TV Transmission quirk

[XFool]

I'd have liked to append this to the several previous queries I have made wrt this particular TV programme and channel, but I cannot now find the thread.

I watch The Bill, being repeated on Drama channel, on and off there have been a number of 'issues' that I have asked about previously wrt this programme's transmission (and other programmes, channels). A new one has popped up!

Some days ago (last week?) I suddenly found the contrast was 'wrong' on this programme as received - too high. Either the signal level for the programme feed was raised, or possibly black level is set wrongly. This issues seems to be persisting. OK I can adjust my TV... etc, etc.

Does anyone have any particular notion why a problem like this should ever come about? (OK. It may be an unanswerable question, but in prior issues with transmissions of this programme I received useful information which pointed to plausible explanations.)

NB. I am NOT asking about my television etc! It is about just THIS programme on THIS channel.

To ram this point home, just had a quick look at Classic Eastenders transmission on Drama (in 'forced' 4:3 format). No problem

[scrumpyjack]

Channels on Freeview do not all get the same bandwidth

https://en.wikipedia.org/wiki/Freeview_(UK)

Might that account for a poor picture on one channel compared to another?

[XFool]

Channels on Freeview do not all get the same bandwidth

https://en.wikipedia.org/wiki/Freeview_(UK)

Might that account for a poor picture on one channel compared to another?

Thank you. But I cannot see how.

I did go to pains in my OP to point out this was a particular programme issue. Indeed, it is only since one day last week that The Bill suddenly suffered from this issue. It appears to me to only have an internal, broadcaster, 'studio' based cause. (Wouldn't be the first time on Drama with The Bill!)

[csearle]

I can only imagine it is a change in the encoding of that particular programme because AIUI the signal level of a digital* transmission only has to be high enough to reliably get the data across, excess signal level beyond that doesn't make the picture any better (unlike the analogue transmission of yesteryear).

Chris
* Of course all transmissions are analogue but let's not be pedantic about this.

[Breelander]

I'd have liked to append this to the several previous queries I have made wrt this particular TV programme and channel, but I cannot now find the thread...

No, I can't find it either - and I'm usually quite adept at searching.....

...Some days ago (last week?) I suddenly found the contrast was 'wrong' on this programme as received - too high. Either the signal level for the programme feed was raised, or possibly black level is set wrongly. This issues seems to be persisting. OK I can adjust my TV... etc, etc.

Does anyone have any particular notion why a problem like this should ever come about? (OK. It may be an unanswerable question, but in prior issues with transmissions of this programme I received useful information which pointed to plausible explanations.)

The program is transmitted digitally so the strength of the signal you receive can have no effect on picture dynamics, only on the received error rate. Any mistakes in the black level or contrast are therefore in the signal processing leading up to the encoding for transmission.

To ram this point home, just had a quick look at Classic Eastenders transmission on Drama (in 'forced' 4:3 format). No problem

There are two common ways used to 'force' 4:3 format, I've seen both in use across various programs and channels. I have no idea which one Drama have chosen to use.

For the first, the program is encoded in the 4:3 format and transmitted as such. Depending on the 'Aspect' settings of your TV it can auto-switch to display it as 4:3. It is possible to set your TV to override the declared format and stretch it to 16:9. The other way is encode and transmit it as a 16:9 image with black borders to either side, in the same way that widescreen films have a black margin top/bottom.

I can download recordings from my Freeview PVR in the digital format as transmitted. The Bill is next on Drama at 1:35am, about 4 hours from now. I'll record it and see what I can find out about how it's been encoded.....

[XFool]

The program is transmitted digitally so the strength of the signal you receive can have no effect on picture dynamics, only on the received error rate. Any mistakes in the black level or contrast are therefore in the signal processing leading up to the encoding for transmission.

Yes. That's why I think it must be something their end. I have no idea how these programmes are sourced these days.

To ram this point home, just had a quick look at Classic Eastenders transmission on Drama (in 'forced' 4:3 format). No problem

There are two common ways used to 'force' 4:3 format, I've seen both in use across various programs and channels. I have no idea which one Drama have chosen to use.

For the first, the program is encoded in the 4:3 format and transmitted as such. Depending on the 'Aspect' settings of your TV it can auto-switch to display it as 4:3. It is possible to set your TV to override the declared format and stretch it to 16:9. The other way is encode and transmit it as a 16:9 image with black borders to either side, in the same way that widescreen films have a black margin top/bottom.

