On 20 June 2011 00:13, Mike Isely <[email protected]> wrote: > On Mon, 13 Jun 2011, Tom Warren wrote: > > > On 4 May 2011 13:17, Tom Warren <[email protected]> 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 >
Hi Mike, Thanks for your comprehensive and informative response. My hardware is fine, and I am happy to report I have solved the problem. I hope this information may help to solve it for others. When I initially set up the WinTV boxes, I used the 'scan' utility to obtain the channel frequencies. It turns out that most of the frequencies were wrong, and I believe I know why this happened. My local cable provider is using PAL B/G but it seems also places some programmes on other (D/K) frequencies adjacent to the official B/G ranges. I think this must have confused the utility and it chose the D/K channel spacing instead of B/G. To solve the issue, I found some PAL B/G frequency charts via Google, erased all of the errant values and created new ones following the chart. I then went back and filled in the D/K frequencies (which are between the official bands) and now the channels tune perfectly. Thanks again for your help, and I hope you'll check out Tvheadend because it really is an excellent back-end for both DVB and analogue feeds: lonelycoder.com/hts . Regards, Tom -- _______________________________________________ pvrusb2 mailing list [email protected] http://www.isely.net/cgi-bin/mailman/listinfo/pvrusb2
