[FFmpeg-user] Grabbing quality from TV card

[tovis]

I'm still struggling to have good streaming quality for my TV card, driven
by bttv driver module, and v4l2 subsystem.
I have clear the support for libv4l2 (configuration option
--enable-libv4l2) and error messages:
"libv4l2: error dequeuing buf: Resource temporarily unavailable"
are gone :)

But the streaming quality still unacceptable :(
Carl said that yadif filter is must be for interleaved video source, and
only me could decide this by "visualization" OK! What I should have see?

For now w/o yadif and qscale I can see big digital spots - really rude
digitalization errors. I'm suspect that this is because of v4l2 settings.
The ffmpeg, in case of "-f video4linux2 -i /dev/video0" changes any,
previously set parameters for v4l2 subsystem, or simply use it, does not
meter what is it set on?

If ffmpeg leave v4l2 settings untouched, I can set them before or even
change settings under active grabbing? Please give me a short description
how ffmpeg handling the video4linux2 input.

Sincerely
  tovis

PS: I suspect that libv4l2 support have some problems, I have read several
bug reports about ubuntu where they conclude that cause of this error is
not in the driver, but the application.