On Mon, 2010-01-18 at 04:54 -0500, Dale Pontius wrote:
> I suspect I'm going to need to set up some data collection. I'm running
> Gentoo, and it appears that though I'm running lm_sensors-2.10.7 at the
> moment, I have lm_sensors-3.1.1 available, so I need to look into logging.
>
> In addition, though I don't know if I need it any longer, I'm still
> using the supplemental "tune.sh" script at mythbackend startup that does
> a dummy capture or two on each card, and throws it away. This is/was
> because the audio didn't work right on the first capture.
The initial short capture is unnecessary now. The audio problem on first
analog capture has been fixed for a while.
> I need to
> beef up this script to collect some statistics, and in particular add
> Andy's suggested "v4l2-ctl -d /dev/video0 --log-status" as a normal part.
>
> There look to be 4 parts...
> 1 - Build up a more detailed picture of "normal"
> 2 - Keep current boot statistics so if it turns out that I have the
> dread red screen, I can compare that with a normal boot.
> 3 - Autodetect problems so I can recover promptly, and not lose recordings.
The next time you get a red screen, do a short cat from /dev/video32 to
get a frame or two of a YUV capture. Then use xxd to take a look at the
data - it should look really uniform. For a full size (720x480) NTSC
black screen:
Initial luminance (Y) values for the first frame:
$ xxd -c 32 -g 1 -l 128 -s 0 foo.yuv
0000000: 10 10 10 10 10 10 10 11 10 10 10 10 10 10 10 10 10 11 11 10 10 10 10
10 10 10 10 10 10 10 10 10
0000020: 10 10 10 10 10 10 10 10 10 11 11 10 10 10 10 10 10 10 10 10 10 10 10
10 10 10 10 10 10 10 10 10
0000040: 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 11 11 10
10 10 10 10 10 10 10 10 10
0000060: 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 11
11 11 10 10 10 10 10 10 10
Initial chrominance (U/V) values for the first frame:
$ xxd -c32 -g1 -l 128 -s 345600 foo.yuv
0054600: 80 80 80 80 80 80 80 80 80 80 7f 80 80 80 80 80 80 80 7f 80 80 80 80
80 80 7f 80 7f 80 80 80 80
0054620: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 7f 80 7f 80 80 80
80 80 80 80 80 80 80 80 80
0054640: 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 80 7f
80 80 80 80 80 80 80 80 80
0054660: 80 80 80 7f 80 80 80 80 7f 80 7f 80 7f 80 80 80 80 80 80 80 80 80 80
7f 7f 7f 7f 80 80 80 80 80
Note:
345600 = 720 x 480; cx18 YUV captures always have lines of 720 pixels,
but screen lines need just be some multiple 32 that you or
MythTV has set
The floor (darkness) for Y values is 0x10.
The midpoint (no color) for U and V values is 0x80.
If you know what the contents of a YUV frame looks like from a capture
of a red screen, you may be able to figure out some poor man's image
processing in a script to check for a red screen without having a person
inspect it.
> 4 - Figure out what the real problem is.
>
> It looks like it starts with adding data collection to "tune.sh" and
> adding logging to lm_sensors.
Sounds like a plan. Good luck.
Regards,
Andy
> Dale
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