isnt DVB-S broadcast with a higher resolution than the standard analog broadcasts? I cant recall the technical details but i'm certain i've never seen an analog broadcast look better than a freeview dvb-s broadcast on my 40" SD plasma screen.

I've definately seen some crappy SKY dvb-s broadcasts though - some of their channels were using such low bitrates they would have looked worse than an analog broadcast of the same content....

Most DVB-S is broadcast in 720x576 and flagged as either 16:9 or 4:3, with the exception of some Sky channels which broadcast at a lower resolution.

In general this is an equivalent digital resolution to the analogue broadcast.

When considering picture quality you need to look at some high motion footage, or something using strobe lights. Often broadcast MPEG2 can't keep up with the picture changes which can look perfectly fine on old analogue TV.

Steve

Jaxson

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Reply # 171219 15-Oct-2008 09:06

C4 is broadcast at 576i on all formats, possibly not a good channel to compare but....

Analogue can be good, I agree with openmedia on that, because it has no compression applied to it. If you've got a great signal, then the old analogue format can be good, but mostly it's not broadcast in widescreen in NZ. The digital broadcasts are all in widescreen and I'd say that alone makes them the way to go for anyone with a new TV.

The freeview uhf compression format is mpeg4 vs mpeg2 for the satellite. Also the tv1/tv2/tv3 freeview uhf channels have been upscaled using an expensive scaler, so they are more likely to appear better than their freeview satellite alternatives. Freeview formats, be it sat or uhf, all have more bandwidth to give to their channels than sky does. That's the tradeoff sky has to make to give you 50 channels of tv.

If you want TV for the standard channels only, then freeview will give you the best picture, and if you live in a freeview uhf area, then really that is the way to go. If you want SKY pay for live sport/movies etc, then there is only one option, -SKY. If you have an older TV ('square shape, not widescreen) and only want normal channels, and get good reception, then really it's easiest to stick with the analogue.

lchiu7

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Reply # 171227 15-Oct-2008 10:01

I guess from my POV the quality is in this order

Analogue - I have terrible analogue reception even though I have a good external antenna because of hills etc
Analogue via TCL cable - basically receiving the analogue channels down the cable that TCL don't encrypt - okay
Digital (TCL) - on TV1, TV2, TV3 it's pretty good and has improved lately
DVB-S - despite being MPEG2 and SD I find on TV1, TV2 and TV3, the PQ is very good
DVB-T - excellent on the SD stuff that's upconverted and of course on true HD stuff, really nice

Don't have Sky but I would imaging it would be close to TCL - others may have different views on this

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richms

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Reply # 171392 15-Oct-2008 23:45

I would put analog ahead of sky for picture quality, sky is pretty bad.

I havent seen freeview dvb-s but I assume its better then the sky one,

dvb-t of course blows both away.

Lack of widescreen on C4 isnt really an issue since most of what they play is postagestamped anyway so you still get black on all 4 sides on digital, its just a bit smaler then when viewing analog.

Richard rich.ms