MythTV Official Community Forum

Hello everyone this is my 1st post*

Can somebody recommend a reliable for Linux, UK (Freesat), USB, DVB-S2 dongle ? This is to plug both (dual LNB I assume) of my Sky cables into.

The mythtv box I'm using is a tiny form factor, so I'm very keen to stick to USB. I previously used a DVB-T2 (PlayTV) USB device. I've moved house and now have newly installed Freeview and Freesat signal available, I'm assuming the Freesat would be better/more useful, but I'd be open to a suggested UK compatible USB DVB-T2 dongle to replace the PlayTV one which crashes approximately each month** and doesn't support HD in the UK.

In addition to gaining a Sky dish the house move sadly jogged the main HDD which was an external USB, and this has mostly conked out. It oddly works for a few hours at a time if used vertically ('twas horiz before), but is clearly on its last legs. I've backed up what I could, but this basically means I'll be running the very latest 64bit Ubuntu LTS and mythtv on a 1TB SSD (I might even compile fresh if there is a compelling reason to do that rather than the dpkg version with Ubuntu).

My forum search for "DVB-S2 USB recommended" returned one page which didn't yield much in the way of suggestions.

To clarify my query, I'm looking for really compatible and reliable USB receiver, ideally Sky but Freeview also okay, and this is for latest Linux. Props for an amazon url!


Thanks for any help.

- Damion


*At least I think so, I may have had an older username on here but it would have been _years_ ago. I've been using MythTV for probably a decade or so, mostly uneventfully. I've been using Linux since the late 1900s.

**This started around a year or so back with no software changes involved (unless I got exploited). I can't blame the PlayTV dongle as I have two and after switching, the other also started doing it. It'll sometimes be fine for >30 days but sometimes as short as a week, it'll crash needing modprobe -r or if I'm unlucky, a reboot. The only thing that could really have changed is how full the disk got. I guess potentially some weird freeview signal problem or maybe the usb h/w on the PC which would be odd and unfortunate as I also use an external HDD. The latest SSD and Ubuntu LTS would mean I'd need to start debugging from scratch having mostly ruled out s/w and disk load issues. But that's kind the point of this post as don't plan on sticking with PlayTV anyway.

For DVB-T2 the Hauppauge WinTv-dualHD is rock solid. It works out of the box in Ubuntu and on Rasberry Pi. As there are only a couple of HD muxes in use a single one of these can record everything needed. I have no issues recording 3 HD streams on a NUC.
For DVB-S2 a single PCTV 461 E is also rock solid. It needs the Hauppauge PPA with Ubuntu 20.04 to get the latest driver. I suspect it would work out of the box with Ubuntu 20.10 but have not tried it.
However I have not managed to get 2 PCTV 461 E tuners working togethrer off the same CPU. I run one in a NUC and another in a slave backend hosted on a Pi 3.
Because of the way the channels are allocated to multiplexes 2 DVB-T2 tuners are more capeable than 2 DVB-S2 tuners.
This has to be balanced against the slight quality improvement of Satellite over Terrestrial the bit rate is higher.
I have never found two DVB-S2 tuners that will reliably work together.
An alternative thing to consider is using the Sat>IP client support currently being developed in Master that could give you up to 4 sat receivers over ethernet. See https://code.mythtv.org/trac/ticket/13121. I don't know how the development is going but it looks like the best solution.

There are some more options for USB DVB-S/S2:
Dual DVB-S/S2/S2X USB:
https://shop.sundtek.de/en/DVB-S-S2-S2X ... 2-S2X.html
Single DVB-S/S2/S2X USB:
https://shop.sundtek.de/en/DVB-S-S2-S2X ... 2-S2X.html

Dual is basically the same as single DVB-S2 except it includes two receivers and a high speed mux IC (over 110 MBit/Channel).

(2nd attempt at a reply days later, I think I forgot save after preview mode - I am a giddy goat!)

Thanks! I purchased both and so far got everything working on the DVB-T2 Hauppauge WinTv-dualHD. I'll try the satellite dongle tomorrow. It was nice to see FreeviewHD once I turned on VDPAU

I've been administrating Linux/Unix for over 25years but I'm clearly a tad rusty it seems And it appears to have been about 7years since my last mythtv install (the old box was ubuntu 13.10) but not that much has changed in ubuntu/mythtv and I remembered the mythtv-setup shenanigans. I messed up accepting default mysql install stuff initially with a ^C and needed to purge mysql-common which uninstalled stuff - my broadband isn't that quick so that was annoying. I also didn't notice I needed a .fw file until I checked dmesg after channel scanning found nothing.

Also it's 2020 and /boot being too far into a large partition is STILL a thing! I nerded out fixing this without a reinstall and learning more about grub-rescue but I shouldn't digress from mythtv hardware

Again thank you for suggested hw, I reply once I test the satellite thing.

When you do a Freesat channel scan then mythtv-setup can now pickup the correct channel numbers, as described in WIki page https://www.mythtv.org/wiki/DVB_UK. Compared to 7 years ago there have been a few changes in both the GUI and the functionality of mythtv-setup but the complete channel scanning process is now described in Wiki page https://www.mythtv.org/wiki/Channel_Scanning.

