TVHeadEnd - BBC 4 has vanished

Quote from LybsterKodi

Its been a while since I wanted to record anything from BBC 4 but I did today and its vanished from TVHeadEnd on both my Dell Optiplex i5 with Haupage and my RPi4 with TV hat, but its still showing on my TV.

Other channels coming in on the same mux (Rumster Forest 522MHz) are still there. I can't find anything indicating that BBC4 is off the air or something has happened to it.

I'm in the process of trying to reinstall TVHeadEnd on the RPi4 to see if that cures it. Its stuck at 91% mapping the services at present.

Any suggestions as to other actions to try?

Something's wrong if it's stuck at 91% doing a regular Freeview SD/HD map.

Is it BBC Four SD or BBC Four HD that has gone ? (I didn't see if you were DVB-T or DVB-T/T2 capable)

You were scanning after 7pm weren't you? (CBeebies uses the same space as BBC Four during the day and TV Headend will ignore it I think) I usually do a scan during the daytime and then another one at night to get both BBC Three/CBBC and BBC Four/CBeebies - which are the main time-ex(clusive) services on Freeview SD and HD.

Quote from LybsterKodi

It was BBC4 SD (old eyes not good enough for HD ) but is was during the day not after 7pm. This "CBeebies uses the same space as BBC Four during the day " may well be the problem since, not having kids, I've removed CBeebies. I'll reenable and see what happens.

You probably need to re-scan during BBC Four's transmission hours (it starts at 1900 every night). During the pre-1900 hours it doesn't have any video or audio PIDs associated with it - so TV Headend kind of ignores it as it's not a radio or TV channel at that time of day.

I doubt re-enabling CBeebies will do much for you - they are separate services that switch from being placeholders to channels at opposite times of the day - sharing the same audio and video PIDs (I think)

(PIDs are kind of labels for discrete streams in the MPEG2 transport stream carried by each RF multiplex)

Quote from LybsterKodi

You're probably right and I'll get round to checking at some point (probably the next time I spot something I want to record). I tested on my sichbopvr setup on a PC using an august adapter which Kodi doesn't recognise and its scan turned up CBeedbies and BBC 4 just with BBC 4 not active

If you want to use the August USB tuner in TV Headend on Libreleec, a lot of adaptors will just require you to download the right firmware and copy it over for them to be seen by Linux - and thus appear in TV Headend (as not all DVB tuner firmware is distributed in the core LibreElec system - I think for rights reasons).

If you go to the Linux TV wiki page for your adaptor you may find a download link for the firmware.

https://wiki.libreelec.tv/how-to/add-firmware has details of where to copy the firmware too.

I've had success with some August DVB-T2 tuners using this method - though it does depend on Linux support for the tuner's chipset in the kernel as well.

If you're comfortable SSHing into your LE box with Putty etc. then you can check dmesg for DVB stuff (plug the adaptor in just before you type dmesg and you'll see an error if it's recognised the tuner but not been able to load the firmware)

There used to be an optional repo that also downloaded firmware (CrazyCat?) but I have a feeling it's no longer active.

Quote from LybsterKodi

Thanks for the info but I'll leave the August tuner for the PC - it gives me the Hauppage Dual tuner on my Dell Optiplex/LibreElec/Kodi, a TVHat on a RPi4/LibreElec/Kodi and the August on Windows. That means I can record 4 channels simultaneously if I ever go so mad!

You can record a lot more than 4 channels with 4 tunes - if your tuner is up to it you can record BBC One HD, BBC Two HD, ITV HD, C4 HD and C5 HD simultaneously with just one tuner

You only really need one tuner per multiplex if it's capable of streaming the full mux over its USB/SPI connection. (The Pi TV Hat can't stream the whole of the UK 40Mbs DVB-T2 mux over its SPI connection - or couldn't last time I checked - but other USB-based tuners can)

noggin is technically right. Many tuners can only handle 1 transponder/frequency at the same time. A transponder contains various multiplexed channels. If the channels/programmes are received via the same transponder/frequency you doesn't need an additional tuner.
I assume, that the programmes mentioned by noggin example are played out via the same transponder. On that way, you can theoretically record/look more than 4 programmes at the same time with only one tuner if your hardware is fast enough. Some sat receivers working like that and you can record 8+ channels/programmes at the same time if CPU/HDD doesn't limit.

