v30 Could not open Decoder on LiveTV

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jiminorris
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v30 Could not open Decoder on LiveTV

Post by jiminorris » Mon May 06, 2019 3:11 pm

I've been using Myth since 0.19 generally with little/no issues. Since upgrading to v30, however, I have two recurring issues I can't seem to figure out.

First is my localisation settings just won't save...

but the main issue is that about 75% of the time, when trying to watch live tv, I get kicked back to the main menu with an error, "could not open decoder," I'm not sure if it's a related issue, but sometimes it does open the decoder, I get a live picture, but there's no sound... any ideas?

Running a Xubuntu 18.10 with mythbuntu repos.

MikeB2013
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Re: v30 Could not open Decoder on LiveTV

Post by MikeB2013 » Mon May 06, 2019 4:48 pm

For the localisation settings issue and without any logs, so I am guessing.
It could be due to your user not being in mythtv group (there is a bug in current mythtv packaging due to underlying *ubuntu changes - removal of gksu).
In a terminal session what is the output of groups command, you should get something like (in my case the user is "mike")

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mike@myth-server-1:~$ groups
mike adm cdrom sudo dip plugdev lpadmin sambashare mythtv
If mythtv is missing from the output, fix it as follows (after which log out or reboot)

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sudo adduser $USER mythtv
For the "could not open decoder" issue, and you are using DVB-T/DVT2 e.g. UK Freeview, there is a known bug see https://code.mythtv.org/trac/ticket/13292 and is still present in latest mythtv master (31pre). There is a workaraound but it involves building mythtv from source - I can provide details if you would like.

One other point (you may be aware, but just in case), for Ubuntu/Debian systems using systemd (xubuntu does), mythtv-setup and manual start/stop of mythtv-backend must be done in a terminal session using systemctl commands as follows:
to stop mythv-backend before using mythtv-setup

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sudo systemctl stop mythtv-backend
then run mythtv-setup, when finished start mythtv-backend as follows:

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sudo systemctl start mythtv-backend
Mike

jiminorris
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Re: v30 Could not open Decoder on LiveTV

Post by jiminorris » Tue May 07, 2019 5:19 pm

MikeB2013 wrote:
Mon May 06, 2019 4:48 pm
For the localisation settings issue and without any logs, so I am guessing.
It could be due to your user not being in mythtv group (there is a bug in current mythtv packaging due to underlying *ubuntu changes - removal of gksu).
In a terminal session what is the output of groups command, you should get something like (in my case the user is "mike")

Code: Select all

mike@myth-server-1:~$ groups
mike adm cdrom sudo dip plugdev lpadmin sambashare mythtv
If mythtv is missing from the output, fix it as follows (after which log out or reboot)

Code: Select all

sudo adduser $USER mythtv
No luck there, I'm 100% in the mythtv group!
MikeB2013 wrote:
Mon May 06, 2019 4:48 pm
For the "could not open decoder" issue, and you are using DVB-T/DVT2 e.g. UK Freeview, there is a known bug see https://code.mythtv.org/trac/ticket/13292 and is still present in latest mythtv master (31pre). There is a workaraound but it involves building mythtv from source - I can provide details if you would like.

Mike
Sounds like I'll have to last it out and cross my fingers the fix makes it in to master soon and hope for a backport into -fixes. I can't imagine the wife agreeing to building from source and the risk of downtime on our family TV. I've been spoilt by Debian/apt and haven't built anything (complicated) from source for over 15 years!

TMonster
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Re: v30 Could not open Decoder on LiveTV

Post by TMonster » Wed Jun 19, 2019 6:16 am

Just adding a "me too" post, but I'm using Arch Linux

The MythTV package has been moved to the "AUR" so I have to compile it now anyway, so I'm interested in the workaround:
There is a workaraound but it involves building mythtv from source - I can provide details if you would like.
Looking at the bug report, I can see the patch provided by Mike Bibbings, so I'm guessing that's what's involved? Or is there more?

