[mythtv-users] Blank white screen in .24

Shocky Shocky1 at users.sourceforge.net
Thu Dec 9 01:06:21 UTC 2010

On December 7, 2010 05:22:51 pm Devin Heitmueller wrote:
> On Tue, Dec 7, 2010 at 7:13 PM, Shocky <Shocky1 at users.sourceforge.net> 
> >> 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.
> Ok.

Just to confirm, the card type should be "Analog V4L capture card", right?

> > 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).

First screen, with the OSD showing that lasts several seconds:

Second screen, showing blue screen that lasts about 2 seconds (top to bottom 
shading is an artifact of my poor photography, it's really all the same shade 
as the top part):

Third screen, showing the all white screen that finally shows up:

Sometimes instead of this sequence it just crashes with a segmentation 
violation, especially if I try it several times.

> >> 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.

Okay. I was hoping you would say to recompile the driver with a debug option 
or something like that 8^). I've been perusing the logs with various verbose 
options, but the problem is I don't know what they should look like when 
everything's working, so I don't know what's out of place if it's not an 
obvious error. I can pastebin a log file if you tell me what verbose options I 
should use.

> 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.

This device only has the cable connector (and a little plug for the broadcast 
HD antenna, which I don't have connected), no composite or s-video connectors. 
If I hooked up a DVD player, wouldn't it just come in on the television input?

> Devin


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