Posts by noggin

Quote from ghtester

I know but I spent a huge time, trying to discover the root of the "subtitle issue". Most likely it's not the TVH4.3 itslef but some incompatibility with LE. It depends on DVB-T2 provider and there's no way to fix this issue by LE or by TVH settings... Unfortunately perhaps only a small group of LE users has the same scenario like me so debugging must be tough.

I'd report it again or update your report. One key thing to be aware of is that DVB platforms can use two very different subtitling systems (some platforms like satellite in the UK use both systems for compatibility with Sky and Freesat receivers)

The most widely used system is based on the old teletext standard (aka WST Subtitles) and sends text characters.

The newer system is usually called DVB Subtitles and is based on graphic bitmap images of the text being sent - not text characters.

Knowing which system your platform uses will be useful.

Quote from Da Flex

Yep, the AVR definitely adds some data.

Yes - the AVR has to add the audio formats it adds support for in an additional EDID block (so that sources know that the AVR+Display sink combo now supports True HD, DTS HD MA etc. and not just the audio formats the TV supports). It can also add data with the AVR name.

A common problem with early '4K' compatible AVRs is that they only support the low (HDMI 1.4-compatble) bandwidth 2160p50/60 modes with 4:2:0 (which the Pi can't support) OR you have to enabled 'Enhanced HDMI 4:2:2' or similar to allow the high bandwidth modes to be added.

AIUI some AVR+TV combos will remove formats the TV supports but that the AVR can't pass through from EDID in this situation.

Also worth knowing that some TVs will go into 'PC' mode when they detect RGB rather than YCbCr (aka YUV - if you are happy to use UV incorrectly ) sources - as most consumer equipment is YCbCr output, and most PCs are RGB output.

Quote from Da Flex

I think you should try that. We have reports on the forum that different HDMI ports act differently. Usually the first HDMI port of the TV is the most capable one.

NB this isn't the case with a lot of Sony displays - particularly those in the early era of HDR UHD and Dolby Vision UHD support.

On 4 HDMI input Sony models from that era (My XE/XF 9000 series for example), HDMI 1 and 4 are often low bandwidth (so only support 4:2:0 at 2160p50/60 which the Pi doesn't) with HDMI 2 and 3 having full-bandwidth support for 12-bit 4:2:2 at 2160p50/60. One of these is the ARC port which is the port you'd always use for an AVR (so you get TV->AVR audio back to the AVR via ARC)

(4:2:0 2160p50/60 - at least at 8-bit - was added to the HDMI 2.0 specs as it was backwards compatible with HDMI 1.4 bandwidth connections so allowed old HDMI 1.4 physical hardware to carry 2160p50/60 video... )

This isn't as simple as RGB vs YCbCr output is it? PCs often output RGB, most other consumer HDMI devices almost always output YCbCr - if the Pi is outputting RGB then that might be triggering PC mode? (Is there an option in the Pi version of LE+Kodi that forces YCbCr 4:2:2 output mode at all times?)

I have an LG C3 with a Pi 5 routed through a Denon AVR with all the full-bandwidth 'enhanced' HDMI stuff enabled and sometimes notice the PC stuff appear.

However I can't watch content with any motion interpolation, contrast enhancement or noise reduction enabled (I just want to see the original content - warts and all) - so PC mode poses no problems for my viewing as far as I can see. (video levels are OK - though I've not checked BTB and WTW content below 16/64 or above 235/940)

Quote from emveepee

Thanks for that. I guess there could be a related issue if the audio PIDs increase or in the Swedish case you noted more video PIDs. I'd love to get a full mux from Sweden when the regional news is plays to send to my demodulator.

https://www.digitalbitrate.com/dtv.php?mux=MU…live=38&lang=en shows the main DVB-T SVT HD mux in Stockholm - you can see two regional variations of SVT1 with the same video and audio PIDs most of the time.

If you look at the mux graph at the bottom you can see SVT1 Sörmland with SID 5850 switches between 5771 and 5851 for Video PIDs, whereas SVT1 Stockholm with SDI 5770 stays with 5771 Video PID all the time (as Stockholm = Network)

The switch is done by their muxing provider on a clock start I believe - unlike in the UK where BBC regions switch themselves.

Quote from emveepee

Sorry to perhaps hijack this thread but it could explain the users problem. When I compare the two results from libdvb I only see the video and audio pids change of note. The tsid changes but that is for all frequencies so that probably can be ignored.

