[Closed] Why is my tv reception badly pixelated over the last few weeks? Hants.

Niche pron?

trees growing?

Recent retune to the new stations required.

Just did a retune. Hasn’t helped. Might have to try a rod hull and get up there and take a look....

I'd guess it's got misaligned.

Trees, the wind has moved the aerial or water in the connectors?

Ours is pretty poor, churchyard Yew tree right behind us is now blocking the signal, worse if it's wet and windy.

I can't get a terrestial signal in this flat, haven't done for a few years now. Probably the bets thing that ever happened to my TV viewing, just watch everything through the internet now. A bliss of very few adverts and much less channel surfing utter nonsense! 😆

Ours has seriously deteriorated recently. Its been noticeably worse in wet and stormy weather but that the last week or so it has really dropped off. Probably time to get the ladders out, anyone have a number for John Noakes?

just watch everything through the internet now. A bliss of no adverts!

If anything I'd say its the other way round. With our recent dodgy signal one of my E4 series links has messed up so now I need to catch up on "all 4" so I can't skip ads like on the recording

A couple of years a go, a storm moved my aerial slightly and affected the picture (pixelation on some but not all channels). I know the aerial moved because I installed it and lined it up with my neighbours aerial. After the storm, it was a couple of degrees out. The weather improved and so did the picture but now I don't care as I rarely watch live TV and the channels most affected are BBC which I can watch live on iplayer anyway. But the pixeltion does get worse in bad weather, heavy rain especially. Given the weather we've had over the past few weeks, it may need a slight realign

this is unlikely but have a look anyway

https://www.theregister.co.uk/2019/06/04/supra_cloud_tv_flaw/

one thing to consider, how far away are you from the mast and how new is your aerial? we had a very old aerial on our house so a repair man came round. He said 'the signal from this new one may actually be too strong, I can see winter hill from your roof !'

He said ‘the signal from this new one may actually be too strong, I can see winter hill from your roof !’

I've got the opposite problem, I'm right on the edge of a transmission zone. I live in a terrace, five or six doors up from me all the aerials change direction. (They're on Winter Hill, I think mine is Pendle Forest.)

thing is its ok for a while then goes bad generally in the evenings. We don't watch a lot of tv but its annoying when I do want to watch something.

We had this and used to blame the neighbours, tried new aerial and eventually figured out that it was our chrome cast causing it. Now it gets removed when not in use.

Chinese spy satellites, oh and Brexit.

Err that's not pixellation but macro-blocking. It's caused by the Bit Error Rate of the received signal being too high for the decoder to correct so rather than each JPEG/MPEG macro-block of 16x16 pixels being displayed correctly it gets shown as a single block. The weird colours are because the colours for each block are in their own 16x16 block so if the errors are there then that colour gets messed up.

Pixellation is the zooming in to the point where it is possible to distinguish each individual pixel in an image or video. Not necessarily a fault in the distribution of or the content itself.

Err that’s not pixellation but macro-blocking

Good news burko, your TV no longer suffers from pixellation!

wahey. I think i'll be fine then.I can cope with macro-blocking....

I'm in Hampshire and I've noticed the same thing. Also Dave has no signal whatsoever but Dave ja vu is perfect. Movies4men has the same issue.
And there is another retune due on Monday.

Just staying in a flat in that London and they currently have no Dave or BBC1/2/4. Everything else seems ok. Something going on

Have a look here https://ukfree.tv/maps/freeview You'll need to figure out which transmitter you are using to see if there's any problems.

Dave and Movies4Men are on the same mux* so if that's been moved to a different frequency you'll need to do a full scan to pick everything up again.

* Digital TV channels are multiplexed (hence mux) together and transmitted on one frequency. When you "tune" to a channel your settop box demuxes these and picks the channel you asked for.

I have a Sky based conspiracy theory that “normal” quality is allegedly being

reduced to force us to pay HD subscriptions.

I have a Sky based conspiracy theory that “normal” quality is allegedly being

reduced to force us to pay HD subscriptions.

I share that theory. I think satelite/cable quality is definitely capped so freeview doesn't look sh1t.

And there have been times in the past where the BBC, and probably Sky, have reduced the quality/upped the compressson to see how many people would complain.

I can't remember which royal event it was when the BBC where doing it but the picture was such a mess when everyone started waving their flags in trafalgar square.

I complained and the BBC reply basically admiited that is what they were doing.

Are there any major towns with new buildings near your line to the transmitter ?

Being exactly aligned with your neighbors arial might not actually be correct.

Sky used to transmit their news channels in quarter resolution and STBs would upscale it to standard size. Basically they were relying on not much changing in the picture, basically a newsreader against a static background, so that there wasn't much discernable difference between a genuine full frame broadcast and the quarter frame one.

Due to the way that the MPEG compression works a scene of a crowd waving flags is about as computationally intensive as you can get and is really hard work for both encoder and decoder.

There's no reason for commercial broadcasters to make their channels look shit in comparison with Freeview and pretty much every reason to make them look better. Cable in particular has a huge amount of bandwidth available that even with several hundred channels being broadcast there's no need to reduce the quality.

