[RFC] Add 10 bit packed greyscale format.
Commit Message
A 10 bits per pixel greyscale format in a packed array representation is
supplied for instance by Kinect sensor device.
Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
---
Hi,
This is the first attempt to add v4l support for the 10bpp packed array format
used by the Kinect sensor device for depth data and for IR mode (in this mode
the device streams the image as seen by the monochrome sensor).
This version is mainly to start the discussion about the format and how it
should be seen by v4l, the doubts I still have are about:
1. The name of the format: is Y10P OK? Moreover, "packed" here is used in a
_stronger_ meaning compared to the other packed formats, and I also saw the
name "compact array" used somewhere for these kind of objects.
2. The actual order of the bits, please check the documentation below to see
if I got it right.
And maybe I should not mention the unpacked version of the data as this
depends on the unpacking algorithm, what do you think?
3. The way to illustrate the packed array concept in the documentation: I
used a bit-field syntax like in hardware registers docs, does this look
meaningful to you? Or should I find a way to clearly show the difference
between _byte_alignment_ and _element_alignment_.
If you could point to some literature about packed array representations I'd be
happy to take a look at it.
After these issues are addressed, I am going to submit changes to libv4l as
well.
Thanks,
Antonio Ospite
http://ao2.it
include/linux/videodev2.h | 1 +
Documentation/DocBook/v4l/videodev2.h.xml | 1 +
Documentation/DocBook/v4l/pixfmt-y10p.xml | 47 +++++++++++++++++++++++++++++
Documentation/DocBook/media-entities.tmpl | 1 +
Documentation/DocBook/v4l/pixfmt.xml | 1 +
5 files changed, 51 insertions(+), 0 deletions(-)
create mode 100644 Documentation/DocBook/v4l/pixfmt-y10p.xml
Comments
On Thu, 16 Dec 2010 12:29:44 +0100
Antonio Ospite <ospite@studenti.unina.it> wrote:
> A 10 bits per pixel greyscale format in a packed array representation is
> supplied for instance by Kinect sensor device.
>
> Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
> ---
>
Ping.
> Hi,
>
> This is the first attempt to add v4l support for the 10bpp packed array format
> used by the Kinect sensor device for depth data and for IR mode (in this mode
> the device streams the image as seen by the monochrome sensor).
>
> This version is mainly to start the discussion about the format and how it
> should be seen by v4l, the doubts I still have are about:
>
> 1. The name of the format: is Y10P OK? Moreover, "packed" here is used in a
> _stronger_ meaning compared to the other packed formats, and I also saw the
> name "compact array" used somewhere for these kind of objects.
>
> 2. The actual order of the bits, please check the documentation below to see
> if I got it right.
> And maybe I should not mention the unpacked version of the data as this
> depends on the unpacking algorithm, what do you think?
>
Ok, I checked that the order of the bits in the packed representation
used on the kinect is the natural one (most significant bits come
first from the left). And about the unpacking, well, if we called this
format Y10P, are we implying that the unpacked format is Y10, hence
with little-endian order? Or should we consider the two formats
independent even if the names are so similar?
> 3. The way to illustrate the packed array concept in the documentation: I
> used a bit-field syntax like in hardware registers docs, does this look
> meaningful to you? Or should I find a way to clearly show the difference
> between _byte_alignment_ and _element_alignment_.
>
Now that I've checked the actual data format I am dealing with, I think
I can improve the illustration as well.
> If you could point to some literature about packed array representations I'd be
> happy to take a look at it.
>
> After these issues are addressed, I am going to submit changes to libv4l as
> well.
>
> Thanks,
> Antonio Ospite
> http://ao2.it
>
[...]
