Anyone working on V4L2 for BSD?

[Harti Brandt]

On Wed, 13 Apr 2005, Julian Elischer wrote:

JE>John-Mark Gurney wrote:
JE>
JE>> Alexander Leidinger wrote this message on Wed, Apr 13, 2005 at 14:31 +0200:
JE>>  
JE>> > Julian Elischer <julian at elischer.org> wrote:
JE>> > 
JE>> >    
JE>> > > I'm considerring it.. It looks quite doable. (assuming we can get
JE>> > > compatible include files
JE>> > > without copyright problems.)
JE>> > > 
JE>> > > For compatibility we'd probably want to keep all the V4L prefixes etc.
JE>> > > 
JE>> > > Is anyone else playing with this?
JE>> > >      
JE>> > There was a discussion about something like this a while ago... a, I see
JE>> > you
JE>> > participated in it too:
JE>> > http://lists.freebsd.org/pipermail/freebsd-multimedia/2003-July/000328.html
JE>> > http://people.freebsd.org/~jmg/videobsd.html
JE>> >    
JE>> 
JE>> Yes, I did...  and unless V4L2 managed to change a lot..  It's API is
JE>> still years behind what we should have...  The reason I haven't said
JE>> anything is that I didn't want to attempt to derail any work that someone
JE>> might be doing..  Yes, V4L2 is not a very good api, but as others have
JE>> pointed out, it makes portability easier...  Plus, I haven't spent any
JE>> time on VideoBSD recently, since I've gotten sidetracked by other
JE>> projects...  (Though if I can get ATI to give me specs for their HDTV
JE>> PCI card, I might spend some more time on it...)
JE>>  
JE>
JE>My sugestion is that we make V4L2 an alternative interface to a videoBSD
JE>framework.
JE>Think "netgraph for video" with a V4L2 frontend for apps and a v4l2 backend
JE>for drivers.

If you take this without the quotes this is something I wanted to do for 
years (started even once to try it on streams under Solaris). There is 
often no need to funnel all the video and audio traffic through user space 
just to pull it out of one device and put it into another one. This 
requires some thought though for memory mapped devices.

harti

JE>The difference is that the framework would interpret all the ioctls etc 
JE>instead of the drivers themselves. The drivers MAY attach using a V4L2 
JE>interface, but the requersts they get MAY or MAY NOT have come from the 
JE>clients. In the middle we have support for modules that do simple 
JE>format conversion, resynching, snipping, and the ability to pass the 
JE>stream out to a userlandeditor and get it back again, for really 
JE>compilcated editing. Some requests fromt the clients may be passed 
JE>through to the drivers. Some may not.
JE>
JE>
JE>> So, if you just want Linux compatiblity, go for it...  If you want a
JE>> real usable video API, then send me comments and look at the VideoBSD
JE>> stuff I have done...
JE>> 
JE>>  
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