Code

[BBC FOUR HD]
    SERVICE_ID = 18048
    NETWORK_ID = 9018
    TRANSPORT_ID = 16522
    VIDEO_PID = 6701
    AUDIO_PID = 6702 6706
    PID_0b = 7302
    PID_06 = 6705
    PID_05 = 7108
    FREQUENCY = 634000000
    MODULATION = QAM/256
    BANDWIDTH_HZ = 8000000
    INVERSION = OFF
    CODE_RATE_HP = 2/3
    CODE_RATE_LP = AUTO
    GUARD_INTERVAL = 1/128
    TRANSMISSION_MODE = 32K
    HIERARCHY = NONE
    DELIVERY_SYSTEM = DVBT2
    STREAM_ID = 0

Display More

and

Code

[BBC FOUR HD]
    SERVICE_ID = 18048
    NETWORK_ID = 9018
    TRANSPORT_ID = 4170
    PID_0b = 7303 7302
    PID_05 = 7109
    FREQUENCY = 634000000
    MODULATION = QAM/256
    BANDWIDTH_HZ = 8000000
    INVERSION = OFF
    CODE_RATE_HP = 2/3
    CODE_RATE_LP = AUTO
    GUARD_INTERVAL = 1/128
    TRANSMISSION_MODE = 32K
    HIERARCHY = NONE
    DELIVERY_SYSTEM = DVBT2
    STREAM_ID = 0

Display More

Yes - I think we're saying the same thing.

The first BBC Four HD details are for when the channel is on-air - and thus Video and Audio PIDs are associated with the Service, and CBeebies HD (which it's time-exclusive with) is off-air.

The second details are for when when BBC Four HD is off-air (and thus has no Video and Audio PIDs associated with it) and CBeebies HD is on-air (which will be using the same Video and Audio PIDs mapped to its Service instead)

When TV Headend scans PSB3/BBCB during BBC Four HD transmission hours it sees the Audio and Video PIDs mapped to the BBC Four HD service and stores them with the BBC Four HD service. When TV Headend tunes the same mux during BBC Four HD non-transmission hours it doesn't see the Audio and Video PIDS associated with the channel and thus doesn't store them (as it has no idea they will be used at other times of day). Instead it will see CBeebies HD active instead and store the same Video and Audio PIDs shared between CBeebies HD and BBC Four HD with the CBeebies HD service. Effectively to get both CBBC and CBeebies AND BBC Three and BBC Four (which they are time-ex with) you need to tune during both pairs of services transmission hours.

In reality the playout and transmission chains for CBeebies HD and BBC Four HD are one and the same, the same network playout area transmits both channels, and the same encoder chains encode them. The only thing that changes is some metadata that tells the mux chains to re-map the Video and Audio pids from the encoders between the two services. (And also to trigger an MHEG5/HbbTV data service that tells you the off-air channel is off-air when you tune to it on a regular TV).

I think this is a quirk of TV Headend that's always been there for time-exclusive services - you need to do a scan during transmission hours for non-continuous, time-exclusive, services like CBBC/BBC Three and CBeebies/BBC Four. It may be that the UK is relatively unusual in implementing time-ex stuff on a channel-basis (to allow CBBC/CBeebies to be on Kids EPG channels and BBC Three/Four to be on general channel numbers in the EPG etc.) as I've seen other countries just keep to one channel/service.

Quote from emveepee

Thanks. I was wondering if TVHeadend knows not to overwrite the non broadcasting channels during the update, since they still are in the scan they just don't have video and audio PIDs.

NextPVR users a separate libdvb style conf file for tuning, that is were the replacement needs to take place

Yes - it seems to have no problem and doesn't overwrite them (they have different LCNs too) - it just doesn't know what to do with the off-air channels as they have no associated audio and video PIDs when they are off-air.

TVH may do something odd in Sweden during regional news - as on their DVB-T platform two SVT1 regional variations are usually broadcast on the same DVB-T mux, with both mapped to the 'network' audio and video PIDs outside of regional news times (so they don't have to send out a pair of identical audio and video streams wasting bandwidth, but then during the regional news there's a crash-bang switch to remap the two SVT1 regional services to two different sets of audio and video PIDs carrying the regional audio and video streams. (Or at least that's roughly what used to happen. They could use the regional audio and video PIDs to associate with either SVT2 or SVT1 regional variations - though I think because of changes on satellite only SVT1 now has regional variations?)

Quote from emveepee

If a user does a a daytime scan, is TVHeadend aware not to change the configuration for the working nighttime values, ie no video PID in the scan? In NextPVR a users would specifically have to remember not to update BBC THREE/FOUR HD.

