On 2011-08-23 08:56, asbesto molesto wrote:
I probably won''t be able to help you, but when you try to capture the
same section of tape multiple times, are the same frames lost each time
and does it freeze in the same place each time?
It seem to freeze almost in the same place, but sometimes the result
is better, sometime not :(
Do the frames that you are able to capture before and after the problem
areas look ok? Do they have any kind of horizontal sync problems at the
top, move vertically or have interlacing issues? Do the colors and
brightness look ok?
Colors and pictures seem OK but when I play the stream directly
(mplayer /dev/video0) i notice some weird lines at the bottom of the
image; I made a screenshot, it's here:
http://zaverio.com/~asbesto/capture1.jpg
(p.s. that image was just me kidding many years ago :D hahahahahahah!!!)
What are those lines and what they mean?
ps everything here is PAL
Old CRT TVs used magnetic fields to guide an electron beam across the
screen. At the end of each field, they needed time for resetting the
magnetic fields back to the beginning, upper left, screen position. That
period is called the vblank. Anything in the video signal that was
output to the TV in this period would be invisible. In addition, they
used a technique called overscan to hide issues with their power
supplies, further hiding signals output to the TV while the electron
beam was in the overscan areas. VCRs often (always?) output junk during
these times, probably related to the way the video heads scan the tape.
I have two cards, a PVR 250 and an HVR 1600. In my experience, both of
these cards are easily confused by junk in the video signals during the
vblank and overscan. It's just bad engineering because LCD TVs have no
trouble at all with the signals. Issues I'm seeing are poor hsync at the
top of the screen, misinterpreted odd/even field signals and poor colors.
My guess is that the tapes you're having trouble with were recorded in
some way that is causing the VCR to output junk during the vblank and/or
overscan periods that cause the card to lose track of the vsync signal
in the video.
I think that a TBC, Time Base Corrector, would fix your issues. It sits
between your VCR and your card and cleans up the video signal. Just for
fun, you could try re-recording your tape onto another tape. That could
fix up the problems, at the cost of worse quality. If you have a DV
camera, you could try recording onto the DV camera and dump the digital
data out via FireWire. Another option is to just send the tapes off to a
company that has professional equipment to do transfers to digital,
though I would not recommend that if there are any beheadings on your
tapes :)
Roger
_______________________________________________
ivtv-users mailing list
[email protected]
http://ivtvdriver.org/mailman/listinfo/ivtv-users
