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

Christoph Willing c.willing at uq.edu.au
Thu Apr 2 17:43:02 CDT 2009

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
>> 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.


Christoph Willing                       +61 7 3365 8316
QCIF Access Grid Manager
University of Queensland

More information about the ag-tech mailing list