[mythtv-users] PVR-350 TV-out distorted
Michael T. Dean
mtdean at thirdcontact.com
Wed Apr 7 14:06:19 EDT 2004
Thomas Börkel wrote:
> The test picture comes out OK from the PVR-350, but if I play MPEG
> (either with the dd command directly from /dev/video0 or with MythTV),
> the output is totally distorted. You can guess, that it's a TV
> picture, but it's teared in multiple directions. Looks like you feed a
> monitor with the wrong frequency, but that can't be, because my TV is
> able to display PAL and NTSC.
>
> I am using ivtv 0.1.9 and I have not yet switched X to the PVR-350.
Sounds like the "teared" picture you're getting is actually a
semi-transparent view of your framebuffer's "picture" on top of the TV
picture. Since you haven't set up X, the framebuffer's "picture" is
actually garbage (some semi-random initial bits in the framebuffer).
Most instructions I've seen refer to this as "about 20 colored lines in
the picture," but for me it was a mess of garbage (sometimes opaque and
sometimes semi-transparent) obscuring the view of the TV picture. Note
that the test picture works because it actually uses the framebuffer
instead of the TV "underlay."
Basically, try these commands:
# Assuming NTSC via S-Video input
test_ioctl -u 0x3000 -p 6
# This makes the framebuffer image transparent
ivtvfbctl /dev/fb1 -globalalpha -nolocalalpha -alpha 0
dd if=/dev/video0 of=/dev/video16 bs=64k
(Note the slight difference in the ivtvfbctl line from most posts which use:
ivtvfbctl /dev/fb1 -alpha -on -globalalpha -nolocalalpha
Interestingly enough, that command works, also, but only by "accident."
The -alpha option requires a value for alpha from 0 (transparent) to 255
(opaque) and uses the first "word" after "-alpha" That word happens to
be "-on" (which is supposed to mean "turn on the framebuffer" and is
never required), but it's not a numeric value "-alpha" expects, so
"-alpha" goes with its default of 0. )
Then, once you have set up X, you can set the framebuffer's background
using your normal background changer (i.e. I use chbg (
http://chbg.sourceforge.net/ ) because it has very few library
dependencies). Once you have a "pretty" picture (instead of garbage),
use the following to go back to an opaque framebuffer (and see your
picture):
# This makes the framebuffer image opaque
ivtvfbctl /dev/fb1 -noglobalalpha -nolocalalpha
HTH.
Mike
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