Whenever I've watched a programme on a BBC or ITV channel on my capture card. I've noticed that the picture quality on the BBC channels seems to be sharper and more detailed than on ITV channels, especially if your watching a football match or live event; ITV's PQ seems to be soft/smooth. (I don't mean the broadcast resolution (720, 704, 544 etc..), because even on Freeview when watching full res I still notice)
I suspect ITV it may be connected to ITV making changes so that ITV4 could run 24hrs on Freeview. Whilst allowing the CiTV Channel to retain its hours and still having ITV2 +1 running at the same time. I don't know what change they made, however I suspect it may have affected the picture quality.
I suspect ITV it may be connected to ITV making changes so that ITV4 could run 24hrs on Freeview. Whilst allowing the CiTV Channel to retain its hours and still having ITV2 +1 running at the same time. I don't know what change they made, however I suspect it may have affected the picture quality.
ITV1-4 (ITV/C4), CITV (SDN) and ITV2+1 (NGW) are all broadcast on different MUXes, so that really shouldn't have anything to do with that.
It's all a little too technical for me, but my understanding is that ITV1 should be broadcasting at the same quality as BBC1 on DTT, where as the other ITV channels do broadcast at lower quality.
ITV channels have always looked like mush on digital services. Apparently football on ITV1 on Sky is or was so bad that it looked like an attack of the dust bunnies was going on.
CITV on Freeview now has incredibly bad quality, its even worse now than it was when ABC1 had that slot. ITV4 is borderline for quality during a busy picture, while ITV2+1 tends to look softer. ITV2 seems pretty solid as does ITV3. This is what happens when you try to cram too many channels on a multiplex.
It is my understanding that BBC One has the highest bitrate of the BBC channels on Freeview anyway. The interactive streams seem to become blocky when the snooker is on but oddly enough I haven't noticed this on the tennis. Parliament would be lowish bitrate anyway for what it spends most of its time showing.
Surprised that this has come up actually, I was only thinking about this the other day. I'm not sure if it's just me, but ITV1 seems to have a lot better picture quality of late.
What happens once the analogue signal is shut down? I read something about the digital signal being made stronger once this happens, is this the case? And if so, will this solve the problem I have of picture breaking up all the time due to a poor signal on an indoor ariel in my bedroom?
1. Broadcast resolution.
BBC One, BBC Two, ITV1, C4 and Five are all broadcast at 720x576 (or 704x576) on Freeview. The BBC (and I think Five) also use this resolution on satellite, and the BBC use this resolution for their other main channels on satellite and Freeview as wel.
ITV use 544x576 for their other digital channels on Freeview on their own multiplex (Mux 2), as do C4 for E4, More4, Film 4 etc on their bit of their mux (Mux 2). The BBC only use this lower resolution for BBC Parliament (on Freeview - not sure about satellite) and BBCi video (again on Freeview, not sure about satellite)
ITV1 and C4 / C4+1 on satellite (at least on Sky - not sure about the separate non-regional FTA C4 and C4+1 streams for freesat) are also broadcast at this lower resolution (the only reason ITV1 and C4 are full-res on Freeview is because Ofcom mandate this)
This is why ITV1 on satellite usually looks softer than ITV1 on Freeview, or BBC One on satellite or Freeview, as it is lower resolution.
2. Bit rate
This is the amount of data that each channel is granted. Crudely - the more data (for a given resolution) the better the picture quality - for a given encoder.
The bitrate of a single service isn't always fixed, as by using statistical multiplexing, groups of channels can share a large chunk of bitrate and effectively "fight" for bandwith based on their content (and sometimes a priority). This works if channels have a varied mix of content - but if all the channels are simultaneously showing demanding content (Fast movement, fast cutting, smoke, random motion - rippling water, smoke, noisy or grainy content etc.) then nobody wins and everyone effectively loses.
3. Encoder quality
Different MPEG2 and H264 encoders will perform differently at a given bit rate. Some do better than others with different content - and some are just better than others. Newer models deliver better results at a given data rate than older ones, which may need more bit rate to deliver a similar picture quality.
4. Source quality
Never in TV has the quality of source material been more important. If video is noisy, has been edited at low bit rates, or has been through a lot of previous compression encode/decode processes, it will look worse than clean video that has been delivered at a high data rate. Avoiding multiple compression processes, producing pictures with no noise (or using a high quality noise reduction system IF YOU KNOW WHAT YOU ARE DOING) can help with this significantly.
Equally - some content is easier to compress than others. People who add film grain effects in post production are killing their picture quality by the time it gets to the viewer at home - as film grain is random, and thus wastes data that would otherwise be used to send more picture content...
