[mythtv] Re:DVB fixes

Martin Smith martin at spamcop.net
Sun Jun 29 14:33:21 EDT 2003


> Ok, with current CVS...changing channel segfaults whether the channel
> moved to is on same multiplex or not...however I have a small patch that
> improves it to only segfaulting when moving between multiplex. That
> patch just deletes the decoder and creates a new one on channel change. 

Hi,

I just noticed DVB the code opens the frontend device, tunes the channel and
closes it again. I don't think this is the right thing to do. 

On my card, when the frontend is closed it loses lock. Watching the output of
femon I get a brief period of lock when mythbackend starts and the channel is
tuned and then it goes away (shown below). Mythfrontend then sits there with a
black screen when I go to 'live tv', presumably because the card isn't providing
data.

I think I also remember reading on the dvb list that some cards go into power
saving mode when the frontend is closed.

I modified the code to hold the frontend open and close it in the Close method
and that lets me watch TV (except for the segfault you're already looking into
above). It's a bit of a hack using a fixed size array for 4 cards so I don't
want to submit it as a patch but I think you probably need to do something similar.

Martin

[mythtv at sleeper-service mythtv]$ /opt/DVB-Kernel/DVB/apps/szap/femon
using '/dev/dvb/adapter0/frontend0'
FE: Grundig 29504-401 (TERRESTRIAL)
status 00 | signal 0000 | snr ffff | ber 00000000 | unc 00000000 |
status 00 | signal 0000 | snr ffff | ber 00000000 | unc 00000000 |
status 00 | signal 0000 | snr ffff | ber 00000000 | unc 00000000 |
status 00 | signal 0000 | snr ffff | ber 00000000 | unc 00000000 |
status 00 | signal 0000 | snr ffff | ber 00000000 | unc 00000000 |
status 1f | signal 3434 | snr e9e9 | ber 00000063 | unc 0000000d | FE_HAS_LOCK
status 1f | signal 3434 | snr e9e9 | ber 000000ac | unc 00000000 | FE_HAS_LOCK
status 1f | signal 3434 | snr e9e9 | ber 0000009c | unc 00000000 | FE_HAS_LOCK
status 1f | signal 3434 | snr e9e9 | ber 0000006e | unc 00000000 | FE_HAS_LOCK
status 1f | signal 3434 | snr eaea | ber 00000095 | unc 00000000 | FE_HAS_LOCK
status 00 | signal 0000 | snr ffff | ber 00000000 | unc 00000000 |
status 00 | signal 0000 | snr ffff | ber 00000000 | unc 00000000 |



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