Which Userland Interface for USB Video Class Driver?

Fritz Katz frtzkatz at yahoo.com
Tue Sep 23 18:32:49 UTC 2008


On Monday, September 22, 2008 5:33 AM, Intron <intron(at)intron(dot)ac> wrote:

> I would write/port a driver for USB video class for FreeBSD's 
> new USB stack (usb2). OpenBSD and NetBSD both has had their 
> own implementations for the device class as some people referred 
> to recently. But which userland interface, bktr(4) or V4L2, should 
> I use for the driver? 

  We've only got two choices: 
  -- bktr is dead, 
  -- and V4L2 doesn't exist.

  bktr is a dead end. The Brooktree company no longer exists.
  Conexant stopped making bktr chips years ago.
  It only supports analog -- analog is a dead end too. 

  Instead, look at Jason Harmening's work on cx88 support:
  http://lists.freebsd.org/pipermail/freebsd-multimedia/2008-September/009116.html
  
  ... that's the future. 

  V4L2 has a well defined interface, and numerous applications
  already support it. It's not tied to any particular hardware,
  company, or chip so it's not going to die like bktr did.

  IMHO, V4L2 should be the future for BSDs as well.

  Implementing a V4L2-IOCTL interface would be a moderately difficult
  but very rewarding project. 

> I have noticed that Julian has done some work for V4L2:
> 
http://perforce.freebsd.org/depotTreeBrowser.cgi?FSPC=//depot/user/julian/julian%5fv4l/sys/dev/video/framework&HIDEDEL=NO
> 
> But I wonder how soon Julian's code can be committed into 
> the main source tree. I wouldn't see the driver sleeps outside 
> the main source tree.

Looks like no activity in that tree since 2006/08/24 -- I don't see it 
being committed anytime soon.

I've started a project to bring V4L2 to BSDs here:
  http://video4bsd.sourceforge.net/

Cheers,
-- Fritz Katz.




      


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