From memory you need to scan time-exclusive services during both transmission times to ensure both get added correctly (I think the video and audio PIDs need to be actively associated with the SID in the SDT for it to be stored correctly?) (In the UK Time-ex services use the same audio and video PIDs for both services and just remap during active hours - I think)

They don't replace each other though, so there's no issue with just doing a straight re-scan.

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.

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

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.

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)

Quote from VLouis

Something like that it could be enoug, no need to be exactly the same.

Because it's a passive splitter, always exist a signal loss. Something splitted in two, always result two halfs. The question is, that "half" will be enough for a tuner or not.

Usually a good antenna could povide enough signal for two tuners, you should check it. If not, you could try to use a short antenna cable as possibile, or/and an RF amplifier. The beter could be to use an antenna with built in amplifier.

Yes - all my DVB-T/T2 stuff is fed from a roof-top antenna system with a strong signal. I have a good quality active splitter to feed multiple DVB-T/T2 tuners as the signal has a good SNR so any noise increased by amplification isn't a problem.

Quote from david91

Thank you

Finally, I think I'll buy a 2GB RAM RPi4 , and I'll try if it can handle the two USB tuners + 2.5" SSD USB 3.0 drive

I live in Spain but we also use DVB-T/T2

VLouis I've never used that kind of RF antenna splitter, I only used others like this one, but usually it has a signal quality loss

I'd recommend a 3.5" HHD not a 2.5" SSD as the 3.5" HDD will be powered by its own PSU. You may hit power draw issues if you use 2 x USB tuners and a USB SSD all powered by the Pi 4 PSU - though an official Pi PSU may be OK. There's no real reason to use an SSD for PVR purposes unless you need it to be silent.

The RF splitters shown are identical - they are both passive splitters (just one has Belling-Lee and other F-type connectors) - you will need a strong signal from your antenna/aerial if you split it between two tuners like that (as each tuner will get 50% of the signal effectively)

Unless things have changed, if you're in the UK, beware the XBox tuners with DVB-T2. In London I never got reliable reception of the UK PSB3/BBCB DVB-T2 mux from Crystal Palace even though I have a great signal (every other T2 device I have has zero errors)

The Linux driver may have been updated since I last tried - but there were reports from around Europe of issues with T2 stuff with the Linux driver when the tuners first appeared at very low prices (£5?).

Quote from david91

Hello

I want to build a PVR using a Raspberry Pi 4/5, two Xbox One TV Tuners and a USB 3.0 HDD to save recordings and I have some doubts.

1. What's the minimum RAM needed to avoid issues?
2. Will I need a hub to connect the tuners and the HDD?
3. Will I be able to record from both tuners and watch something from the HDD all at the same time?

Thank you!

I've run a single tuner install with a TV Hat on a Pi Zero with 512MB RAM - so I suspect a Pi 4 or 5 with 2GB will be more than enough.

I'd try running the two tuners on the two USB 2.0 ports of your Pi and see what happens - if you end up with weirdness then try a powered USB 2.0 hub (they key thing is that it's powered) - but you may find that with an official Raspberry Pi PSU you're fine.

Use a powered external 3.5" HDD not a bus-powered 2.5" HDD plugged in to a USB 3.0 port to ensure you don't have issues with power and the hard drive.

Yes - you can record from both tuners (that means you can record as many channels as you like as long at they are on one of the two frequencies being tuned - assuming your tuners can cope with that - most can) and play a recording from HDD at the same time.

DVB-T channels are running at very low bitrates compared to HDD transfer speeds. The highest bitrate HD on DVB-T2 is a lot less than 2MB/s (i.e. 16Mb/s), some SD stuff is a LOT lower.

The total bitrate on the PSB3 T2 UK HD mux is 5MB/s (i.e. 40Mb/s) and SD T Muxes are around 3.5MB/s (i.e. 28Mb/s) or less and that's the total bitrate for all the channels being sent on a given frequency or mux.

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

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

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 thestraycat

sorry what is cpm an abbreviation of?

cpm is a user over in the CoreElec forums who has done some work on improving Dolby VS10 and other stuff within CoreElec.

Fundamentally - as I understand it - LibreElec runs with the mainstream Linux approach to video (using V4L2 stuff? - and there is some AMLogic support for mainline now) whereas CoreElec has taken a different path that allows their AMLogic specific implementation (using a non-mainline approach) to continue to work with Kodi using the AMLogic proprietary stuff?