[mythtv-commits] Re: Ticket #343: 'Signal 100% (l ) no lock' and no video with DVB-S and DVB-T

MythTV mythtv at cvs.mythtv.org
Tue Sep 27 12:56:27 UTC 2005

#343: 'Signal 100% (l ) no lock' and no video with DVB-S and DVB-T
 Reporter:  daniel.danner at gmx.net  |        Owner:  danielk
     Type:  defect                 |       Status:  new    
 Priority:  major                  |    Milestone:  0.19   
Component:  mythtv                 |      Version:  head   
 Severity:  high                   |   Resolution:         
Comment (by anonymous):

 Perhaps the output from these USB devices isn't supporting PAT and PMT?
 Isn't it the case that it isn't even a full TS? I mean, for USB 1.1, a
 full TS is never going to cross the bus in a timely manner ; it's a
 struggle sometimes to get a single PS across it (esp. on high-bandwidth
 shows). Do the drivers even support TS, and if they do, are they retro-
 constructing a "poor mans" TS with no PAT/PMT?

 I think this may be the problem... and will be common to any USB based
 approach. You've jogged my memory.

 From memory (check the linuxtv drivers board for more details), the
 drivers instruct the device to provide specific PIDS, and they construct
 the TS like stream. I'm not at home for the next few days, however I do
 remember the author of the drivers describing something like that.... yes
 it's a added to kernel (as in I downloaded the source and drivers and
 compiled a module to support USB, I think it went in in .11 or .12).

 Also I think tuning is quick, but channel selection slow (would fit with
 your idead of reconstructing TS's).

 Why it is unreliable rather than failing completely is beyond me...
 timing/race conditions, or timeouts seem the most likely.


Ticket URL: <http://cvs.mythtv.org/trac/ticket/343>
MythTV <http://www.mythtv.org/>

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