Comment 280 for bug 260918

Created attachment 313380

Short intro: I'm a long time Linux developer currently working on improving
webcam support in Linux, see:

I'm one of the authors of the v4l2 rewrite of the gspca usb webcam driver
framework (which supports more then 100 different cams), this v4l2 rewrite has
been merged into the 2.6.27 kernel and thus will become available in the
official Linux kernel soon.

One of the parts of the v4l2 rewrite has been removing conversion from various
manufacturer cam specific video formats to more normal videoformats from the
drivers, as this really does not belong in kernel space.

As a result of this the gspca subdrivers can generate raw video frames in the
following formats:

#define V4L2_PIX_FMT_SN9C10X v4l2_fourcc('S', '9', '1', '0') /* SN9C10x
compressed bayer
#define V4L2_PIX_FMT_SPCA501 v4l2_fourcc('S', '5', '0', '1') /* YUYV per line
#define V4L2_PIX_FMT_SPCA505 v4l2_fourcc('S', '5', '0', '5') /* YYUV per line
#define V4L2_PIX_FMT_SPCA508 v4l2_fourcc('S', '5', '0', '8') /* YUVY per line
#define V4L2_PIX_FMT_SPCA561 v4l2_fourcc('S', '5', '6', '1') /* compressed
GBRG bayer
#define V4L2_PIX_FMT_PAC207 v4l2_fourcc('P', '2', '0', '7') /* compressed
BGGR bayer

As we do not want to see each application implement (nor having to implement)
support for these various formats, as we like to have one code base and only
one code base for these formats. A library has been written (with me as the
main author) to convert from these formats to BGR24 or YUV420. For more on this
library see:

As such I've been working (for a number of days!) on a patch to add support for libv4l to xawtv. This has resulted in my doing a whole patch series, listed in the order in which the patches should be applied.

Some small fixes which are needed for xawtv-3.95 to work with some v4l2 devices at all.

Use libv4l2 to gain support for all kind of camera specific video formats

xawtv does not work on many videocards without specifying -nodga, this patch
fixes this by catching the error and continuing as if the server does not support DGA at all

Allow root to override the detected number of bytes per line, this is needed
to get direct pci transfers to the framebuffer to work on my ati x1950pro

Note that for xawtv to work properly atleast version 0.4.0 of libv4l is needed,
rawhide currently has 0.3.9 and I cannot build 0.4.0 due to an error in the kernel-headers package.


While writing all these patches and with all my recent v4l work in general I've become quite familiar with the xawtv code, so if you want I can become a co-maintainer (and push these patches myself).