[mythtv-users] Blank white screen in .24

Devin Heitmueller dheitmueller at kernellabs.com
Wed Dec 8 00:22:51 UTC 2010

On Tue, Dec 7, 2010 at 7:13 PM, Shocky <Shocky1 at users.sourceforge.net> wrote:
>> Blue background usually means the decoder didn't detect a signal.  Are
>> you using the tuner input?  s-video?  composite?
> I made sure I'm using the television input.


> I should note that this is not a solid bright blue like I would get in tvtime
> if there were no signal. This is a somewhat mottled very dark blue.

It would help if you could make available a screen shot (even if it's
from a camera phone).

>> Also, do you have ATSC or ClearQAM configured?  If so, it's possible
>> that MythTV is trying to use both the digital and analog inputs at the
>> same time (which you can avoid by putting both inputs into the same
>> input group).
> I didn't do anything to configure ATSC or ClearQAM. I did make sure the input
> source was set to NTSC. But I'll check this out and see.

Good.  Keep ATSC/ClearQAM unconfigured at this point, as they can
interfere with analog operation.

>> It's also just possible that the driver is broken with MythTV.  I
>> haven't any cycles to test with MythTV, and lord knows that MythTV has
>> been known to expose bugs in other drivers that don't appear when
>> using other applications.
> Do you know how I might go about determining if it's a driver problem? I don't
> mind doing the leg work to track this down, but I'd need a little guidance. I
> know my way around Linux pretty well, and I am a developer, but my knowledge
> of the internals of video drivers and MythTV is pretty slim.

Yes, I do know, but you won't like the answer that much.  Typically I
have to build MythTV from source and litter it with printf()
statements until I can figure out where the problem is.  Digging
through the MythTV logs can also reveal errors messages which it makes
sense to track down the source of.

Just as a test, you may also wish to switch over to composite/s-video
and hook it to a DVD player to see if you get a picture at all.  That
would help narrow down whether it's a general problem with streaming
the video or if it's specifically related to the onboard tda18271
tuner chip.


Devin J. Heitmueller - Kernel Labs

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