DVB issue since LE switched to kernel 4.9.x

  • spent ages learning tvheadend and seting up , installed 8.2.3 but still getting tons of cont erros on my pi :-


    installed millhouse latest build and seems sorted , just shame cant use xbox one tuner had to switch to astrometa.


    another thing i notice on millhouse build everytime i reboot box i have to gointo addons disable tvheadend and enable tvheadend to get it to start up ... any ideas ?

    Edited 6 times, last by ttech ().

  • Still having Artifacts on my Raspberry Pi 3 runnning LE 8.2.3, TVHeadend 4.2 and a MyGica T230 DVB-C Stick.


    Could my Stick be faulty?


    Something else: Could anyone give me a hint to those millhouse builds? How do I try out those on my RP3?


    Thanks! :)

  • I have t230 stick also. Have no artifacts using the dvb- t2 channels on stick. Havent any dvb-c channels to test.


    Do the artifacts occur when you playback a recording? Are you using tvheadend.


    Try increasing sdram to 500. Then run this command in SSH


    Code
    1. vcgencmd arbiter set arm_uc 13 0


    See if it helps.



    Does the stick play ok on pc?


    Try turning off deinterlace also.


  • I will have to check if it occurs also during playback.


    Where to I set and increase the SDRAM value? Is this the ammount of shared RAM, reserved for the GPU?


    Thanks!

  • I will have to check if it occurs also during playback.


    Where to I set and increase the SDRAM value? Is this the ammount of shared RAM, reserved for the GPU?


    Thanks!

    you need to add the line


    sdram_freq=500


    to config.txt. see here for instructions.


    Raspberry Pi Config.txt [LibreELEC.wiki]


    Reboot pi. Then SSH into pi and run the vgencmd command above. You need to run the vgencmd after ever reboot.


    Try turning off deinterlace first in video settings before changing sdram see if it stops the artifacts. If not then try the sdram & vgencmd.

    Edited once, last by the_bo ().

  • Strangely, without doing your recommended steps, the artifacts stopped, but I am having still another problem: Channel switching is really slow, some times the switching doesnt work at all - then I have to switch back and forth in order to change the channel. Could this be related to the previous problem I had? Signal strength etc. is good as far as I know: SNR 34.0 dB, Signal -27.0 dB

  • You may be suffering from some sort of interference (rf/emi/static). I struggled with this problem a couple of years back and it drove me crazy for over a year. I was experiencing usb drop outs and continuity errors which got worse the longer the machine was running. With the usb drop outs i needed to cold power down the machine and dvb cards to get back to normal. Skytv always used to advise powering down for a couple of minutes with their old boxes as they were known to freeze up when near sources of interference.


    A few tips:

    * try unplugging all nearby devices, and plug them in one at a time to see whether one of them causes the disturbance.

    * try moving both your machine and dvb devices to a different location away from the tv and any other devices that may cause interference. If this helps then...

    * Try different cables (power/usb/rf) - and go for ones that are well shielded/ avoid cheap cables.

    * Look at how your cables are distributed. Cables that are looped round each other and just thrown in a heap/spaghetti junction (like i had previously) can cause interference.

    * some devices such as wireless routers can cause interfence so try to place your machine and dvb devices away from these

    * as well as shielded cables you can look into ferrite clamps. These are cheap and reportedly can reduce interference, though the jury is out for me on that.

    Edited once, last by jahutchi ().

  • Thanks for the hints jahutchi - I will look into this tonight.


    One one hand, I doubt that the quality of the cables is the problem - I'm using an genuine/original RPi power supply (2.5A) and a rather high quality 1m HDMI cable.


    But on the other - the RPi is actually located next to my WiFi router, so this could really have a influence, according to what you mentioned.


    I will also look into my cable management, as I not really payed attention to that - out of lazyness and out of the fact, that I never experienced any problems with the cables being alinged in a "spaghetti" junction as you are calling it.


    But just to be sure that I understood you right: When you are referring to the problems you have been having then - do you mean artifacts or slow channel switching?


    And something else: I am having small drop-outs from time to time when watching TV - the DVB-C stream gets frozen for about half a second, then continues again...


    Thanks for your help guys - I really appreciate it! :)


    (Edit: Out of curiousity - do you think, I should give the latest LE 9 nightly a try - or should I stick to the stable LE 8.2.3?)

  • When you are referring to the problems you have been having then - do you mean artifacts or slow channel switching?

    I've experienced various issues related to interference from other devices - mainly for me it was picture breakups, and usb drop-outs (with these errors in dmesg):

    Code
    1. dvb_usb_v2: usb_bulk_msg() failed=-110

    Interference, whether it be EMI / RF / Static, can cause all kinds of weird issues, and dvb adapters can be more prone to these issues that other devices due to the type of work they're doing - i.e. taking a signal from your aerial and demodulating it into digital images that your machine can understand, which are then transmitted down your USB wire. The types of problems caused by interference may vary from one device to another. It rang alarm bells for me when you said "without doing your recommended steps, the artifacts stopped" - because this is what I was seeing - one day it would be fine and another it would have issues.


    An example of another user with a similar problem to mine can be found here:

    DVBSky S960 USB failed=-110


    The user from that post reported that replacing the power supply for both RPI and DVBSky resolved the issue. I have replaced the PSU on my generic x86_64 machine which didn't make much difference. After that, for nearly a year, I was convinced it was a software rather than hardware issue, and was reluctant to splash out on new cables or hardware.


