[mythtv-commits] Ticket #1141: DVB: Problems tuning on myth server, but no problems tuning on mythbackend.

MythTV mythtv at cvs.mythtv.org
Sun Jan 29 05:53:50 UTC 2006

#1141: DVB: Problems tuning on myth server, but no problems tuning on mythbackend.
 Reporter:  homer_simpson_loves_u at hotmail.com  |       Owner:  danielk
     Type:  defect                             |      Status:  new    
 Priority:  minor                              |   Milestone:  unknown
Component:  mythtv                             |     Version:  head   
 Severity:  medium                             |  
 This applies from SVN 8390 through head. I haven't gotten something
 further back to work recently.

 If I use any SVN version from 8390 to latest and run the frontend on the
 same machine as the backend, channel changes are broken and rarely work on
 channel changes between switch inputs.

 I assumed it was a hardware problem and spent a great deal of time trying
 to get it to work.

 I removed one Nexus DVB card and the other one still failed. I swapped to
 the first card running alone with the same results. Although with only one
 card it seemed more reliable, it still was not 100%.

 I hacked around in the switch routines in the kernel with no noticable

 I played with different PCI slots, adjusted bios settings, stopped
 overclocking. I did everything except swap motherboards, which is too much
 of a pita to even attempt with my time budget.

 Nothing I did made it reliable. I began to feel that my several months of
 stability were a figment of my imagination...

 Then, after giving up, I decided to watch some TV and ran mythfrontend on
 my laptop...

 And it worked perfectly. On my laptop every channel change locks and video
 is displayed. No matter how many channel changes or different switch or
 card inputs I choose. It works flawlessly.

 So I think I thought I was stable because I was testing using the front
 end on my laptop.

 I'm convinced its a timing problem. My laptop is connected via wireless.
 So there is a huge lag between tcp packets traveling from it to the myth

 So today I sat down and generated front end (-v channel) and back end (-v
 channel, record) logs.

 Looking through I can see on the fe/be same machine log a failed lock and
 I can see a lock to the wrong PAT on two channel changes.

 The failed log actually shows serveral failures. I did not have -v

 I have no idea how to track down this problem. I don't know enough about
 the code to know what to look for.

 Daniel, I'm hoping that you'll have time after .19 is released to walk me
 through the steps necessary to debug this.

 I've attached four sample logs. Please note that when the frontend was
 running on my laptop, it crashed for some other reason and that's why
 there aren't as many channel changes.

 Also note the logs are from running 8390. The problem is identical at the


Ticket URL: <http://cvs.mythtv.org/trac/ticket/1141>
MythTV <http://www.mythtv.org/>

More information about the mythtv-commits mailing list