I have tried unsuccessfully from many sources to find a solution for my
problem while recording from VHS. I hope this list can help.
You will likely have some problems. VHS consumer machines put out
pretty bad quality "NTSC" signals. Some are better than others, and you
may be able to get away with it sometimes but not others.
The bottom of the picture I am receiving from the VCR has a wavy, pulsating
line. I have tried both mythtv and ptune record with the same result.
I'm not sure what you mean by "wavy pulsating line". If you're
talking about the bottom of the picture having snow, etc, that's also
typical from VHS bad tapes, bad alignment, etc.
ptune? You connecting via the RF-input? You really want to
connect via composite (or s-vid if your VCR is neato enough to have it).
Someone said that it was because of the 480 scanlines coming from the VCR. He
suggested using the crop filter in mythtv. However this does not work with my
pvr 250 card.
I did an ivtvctl -a and noticed that in VIDIOC_G_FMT the Video Capture height
is 480. I am not sure if this is a measure of scan lines or something else.
Under VIDIOC_ENUMSTD for NTSC the frame lines are 525. Can this number be
changed to correspond with the scan lines from the VHS? Is there a
connection?
The number of scanlines from VHS is the same as the number of
scanlines from ANY NTSC source: 525/frames (262.5/field)... Only 480-ish
of those are visible. The rest are "off the screen"... above the top and
below the bottom. You want to capture 480 lines, not 525.
If you've got persistant fuzz at the bottom, the "crop filter"
suggested would be a post-processing thing once you've recorded it.
Without a more accurate description of the problem, it's hard to figure
out what's causing it.
Likely solution will be at the VCR end... clean heads, try another
VCR, get out a refrigerator magnet and painstakingly repaint the magnetic
signals on the tape by hand (kidding)... etc.
-Cory
--
*************************************************************************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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