[pvrusb2] Two PVR USB2 unit initially tune PAL as black and white

[Mike Isely]

On Mon, 13 Jun 2011, Tom Warren wrote:

> On 4 May 2011 13:17, Tom Warren <psycadillac at gmail.com> wrote:
> >
> > Greetings,
> >
> > I have two WinTV PVR USB boxes I'm using with the pvrusb2 driver which feed into tvheadend playing PAL cable channels. The set up works but I always get the first tuned channel in black & white and have to tune to one (or more) different channels and then go back to the original channel get colour. Occasionally a channel will later go black and white again and I must apply the same fix. Both boxes are the 'new' hardware version.
> >
> > Could this be a driver problem, hardware problem, or fine-tuning problem??
> >
> > I saw a post from 2006 that describes a similar issue but using NTSC:
> >
> > http://www.isely.net/pipermail/pvrusb2/2006-January/000384.html
> >
> > I'm running Ubuntu server 10.10 64-bit with the driver from linux-s2api-tbs6980-1_20101024 (commercial mod for the Tenow International dual satellite card) in which I made a small modification to set:
> >
> > .pixelformat    = V4L2_PIX_FMT_MPEG,
> >
> > ...in the pvrusb2-v4l2.c file in order for tvheadend to recognise it as a valid source.
> >
> > Since both boxes behave the same way, I suspect this is an issue with the driver. What can I do to debug the issue further?
> >
> >
> > Thanks,
> >
> > Tom
> > --
> >
> 
> I have tried "pre-tuning" several channels with a script using v4lctl
> before launching tvheadend, but this does not solve the problem. I've
> compared the settings while B&W vs colour but can't find any
> differences. What could be causing this?

Also, is this only happening with the RF tuner or can you also reproduce 
it with the composite and s-video inputs?  (If it's just the tuner, then 
the search space is narrowed down considerably.)

Incorrect tuning might also do this - if the tuning isn't right then the 
hardware might not be finding the color information in the signal.  That 
can definitely happen with NTSC, but the last time I actually *saw* that 
effect was back in the 1970's using a TV with a crappy mechanical tuner.  
Modern digital tuners usually don't have a problem like this unless 
you're really sending it an incorrect frequency.

There are methods possible by which one can get the tuner and cx25840 
kernel modules to report the in-use video standard.

Has nobody else ever seen this problem?  (Realize that the case in 2006 
was definitely bad hardware so it doesn't count.)

  -Mike


-- 

Mike Isely
isely @ isely (dot) net
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