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Ticket #13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
#13292: LiveTV Channel Switching - DVB-T/T2 UK Freeview
--------------------------------------+--------------------------
Reporter: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Keywords:
Ticket locked: 0 |
--------------------------------------+--------------------------
I am seeing a number of issues in LiveTV when changing to certain channels
on DVB-T/T2 UK Freeview. The symptoms vary from an ok channel change, to
video with no audio, vidio with wrong audio (subtitle fails) to "cannot
open decoder".

It seems that codec detection for LiveTV is having problems with certain
channels, where mp3 codec is detected. It is particularly noticeable for
Sky News channel.


The issues are also present on mythtv 29, so the recent bump to ffmpeg 4
in master does not seem to be the cause.

mythtv 0.28 works but also has the Ring Buffer detection issues, but
channel change is ok.


Note Channel switching times are also long due to Ring Buffer
detection not failing, it falls back to in-file.


Attached are a number of debug logs including ffmpeg, mythffmpeg and
mediainfo data taken from a recording of Sky News channel.

--
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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "mythfrontend.20180605105537.8267-skynews-ok-tuning-with-
audio.log" 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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "mythfrontend.20180605180723.4343-skynews-noaudio.log" 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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "mythfrontend.20180605181230.4437-skynews-could-not-open-
decoder.log" 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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "mythfrontend.20180605181924.4793-recorded-skynews-
playback.log" 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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "mythfrontend.20180606054416.6887-mythtv-028-xubuntu1604.log"
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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "mythfrontend.20180606061614.2257-mythtv29-debian-
stretch.log" 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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "skynews-ts-data.txt" 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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------

Comment (by mikeb2013):

Channel your tv log shows difference with no mp3 codec detected, with Ring
Buffer detection working and quick channel change.

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:1>
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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by mikeb2013):

* Attachment "mythfrontend.20180605175952.4153-yourtv.log" 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: mikeb2013 | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------

Comment (by mikeb2013):

Correction to first post:
"Ring Buffer detection not failing" should be "Ring Buffer detection
failing"

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:2>
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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------

Comment (by Mike Bibbings):

transport dumps for skynews, single channel and full mux are available at
https://www.dropbox.com/sh/0n0t3ebp4nwiy3g/AACeC4WijoHLzj6Mrq1pgdmDa?dl=0

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:3>
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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------

Comment (by bib1963):

Sorry, can't help you other than confirm the problem, although if you up
the card signal & tuning timeouts, that does seem to help. I've set mine
to 10,000ms

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:4>
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: (none)
Type: Bug Report - General | Status: new
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:4 bib1963]:
> Sorry, can't help you other than confirm the problem, although if you up
the card signal & tuning timeouts, that does seem to help. I've set mine
to 10,000ms

Yes, increasing timeouts does help (I had already done this), but they
only mask the problem.

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:5>
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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------

Comment (by Mike Bibbings):

Added another mythfrontend.20180608062200.29257-ITVHD.log, this shows
issues with DVB-T2 HD channel.

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:6>
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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by Mike Bibbings):

* Attachment "mythfrontend.20180608062200.29257-ITVHD.log.zip" 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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------

Comment (by Mike Bibbings):

I have added 8 full ts dump files (all multiplexes from SandyHeath
Freeview Transmitter) to my dropbox
https://www.dropbox.com/sh/0n0t3ebp4nwiy3g/AACeC4WijoHLzj6Mrq1pgdmDa?dl=0

The files are c<nn>-fullts.ts and are 30 second dumps using dvbv5-zap

Mike

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:7>
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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------

Comment (by Mike Bibbings):

Done some more investigations, the issue seems to be (mainly) with audio
stream detection.

I applied a patch which disabled FAIL return in avformatdecoder.cpp
(attached disable_avformatdecoder_return_FAIL_DEBUGONLY.patch)

The attached log mythfrontend.20180615130657.23054-various-channel-switch-
withdebug-patch.log
shows a number of entries like:
2018-06-15 14:07:44.328931 D [23054/23054] CoreContext
avformatdecoder.cpp:205 (has_codec_parameters) - AFD: unspecified frame
size

With the patch applied channel tuning is far faster, as audio seems to
sort itself out, and detection now works in RingBuffer (it no longer drops
back to in-file).

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:8>
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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by Mike Bibbings):

* Attachment "mythfrontend.20180615130657.23054-various-channel-switch-
withdebug-patch.log" 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: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: needs_triage
Component: MythTV - DVB | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
----------------------------------+------------------------------
Changes (by Mike Bibbings):

* Attachment "disable_avformatdecoder_return_FAIL_DEBUGONLY.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 Peter Bennett):

* owner: (none) => Peter Bennett
* status: new => assigned


--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:9>
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):

Due to numerous changes in mythtv 30 since the original patch it no longer
works, updated version for current mythtv 30 is attached, also attached is
patch for current mythtv master (pre31)

Mike

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:10>
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 "disable_avformatdecoder_return_FAIL_DEBUGONLY_v30.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
"disable_avformatdecoder_return_FAIL_DEBUGONLY_master_31.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
----------------------------------+-------------------------------

Comment (by 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?

--
Ticket URL: <https://code.mythtv.org/trac/ticket/13292#comment:11>
MythTV <http://www.mythtv.org>
MythTV Media Center

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