Cable in particular has a huge amount of bandwidth available that even with several hundred channels being broadcast there’s no need to reduce the quality.

so why is it the same quality as freeview which is bandwidth constrained ?

Virgin could wipe the floor then by just broadcasting at higher quality - no-one would have been complaining about the picture quality in the dark scenes on Game of Thrones the other week.

Due to the way that the MPEG compression works a scene of a crowd waving flags is about as computationally intensive as you can get and is really hard work for both encoder and decoder.

It's even worse when the broadcaster was intentionally dropping the quality during that event.

I share that theory. I think satelite/cable quality is definitely capped so freeview doesn’t look sh1t.

It's more like they don't make a higher quality feed available so cable and satellite can show up freeview

@TurnerGuy - I suppose it depends what the quality (SD/HD) is of the material they are broadcasting rather than any deliberate downscaling.

Freeview is bandwidth constrained in that there are limited channels/frequencies that they can use but that doesn't limit the quality of what is broadcast on each frequency they are different things. So if SD content is broadcast on Freeview/FreeSat/Sky/Cable/terrestrial then it will look the same providing there's no interference in the system. It's like a car on a road, doesn't matter if the road is the M6 or a plain A-road, it's still the same car with the same capabilities.

Here's the channel list for a Hampshire (I think) transmitter. https://ukfree.tv/transmitters/tv/Rowridge Notice the number of channels on each mux and how few are on the HD mux (third one down), all the HD channels are on the same frequency/mux as they require a different decoder to SD. Also notice just under the "Frequency" column you'll see "C24 498MHz" that's the channel number. The frequencies for each channel are 8MHz apart, the second mux is C27 @ 522MHz, terrestrial transmitters can't use all the channel frequencies (there's 64) to avoid interfering with one another whereas cable systems are enclosed so can use them all which is why they can offer so many channels.

Of course if the broadcaster is playing around with things at their end then all bets are off!

Freeview is bandwidth constrained in that there are limited channels/frequencies that they can use but that doesn’t limit the quality of what is broadcast on each frequency they are different things.

huh ? they mux several channels onto one frequency don't they, and the number they can mux is dependant on the data rate in each channel.

So by keeping the data rate low they can mux more channels, hence we can get all the needless +1 channels and compromised pictures.

if that wasn't true they why have the BBC dropped the data rates of nearly all the DAB (similar principle) to 96kbps so they can get more channels on ? When they originally recommended that they shouldn't go below 192kbps.

Sort of - don't conflate compression at the distribution end with how things get packed up in the mux. Even if the broadcaster does compress the source more they can't simply put another channel on to a mux without having each receiver delete its current channel table and downloading the new one so that it can find the new channel. Basically the new channel would appear in the channel list presented to the user but they wouldn't be able to actually view it.

So any upstream compression/reduction in quality is likely to be experimental to see what they can get away with. Each channel such as BBC1 is in fact broadcast as at least two streams, one for video and one or more for audio, the DVB spec also allows for a third stream which simply contains syncronisation data known as the Presentation Time Stamp but in practice most broadcasters send these packets in the video data. You can also have multiple audio streams (different languages) associated with each video stream, there's potentially also audio description.

We're on FreeSat and apart from weather related signal loss and subsequent breakup of picture I've not noticed any "compromised" pictures. I didn't notice any on FreeView systems at work either. Not been on Sky or used cable for nearly a decade so no idea what happens there.

Don't know about DAB, that's a different system, even if similar technologies.

but if there were less channels (can the +1 ones for start) on a mux then each channel could use a higher bitrate (doesn't matter about compresson - more data is more data) and the uncompressed signal at the other end will be higher quality, even though it is the same resolution.

A bit like how GOT on bluray was a lot better than the Amzon Prime feed even though the Amazon compresson algorithyms are suppossed to be some of the best. same res but much higher data rates.

No read everything above, but there are issues with digital / freeview where say a new or improved phone mast has appeared and something about 4g, worth looking for local info, FB pages. We had a new vodaphone mast and they said they wrote to all folk in the area but not us, anyway man came round with some filter things and we are OK now.

The broadcasters *could* do that but it's a while since I've been in a broadcast head-end room (understandably they are rather secure places!) so I don't know if they actually do. A lot is down to economics - the use of a transponder on a satellite isn't cheap so there's pressure to use the available space as best they can. Sky don't own the satellites they use BTW, they just lease the transponders.

Bit-rate in a DVB system isn't continuous, there's a set of permitted values depending on guard interval and coding rate - look at the DVB-T entry on Wikipedia for what these are. DVB-T is the transmission standard for SD, T2 is for HD, usually QAM64 is used for terrestrial and cable broadcast and QPSK for satellite, I can't remember ever seeing a mux use QAM16. Most T2 transmissions use QAM256.

Internet based video services use adaptive streaming like DASH so you get the best bit-rate that your device and the network between it and the head-end can support.

Anyway, I quite like the +1 channels, they let me see two programmes that otherwise would clash!

Neighbour has a crap old motorised mower.