Please do reply with the results and it is also interesting to know which USB satellite tuner you have decided upon.

damion2 if you want to run more than one USB device at the same time note that you will need Udev rules to allocate them device numbers as described in https://www.mythtv.org/wiki/Device_Filenames_and_udev.
Something like :-

# Create a symlink /dev/dvb/adapter108 & 109 pointing to dualHD with serial 0014039842
SUBSYSTEM=="dvb", SUBSYSTEMS=="usb", ATTRS{product}=="dualHD", ATTRS{serial}=="0014039842", ENV{dualhd}!="two", ENV{dualhd}="two", PROGRAM="/bin/sh -c 'K=%k; K=$${K#dvb}; printf dvb/adapter_108/%%s $${K#*.}'", SYMLINK+="%c"
SUBSYSTEM=="dvb", SUBSYSTEMS=="usb", ATTRS{product}=="dualHD", ATTRS{serial}=="0014039842", ENV{dualhd}=="two", ENV{dualhd}="one", PROGRAM="/bin/sh -c 'K=%k; K=$${K#dvb}; printf dvb/adapter_109/%%s $${K#*.}'", SYMLINK+="%c"

# Create a symlink /dev/dvb/adapter101 pointing to PCTV 461 with serial 0014078311
SUBSYSTEM=="dvb", SUBSYSTEMS=="usb", ATTRS{product}=="PCTV 461", ATTRS{serial}=="0014078311", PROGRAM="/bin/sh -c 'K=%k; K=$${K#dvb}; printf dvb/adapter101/%%s $${K#*.}'", SYMLINK+="%c"

This worked fine for me on a dual core Haswell but not on a quad core NUC for reasons I dont understand.
Hence the appeal of using SAT/IP.

Thanks for the updates and advice. Unfortunately I've not yet had a chance to plug the "DVB-S2 PCTV 461 E" in and test yet. I have spotted an article indicating it may not power the LNB on 1st attempt until the windows app has been used. This would suck, we don't have windows and haven't for decades. I'll find out maybe in a few days when I can find time.

I have however had a worrying instance of the "DVB-T2 Hauppauge WinTv-dualHD" stop functioning. It was reporting the following in mythbackend.log:
"TuningSignalCheck: taking more than 6000 ms to get a lock. marking this recording as 'Failing'." - every time I tried to start a recording.
Restarting the mythtv-backend service and modprobe -r and back the main module, made it start working again. I'm now checking dmesg and the backend log frequently around recordings.

Now... I had been wobbling usb connections whilst moving drives around, so I'm keeping a close eye on this and it might not reoccur.

I hope to report back on my use of the DVB-S2 dongle within a few days.

I have spotted an article indicating it may not power the LNB on 1st attempt until the windows app has been used.

That issue is fixed if you use the latest driver which is included in the Hauppauge ppa and also possibly in recent kernels - not in 5.4.
Regarding the "DVB-T2 Hauppauge WinTv-dualHD" I have never had an issue with that - check the aerial connections and signal levels.

dvb-fe-tool --femon -a0

Everything looked like it was working out of the box on just plugging the satellite dongle in, no need for hotplug shenanigans. I kept getting confused by the back vs esc menus and kept losing settings for frequency before tuning would take place. I also apparently needed to configure DiSEqC and followed the generic 4 LNB switch suggested in the tuning wiki.

As I had done neither of these correctly initially tuning wouldn't start, so I installed the latest PPA Haupague drivers. The HWE install didn't work for this LTS install but the generic drivers seem to be working.

It was after this install I found all the mistakes I've made on trying to tune so it's not 100% clear it wouldn't have worked have I got those right before. No matter. The TL;Dr version is that I now have loads more channels.

I've a few extra +1h channels which is useful for the odd clash or missed show. Also some tat like the god channel, but I can't honestly determine a quality improvement between Freeview and Sky. I'm slightly anxious of all the adaptors now available and what this'll do going forward. So I might have to take a careful look at whether these extra channels are worth it. This has used up a usb slot I'd have otherwise used for a large HDD full of older recordings accessible to the frontend.

It's ~£100 so I'll probably see what value I can find from this dongle, maybe the HDD can work through a hub without to much issue, iostat shows minimal use when playing videos so I doubt I need high bandwidth.

If you get good results from Freeview HD I would stick with that.
Note that there is no EPG for Channel 4HD on Freesat, there is a workround but it adds more complexity.
Keep it simple.

I realised I'd forgotten a show 15mins after it began and found Satellite's BBC Scotland showed it an hour later, so seeing as nothing has gone wrong I think I just need to remove dozens of weird channels, gain an hd and +1 or two from the sky dongle and go with this setup.

Thanks for the suggestion of these dongles they are working so far. I'll update this if I get anything happen.

Oh one weird semi-non issue is the ubuntu firmware deb which I found whilst reading about the backport ppa, which replaces a downloaded .fw, now reloads every minute filling syslog at a slow pace.

Sorry if these updates are in any way annoying for people but I do have an update. I only have a few minutes a day between work/kids/actually watching tv so this is slow progress.