Yes. Plus there is (apparently) a third method - what I refer to as 'Forced 4:3'. My decoder's AFD Automatic is set to OFF at the moment but, nevertheless, some channels 'Force 4:3' format when showing old 4:3 material. e.g. Drama with 'Classic East Enders' as mentioned above. As I am still watching on an old 4:3 CRT TV(!) that suits me as, without any action from me, it correctly displays full-screen, as it should!

Interestingly, BBC Parliament, never seem to do this. So, watching say a 4:3 1970s general election broadcast, (a niche taste I guess...) it ends up 'pillar boxed' and, on my 4:3 CRT, 'letter boxed' as well. Never mind, I just Pan&Scan to full screen and it's the 1970s all over again.

The Bill is being broadcast widescreen at this point. Though screen formatting was a previous issue/query with this channel/programme!

I can download recordings from my Freeview PVR in the digital format as transmitted. The Bill is next on Drama at 1:35am, about 4 hours from now. I'll record it and see what I can find out about how it's been encoded.....

Thanks Breelander. Though not sure what you mean here by "encoded".

[XFool]

...Hang fire.

I'm having some doubts about this now - 'New Tricks' on Drama looked a bit too contrasty to me, so I have fiddled with the TV settings. All I know is that one day, when The Bill came on it definitely looked wrong, all of a sudden noticeably too contrasty. Will have to see what The Bill looks like tomorrow.

[Breelander]

...Hang fire.

I'm having some doubts about this now - 'New Tricks' on Drama looked a bit too contrasty to me, so I have fiddled with the TV settings. All I know is that one day, when The Bill came on it definitely looked wrong, all of a sudden noticeably too contrasty. Will have to see what The Bill looks like tomorrow.

I actually watched a bit of 'New Tricks' while researching my reply. It looked normal to me. Do you see the same effects on Drama+1 ? You may need to retune to see it, Drama+1 launched on 1st February.

A timeshift channel, Drama +1 was launched on Sky and Virgin Media on 16 September 2019 replacing Travel Channel +1. On 25 January 2021, it was announced that the timeshift channel would be taking over CCXTV's Freeview slot (channel 73) on 1 February 2021

https://en.wikipedia.org/wiki/Drama_(British_TV_channel)

As an aside, along the way I discovered that UKTV (owners of Drama, Dave, Yesterday, at. al.) was jointly owned by BBC and Discovery up to 2019, when Discovery sold most of it to the BBC. Drama is now wholly owned by the BBC.

For many years, the BBC and Discovery co-owned the UKTV broadcaster that supplies 10 traditional TV channels, most of which can be seen on Freeview and Freesat... Discovery Inc ... was keen to offload UKTV onto the BBC, whilst cutting a deal for the BBC archive and future production of suitable shows...

https://ukfree.tv/article/1107052560/Wh ... icences_to

...I'll record it and see what I can find out about how it's been encoded.....

... not sure what you mean here by "encoded".

Digital broadcasts are encoded using the MPEG-2 (aka. H.222/H.262) codec. The MPEG-2 standards allow for various parameters to be set, such as the bitrate (ie. how much compression), the image size in pixels (eg. 720x576) and the aspect ratio. My PVR recording is the data exactly as broadcast, so I'll be able to see if there's anything unusual in the way it has been encoded for broadcast.

[Breelander]

I watch The Bill, being repeated on Drama channel ... Some days ago (last week?) I suddenly found the contrast was 'wrong' on this programme as received ... possibly black level is set wrongly. This issues seems to be persisting. OK I can adjust my TV... etc, etc.

I've had a chance to check my recording now. Yes, the contrast does seem a little too high. In fact the colour saturation seems to have been turned up a bit too. I've watched some more Drama channel content now and it seems to be applied to all their output, adverts included. It seems to be their universal policy to 'brighten up' all their output, perhaps to make the adverts more 'engaging' - or they just think it looks 'better' and you'll keep watching their output in preference to that of other channels.

I suspect that the original video source for The Bill started off with a lower black level than most, so suffers more from this 'processing'. Some other programs I watch don't seem to have any totally black content, even the darkest shadows are not completely black.

As for the encoding, it looks normal MPEG-2 video, though the resolution is low at 544x576 pixels, and the compression is high with a bitrate of just 5854 kb/s.Typically the BBC broadcasts with 720x576 (or 704x576) at 15000 kb/s. That too could go some way to explaining fine details missing in the shadow areas (in the same way that too much jpeg compression can be bad for photos).

