[AG-TECH] Problem with firewire camera and H261 video producer

Douglas Kosovic douglask at itee.uq.edu.au
Thu Apr 2 16:35:39 CDT 2009

Hi Steve,

> I am setting up a small AG node with 3.1 on Ubuntu Hardy.  I have a 
> Unibrain Fire-i firewire camera.  I can use vloopback and 
> dc1394_vloopback to get a nice 320x240 or 640x480 stream with the H.264 
> video producer, but the older H.261 does not work, giving me odd 
> patterns of mostly green diagonal lines.
> I read somewhere that VIC expects RGB 16 bits per pixel. This may be my 
> problem since the firewire setup offers only RGB 24 bit, YUV 422, 
> YUV422p, and YUV420p.  I could modify dc1394_vloopback to convert the 
> video, but is there an easier way?

VIC's V4L2 grabber supports YUV422, YUV422P, YUV420P, MJPEG and JPEG 
pixel formats.

VIC's V4L grabber supports YUV422, YUV422P and YUV420P pixel formats.

The preferred format for H.261 and H.264 would be YUV420P as that's what 
the codecs use.

The issue with the H.261 codec is that it only supports the traditional 
video conferencing resolutions of CIF (352x288) and QCIF (176x144), so 
will pad with a black border (or gray if older).

If you can run vic on the command-line, e.g.:
select the device and transmit, then copy the console output, that would 
be handy for me to tell what's going wrong.

I suspect your version of VIC is using an earlier broken V4L2 grabber code.


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