[mythtv-users] v4l and 2.6.19 problem

Nick Morrott knowledgejunkie at gmail.com
Mon Jan 1 15:15:02 UTC 2007


On 01/01/07, W.Kenworthy <billk at iinet.net.au> wrote:
> On Mon, 2007-01-01 at 20:32 +0900, William Kenworthy wrote:
> > I have an old capture card (and a modern DVB card that works) in a
> > mythtv system.
> >
> > On kernel 2.6.18 it works fine capturing a video feed from the composite
> > input.  In 2.6.19 (R1 and R2) I just get a black screen, no errors in
> > the log or dmesg.  Boot back into 2.6.18 and it works fine
> >
> > I see there seem to be lots of changes to the DVB side of V4l, but
> > nothing obvious that would affect this.
> >
> > Any hints at all appreciated!
> >
> > BillK
> >
> Wouldnt you know it - Ive been chasing this for days, and I stumble over
> the cause a few minutes after sending the message :(
>
> udev is numbering the video devices differently depending on the kernel
> version.  As a short term fix, Ive just changed the capturecard to that
> wanted by 2.6.19 - will have to look into a udev rule to to fix video0
> to the wanted hardware.

My favourite (and many others') udev resource is
http://www.reactivated.net/writing_udev_rules.html. There are also
some examples of udev rules on the ivtvdriver.org site (aimed at ivtv
card users obviously). I've seen this same issue on older kernels when
using ivtv cards with DVB cards that have analogue inputs in addition
to their DVB hardware. Creating devices like /dev/ivtv0 and
/dev/dvbvideo0 helps to keep track of which devices belong to which
cards.

Nick

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