There are also tuner modules available with FBC (Full Band Capture) support. Such kind of tuners can handle multiple frequencies at the same time. I don't know if these are exists for DVB-T2 too and supported by Tvheadend, but this would additional multiply the count of simultaneous records with only one tuner.

I would like to provide you with some useful links. But I'm not familiar with the behaviour of tvheadend because I don't use it and don't have the equipment to simulate it on your behalf. I use set-top boxes/SAT receivers for live TV and therefore know the limitations associated with it.

Please understand the possibility to record multiple programmes from the same transponder (MUX) with only one tuner in use as a benefit for free. I would assume that tvheadend supports that out of the box, without special settings. It depends more on your typical TV usage if you a have a benefit of it or not.

For example:
If you have a primary place in your home, where you and your family most times join to watch TV together I would place the device with the most available tuners there. From your mentioned list the Hauppauge Dual Tuner looks like something to me, because it's mostly directly supported by the linux kernel. You are able to watch a show with the first tuner unit and can run a record in the background at the second tuner. If you have a second overlapping/simultaneous record scheduled and fortunately the additional program to record is receivable via one of the already tuned transponders (tuner1: live tv, tuner2: current running record), then this additional record is also possible. If this program is played out on a third transponder only, this 2nd record isn't possible. Thats all.

It looks to me like you could use the remaining devices (RPi with HAT, August on Windows) as a Tvheadend SAT>IP server. If you need a 3rd or 4th tuner in your typical use case, you could add these devices as network tuners in Tvheadend and have a total of 4 tuners available in one KODI instance. Several combinations of your 3 devices are possible, but to make it useful for everyday use, the remote devices should run 24/7 without interruption.

I hope this attempt to explain clarify somethings to you.

Quote from LybsterKodi

I think we may have a communications breakdown. Does replacing channels with programmes alter the sense?

I'll try again.

Unlike analogue TV where each TV channel - BBC One, BBC Two, ITV, C4 etc. was broadcast on its own frequency - and thus a single tuner could only receive one channel at a time, DVB-T/T2 digital television sends out high bitrate data streams on frequencies, and each of these high bitrate data streams (called a transport stream) on a given frequency carries multiple channels simultaneously. This transport stream contains individual smaller data streams containing video, audio, subtitles, EPG, Red Button etc. data on its own uniquely identified sub-stream, and an index so the receiver knows how to combine them into a channel.

In the UK we have 6 of these high speed data streams being broadcast on 6 frequencies in each area (excluding local TV) - which are called multiplexes or muxes - and together they carry a large number of channels. (Some poor reception areas may only get the 3 public service frequencies)

The BBC has an SD mux (BBCA or PSB1) which carries all the BBC SD TV services and radio services on a single frequency delivering 24Mb/s of data - but each channel will only use 2-3Mb/s on average to deliver sound and video. (ITV and C4 share another frequency D34 or PSB2 - which carries many of the ITV and C4 SD services and also carries the main SD C5 service)

Therefore if you have a suitable DVB-T/T2 PC tuner, you can tune to the single BBC SD frequency, and a single tuner can deliver every BBC SD TV and radio service to your PC for you to record or watch live - meaning you could watch BBC One SD live, whilst recording BBC Two SD and BBC Four SD for later viewing, all with the same tuner.

There is just one DVB-T2 mux in the UK (outside of Northern Ireland) called BBCB or PSB3. This carries all the Freeview HD channels in a 40Mbs data stream (each channel averages around 3.5Mb/s but can peak up to 13.5Mb/s as they dynamically share the 40Mb/s pool of data).

