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Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: assigned
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------

Comment (by Mike Bibbings):

I never investigated the loop timings, I just noticed that certain codec
parameters were not being found, so I tried disabling the error return and
everything started working.
There are two different detection mechanisms, the first in livetv ring
buffer and then the in-file detection which seem to behave differently.

In skynews-ts-data.txt file ffmpeg and mythffmpeg both show
"Could not find codec parameters for stream 2 (Audio: mp3 (mp3float), 0
channels, fltp): unspecified frame size" which fails in livetv ring buffer
tests, but the in-file tests don't seem to care.

Mike

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:12>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: assigned
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------

Comment (by mymatenige):

This workaround also resolves the same issue for me. I'm in the UK using
PCTV 292e devices.

Has anyone been able to investigate the root cause?

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:13>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: assigned
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------

Comment (by Mike Bibbings):

Replying to [comment:11 Peter Bennett]:
> By always returning 1 from the FAIL macro, the patch means that the
function has_codec_parameters always returns true. In that case the
has_codec_parameters function as well as the loop from where it is called,
will have no effect and could be removed.
>
> It looks like the loop is designed to pause for 50 ms if the data is not
ready for live tv.
>
> Is that loop really unnecessary? It seems that the worst it can do is
cause a fraction of a second delay, while removing it could cause playback
to fail if the data is not really there when needed.
>
> Am I understanding this correctly? Do you have any insight on why this
fixes the problem?

Peter,
Done some more testing by completely removing has_codec_parameters
function and the loop.
Live TV channel changes worked with no problems for DVB-T/T2 and DVB-S/S2,
channel changes are faster (to be expected) and do not result in dropping
back to in-file detection.
FindStreamInfo() is happy, it is just that the checks failure.

My only concern about totally removing the function and the loop is
possible side effects on other transmission systems e.g atsc, which I
don't have and cannot test.

I have created a patch (for fixes/30 and master) which makes the checks
conditional on a new mythbackend setting.

No action is required for most users, as the default is to allow the
checks to run.
For those users with DVB-T/T2 tuners having the problem e.g. UK Freeview,
mythtv-setup>General>Locale Settings has a new option "Live TV Codec
Checks" which when set to "No" bypasses the checks.

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:14>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: assigned
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------
Changes (by Mike Bibbings):

* Attachment "20190828_fixes30_LiveTVCodecChecks.patch" added.


--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: assigned
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------
Changes (by Mike Bibbings):

* Attachment "20190828_master_LiveTVCodecChecks.patch" added.


--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: assigned
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------
Changes (by Mike Bibbings):

* Attachment "mythfrontend.20190829121946.30123.log" added.

mythfrontend log with mythbackend "Live TV Codec Checks" set to "No", so
checks are bypassed.

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: assigned
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------

Comment (by Mike Bibbings):

This problem has been fixed in mythtv 31 and on.
Suggest ticket is closed, together with a note of not fixing for earlier
versions of mythtv.

Mike

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:15>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: closed
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution: Fixed
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------
Changes (by Peter Bennett):

* status: assigned => closed
* resolution: => Fixed


--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:16>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview [ In reply to ]
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
----------------------------------+-------------------------------
Reporter: Mike Bibbings | Owner: Peter Bennett
Type: Bug Report - General | Status: closed
Priority: minor | Milestone: 31.0
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution: Fixed
Keywords: | Ticket locked: 0
----------------------------------+-------------------------------
Changes (by Stuart Auchterlonie):

* milestone: needs_triage => 31.0


--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:17>
MythTV <http://www.mythtv.org>
MythTV Media Center

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