Re: [PATCH 1/2] Add Mars-Semi MR97310A format

[Kyle Guinn <elyk03@gmail.com>]

On Thursday 15 January 2009 05:49:46 Jean-Francois Moine wrote:
> On Wed, 14 Jan 2009 20:59:34 -0600
> Kyle Guinn <elyk03@gmail.com> wrote:
> > Add a pixel format for the Mars-Semi MR97310A webcam controller.
> >
> > The MR97310A is a dual-mode webcam controller that provides
> > compressed BGGR Bayer frames.  The decompression algorithm for still
> > images is the same as for video, and is currently implemented in
> > libgphoto2.
>
> Hi Kyle,
>
> What is the difference of this pixel format from the other Bayer ones?
>

This is a standard BGGR Bayer format which is compressed using a 
vendor-specific compression algorithm, much like V4L2_PIX_FMT_PAC207.  I 
don't believe the compression algorithm matches any of the other pixel 
formats.

The first two pixels in the first two rows are stored as raw 8-bit values (the 
top-left BGGR square), but the rest is Huffman compressed.  Take a look at 
precalc_table() and mars_decompress() in libgphoto2/camlibs/mars/mars.c for 
all of the details.  If you recognize this as an existing pixel format, 
please let me know.

> Also, did you ask Hans de Goede to add the decoding to the v4l library?
>

That is next on my TODO list.  I have a patch ready to send, but I first want 
to make sure there are no problems with adding this pixel format.

Regards,
-Kyle