I deleted loads of dupe channels making it more usable and set out to see about comparing sat/terrestrial quality. There are a tiny handful of extra channels with satellite which is useful, but dual recording is more valuable and this only presents a single adaptor.

I then decided to see how my old backup drives would work through a usb hub when I had cause to power down for power/fuse reasons. This way I could do more than one drive at once on my spare usb port. On powerup this appeared to work fine.

However the order of usb devices switched so adaptor*/frontend* moved confusing mythbackend. So I should have heeded the hotplug advice afterall

I temporarily addressed this by replugging as that was by far the easiest quick fix. I'm probably hung up on the sat dongle investment and how I had assumed a quality improvement and more HD/+1 channels but maybe I'll give up. I'll revisit sorting the hotplug once at a laptop (this is typed on a phone), but this dongle is on its last warning

For anyone still interested and following along the latest update is after I needed to repower again I decided to check the udev config.

The example file in this post is close to as documented in Device_Filenames_and_udev and when placed as a 00-something in /etc/udev/rules.d did created adaptor10x/* symblinks.

Weirdly adaptor109/{demux0,dvr0,net0} were all links to adaptor0/* rather than adaptor1/* but frontend0 was correct. Because nothing mentions anything other than the frontendX in configs, dmesg, myth*.log files I hoped this might work. I rejigged the capture cards in mythtv-setup to match these now hopefully static links, I omitted running mythfilldatabase.

Mythtv was very confused and I was getting no success from anything and I/O and timeouts from the device links. Also fuser /dev/dvb/*/* confirms mythbackend attaches to all the files, so I think it was naïve to assume we only needed frontend0.

I tried replugging which made one of the DVB-T2 devices work. I then noticed the symlinks for the new 1st DVB-T2 device directory were all pointed at the original 2nd directory along with the 2nd new symlink one. This might indicate the `ENV{dualhd}` trick remained somewhere. Either way this was all becoming a bit shonky and I was having no luck what so ever with satellite.

So decided to back out and configure it for at least the ordering with the current USB hub plugged in. I might be mostly lucky with consistent positioning of devices as long as I don't add extra devices or undo the hub to directly connect the disk which would likely swap things back.

I then realised the satellite had lost its DiSEqC setup which I guess makes some sense as this wasn't back to exactly how it was before. I opted to try direct LNB because I only have one thing plugged in and I didn't have time to faff about re-reading through the walk through to connect up a 4 way switch, also WTF is that I don't know/think I have a switch unless that's some magic attached up on the LNB on the roof, or built into the USB dongle? Maybe I can only record one thing at once now even if on the same mux?

I also ran mythfulldatabase. So...

1. Perhaps not running mythfilldatabase was to blame
2. Perhaps replugging the usb helped - this would be bad as a reboot should be fine
3. LNB works fine for individual satellite watching, so :shrug:
4. I've possibly not configured the udev stuff right, it seems correct but is not working.

Next plan:

Always run mythfilldatabase after using mythtv-setup, because I only vaguely know what this looks like it does and although it doesn't seem that necessary it may potentially have something do with syncing mythtv-setup config changes into mythtv for things like DVB device ordering.

Read up on LNB/DiSEqC or simply redo DiSEqC as it appeared to work and might be better?

Hardwire the devices! Right, you heard me I'm sure before the mythtv-backend service starts I can place some symlinks into /dev/dvb/ matching exactly the right configuration for what I've configured into mythtv-setup. This should just need a run of udevadm info -a -p $(udevadm info -q path -n /dev/dvb/adapter$X/dvr0) (cycling through $X) searching for {product}. I don't need to work around udev's parsing of the rule files and can just put exactly what I expect exactly where mythtv expects it in my bash startup code.

I believe this is unlikely to go wrong unless there are some weird usb device drop-out issues occurring which might be plaguing my debugging here. I also wonder slightly if there are some issues with mythbackend talking to the devices via the redirection of a symlink, but this is highly unlikely.

I don't understand the relevance of using mythfilldatabase but I never got udev to stably identify the tuners so you might be correct.
I also tried :-
'More complicated setup with multi-tuner cards having no difference in udevadm info output coexisting with other cards based on the same A/V decoder'
as mentioned in https://www.mythtv.org/wiki/Device_Filenames_and_udev.
However I could not get that to work either but it might form the basis for what your trying to do.
The whole thing is very annoying - as I stated before Udev rules worked perfectly on a Haswell chipset with the same software environment Ubuntu 20,04.
Perhaps its a BIOS issue have you tried updating your BIOS to the latest version.

If you use EIT for program guide information then you do not need to run mythfilldatabase.

A four-channel DiSEqC switch is a box the size of a pack of cigarettes with five F-type connectors, four of them going to the LNBs and one to your tuner.
If you do not have that then most likely you do not need to worry about DiSEqC switches.
N.B. There actually are dual LNBs with built-in DiSEqC switches but then the LNBs point in different directions for different satellites. I assume you do not have that.
You do need to select an LNB, you cannot leave it at Unconnected which is the default. See
https://www.mythtv.org/wiki/Channel_Sca ... ation.29_2