[mythtv-commits] Ticket #12792: default timeouts are to tight for channel scan with a HDHR3-4DC on DVB-C

[MythTV]

#12792: default timeouts are to tight for channel scan with a HDHR3-4DC on DVB-C
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 Reporter:  Karl Egly             |          Owner:  Karl Egly
     Type:  Bug Report - General  |         Status:  new
 Priority:  minor                 |      Milestone:  unknown
Component:  MythTV - HDHomeRun    |        Version:  Unspecified
 Severity:  medium                |     Resolution:
 Keywords:                        |  Ticket locked:  0
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Comment (by Klaas de Waal):

 This problem is possibly not a question of a timeout value.\\
 \\
 The mythtv-setup code sees all the HDHomerun devices that support DVB-T,
 DVB-C or both, as DVB-T devices.
 It can work with DVB-C devices such as the HDHR3-4DC because mythtv-setup
 generates an "auto" tuning command that is the same for both DVB-T and
 DVB-C devices.\\
 For example, for the 474MHz frequency the command is "auto:474000000".\\
 \\
 The HDHR3-4DC tries all the modulation values in parameter
 /sys/dvbc_modulation and if one of these is correct for the signal then
 tuning succeeds in one second or so. But if the modulation values are not
 correct or not present then tuning will never succeed.\\
 \\
 The modulation values can be read and written with the hdhomerun_config
 utility which can be downloaded from the Silicon Dust website.\\
 For example, this are the values for my test system:
 {{{
 [klaas at modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
 a8qam64-6875 a8qam256-6900
 [klaas at modu ~]$ hdhomerun_config 1410F45C set /sys/dvbc_modulation ""
 [klaas at modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation

 [klaas at modu ~]$ hdhomerun_config 1410F45C set /sys/dvbc_modulation
 "a8qam64-6875"
 [klaas at modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
 a8qam64-6875
 [klaas at modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
 a8qam64-6875
 [klaas at modu ~]$ hdhomerun_config 1410F45C set /sys/dvbc_modulation
 "a8qam64-6875 a8qam256-6900"
 [klaas at modu ~]$ hdhomerun_config 1410F45C get /sys/dvbc_modulation
 a8qam64-6875 a8qam256-6900
 [klaas at modu ~]$

 }}}
 The modulation value is built as follows:
 {{{
 a       is always present
 8       bandwidth in MHz
 qam256  modulation
 6900    symbol rate

 }}}
 Of course, the parameters have to be chosen for the local DVB-C signal.\\
 \\
 It would be better if the MythTV did not depend on a configuration item;
 if the MythTV code would be changed to have explicit tuning commands, e.g.
 "a8qam64-6875:474000000", then the HDHR3-4DC would always work independent
 of the /sys/dvbc_modulation parameter configuration.

-- 
Ticket URL: <https://code.mythtv.org/trac/ticket/12792#comment:3>
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