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

[Douglas Kosovic]

Hi Chris,

> On 03/04/2009, at 8:29 AM, Christoph Willing wrote:
> 
> > On 03/04/2009, at 7:35 AM, Douglas Kosovic wrote:
> >
> >> 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.:
> >> vic 234.5.6.7/15000
> >> 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.
> >
> >
> > Doug,
> >
> > If the OP is using latest vic for hardy, then its derived from UCL
> > repo 13th Jan 2009. Has there been any significant change to V4L2
> > grabber code since then?
> 
> 
> One other thing,
> 
> 
> The same vic is used for h264 as for h261 so the vic version can't be
> the problem.

Feb 12 had the latest modifications to the V4L2 grabber code. It might
be the vic version as h261 needs to capture at CIF, while h264 doesn't
and the code which selects the capture resolution and then performs the
pixel format conversion and padding might be suspect from around that
time.

dc1394_vloopback may even be using VIC's V4L grabber, in which case the
issue may be something completely different. 

Using VIC's console output, I might be able to tell what going wrong. 


Cheers,
Doug