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author | 2011-03-11 06:16:22 -0300 | |
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committer | 2011-03-22 04:54:22 -0300 | |
commit | bd08a0cd5f546916a9454ae2c35756ed77957458 (patch) | |
tree | 887ec84169ae57ef697458c3f845adf06937b9e0 /Documentation/DocBook/v4l/pixfmt-nv12mt.xml | |
parent | [media] s5p-fimc: Fix G_FMT ioctl handler (diff) | |
download | linux-bd08a0cd5f546916a9454ae2c35756ed77957458.tar.gz linux-bd08a0cd5f546916a9454ae2c35756ed77957458.tar.bz2 linux-bd08a0cd5f546916a9454ae2c35756ed77957458.zip |
[media] v4l: Documentation for the NV12MT format
Added documentation for V4L2_PIX_FMT_NV12MT format. This is a YUV 4:2:0
format with macro block size of 64x32 and specific order of macro blocks
in the memory.
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook/v4l/pixfmt-nv12mt.xml')
-rw-r--r-- | Documentation/DocBook/v4l/pixfmt-nv12mt.xml | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/pixfmt-nv12mt.xml b/Documentation/DocBook/v4l/pixfmt-nv12mt.xml new file mode 100644 index 000000000000..5cb5bec8b653 --- /dev/null +++ b/Documentation/DocBook/v4l/pixfmt-nv12mt.xml @@ -0,0 +1,74 @@ + <refentry> + <refmeta> + <refentrytitle>V4L2_PIX_FMT_NV12MT ('TM12')</refentrytitle> + &manvol; + </refmeta> + <refnamediv> + <refname id="V4L2-PIX-FMT-NV12MT"><constant>V4L2_PIX_FMT_NV12MT +</constant></refname> + <refpurpose>Formats with ½ horizontal and vertical +chroma resolution. This format has two planes - one for luminance and one for +chrominance. Chroma samples are interleaved. The difference to +<constant>V4L2_PIX_FMT_NV12</constant> is the memory layout. Pixels are +grouped in macroblocks of 64x32 size. The order of macroblocks in memory is +also not standard. + </refpurpose> + </refnamediv> + <refsect1> + <title>Description</title> + + <para>This is the two-plane versions of the YUV 4:2:0 format where data +is grouped into 64x32 macroblocks. The three components are separated into two +sub-images or planes. The Y plane has one byte per pixel and pixels are grouped +into 64x32 macroblocks. The CbCr plane has the same width, in bytes, as the Y +plane (and the image), but is half as tall in pixels. The chroma plane is also +grouped into 64x32 macroblocks.</para> + <para>Width of the buffer has to be aligned to the multiple of 128, and +height alignment is 32. Every four adjactent buffers - two horizontally and two +vertically are grouped together and are located in memory in Z or flipped Z +order. </para> + <para>Layout of macroblocks in memory is presented in the following +figure.</para> + <para><figure id="nv12mt"> + <title><constant>V4L2_PIX_FMT_NV12MT</constant> macroblock Z shape +memory layout</title> + <mediaobject> + <imageobject> + <imagedata fileref="nv12mt.gif" format="GIF" /> + </imageobject> + </mediaobject> + </figure> + The requirement that width is multiple of 128 is implemented because, +the Z shape cannot be cut in half horizontally. In case the vertical resolution +of macroblocks is odd then the last row of macroblocks is arranged in a linear +order. </para> + <para>In case of chroma the layout is identical. Cb and Cr samples are +interleaved. Height of the buffer is aligned to 32. + </para> + <example> + <title>Memory layout of macroblocks in <constant>V4L2_PIX_FMT_NV12 +</constant> format pixel image - extreme case</title> + <para> + <figure id="nv12mt"> + <title>Example <constant>V4L2_PIX_FMT_NV12MT</constant> memory +layout of macroblocks</title> + <mediaobject> + <imageobject> + <imagedata fileref="nv12mt_example.gif" format="GIF" /> + </imageobject> + </mediaobject> + </figure> + Memory layout of macroblocks of <constant>V4L2_PIX_FMT_NV12MT +</constant> format in most extreme case. + </para> + </example> + </refsect1> + </refentry> + + <!-- +Local Variables: +mode: sgml +sgml-parent-document: "pixfmt.sgml" +indent-tabs-mode: nil +End: + --> |