Bottom line: I'm afraid it's not you, it's them. You'll just have to keep fiddling with your TV to make The Bill look acceptable.

[servodude]

I watch The Bill, being repeated on Drama channel ... Some days ago (last week?) I suddenly found the contrast was 'wrong' on this programme as received ... possibly black level is set wrongly. This issues seems to be persisting. OK I can adjust my TV... etc, etc.

I've had a chance to check my recording now. Yes, the contrast does seem a little too high. In fact the colour saturation seems to have been turned up a bit too. I've watched some more Drama channel content now and it seems to be applied to all their output, adverts included. It seems to be their universal policy to 'brighten up' all their output, perhaps to make the adverts more 'engaging' - or they just think it looks 'better' and you'll keep watching their output in preference to that of other channels.

I suspect that the original video source for The Bill started off with a lower black level than most, so suffers more from this 'processing'. Some other programs I watch don't seem to have any totally black content, even the darkest shadows are not completely black.

As for the encoding, it looks normal MPEG-2 video, though the resolution is low at 544x576 pixels, and the compression is high with a bitrate of just 5854 kb/s.Typically the BBC broadcasts with 720x576 (or 704x576) at 15000 kb/s. That too could go some way to explaining fine details missing in the shadow areas (in the same way that too much jpeg compression can be bad for photos).

Bottom line: I'm afraid it's not you, it's them. You'll just have to keep fiddling with your TV to make The Bill look acceptable.

That's a great and fascinating investigation!
I didn't consider that PVRs would be recording the "raw" but it makes sense.
And I'll agree that it sounds like a bad up/re-scaling (or more loss of dynamic range through a series of compressions)
- something you could almost fix with scaling to the sync pulse on an old analog signal

Might be worth trying the "on demand" option if it exists for the show? The BBC used to make them available (and rippable) in a variety of bit depths and rates
- but it really just sounds like someone's used the wrong options when preparing this for TX
-sd

[Breelander]

I didn't consider that PVRs would be recording the "raw" but it makes sense.

Yes, my PVR has a USB socket and I can export recordings I want to keep as a .TS file to a usb stick. Besides the video stream, there's a stereo audio stream with mp2 encoding, a 48,000 kHz sample rate and (typically) 192kbps bitrate, a mono stream at 64kbps for the visually impaired, and usually a dvb_subtitle stream too.

I'll process the recordings I want to keep on my PC, recoding to a .mp4 using the more efficient h264 codec for the video and aac for the audio. Then I can watch them on the PC or cast them to my TV. The resulting .mp4 is virtually indistinguishable from the original recording, but the file size is usually a tenth of the original .TS file.

Only possible for SD recording though, PVRs are required by the Freeview HD licencing to store their HD recordings in encrypted form. There are ways around that, but it usually involves hacking the firmware of the PVR!

[servodude]

I didn't consider that PVRs would be recording the "raw" but it makes sense.

Yes, my PVR has a USB socket and I can export recordings I want to keep as a .TS file to a usb stick. Besides the video stream, there's a stereo audio stream with mp2 encoding, a 48,000 kHz sample rate and (typically) 192kbps bitrate, a mono stream at 64kbps for the visually impaired, and usually a dvb_subtitle stream too.

I'll process the recordings I want to keep on my PC, recoding to a .mp4 using the more efficient h264 codec for the video and aac for the audio. Then I can watch them on the PC or cast them to my TV. The resulting .mp4 is virtually indistinguishable from the original recording, but the file size is usually a tenth of the original .TS file.

Only possible for SD recording though, PVRs are required by the Freeview HD licencing to store their HD recordings in encrypted form. There are ways around that, but it usually involve hacking the firmware of the PVR!

I guess there's no need currently to compress TV efficiently for broadcast; as it's being viewed in "real time"
- actually thinking about it... it makes sense to "stretch it out" so any transmission issue affects less of the video stream
- different altogether for "streaming on demand" where there is a buffer at the user end

I've followed for decades the different approaches to DRM in this space with interest; I think I've convinced myself that the best approach is to make people not want to "steal" your stuff.
Make them invested in your output - not necessarily your data!
- anything else is just getting in the way of what will inevitably happen
- whether by hacking fw, by accessing manufacturing codes, or transcoding

-sd

[XFool]

I watch The Bill, being repeated on Drama channel ... Some days ago (last week?) I suddenly found the contrast was 'wrong' on this programme as received ... possibly black level is set wrongly. This issues seems to be persisting. OK I can adjust my TV... etc, etc.

