[mythtv-commits] Ticket #5754: Enhancement to make EIT Active Scanning end after a period, then restart later (a duty cycle)

MythTV mythtv at cvs.mythtv.org
Wed Oct 1 09:25:05 UTC 2008

#5754: Enhancement to make EIT Active Scanning end after a period, then restart
later (a duty cycle)
 Reporter:  simonwalls at yahoo.com  |       Owner:  stuarta   
     Type:  enhancement           |      Status:  new       
 Priority:  major                 |   Milestone:  unknown   
Component:  eit                   |     Version:  0.21-fixes
 Severity:  medium                |     Mlocked:  0         

 I want to see if the power consumption of my server reduces if I don't
 have a tuner card doing Active EIT Scan all the time. I am in the UK and
 using Nova-T PCI DVB cards.

 Also, some folks have experienced issues which have been blamed on Myth's
 continuous EIT scanning. (Example: ticket #2741 : disable the active EIT
 scan for open on demand DVB cards. "Some dibcom based usb devices
 (including the Nova-T500) have a nasty bug which is mostly triggered by
 our continuous eit scanning.")

 I have noticed on various forums, conversations mentioning how nice it
 would be to make EIT scanning have a duty-cycle rather than be continuous
 but it has not been possible to date. (However, it's not immediately
 apparent from mythtv-setup but it is true that Active EIT scan yields to a
 recording, so using Active Scan does not 'cost' you a tuner card, merely
 makes it busy when it's not being used for recordings).

 So this patch is for a simple modification to the Active EIT Scan
 behaviour. It has hard-coded timing information, which it would be nice to
 ultimately have as a GUI control (in mythtv-setup, adjacent to the EIT
 Active Scan tickbox I guess....) but I have not got the skills to code
 that yet.

 It shouldn't be necessary to scan EIT continously to keep a full program
 guide, and this patch will allow me to work out how much scanning time is
 required in general. I will also update this ticket with any power (ie.
 wattage) information I find out (I have a Nova-T PCI).  It is very warm to
 the touch, so I hope that 'turning it off' (if this is what happens) is
 going to make it cool and save a few watts.

 The patch is currently set to do 1 hour of scanning in every 8 hour period
 but this is easily adjustable, the appropriate places are commented.

 Some backend logs are also attached, a full log, and a slimmed down log
 just showing the relevant EIT and TVRec log entries with timestamps. The
 timing works as expected, 1 hour of scanning then a 7 hour break. I am
 still testing and have some recordings scheduled today which will test the
 interruption by a recording, and restarting of the cycle.

 Realistically I don't think I will get to add a GUI control in mythtv-
 setup, perhaps interfaced to mythconverg database entries to store user-
 changeable on-time and off-period (per card) for this 'Improved Active
 Scan' so if anyone else wants to write that, please do. GUI programming is
 not my forte.

 Other possible improvements:
  - I originally wanted to make the scan duration dependent upon the number
 of multiplexes received by the card. This will be more scalable for when
 the number of multiplexes increases as it surely will. This information is
 in a different scope however, is is available in EITScanner not in TVRec.
 I'm sure a better programmer than I could make activeScanChannels more
 global, so that code in TVRec can find out its size.

Ticket URL: <http://svn.mythtv.org/trac/ticket/5754>
MythTV <http://www.mythtv.org/>

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