Thanks,
Antonio
@@ -288,6 +288,7 @@ struct v4l2_pix_format {
#define V4L2_PIX_FMT_Y4 v4l2_fourcc('Y', '0', '4', ' ') /* 4 Greyscale */
#define V4L2_PIX_FMT_Y6 v4l2_fourcc('Y', '0', '6', ' ') /* 6 Greyscale */
#define V4L2_PIX_FMT_Y10 v4l2_fourcc('Y', '1', '0', ' ') /* 10 Greyscale */
+#define V4L2_PIX_FMT_Y10P v4l2_fourcc('Y', '1', '0', 'P') /* 10 Greyscale as a packed array */
#define V4L2_PIX_FMT_Y16 v4l2_fourcc('Y', '1', '6', ' ') /* 16 Greyscale */
/* Palette formats */
@@ -289,6 +289,7 @@ struct <link linkend="v4l2-pix-format">v4l2_pix_format</link> {
#define <link linkend="V4L2-PIX-FMT-Y4">V4L2_PIX_FMT_Y4</link> v4l2_fourcc('Y', '0', '4', ' ') /* 4 Greyscale */
#define <link linkend="V4L2-PIX-FMT-Y6">V4L2_PIX_FMT_Y6</link> v4l2_fourcc('Y', '0', '6', ' ') /* 6 Greyscale */
#define <link linkend="V4L2-PIX-FMT-Y10">V4L2_PIX_FMT_Y10</link> v4l2_fourcc('Y', '1', '0', ' ') /* 10 Greyscale */
+#define <link linkend="V4L2-PIX-FMT-Y10P">V4L2_PIX_FMT_Y10P</link> v4l2_fourcc('Y', '1', '0', 'P') /* 10 Greyscale as a packed array */
#define <link linkend="V4L2-PIX-FMT-Y16">V4L2_PIX_FMT_Y16</link> v4l2_fourcc('Y', '1', '6', ' ') /* 16 Greyscale */
/* Palette formats */
new file mode 100644
@@ -0,0 +1,47 @@
+<refentry id="V4L2-PIX-FMT-Y10P">
+ <refmeta>
+ <refentrytitle>V4L2_PIX_FMT_Y10P ('Y10P')</refentrytitle>
+ &manvol;
+ </refmeta>
+ <refnamediv>
+ <refname><constant>V4L2_PIX_FMT_Y10P</constant></refname>
+ <refpurpose>Grey-scale image as a packed array</refpurpose>
+ </refnamediv>
+ <refsect1>
+ <title>Description</title>
+
+ <para>This is a packed grey-scale image with a depth of 10 bits per pixel. Pixels
+ are stored in a packed array of 10bit bits per pixel, thus with no padding
+ between them. When unpacked to a Y10 format the least significant byte is
+ stored at lower memory addresses (little-endian).</para>
+
+ <example>
+ <title><constant>V4L2_PIX_FMT_Y10P</constant> 4 pixel data stream taking 5 bytes</title>
+
+ <formalpara>
+ <title>Packed representation</title>
+ <para>pixels cross the byte boundary and have a ratio of 5 bytes for each 4
+ pixels.
+ <informaltable frame="none">
+ <tgroup cols="9" align="center">
+ <colspec align="left" colwidth="2*" />
+ <tbody valign="top">
+ <row>
+ <entry>start:</entry>
+ <entry>Y'<subscript>00[1:0]</subscript></entry>
+ <entry>Y'<subscript>00[9:2]</subscript></entry>
+ <entry>Y'<subscript>01[1:0]</subscript></entry>
+ <entry>Y'<subscript>01[9:2]</subscript></entry>
+ <entry>Y'<subscript>02[1:0]</subscript></entry>
+ <entry>Y'<subscript>02[9:2]</subscript></entry>
+ <entry>Y'<subscript>03[1:0]</subscript></entry>
+ <entry>Y'<subscript>03[9:2]</subscript></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </para>
+ </formalpara>
+ </example>
+ </refsect1>
+</refentry>
@@ -253,6 +253,7 @@
<!ENTITY sub-srggb10 SYSTEM "v4l/pixfmt-srggb10.xml">
<!ENTITY sub-srggb8 SYSTEM "v4l/pixfmt-srggb8.xml">
<!ENTITY sub-y10 SYSTEM "v4l/pixfmt-y10.xml">
+<!ENTITY sub-y10p SYSTEM "v4l/pixfmt-y10p.xml">
<!ENTITY sub-pixfmt SYSTEM "v4l/pixfmt.xml">
<!ENTITY sub-cropcap SYSTEM "v4l/vidioc-cropcap.xml">
<!ENTITY sub-dbg-g-register SYSTEM "v4l/vidioc-dbg-g-register.xml">
@@ -592,6 +592,7 @@ information.</para>
&sub-packed-yuv;
&sub-grey;
&sub-y10;
+ &sub-y10p;
&sub-y16;
&sub-yuyv;
&sub-uyvy;