[mythtv-users] Firewire source and channel changer

Brian C. Huffman huffman at graze.net
Tue Oct 25 15:40:54 EDT 2005

On Tue, 2005-10-25 at 13:05 -0600, Curtis Stanford wrote:
> On Oct 25, 2005, at 12:01 PM, Brian C. Huffman wrote:
> > All,
> >
> > Is there anyone that is successfully using Firewire as both a  
> > source as
> > well as a method to change channels on the DCT6200 (using another
> > source).
> >
> Yes ... well, mostly
> > I'm trying to setup Firewire to handle the analog channels and then  
> > use
> > a PVR-250 w/ the 6200ch contributed program to change channels on the
> > other source.  I've setup two different lineups in zap2it and that  
> > part
> > is working as it should.
> >
> > However, I have spent hours troubleshooting and trying different
> > combinations of point to point vs. broadcast and I can't get both to
> > work reliably.  Somtimes the firewire works great by itself -  
> > meaning I
> > can enter and exit liveTV repeatedly and flawlessly and sometimes it
> > doesn't.  Sometimes I can use LiveTV in the Firewire and then switch
> > back and forth to the other input and change channel using 6200ch, but
> > at most, I've been able to make this flip-flop about 4 times before  
> > the
> > firewire stops working.
> >
> > When this happens, sometimes I'm able to stop mythbackend, unload all
> > *1394* modules, reload the modules, and then start mythbackend and it
> > will work again.  Sometimes not.  This is one of the most finicky and
> > unpredictable things that I think I've ever worked with.
> >
> > FYI - I've experimented w/ the options mentioned in another email:
> >
> >
> >> plugctl -n 1 opcr[0].channel=63
> >> plugctl -n 1 opcr[0].bcast_connection=1
> >>
> >
> > or:
> >
> >> plugctl -n 1 opcr[0].n_p2p_connections=1
> >>
> >
> > Neither one *completely* fixes my problem.  I've gotten either of  
> > these
> > (with some fiddling) to get the firewire source to work
> > predictably....until I bring the other source w/ the 6200ch binary  
> > into
> > the equation - then it goes to crap again.  :-(
> >
> > Any advice would be appreciated.
> >
> > Thanks,
> > Brian
> The options you mentioned brought me from about 50% reliability to  
> more like 95%. Although 6200ch never gives me a problem (I had to add  
> my DCT2000 model to 6200ch to get it to work), the firewire video  
> itself is sometimes a little flakey.

Hmmm...DCT2000?  I thought that was one of the older boxes that didn't
support firewire out?  Or do I have something confused?  Either way, how
did you determine the model # - I'm assuming it's a hexidecimal #.  And
then was it simply adding it into the defines at the top of the 6200ch.c
file?  I wish I had the code in front of me so that I could ask the
question more intelligently.  

> I've found using the first two plugctl options above works best for  
> me with myth set to broadcast and node 1. Sometimes, recordings are  
> short as I've mentioned in previous messages and sometimes the video/ 
> audio goes choppy after changing channels. Also, LiveTV seems to  
> screw things up occasionally so that I have to restart the backend.

Do you put these in an init script somewhere?  Or create an init script
that runs before mythbackened?  I've also seen someone mention actually
hardcoding these into a function (presumably in mythtv).

> It's not quite bad enough that I want to go back to my PVR-250 but  
> it's close. If it weren't for HD, I would go back to my PVR-250 in a  
> minute.
> Curtis

Sort of off topic, but what kind of hardware do you have?  Is your
backend / frontend the same machine (for the HD)?  I have a P4 2GHz w/
512 meg of memory and (I believe) an 845GVB motherboard.  I *know* that
my board does not support hyperthreading (I was being cheap at the
time).  I'm also using the Nvidia GeForce4 MX 440.  I know that my
motherboard only supports 4X AGP (not 8X).  So I don't know if any of
these are my problem....

With preliminary testing (when the firewire is working), I get sort of a
continual "stop and start" when playing back HD content as if
*something* can't keep up.  It doesn't look to me like my CPU is being
killed - I see it at around a load of 2-3 (which is a little higher than
regular content), but didn't seem terrible.  And watching hard drive
activity (which is set to use DMA) also doesn't seem bad at all...so I'm
not sure if it's a bus or an IRQ issue or what.  I'll be happy to just
get the firewire straightened out first and then look into this issue.


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