Again if your USB tuner is capable of passing the full 40Mbs stream to your computer, you can watch ITV HD live, whilst recording C4 HD, BBC One HD and BBC Two HD for example - all using just one tuner. Or you can watch use a single tuner on a single TV Headend server to watch BBC One HD in your living room on one computer, whilst watching BBC Two HD in another room, all streaming from one tuner.

This is the really clever thing about digital TV - it no longer needs a tuner per channel, just a tuner per frequency. TV Headend is clever enough to cope with this - which makes it a really powerful solution.

Some tuners have a half-way house where they can't send the full data stream - but can hardware filter a certain number of data streams still - so may let you pass two or three channels rather than all of them, or just one of them.

WSL2 won't give you h/w kernel support or or driver support you can't get in Linux. You can always just install NextPVR on Window if you want an that extra tuner in LE. NextPVR also supports multi-rec so technically you get more than one channel for one tuner as described above.

Because of the Kodi UI you won't really notice that it is another backend. However If you only want one PVR with multiple instance install NextPVR directly LE or just move the LE tuner to Windows. I'd probably wait though since the version 7 of NextPVR is about to be released.

Quote from LybsterKodi

noggin

Thanks for that, its very interesting from a technical viewpoint, but as I said earlier replace channels with programmes. From an end user viewpoint with the TVHat I can only access one programme at a time, with the Huappage Dual tuner only two. It doesn't matter how many are multiplexed onto the same frequency. Now if I could get at them to record simultaneously that would be different.

Sorry - I've obviously not explained it clearly enough.

I don't mean replace channels with programmes - I mean channels. A single tuner can be used to receive and record or stream multiple channels simultaneously if they are on the same frequency/mux. You only need to use the second tuner in your Hauppauge dual tuner if you need to record, or stream live, channels that are on two different frequencies concurrently.

Ignoring local TV and Northern Ireland differences there are only 6 frequencies in each Freeview area, and only 3 frequencies in the Freeview Lite areas (that only get the BBC SD, ITV/C4/C5 SD and BBC/ITV/C4/C5 HD channels)

When I say you can receive multiple channels simultaneously if they are broadcast in the same mux or frequency I mean just that. You can record BBC One HD, BBC Two HD, ITV HD and C4 HD shows broadcasting simultaneously, at the same time, with just one suitable tuner tuned to the PSB3 / BBC B frequency (which carries all of those channels), or you can watch BBC One HD live whilst recording ITV HD using just one tuner.

If you have more than one Kodi device around your house on your network you can watch different channels live in different rooms streaming from one tuner via a single TV Headend if the channels are on the same mux/frequency (i.e. BBC One HD in a living room and ITV HD in a kitchen)

Quote from LybsterKodi

noggin

As I said before - the problem is my tired old brain. I just tried it on my RPi4 setup and yup you are right.

I'm going to need to identify what's coming in on which frequency so I can test properly. At the moment I'm recording BBC1 & BBC2 but anything else I try I get recording conflict .

The RPi4 is running a TVHat

https://ukfree.tv/transmitters/multiplexes will show you what is on which mux.

PSB1/BBCA carries all the BBC SD services.

PSB2/D3+4 carries SD services from ITV, C4, C5, incuding ITV2-4 SD and E4/More4/Film4 SD, and some (but not all) of the +1s.

PSB3/BBCB carries all the UK HD services (This is really handy as you can watch and/or record any or all Freeview HD services at the same time with just one tuner, if your tuner and TV Headend platform can cope)

There are then 3 three commercial muxes COM4/SDN, COM5/ARQA and COM6/ARQB which carry a mix of SD channels - the UKTV stuff, Sky News, Sky Arts, the C5 spin-offs and C5 and spin-off +1s, some of the ITV2-4/E4/More4/Film4+1s, the shopping channels etc.

In some areas you'll have a 7th local TV mux too.