Whenever i watch moving sport especially football I experience much poorer pictu
Brian Butterworth published on UK Free TV What you are seeing is one of the two problems that are well know about the "MPEG-2" system that is used to encode digital TV.
Because of the way the system works, horizontal movement across a crowd requires a disproportionate large amount of data to encode.
Because the bandwidth on Freeview is so limited, and as most broadcasters have decided to have more channels rather than better quality pictures, on most channels the bandwidth is so limited that the effect you see, a blurry mass of blocks is visible.
The sceptical will say that this is simply an excuse to sell you HDTV equipment and channel packages.
The other problem you will see is when strobe effects are used - this will often look like very large black and white boxes.
If these effects trouble you, do not go out and buy yourself a massive TV as they will be simply much clearer to you.
Friday, 25 February 2011
David Haworth: OK. Yes, still here despite everything...
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Saturday, 26 February 2011
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Emma Archard8:08 AM
London
Hello, for about 2 weeks now I have been experiencing loss of multiple digital channels on my freeview tv - channels lost include ITV and Channel 4 (although can get these channels on analogue in poor quality). Called M&S who i bought the TV from and they said this is due to work on Crystal Palace transmitter and suggested posting here for advice. Have been re-tuning TV every day. Postcode is NW1 1NL. Thanks!
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Emma's: mapE's Freeview map terrainE's terrain plot wavesE's frequency data E's Freeview Detailed Coverage
Emma Archard: Hi. There is no work being done at Crystal Palace.
Please can you see Single frequency interference | ukfree.tv - independent free digital TV advice for some help?
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David Haworth5:22 PM
Re centre channel on BBC1 HD - I did try (by no means an easy task) to complain to Beeb and I thought I may have had some success but now it seem to be intermittent, sometimes on sometimes off but only on this channel. The other 200+ channels are all OK.
Don't know if you have heard of anything since.
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Sunday, 27 February 2011
David Haworth: Most channels do not have 5.1 sound, so you would not expect them to be effected.
No one else has mentioned this problem yet.
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Monday, 28 February 2011
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David Haworth6:28 PM
Re Centre channel - my technical advisor (son) says that anything broadcast in stereo will activate the A/V software and produce a suedo centre channel.
Problem lies with BBC who often send signals that state DD 5.1 but are actually 2.1 (eg Arsenal v Birmingham cup final) , the A/V amp thinks its 5.1 so the software is not activated and therefore the sound will only be broadcast in stereo with no centre channel. Are we on the right track and if so are the BBC being economical with the truth in stating 5.1 when it not so?
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David Haworth: No, your technical advisor is incorrect.
The BBC HD channel on SATELLITE and CABLE is in Dolby AC-3 format, which is true "5.1" in that it carries six separate sound signals.
This has OUTBAND signalling, so it will be activated automatically, as long as you have used SPDIF to connect the box to the amp, or HDMI to the TV with 5.1.
On FREEVIEW the BBC HD channel is stereo.
What happens on a 5.1 system to a stereo signal, and it doesn't matter if it SPDIF, HDMI or plain old dual-phono, depends on the buttons you press on the remote, as there is no INBAND or OUTBAND signalling.
If you select Dolby PLII (Pro-Logic II) the stereo source will be processed into left, right, rear left+right, center and sub. This is done by a mixture of filters.
The rear is created by the phase difference between left and right, the sub (the .1) is done from a low-pass filter. The centre is done from a mono mix of the vocal range and what's left gets put into the left and right.
If the BBC only provide 2.0 on some programmes, and they will do that when there is no 5.1 source available, then you must decide what you want your amp to do.
Most of the processing options for 2.0 to 5.1 have flaws, which is why there are usually SPORT and MOVIE and MUSIC and SPEECH options somewhere to choose from.
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...you should generally only use the PLII settings for programmes that were "encoded" in that format. It will make other things sound strange.
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David Haworth8:21 PM
So what are you suggesting - that I should change the options even when you are not sure what the BBC are sending out.
As far as I am aware ITV HD is always OK - is this just a BBC thing that sometimes they send the signal out in 5.1 but it is actually 2.1. If it was 5.1 then there would not be a problem and I would have all channels with sound. The problem seems to be that they say it is 5.1 when it isn't so the amp doesn't recognise it. How is one to know apart from the hole in the middle.
Hate to think what "technical pygmies" would think of that!!!
Freesat connection is by optical HDMI cable through the amp (all the inputs are routed through the amp) which means that the amp does all the switching from one input to another with a single connection from amp to TV.
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David Haworth: If the BBC only have a stereo source then they send it out as 2.0 over the 5.1, ie left and right only, nothing in center, backleft, backright and sub (and also as stereo).
Not all programmes are available in 5.1, and the BBC rules forbid "messing" to create virtual 5.1.
There is no "hole in the middle" the sound is just stereo. I explained about about how to select your amp to change this if you don't like it by selecting the appropriate option.
A lot of programmes on ITV1 HD are not produced in 5.1, I don't know if they virtualize it, they have lower quality standards than the BBC.
It is not "wrong" in anyway to leave a stereo-sourced programme (or indeed a mono one) as 2.0.
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