[mythtv-users] Can't open video device: /dev/v4l/video1

[Robert Denier]

I'm not sure this helps anyone since I didn't keep careful notes of what
I did.  I started with linux-2.6.12-gentoo-r9  with preemption, and
everything compiled in the kernel for the bttv based card to work.  I
also started with ivtv 0.3.8 and I remember being able to dd
if=/dev/video1 of=foo.mpg bs=1MB count=100 and get a playable file via
mplayer.

I also tried 0.2.0 ivtv in the middle, but that never did anything
useful for me.  It seemed worse in fact...

I just tried 0.3.7 and I was a little more alert now than when I was
trying to get it to work and noted a kernel error in the dmesg, so I
glanced at what kernel I was running and decided to just go to plain
vanilla 2.6.13 and then when I glanced in there I decided that preeption
might be causing trouble so I got rid of that.  (It is not as if a
dedicated backend should need it.)  After that I recompiled and then
erased my 0.3.7 directory and extracted it again from the source file
then recompiled and reinstalled that then did

update-modules
and
modprobe ivtv
.

A glance at dmesg revealed that yes the dmesg was error free, so I reset
things in mythsetup and then opened a frontend and whee, it worked.

I have no clue if the problem gentoo-sources, preemption, 0.3.8 or just
some wierd combination, but for now I'm going to declare victory.  

The installation I based this off of was sort of a generic compile of
Gentoo linux.  Gentoo-sources serve no particular purpose on Myth
backend, or at least none I can think of.  At any rate it is working
now.  The next thing to do would be to buy a 500 or two more 150's I
suppose and get it working with 3 dish network receivers.

The only obvious issue I can see is with 3 receivers/capture interfaces
your limited to using a max of 3 myth boxes for playback at one time.
Basically if I understand correctly, if I had one running at 3
locations, I'd have to go shut off one if I wanted to start playback at
a new location.  (There is only 2 people in this house normally, so this
is only  annoying.)  Someone please correct me if this is incorrect or
the problem is already solved another way.  What would seem ideal is for
live tv on a particular node to normally be unlocked, unless you
specially say otherwise, meaning if you run out of tuners a particular
node steals tuners in a specified order.  Again I haven't looked, so
maybe this issue is addressed another way.

In general I'd rather not go beyond 3 dish network tuners since each
additional one adds $5 to the monthly bill.  If it would be useful I'd
connect an additional capture card or just use the old bttv for a fourth
card, but with only 3 capture sources I'm not sure that is useful.
Maybe if the fourth is connectedd to the aerial antenna.  I wonder if
myth knows, or can be told, that the broadcast channels are the same
regardless of where they come from.  Come to think of it I might stop
paying for local channels and just connect the antenna input on all the
tuners.  That would save $5 a month and still be organised.

All in all I'm just glad its working.  Now to get a frontend working
with a tv.  I'll start with Knoppmyth and then work on the version
booting off of nfs.

-Robert

p.s. I assume their is no way to input a digital audio signal into a
150/250/350/500?  I haven't looked, but it just seems a slight waste to
do that additional D/A -> A/D conversion.


On Thu, 2005-09-08 at 04:35 -0500, Robert Denier wrote:
> Basic Setup
> Backend
> nforce2 chipset, 2.2ghz amd sempron
> 1 pvr 150mce
> 1 some other cheap capture card used for testing myth some months ago.
> 
> Connected is a dish network receiver to the s-video jack on the pvr150
> mplayer /dev/v4l/video1 works fine, albiet really slow in a vnc window
> (the slow is due to vnc.)
> 
> The backend reports when you run it 
> Can't open video device: /dev/v4l/video1
> 	and I even did a chmod 777 out of desperation..  It shouldn't be having
> issues there...
> 
> The frontend gets
> RemoteFile::REad() failed in RingBuffer::safe_read()
> 
> Does anyone recognize the problem?  I used the firmware on the cd per
> some set of directions..
> 
> It just seems to me that if mplayer can read it, then myth should when
> they are both running as root right now..
> 
> -thanks in advance,
> -Robert
> 
> 
> 
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