[mythtv-commits] Ticket #7292: DVB-T channel scan timeout on HVR-1300

[MythTV]

#7292: DVB-T channel scan timeout on HVR-1300
---------------------------------------------+------------------------------
 Reporter:  Marc Randolph <mrand at pobox.com>  |        Owner:  danielk
     Type:  defect                           |       Status:  new    
 Priority:  minor                            |    Milestone:  unknown
Component:  MythTV - Channel Scanner         |      Version:  unknown
 Severity:  medium                           |   Resolution:         
  Mlocked:  0                                |  
---------------------------------------------+------------------------------

Comment(by hogliux):

 I have the same error on my computer and i'm trying to further nail down
 the problem. I've noticed that with upgrading the kernel to more recent
 kernel versions kaffeine also doesn't lock to all available stations (
 only to some ). tzap in the dvb-utils package can lock on all available
 channels. So i compared the tuning code of caffeine and tzap and modified
 both codes to give me a hexdump of the FE_SET_FRONTEND ioctl structure.
 Both were exactly the same. That means kaffeine and tzap send the exact
 same parameters to tune the drivers, but for some reason kaffeine fails to
 get a lock.

 The next difference i noticed is that when kaffeine or mythtv tunes and
 sleeps waiting for a lock the system load goes up on some kernel threads.
 This doesn't happen with tzap. So this is my guess (haven't checked it
 yet, but will do so this week): the Hauppage 1300 has a built-in mpeg
 decoder and i think tzap sets up the driver in such a way ( with the
 DMX_SET_PES_FILTER ioctl and the DMX_OUT_TS_TAP parameter ) that the mpeg
 tes data is not decoded but sent to dvr0, while tuning. kaffeine sets this
 flag AFTER tuning and i guess the card is then in decode mode by default
 meaning, that the card will try to decode the mpeg-ts data in hardware.
 Maybe, if this, for some reason fails ( maybe because of bad mpeg decoder
 firmware or weak signal ) then the driver won't lock the signal ( which
 would actually be a driver bug, because the signal lock should have
 nothing to do with the hardware mpeg decoder ). I really haven't checked
 this yet but will do so if i have time this week.

 Did someone else observe the system load go up while tuning?

 Thanks for your replies Mark!

 hogliux

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/7292#comment:2>
MythTV <http://www.mythtv.org/>
MythTV