Thanks

MikeB2013
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Joined: Mon Jul 25, 2016 4:16 pm
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Re: v30 Could not open Decoder on LiveTV

Post by MikeB2013 » Wed Jun 19, 2019 8:10 am

Due to changes in mythtv 30 since the original patch (12 month ago) it no longer works.
I have just updated the ticket https://code.mythtv.org/trac/ticket/13292 with latest version of the patch for current mythtv 30, and provided a patch for current mythtv master (31pre)

Mike

edc73
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Re: v30 Could not open Decoder on LiveTV

Post by edc73 » Tue Jul 16, 2019 6:40 pm

Hi

I’m getting this error quite often on lots of channels (UK DVB T2)

I’ve always installed from mythbuntu repos. Is there any guide for building from source and applying this patch?

Thanks!

jksj
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Re: v30 Could not open Decoder on LiveTV

Post by jksj » Wed Jul 17, 2019 7:53 am

The instructions are here for building from source. https://www.mythtv.org/wiki/Build_from_Source

MikeB2013
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Re: v30 Could not open Decoder on LiveTV

Post by MikeB2013 » Wed Jul 17, 2019 8:08 am

edc73 wrote:
Tue Jul 16, 2019 6:40 pm
Hi

I’m getting this error quite often on lots of channels (UK DVB T2)

I’ve always installed from mythbuntu repos. Is there any guide for building from source and applying this patch?

Thanks!
The general instructions for building from source are at https://www.mythtv.org/wiki/Build_from_Source

Here are some more detailed instructions for Xubuntu 18.04 and mythtv fixes/30 branch
These instructions are used by me on my mythtv systems and should give you a system to see if it solves your DVB-T/T2 issue
I initially install from the mythbuntu ppa as it sets up many things e.g. mythconverg database, logging etc. which if you only build from source have to be done manually (not a trivial task).
Note it is best to copy and paste the commands to avoid typing errors
Using a terminal session:
1. create a build directory

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mkdir -p build
cd build
2. update and install git ansible

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sudo apt update
sudo apt install ansible git -y
3. get mythtv,ansible and patch sources

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wget https://code.mythtv.org/trac/raw-attachment/ticket/13292/disable_avformatdecoder_return_FAIL_DEBUGONLY_v30.patch
git clone -b fixes/30 https://github.com/MythTV/mythtv.git
git clone https://github.com/MythTV/ansible.git
4. run ansible to install all mythtv build dependencies, this will take a few minutes

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cd ansible
sudo ansible-playbook -i hosts qt5.yml
5. apply patch

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cd ../mythtv
patch -p1 <../disable_avformatdecoder_return_FAIL_DEBUGONLY_v30.patch
6. build and install mythtv - this take a while maybe 1 hour depending on your system

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cd mythtv ./configure
make -j4
sudo make install

7. optional - build mythplugins (mythbrowser, mythnews etc)

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cd ../mythplugins
./configure
make -j4
sudo make install
8. Adjust systemd mythtv-backend.service file by creating an override file
do not edit the mythtv-backend.service file directly

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sudo systemctl stop mythtv-backend
sudo systemctl edit mythtv-backend.service
add the following 4 lines:
# Change mythbackend start to use /usr/local/bin instead of /usr/bin/
[Service]
ExecStart=
ExecStart=/usr/local/bin/mythbackend --quiet --syslog local7 $ADDITIONAL_ARGS

9. restart mythtv-backend

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sudo systemctl daemon-reload
sudo systemctl start mythtv-backend
10. From now on do not use menu options to control mythtv-setup or mythfrontend, use a terminal session.

To manually stop or start mythtv-backend use systemd systemctl commands (it will automatically start at boot)

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sudo systemctl stop mythtv-backend
sudo systemctl start mythtv-backend
To run mythtv-setup:

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sudo systemctl stop mythtv-backend
mythtv-setup
sudo systemctl start mythtv-backend
To start mythfrontend, logging goes to /tmp/ and will be lost on machine restart

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mythfrontend --logpath /tmp
Mike

edc73
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Re: v30 Could not open Decoder on LiveTV

Post by edc73 » Thu Jul 18, 2019 3:15 pm

Thanks for the detailed explanation!

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