    At one point I purchased a new TV cabinet (not to try and solve the issue), but this forced me to have a real good tidy-up of my wiring. I also moved the router well away from my machine and dvb devices. I also had an external hard disk near the dvb adapters which I don't think was helping things and that was completely removed. At the same time I replaced some of the USB cables for ones with ferrite chokes, and made sure my T220 DVB-T2 cards weren't plugged directly into the back of the machine, but were connected through a USB M-F cable (£3 of amazon) which had good shielding and ferrite chokes at both ends. I'm not exactly sure which of these actions helped, but the drop outs stopped for several months, though I do still have very occasional (split second) glitches in the picture (maybe 2-3 times per week). I recently purchased a soundbar and had to re-arrange the wiring a little which disturbed things, and the usb drop-outs and frequent picture disturbances returned :-( I therefore tidied the wiring once more and it's been OK the last few days (fingers crossed).


    Obviously, I have no idea whether interference is the cause of your issues, but speaking from my personal bad experiences it's well worth investigating. If the problem is easy to reproduce then even try temporarily moving the equipment to another room, to run some tests to determine whether you're device is being influenced by the surrounding environment. Also, I don't know whether your Pi is enclosed in proper casing - I would assume it does, since most come with the casing included by standard nowadays.


    Note: I personally still have small amounts of interference - i.e. very, very occasional split-second glitches and continuity errors in my logfile, so I think I still have small amounts of interference. I've just purchased a bag of ferrite chokes which I'm going to install on several of my wires. I'm not sure if this will help, but they're cheap so it's worth a go. Failing that, I've not yet replaced the power supplies that came with my DVBSky adapters, but may try that next since the power supplies they came with have very thin wires (2-3mm) which don't appear to have good shielding and don't have ferrite chokes.


    In general I'm now really pleased with my picturewhich is perfect 99.9% of the time, but I'm still striving to reduce the interference further.


    If you search around the internet for TV interference issues (not just with linuxdvb) then you will see that this can effect any household using any device (SkyTV / Freeview / etc), and you can find some real horror stories out there!


    It may also be worth trying the latest LE9 nightly - what harm can it do. It would certainly rule out whether the upstream drivers for your DVB card work better. If you backup the relevant folders on your /storage partition, then you can always put everything back to exactly the way it was afterwards should it not help.


    I hope some of these suggestions help, should your issue be related to interference.

    Edited once, last by jahutchi ().

  • Thanks so much for your quick and extensive reply, jahutchi! :)


    To be honest, I never closely investigated the logs, as I was a little overstrained with the amount of different logs and messages. Which would be relevant log be - to be fetched with dmesg?


    I am using a Raspberry Pi 3 by the way, with a Geniatech/MyGica T230 stick using its DVB-C tuner. The RPi3 is enclosed in a simple acryl housing, sitting between the TV and the WiFi router. Beneath to it, there is a NAS with 2 HDDs running 24/7. I guess there are a lot of sources for interference - and I will give your tips a go tonight or the next days - thanks!


    Do you think, the slow channel switching can also be lead back to interference problems? After all - as far as I understand - my good signal (SNR 34.0 dB, Signal -27.0 dB) should rather allow fast channel switching? Or is the "switching speed" dependant on other aspects like cpu power, etc?


    Concerning the upgrade to LE9: Is the internal backup solution via the LibreELEC menu enough to be able to restore everything as it is now? Or do I have to manually backup certain folders (because you have mentioned to backup relevant folders in /storage).


    I am a little confused wheter I should upgrade to LE9 - after all it is a Alpha - but still a lot of people claim that it runs even smoother than LE 8.2.x...


    Thanks again for your help! :)

  • Quote

    To be honest, I never closely investigated the logs, as I was a little overstrained with the amount of different logs and messages. Which would be relevant log be - to be fetched with dmesg?


    If you're having issues with channel switching then you probably want to in the the TVheadend logfile:

    /storage/.kodi/userdata/addon_data/service.tvheadend42/service.log

    Quote

    Do you think, the slow channel switching can also be lead back to interference problems?

    Seriously, I have no idea. As I mentioned in my previous post interference can cause all kinds of weird issues. But it's something you can easily rule out by trying the suggestions in my previous post.


    Quote

    Concerning the upgrade to LE9: Is the internal backup solution via the LibreELEC menu enough to be able to restore everything as it is now? Or do I have to manually backup certain folders (because you have mentioned to backup relevant folders in /storage).

    Personally, I manually backup anything that's on my storage partition that might be affected by an upgrade. I don't know what stuff you have installed so can't give you a definitive list on what to backup. Just have a look on your storage partition and figure out for yourself which files/folders need to be backed up. Prime candidates are ~/.kodi ~/.config ~/.cache. I don't use the internal backup solution provided by the LE addon, but others may be able to comment further on this.


    Quote

    I am a little confused wheter I should upgrade to LE9 - after all it is a Alpha - but still a lot of people claim that it runs even smoother than LE 8.2.x...

    As mentioned, it wouldn't hurt to try it and you can always revert back afterwards, as long as you've done a backup.

  • Thanks for your insights and thoughts - I will give your suggestions a try and keep you up-to-date! :)

  • So - I've rearanged my devices and cables this weekend - with only little success: I have no more artifacts when viewing TV, but still slow (or no) channel switching sometimes - as well as short dropouts/freezes of the stream (about one sec).


    Somehow - I still cant believe that those dropouts or especially the slow channel switching can be related to interference, but rather to a software or hardware issue.


    Anymore hints? Otherwise I'll try to reinstall everything... And maybe switch to LE9