[mythtv-users] Fun with FireWire

Steve Heistand steve at heistand.org
Thu Jul 10 14:07:13 UTC 2008

> > > When I try to record, though, the results appear to be erratic.
> > > 
> > > What should I be looking at?
> > 
> > could you expand some on "erratic"?
> Missing recording files. System lock-up in one case.
> -dsr-

there is a 'disable firewire reset' checkbox I think in the general
settings menu, make sure that isnt checked.
every so often when I was using firewire in a similar setup (comcast cable)
I had to unplug the cable box, unplug the firewire cable. turn on the cable
box wait for it to be fully on and then plug the wirewire in. about once 
every 3-4 months of uptime things would get wedged. also when my mythtv machine
turned on it would in its startup scripts do a chmod of the raw1394 port (which you
have already done) but it would also send reset packets down the firewire line.
at which point it would start up the BE server. the scripts to do the reset 
are included at the end of this email for reference.
for a while I would also have a cron job at 2pm reset the firewire
line just to be sure. kept issues down. 2pm being at time I normally
wasnt recording anything.

the connection speed in the mythtv-setup section was key as well.
while supposedly the box would run at 400mbps it would only reliably work
at 200. which is still fast enough for HD. occasionally it would bounce
around to the 2nd channel on the firewire port, which didnt really cause
mythtv any problems it did cause issues for my channel changing script
mythtv uses. (the box would take commands on the firewire line to change 
channels so I didnt need an IR setups)

When I first started using the box its model number wasnt in the mythtv
database of boxes to talk to. it does something like a probe on the line
to get a model number and compare it to a list it knows about.
I had to add in the model number to my svn tree and recompile.
but if you say it recognized your box so that probably isnt an issue here.

mpc:heistand% cat /usr/local/sbin/dct_reset
/bin/chown mythtv:mythtv /dev/raw1394
set line=`/usr/local/sbin/get_firewire_node`
if ( $line == 12 ) then
  set node=1
  set node=0

/usr/bin/plugctl -n $node "oPCR[0].n_p2p_connections=0"
/usr/bin/plugctl -n $node "oPCR[0].bcast_connection=0"
/usr/bin/plugctl -n $node "oPCR[0].data_rate=2"
/usr/bin/plugctl -n $node "oPCR[0].channel=160"
/usr/bin/plugctl -n $node "oPCR[0].n_p2p_connections=0"
/usr/bin/plugctl -n $node "oPCR[0].bcast_connection=1"
sleep 5
#/usr/local/sbin/firewire_tester -n $node -b
/usr/local/sbin/firewire_tester -n $node -B
#/usr/local/sbin/firewire_tester -n $node -b

exit 0
mpc:heistand% cat /usr/local/sbin/get_firewire_node
/usr/X11R6/bin/plugreport |& /bin/grep -n online | /usr/bin/awk -F':' '{print $1}'

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