Mailing List Archive

Ticket #13052: MythTV assumes demux1 when frontend1 is in use, but no demux1 device is available only demux0
#13052: MythTV assumes demux1 when frontend1 is in use, but no demux1 device is
available only demux0
------------------------------------------+--------------------------------
Reporter: Matt <maff667@…> | Owner:
Type: Bug Report - General | Status: new
Priority: minor | Milestone: unknown
Component: MythTV - Channel Scanner | Version: Unspecified
Severity: low | Keywords: demux1,demux0,scan
Ticket locked: 0 |
------------------------------------------+--------------------------------
When using a TBS-5520SE the following devices are available: demux0, dvr0,
frontend0, frontend1, net0

mythtv-setup and mythtv backend seem to make the assumption that if
frontend1 is chosen then demux1 should be used even if no such device
exists.

I think i have narrowed it down to line 606 of streamhandler.cpp

QString demux_fn = CardUtil::GetDeviceName(DVB_DEV_DEMUX, dvb_dev);

and/or lines 2077-2096 of cardutil.cpp i.e. the GetDeviceName function.

hope that's helpful.

The same issue appears to effect the astrometadvbt2 usb device. And a
workaround would be to rename frontend1 to frontend0.

Cheers

Maff


Reference urls with more details:
https://forum.mythtv.org/viewtopic.php?f=36&t=2156&p=10617#p10617
https://forum.mythtv.org/viewtopic.php?t=1582

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Ticket URL: <https://code.mythtv.org/trac/ticket/13052>
MythTV <http://www.mythtv.org>
MythTV Media Center
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Re: Ticket #13052: MythTV assumes demux1 when frontend1 is in use, but no demux1 device is available only demux0 [ In reply to ]
#13052: MythTV assumes demux1 when frontend1 is in use, but no demux1 device is
available only demux0
--------------------------------------+-----------------------------
Reporter: Matt <maff667@…> | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: unknown
Component: MythTV - Channel Scanner | Version: Unspecified
Severity: low | Resolution:
Keywords: demux1,demux0,scan | Ticket locked: 0
--------------------------------------+-----------------------------

Comment (by Mike Bibbings):

This behaviour stems from a very old trac ticket (2009)
?https://code.mythtv.org/trac/ticket/5061 which mentions HVR3000 and
HVR4000 cards. Prior to this change demux0 was always used.

Today there are many devices which have two frontends per adapter but only
1 demux/dvr, demux0, dvr0. Only one of the frontends can be used at anyone
time with this demux/dvr.

For example TBS 6522 has two frontends for each adapter, frontend 0 is
DVB-T/T2 demux0, frontend 1 is DVB-S/S2, demux0.

Whilst it is possible to "hack" by sym linking demux0 to demux1, this is
not very user friendly.

A change in cardutil.cpp CardUtil::GetDeviceName is required. To maintain
existing behaviour, test to see if demux<n> exists where <n> is the
frontend number, if the test fails return demux0. Similarly for dvr<n>.

Attached is a patch, tested against current master (but can be backported
to mythtv 29 and 30 if needed).

Test system Xubuntu 18.04 with TBS 6522 PCI-e Dual DVB-S/S2,DVB-T/2 and
Astrometa USB DVB/T/T2 tuners.

Patch also applied to my production system, which has Hauppauge QuadHD
DVB-T/T2 and TBS-6981 Dual DVB-S/S2 tuner, with no ill effects.

Mike

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Ticket URL: <https://code.mythtv.org/trac/ticket/13052#comment:1>
MythTV <http://www.mythtv.org>
MythTV Media Center
Re: Ticket #13052: MythTV assumes demux1 when frontend1 is in use, but no demux1 device is available only demux0 [ In reply to ]
#13052: MythTV assumes demux1 when frontend1 is in use, but no demux1 device is
available only demux0
--------------------------------------+-----------------------------
Reporter: Matt <maff667@…> | Owner: (none)
Type: Bug Report - General | Status: new
Priority: minor | Milestone: unknown
Component: MythTV - Channel Scanner | Version: Unspecified
Severity: low | Resolution:
Keywords: demux1,demux0,scan | Ticket locked: 0
--------------------------------------+-----------------------------
Changes (by Mike Bibbings):

* Attachment "201902031457_mythtv_multi-standard_frontend_support.patch"
added.


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Ticket URL: <https://code.mythtv.org/trac/ticket/13052>
MythTV <http://www.mythtv.org>
MythTV Media Center