I've had a chance to check my recording now. Yes, the contrast does seem a little too high. In fact the colour saturation seems to have been turned up a bit too. I've watched some more Drama channel content now and it seems to be applied to all their output, adverts included. It seems to be their universal policy to 'brighten up' all their output, perhaps to make the adverts more 'engaging' - or they just think it looks 'better' and you'll keep watching their output in preference to that of other channels.

Thanks Breelander, for your help. Especially for drawing my attention to Drama + 1, which I didn't know about.

This morning I watched the last ten minutes of 'Classic Casualty' on Drama, before 'The Bill'. I don't watch Casualty but wanted to check how it looked before The Bill started, after last night's adjustments to my TV. It seemed OK to me, when The Bill started it was still too contrasty. Especially as opening scenes of this episode were at night, almost unwatchable! So, for once, it definitely wasn't just me.

Strange how The Bill was fine on Drama until suddenly one day last week it wasn't. But, as I said, in my experience the Drama channel have form with sudden, strange, inexplicable changes to programme transmission standards. As I said, the preceding programme (Casualty) looked fine with my current TV settings. With their advertising, a mixture of commercial ads and programme promos, I noticed it varied - commercials mostly OK but programme promos varied tremendously. So, for some reason now, on Drama channel, the effect is dependent on which actual programme source they are transmitting. Very strange.

Bottom line: I'm afraid it's not you, it's them. You'll just have to keep fiddling with your TV to make The Bill look acceptable.

Whatever happened to 'simple'? Increasingly it seems like a distant, fading memory. Everything involving ordinary, everyday radio/TV reception seems to be becoming a major technical minefield. That's before we even get to broadband...

[Alaric]

As an aside, along the way I discovered that UKTV (owners of Drama, Dave, Yesterday, at. al.) was jointly owned by BBC and Discovery up to 2019, when Discovery sold most of it to the BBC. Drama is now wholly owned by the BBC.

1990s editions of "The Bill" are available on demand from the UKTV streaming service. That may explain why a programme made by Thames shows a BBC logo before the titles. (These are the episodes where the opening titles are a patrol car with sirens racing towards the camera, followed by a series of brief shots of the main characters).

[XFool]

...Seems better today. (Apart from, noticeably, in a very brief extract of The Bill during a trailer in an advertising break)

So a temporary glitch, or somebody complained?

[MrFoolish]

I don't suppose these minor channels put a lot of effort into the technical quality of their output. They are just re-sellers of old content. When it was originally transferred from analogue tape to digital, whoever did it might not have gone with the most pristine master or put a lot of care into the process.

[XFool]

XFool wrote:

Whatever happened to 'simple'? Increasingly it seems like a distant, fading memory. Everything involving ordinary, everyday radio/TV reception seems to be becoming a major technical minefield.

Never a truer word...

Thanks Breelander, for your help. Especially for drawing my attention to Drama +1, which I didn't know about.

...This is a kind of follow on question resulting from my being told about Drama +1. Don't ask! Or I might be forced to tell/kill you.

Anyway, the actual question is: Following the Digital UK led 700Mhz Clearance Programme*, presumably completed, what is the current status of the COM7 (ARQ C) multiplex? Has it now been switched off, as with the other 'temporary mux' COM8 (ARQ D)? My transmitter is Crystal Palace and I can find no trace of it on UHF channel 55. OK, I don't have a HD digital box or TV, so that is not an issue. But I don't see More 4 +1 either - merely as an example of a non HD channel that was on COM7. So, if still there, I should see at least a sign of it.

This, about Crystal Palace, still shows COM7 present, but I don't know how current the article is:
https://en.wikipedia.org/wiki/Crystal_Palace_transmitting_station#After_switchover

More surprisingly, it is still shown listed in this table, shown current as at February 15, 2021:
https://en.wikipedia.org/wiki/List_of_DTT_channels_in_the_United_Kingdom

There, COM7 is shown as carrying BBC 4 HD (on LCN 106), BBC News HD (LCN 107) as well as the non HD More 4 +1 (LCN 86) etc. What has happened to these if COM7 has gone? BBC website is still showing schedule for BBC 4 HD. So I'm mystified (again), assuming BBC4 HD is a Free to Air channel. Anyone know what is going on?


