[mythtv-users] Firewire source and channel changer

[Curtis Stanford]

On Oct 25, 2005, at 1:40 PM, Brian C. Huffman wrote:

> On Tue, 2005-10-25 at 13:05 -0600, Curtis Stanford wrote:
>
>>
>> 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.
>
Sorry! I meant DCT6200. The plugreport command shows a thing called  
GUID,
which in my case was 0x0014e8fffe1d4773. The first 6 hex digits seem  
to be the ID
needed for 6200ch (in my case 0014e8).
>
>>
>> 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).
>
I just made a script that for now I just run by hand after a reboot  
or other screw up.
>
>>
>> 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.
>
> Thanks!
> Brian

My backend is separate from the frontend. My backend is an Athlon  
2300 with some cheap ECS motherboard. I bought a $20 firewire card to  
connect to the DCT-6200. I use two 80GB drives with software RAID  
striping to get better disk performance. Not sure if I need that or not.

I haven't build a frontend for HD yet so I'm testing with my old  
Shuttle which contains a 2.4GHz P4 with hyperthreading and a Nvidia  
FX5200 card using DVI output.

If you're using the same machine for front and back, you may have a  
problem watching HD LiveTV as it is recording and playing back at the  
same time. My front end CPU usage is only 20-25% when watching HD  
because the XvMC on the FX5200 is helping out a lot. There's not much  
load on the backend as it's just copying stuff from firewire to the  
hard drive.

By the way, load is not a good way to measure CPU usage. It's just  
showing the average number of jobs in the queue. Try 'top' or  
'vmstat'. I usually just type 'vmstat 2' and it spits out a line  
every two seconds showing the CPU busy/idle stats on the right side.

Curtis