tim at 7thheaven.org
Fri Sep 16 19:44:40 UTC 2005
I had posted a while back about a problem I was having with video capture.
Basically, I get about 10 black pixels on the left edge of captured
stream, and about 20 pixels at the bottom, which are mostly black, but
with some grey blocks in it. I'm pretty sure it's entirely an issue
with my very cheap SAA7130 based capture card. I looked into the
hardware specs for the chip, and it turns out this chip can do hardware
cropping and scaling. Based on looking at the source for the Linux
driver for this chip, it looks like it supports at least some of the
I futzed around and added some code into NuppelVideoRecorder.cpp to ask
the driver to crop (inside DoV4L2()), and viola, it seems to work
perfectly now, and I don't have to use the crop filter on playback
(which was no good anyways, because I want the captured stream to be
right, not to correct it in the viewer on playback, which means I have
to configure each front end seperately, and I have to set up the
transcoder to crop out those annoying bits if I want to watch my stuff
in some other format).
Am I the only one who has this issue? Do other cards capture pretty
much perfectly, right out of the box?
Would it be worth having the UI in the "Capture Card" settings dialogs
to be able to specify a crop rectangle?
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