[mythtv] [mythtv-commits] Ticket #9765: Active EIT scanning permanently increases power consumption / feature request and workaround

Michael T. Dean mtdean at thirdcontact.com
Thu May 5 19:39:09 UTC 2011

On 05/05/2011 05:52 AM, MythTV wrote:
> #9765: Active EIT scanning permanently increases power consumption / feature
> request and workaround
> ----------------------------------+------------------------
>       Reporter:  bjoernv@…         |      Owner:  stuarta
>           Type:  Developer Task    |     Status:  new
>       Priority:  minor             |  Milestone:  unknown
>      Component:  MythTV - EIT      |    Version:  Trunk Head
>       Severity:  medium            |   Keywords:
> Ticket locked:  0                 |
> ----------------------------------+------------------------
>   The option "Use DVB card for active EIT scan" is very helpful. This option
>   ensures, that the EPG data for all configured channels is permanently
>   updated. Switching off this option causes the problem, that only passive
>   EIT scanning takes place. As far as I know, only recording streams and
>   live TV streams were considered in passive EIT scan.
>   Unfortunately the option "Use DVB card for active EIT scan" also increases
>   the power consumption. Because the active scanning permanently takes
>   place, also the power consumption increases permanently.
>   Because I want to save power consumption, but also want to have current
>   EPG data, I currently use a workaround. A script does the following:
>   1. Switch on dvb_eitscan in database table capturecard:
>      update capturecard set dvb_eitscan=1 where cardtype='DVB';
>   2. Restart mythbackend
>   3. Sleeps 60 minutes
>   4. Switch off dvb_eitscan
>   5. Restart mythbackend
>   I am not very comfortable with this workaround. One problem is, that
>   restarting mythbackend interrupts live TV and recordings. It would be much
>   better to have an option in mythfilldatabase which forces an active EIT
>   scan also with option "Use DVB card for active EIT scan" turned off. But
>   this still would be a workaround. I would prefer an option for mythbackend
>   itself.

bjoernv, if you're interested in working on this, the plan is for someone to write code which just "does the right thing" without requiring users to set any settings.  This would make the backend scan EIT "as appropriate" based on the previously-seen data and how often it repeats and such.  Unfortunately, I don't know of any specific description of the desired approach, though I'm sure several of the developers could provide additional information (and possibly a complete design idea) to anyone who's serious about working on it (here on the list or in IRC).

See http://code.mythtv.org/trac/ticket/5754 for more information, and note that #5754 was rejected since it added new complexity (and new settings) instead of simplifying setup.  The desired approach would also, due to the fact that it wouldn't be scanning constantly, fix http://code.mythtv.org/trac/ticket/3597 (again, without any additional settings)--which would allow you to easily get the best power savings, by shutting down your mythtv system when not in use.  (And, in the process, would gain the gratitude of many EIT users.)  Last I knew (though this may have changed if something was modified to work around the issue described by #3597), shut down with active EIT scanning typically required external shutdown support due to the frequent updates for EIT data.


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