BSD video capture emulation question
steve at sohara.org
Thu Jul 10 22:09:27 PDT 2003
On Thu, 10 Jul 2003 13:40:47 -0700
John-Mark Gurney <gurney_j at efn.org> wrote:
JMG> Yes, I followed the bktr interface, but the bktr interface needs to
JMG> disappear ASAP! The bktr interface is very bad as we make FreeBSD
JMG> multiplatform. It lets the user supply the physical address when
JMG> doing video overlay to the video card. This should be handled by the
JMG> driver, not the userland app.
Hmm, that implies that the driver must know how to find the
overlay area that the userland app wants it to use - irrespective of the
video out driver in use.
Conclusion the overlay areas have to be entities of some kind in
the in the multimedia infrastructure.
JMG> > AFAICS what's needed is someone with some insight into what makes
JMG> > a good video API if FreeBSD is ever going to get one. The innards
JMG> > of things like ffmpeg and transcode are probably worth looking at
JMG> > as models.
JMG> Hmmm. I'll have to look at that.
JMG> But there is more than just codec handling. One of the features that
Oh sure - but seamless plumbing of codecs, sources and sinks is
a very desirable feature IMHO. This is the bit that these apps seem to
JMG> the Zoran card supports is the ability to have two sources (since as
JMG> external video and MJPEG playback) one in a window of the other. But
JMG> you need to only have one video clock running the output. This
JMG> should be handled by the video api so the drivers just write the raw
JMG> interface and the api does the manipulation of the driver.
Yep seamless plumbing - so somehow the PIP has to present as a video
sink and DTRT when you plumb the other video source into it - even if that
turns out to be the output of mplayer playing a VCD and not the expected
other bit from the card. If it can't do it the plumbing must fail.
ISTM the plumbing actions either require a smart plumber or a
dialogue between the interfaces being plumbed. The latter seems to fit
the UNIX device model better.
Are thinking in similar terms ?
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