When it comes to ITV - on all their platforms they are using very low bit rates, often lower resolution, and not all their source content is that great. Not sure about their encoders...
ITV1 on satellite is a joke - effectively unwatchable IMHO. I've certainly stopped watching their saturday night shows like The X Factor. The fast cutting and detailed sets may look good in the gallery, but by the time they reach me at home, they look like mush. In comparison, Strictly, even in SD, looks great, and in HD looks stunning.
(Shooting in HD usually improves the quality of your SD stuff as well - as any noise is at HD resolutions and almost disappears in the downconversion, giving cleaner pictures at SD than an SD camera would)
BTW - the 16QAM vs 64QAM issue is only relevant in marginal signal situations, where a 64QAM signal may have more errors (and thus break-up) more than a 16QAM signal. If you get error-free reception of both then there is no picture quality issue caused by the difference between the two modulation schemes.
So the softness could possibly be caused by their encoders? Because the ITV2+1 caps I took was at a pretty decent bitrate. 5mbps + for the Sugababes scene (Nelson Mandela concert) and around 3.5mb for the studio.
So the softness could possibly be caused by their encoders? Because the ITV2+1 caps I took was at a pretty decent bitrate. 5mbps + for the Sugababes scene (Nelson Mandela concert) and around 3.5mb for the studio.
ITV2+1 is not on the ITV/C4 mux (Mux 2), it is on Mux D (which is one of the NGW muxes) This is, ISTR, full resolution (720x576) in comparison to ITV2 (which is on Mux 2 but 544x576), but it may have all sorts of heavy noise reduction and pre-processing done to it to "improve its compressibility" (i.e. reduce the blocking caused by compression by filtering out all the noise and lots of HF detail prior to compression)
So the softness could be the encoders (and pre-processing) combined with running at a high resolution at a relatively low data rate - with quite challenging source material. Pop concert content needs a high data rate as it usually has fast moving cameras, fast cutting, lots of detailed LED screens and lots of dynamic lighting, none of which compress well...
(Just watch when BBC Two and BBC Three, or BBC Four and BBCi are both showing Glasto stuff... They both disappear into a mushy, blocky mess)
That said - I think that the Mandela concert, whilst shot in HD, had quite a lot of "soft focus" filtering (pro mist or similar filters on the cameras) going on for artistic effect?
The other issue is one of the others I mentioned - that of compression upstream of the final encoder. If ITV 2+1 is delayed using a compressed server solution then that will add another encode (though it should be a small quality issue if done well), however if ITV were also delaying the Mandela concert to edit it then there will be a compression in their editing system as well. Add to that a compressed circuit from Hyde Park to the South Bank (possibly via a cheapskate satellite circuit? "It's on ITV2 - Joe Public won't notice etc. etc.") - which is potentially the large quality hole - then you may end up with the nasty mush.
Also the lighting on the Phil Schofield studio doesn't seem to be doing anyone many favours...
As for the BBC grabs - a talking head close-up on the News Channel should compress very well, and a lot of the Glasto stuff is HD (the main stages are), and their studios are usually well lit and nicely set-up, with good quality fibre circuits back to TVC most years I believe.
For info - ITV2+2 and Film Four are on Mux D, and E4+1 is on Mux C. C and D are both NGW muxes, and these three services are likely to be 720x576 not 544x576.
ITV1, ITV2, ITV3, ITV4, CITV, C4, C4+1, E4, More4 (and Teletext etc.) are on Mux 2 - with only ITV1 and C4 being 720x576 (or 704x576) with the rest being 544x576 ISTR.
How does Virgin work in all this? Whenevr this topic comes up we always focus on freeview and satelite. What res/bitrate do they all broadcast on Virgin?
I've always been under the impression that ITV in particular looks nicer on Virgin than in does on Sky but I don't really watch must of it.
Does STV get compressed to the same levels? I take it the specs are mandated by the Network Centre rather than just PLC trying to do stuff on the cheap?
I agree with noggin that ITV1 on Sky is absolutely unwatchable. It's not just the anorak in me, either. I've heard 'non-anoraks' saying how poor the ITV1 picture quality is, particularly when football is on. I've also noticed during Granada Reports that the T&Cs on competitions are illegible. The picture is that soft that it is impossible to discern each letter in such a small font size.
Luckily, I can watch ITV1 on Freeview. I still think analogue gives a clearer picture though if you have good reception. The only reason I have to watch a digital source is because I have a widescreen TV. If I still had a 4:3 TV, I would definitely still be watching analogue.
i've often wondered why itv looks like it was downloaded off youtube. it's weird on sky, sometimes it's not that noticeable, other times, the idents and the itv news are pretty unwatchable.