Hi Christian, On Wednesday 13 July 2011 20:58:12 Christian Gmeiner wrote: > 2011/7/11 Christian Gmeiner <christian.gmei...@gmail.com>: > > 2011/7/11 Laurent Pinchart <laurent.pinch...@ideasonboard.com>: > >> On Sunday 10 July 2011 20:14:21 Christian Gmeiner wrote: > >>> Signed-off-by: Christian Gmeiner > >>> --- > >>> diff --git a/Documentation/DocBook/media/v4l/subdev-formats.xml > >>> b/Documentation/DocBook/media/v4l/subdev-formats.xml > >>> index 49c532e..18e30b0 100644 > >>> --- a/Documentation/DocBook/media/v4l/subdev-formats.xml > >>> +++ b/Documentation/DocBook/media/v4l/subdev-formats.xml > >>> @@ -2565,5 +2565,43 @@ > >>> </tgroup> > >>> </table> > >>> </section> > >>> + > >>> + <section> > >>> + <title>YCrCb Formats</title> > >>> + > >>> + <para>YCbCr represents colors as a combination of three values: > >>> + <itemizedlist> > >>> + <listitem><para>Y - the luminosity (roughly the > >>> brightness)</para></listitem> > >>> + <listitem><para>Cb - the chrominance of the blue > >>> primary</para></listitem> > >>> + <listitem><para>Cr - the chrominance of the red > >>> primary</para></listitem> > >> > >> How does that differ from YUV ? > > > > I need to say that I am very new to this whole format stuff and so I > > am not really sure. > > In the data sheet > > http://dxr3.sourceforge.net/download/hardware/ADV7175A_6A.pdf there is > > on the > > first page a FUNCTIONAL BLOCK DIAGRAM which shows that there is a > > "YCrCb to YUV Matrix" > > stage in the pipeline. I am also fine to use a YUV format for the media > > bus. Any suggestions? > > Okay I think I have found the difference between YUV and YCrCb - see [1] > > YCbCr 4:2:2 > (Redirected from YUV 4:2:2) > > FourCCs: YUY2, UYVY, YUV2 (Apple Component Video stored in MOV files) > Samples: http://samples.mplayerhq.hu/V-codecs/YUV2/ > > (These FourCC names only reflect that the YCbCr of digital media is > often falsely mixed up with analog PAL's YUV color space.) > > YCbCr 4:2:2 is a packed YCbCr format in which a pair of consecutive > pixels is represented by 1 Y sample each but share a Cb sample and a > Cr sample. > > This type of data may be packaged in a container format with a a > FourCC of YUY2 which indicates the following byte formatting: > > > [1] http://wiki.multimedia.cx/index.php?title=YUV_4:2:2
According to http://en.wikipedia.org/wiki/Yuv, "Historically, the terms YUV and Y'UV were used for a specific analog encoding of color information in television systems, while YCbCr was used for digital encoding of color information suited for video and still-image compression and transmission such as MPEG and JPEG. Today, the term YUV is commonly used in the computer industry to describe file-formats that are encoded using YCbCr." V4L2 seems to suffer from the ambiguity, as we use YUV as generic term to mean a digital luma/chroma format. I thus think your driver should use the existing YUV pixel codes. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
