[mythtv-users] Backend consolidation, round 3.

Clay ctmythtv at pacbell.net
Thu Jul 22 18:36:08 UTC 2010

Kevin Kuphal wrote:
> On Wed, Jul 21, 2010 at 2:21 AM, Clay <ctmythtv at pacbell.net 
>         3.  You have 3 /dev/video{0,1,2} - do you have 3 pvr150s or is there
>         another device which comes up as /dev/videoN ?? If so then the order
>         they come up in can indeed be a problem. If you have a webcam or
>         something, unplug it until you sort everything else then adjust your
>         udev rules so you get consistent naming.
>     (2) PVR-150s. Nothing else on this box. When I set them up last
>     night, -setup found them at /video0 and /video1. Tonight they're at
>     /video1 (or2?) and /video3.
>     Next restart they'll be something different... Dapper never screwed
>     them around this way...
>     I haven't even begun to mess with udev rules. Never needed them in
>     the past. It's almost easier just to fix the setup when (if) I reboot...
>         4. I am not familiar with ATSC cards, but I do have DVB-S cards. The
>         do not create /dev/videoX nodes, but rather /dev/dev/adapterX nodes
>         (that have other dirs and nodes below too). Again you may be getting
>         naming issues depending what order they come up in.
>     /dev/dvb/adapterX/frontend0
>     -setup is detecting them correctly, for now...
>     These are DVB-C cards. Kworld calls theirs ATSC115.
>     <http://www.linuxtv.org/wiki/index.php/KWorld_ATSC_115>
>     <http://www.linuxtv.org/wiki/index.php/AVerMedia_AVerTVHD_MCE_A180>
>      ...there was a time when I could get ATSC with these cards, and
>     many other channels, but upgrades 'fixed' that.
> I don't know much about mythbuntu, but be sure you're not loading the 
> "analog" drivers for your DVB cards.  This can cause the /dev/video 
> devices for them to appear in addition to or instead of the /dev/dvb 
> nodes.  And depending on the order the cards are detected, this will 
> move your PVR-150 devices.  I've never been good at understanding the 
> udev rules so I've always used the ivtv_first_minor=X option in my 
> modprobe.conf (not even sure if that still exists these days on newer 
> distros) which causes the IVTV driver to always start at the /dev/videoX 
> device.  I'm not sure if you use =1 if it uses /dev/video1 or if it is 
> zero based, or what.  Just try it and see.  I typically use this to set 
> the value higher than the number of other tuners in my system so that no 
> matter what other drivers load, my IVTV nodes are always the same.
> Kevin

I'm pretty sure I've seen v4l loading along with the other drivers. 
mythtv-setup detects the (DVB) cards as analog devices as well as DVB.
I haven't configured any 'analog' (other than the PVR-150s) although I'd 
sure like to use them for analog. Way back when, I found many more 
channels on (TW) cable, scanning with them. Picture quality was better 
(imo) than the PVRs and file size was smaller (I know, storage is cheap).

The two PVR's get randomly assigned to /dev/video0, video1, video2, or 
video3 at boot. I also see /video21, video31, etc. in /dev/ and 
mythtv-setup. I haven't tried them to see what they do or what they are.

At the end of the day, it's a simple matter to go into m-setup and fix 
/dev/videoX after I restart. Hopefully, once I've finally put the cover 
on it, that won't be very often...

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