[mythtv-commits] Ticket #13014: switching to required delivery system

[MythTV]

#13014: switching to required delivery system
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 Reporter:  willem@…              |          Owner:  Stuart Auchterlonie
     Type:  Bug Report - General  |         Status:  assigned
 Priority:  minor                 |      Milestone:  31.0
Component:  MythTV - DVB          |        Version:  0.28.0
 Severity:  medium                |     Resolution:
 Keywords:                        |  Ticket locked:  0
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Comment (by stefanb2):

 One of the changes for #12638 (Switch to using DVB APIv5) commit
 55e1cac4bd249ec2e9463684a50121661af60417 (Partial support dvb v5 API)
 introduced a regression for multi delivery system HW, like the Hauppauge
 WinTV dual-HD DVB-T/T2/C USB stick.

 If the frontend responds to the ioctl `FE_GET_PROPERTY`/`DTV_ENUM_DELSYS`
 query with a list that contains `SYS_DVBS2` or `SYS_DVBT2`  then that will
 override anything else. If you had set up the device with 0.29 on a DVB-C
 multiplex, then 0.30 will try to tune a DVB-T2 device with those
 parameters (e.g. QAM), which of course fails:

 {{{
 2019-03-06 21:26:05.196847 W [3348/3348] CoreContext dtvmultiplex.cpp:286
 (ParseDVB_T2) - DTVMux: Invalid T2 modulation system parameter '',
 aborting.
 2019-03-06 21:26:05.196854 E [3348/3348] CoreContext
 recorders/dtvchannel.cpp:292 (SetChannelByString) -
 DTVChan[16](/dev/dvb/adapter2/frontend0): SetChannelByString(51): Failed
 to initialize multiplex options
 }}}

 There is no easy fix for this, because the root cause is that mythtv
 doesn't have support for specifying the DVB card subtype. It will always
 try to auto-detect when opening the frontend, which explains why solutions
 based on `dvb-fe-tool`don't work.

 For proper multi delivery system HW support IMHO the following changes
 would be required to mythtv:

 * libmythtv/cardutils returns the full list of develiver systems supported
 by a frontend
 * change mythtv-setup/Capture Cards that card subtype would be a selection
 list (currently the subtype is a read-only text field)
 * the table `capturecard` needs a new column `cardsubtype` which records
 the users choice
 * libmythtv/recoders/dvbchannel.c should use the setting from the database

 FYI: as a workaround for the Hauppauge WinTV dual-HD issue I've submitted
 a [https://patchwork.linuxtv.org/patch/54970/ patch proposal for the
 si2168 kernel module]: it adds a parameter to disable DVB-T/T2 support.
 I.e. the frontend will only report DVB-C support and thus mythtv 0.30 is
 able to tune the device again. Such a change should be easy for other
 frontend kernel modules too.

-- 
Ticket URL: <https://code.mythtv.org/trac/ticket/13014#comment:11>
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