* https://www.freeview.co.uk/700mhz

[Breelander]

Anyway, the actual question is: Following the Digital UK led 700Mhz Clearance Programme*, presumably completed, what is the current status of the COM7 (ARQ C) multiplex? Has it now been switched off, as with the other 'temporary mux' COM8 (ARQ D)? My transmitter is Crystal Palace and I can find no trace of it on UHF channel 55. OK, I don't have a HD digital box or TV, so that is not an issue. But I don't see More 4 +1 either - merely as an example of a non HD channel that was on COM7. So, if still there, I should see at least a sign of it.

COM 7 is now named COM 7 HD, there is no COM 8 any more. The HD channels are on BBC B and COM 7 HD. Some SD channels are also carried on these Mux, and therefore cannot be seen by an SD-only receiver. They are...

Last updated: 15 Feb 2021

DTT channel and multiplex listings for industry professionals

KEY: E = England, W = Wales, S = Scotland, NI = Northern Ireland, CI = Channel Islands.

LCN  Service            Genre           Mux       E   W   S   NI   CI

65   TBN UK             Entertainment   BBC B     ✓   ✓   ✓   ✓   ✓
72   Shopping Quarter   Entertainment   BBC B     ✓   ✓   ✓   ✓   ✓


64   FreeSports         Entertainment   COM7 HD   ✓   ✓   ✓   ✓   
70   Quest Red+1        Entertainment   COM7 HD   ✓   ✓   ✓   ✓   
76   NOW 80s            Entertainment   COM7 HD   ✓   ✓   ✓   ✓   
83   Together TV+1      Entertainment   COM7 HD   ✓   ✓   ✓   ✓   
86   More4+1            Entertainment   COM7 HD   ✓   ✓   ✓   ✓   
87   PBS America +1     Entertainment   COM7 HD   ✓   ✓   ✓   ✓   
89   Court TV           Entertainment   COM7 HD   ✓   ✓   ✓   ✓   
96   Forces TV          Entertainment   COM7 HD   ✓   ✓   ✓   ✓

https://www.freeview.co.uk/corporate/pl ... fessionals

[XFool]

Thanks for your help, Breelander, I used to take an interest in and be on top of a lot of this stuff, prior to and around DSO. But since then I just forgot about it and reverted to being a 'normal' TV viewer. Unfortunately, with digital, that doesn't really work.

There seems to be a lot of contradictory or ill informed stuff online, on BBs - or possibly I'm misinterpreting it.

I knew COM8 had gone but now understand that currently, despite the 700MHz Clearance, COM7 is still there. But, as it is a HD Mux, I can't pick it up on my equipment, same with BBC B (PSB3).

I seem to be missing a couple of Freeview channels where I am, for instance, More 4 +1 which is on COM7. I assumed, as More 4 +1 is itself not HD(?), I should still receive it. But as I don't I guess the explanation must be that, whatever its mode, as it is being broadcast on a DVB-T2 HD Mux I cannot decode it. Does that make sense?

I also now realise (partly) what is behind a lot of the more recent TV reception problems I have been having. My transmitter is Crystal Palace but, for whatever reason(s), my box is - like a moth to a flame - unremittingly attracted to the Bluebell Hill transmitter in Kent. This, despite the fact that Bluebell Hill is one tenth the power of Xtal Palace and nearly three times further away! I had previously missed this clue.

Having spent time yesterday getting back on top of these matters, to at extent at least, I am again in a position to take control of events in future - if only I can remember! Such as, remember to keep Automatic Background Scan OFF, restrict Automatic Scan to the UHF channels from Xtal Palace (leaving out COM7), check the UHF channel number being used if there are reception problems on a TV programme. Finally, and usefully, if on Mux from 'wrong' transmitter, look up correct UHF channel for Mux on Xtal Palace and use Manual Scan to acquire it.

Remember when it was "Push button 1 for BBC 1, button 2 for BBC 2..."?

[Breelander]

...I assumed, as More 4 +1 is itself not HD(?), I should still receive it. But as I don't I guess the explanation must be that, whatever its mode, as it is being broadcast on a DVB-T2 HD Mux I cannot decode it. Does that make sense?

Yes I'm afraid it does. Although More4+1 and the others in the table I gave above are all SD channels, because they are carried on an HD Mux you must have a tuner that can decode a DVB T2 HD Mux in order to find them.