On Wed, 21 Dec 2011, Laurent Pinchart wrote:
> Hi Manju,
>
> On Wednesday 21 December 2011 14:56:36 Hadli, Manjunath wrote:
> > On Wed, Dec 21, 2011 at 05:32:08, Laurent Pinchart wrote:
> > > On Friday 16 December 2011 14:42:48 Hadli, Manjunath wrote:
> > > > On Thu, Dec 15, 2011 at 18:30:47, Laurent Pinchart wrote:
> > > > > On Thursday 15 December 2011 13:24:58 Manjunath Hadli wrote:
> > > > > > add new macro V4L2_PIX_FMT_SGRBG10ALAW8 to represent Bayer format
> > > > > > frames compressed by A-LAW alogorithm.
> > > > > > add V4L2_PIX_FMT_UV8 to represent storage of C (UV interleved)
> > > > > > only.
> > > > > >
> > > > > > Signed-off-by: Manjunath Hadli <manjunath.hadli@xxxxxx>
> > > > > > Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > > > > > ---
> > > > > >
> > > > > > include/linux/videodev2.h | 6 ++++++
> > > > > > 1 files changed, 6 insertions(+), 0 deletions(-)
> > > > >
> > > > > Could you please also document these formats in
> > > > > Documentation/DocBook/media/v4l ?
> > > >
> > > > I will. Sorry to have missed that out.
> > > >
> > > > > > diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> > > > > > index 4b752d5..969112d 100644
> > > > > > --- a/include/linux/videodev2.h
> > > > > > +++ b/include/linux/videodev2.h
> > > > > > @@ -338,6 +338,9 @@ struct v4l2_pix_format {
> > > > > >
> > > > > > #define V4L2_PIX_FMT_HM12 v4l2_fourcc('H', 'M', '1', '2') /* 8
> > > > > > YUV
> > > > > >
> > > > > > 4:2:0 16x16 macroblocks */ #define V4L2_PIX_FMT_M420
> > > > > > v4l2_fourcc('M', '4', '2', '0') /* 12 YUV 4:2:0 2 lines y, 1 line
> > > > > > uv interleaved */
> > > > > >
> > > > > > +/* Chrominance formats */
> > > > > > +#define V4L2_PIX_FMT_UV8 v4l2_fourcc('U', 'V', '8', ' ') /*
> > > > > > 8 UV 4:4 */ +
> > > > > >
> > > > > > /* two planes -- one Y, one Cr + Cb interleaved */
> > > > > > #define V4L2_PIX_FMT_NV12 v4l2_fourcc('N', 'V', '1', '2') /* 12
> > > > > > Y/CbCr
> > > > > >
> > > > > > 4:2:0 */ #define V4L2_PIX_FMT_NV21 v4l2_fourcc('N', 'V', '2',
> > > > > > '1') /* 12 Y/CrCb 4:2:0 */ @@ -366,6 +369,9 @@ struct
> > > > > > v4l2_pix_format { #define V4L2_PIX_FMT_SRGGB12 v4l2_fourcc('R',
> > > > > > 'G', '1', '2') /* 12 RGRG.. GBGB.. */ /* 10bit raw bayer DPCM
> > > > > > compressed to 8 bits */ #define V4L2_PIX_FMT_SGRBG10DPCM8
> > > > > > v4l2_fourcc('B', 'D', '1', '0')
> > > > > > + /* 10bit raw bayer a-law compressed to 8 bits */ #define
> > > > > > +V4L2_PIX_FMT_SGRBG10ALAW8 v4l2_fourcc('A', 'L', 'W', '8')
> > > > > > +
> > > > >
> > > > > That's not very future-proof, how would you describe SGBRG10ALAW8
> > > > > for instance ?
> > > > >
> > > > > Maybe it's time to standardize FOURCCs for Bayer new formats. We
> > > > > have 4 characters, we could start with 'B' to denote Bayer, followed
> > > > > by one character for the order, one for the compression, and one for
> > > > > the number of bits.
> > > >
> > > > I agree.
> > > > May be ('B', 'G', 'A', '8') is fine for the above?
> > >
> > > We need to describe at last BGGR, GBRG, GRBG and RGGB. We could use 'B',
> > > 'g', 'G' and 'R' respectively for the second character. The third
> > > character would be 'A' for A-law and 'D' for DPCM, and the fourth
> > > character could describe the bus width in bits from 0 to 15 with '0' -
> > > '9', 'A' - 'F'. However, I suspect that we will need 16-bit wide busses
> > > for raw Bayer at some point, and a 0 width is definitely not useful. We
> > > could thus offset the width by some value.
> > >
> > > This is just a preliminary idea, I'm open to suggestions.
> >
> > I think it is a very good suggestion that we can go with.
> > B : BGGR
> > g : GBRG
> > G : GRBG
> > R : RGGB
> >
> > and 0-F can signify 1-16.
>
> Hans, Guennadi, Sakari, any opinion on that as well ?
Is there any risk of confusion, if we don't reserve the first character
for 'B'? I'm just trying to avoid mixed cases, I'm not a great fan of
those;-) What if we use the first two characters for the order like "GR",
"GB",... AFAICS, 'G' so far only also occurs in GREY and various RGB* /
BGR* / ... formats, which we wouldn't be confusing with. We could further
reduce confusion, if we use some other character for A-law ('L' or 'W'?)
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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