Messages in this thread | | | Date | Mon, 7 Aug 2023 13:37:23 +0200 | Subject | Re: [PATCH 3/5] docs: uapi: media: Add common documentation of tiled NV15 | From | Andrzej Pietrasiewicz <> |
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Hi Nicolas,
W dniu 4.08.2023 o 21:27, Nicolas Dufresne pisze: > This way we don't have to repeat over and over how the pixels are > packed in NV15. > > Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com> > --- > .../media/v4l/pixfmt-yuv-planar.rst | 79 ++++++++++++++++--- > 1 file changed, 68 insertions(+), 11 deletions(-) > > diff --git a/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst b/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst > index 1d43532095c0..052927bd9396 100644 > --- a/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst > +++ b/Documentation/userspace-api/media/v4l/pixfmt-yuv-planar.rst > @@ -373,10 +373,74 @@ two non-contiguous planes. > Tiled NV15 > ---------- > > -``V4L2_PIX_FMT_NV15_4L4`` Semi-planar 10-bit YUV 4:2:0 formats, using 4x4 tiling. > -All components are packed without any padding between each other. > -As a side-effect, each group of 4 components are stored over 5 bytes > -(YYYY or UVUV = 4 * 10 bits = 40 bits = 5 bytes). > +Semi-planar 10-bit YUV 4:2:0 formats. All components are packed > +without any padding between each other. Each pixels occupy 15 bits
Maybe "Each pixel group"?
> +and are usually stored in group of 4 components stored over 5 bytes > +(YYYY or UVUV = 4 * 10 bits = 40 bits = 5 bytes) or partitioned into > +upper 8 bit and lower 2 bits. > + > +.. flat-table:: Sample of 4 NV15 luma pixels > + :header-rows: 2 > + :stub-columns: 0 > + > + * - > + - 8 > + - 7 > + - 6 > + - 5 > + - 4 > + - 3 > + - 2 > + - 1 > + - 0 > + * - byte 0 > + - Y'\ :sub:`0:0` > + - Y'\ :sub:`0:1` > + - Y'\ :sub:`0:2` > + - Y'\ :sub:`0:3` > + - Y'\ :sub:`0:4` > + - Y'\ :sub:`0:5` > + - Y'\ :sub:`0:6` > + - Y'\ :sub:`0:7`
So byte 0 contains Y0, bits 0..7 but then...
> + * - byte 1 > + - Y'\ :sub:`0:8` > + - Y'\ :sub:`0:9` > + - Y'\ :sub:`1:0` > + - Y'\ :sub:`1:1` > + - Y'\ :sub:`1:2` > + - Y'\ :sub:`1:3` > + - Y'\ :sub:`1:4` > + - Y'\ :sub:`1:5` > + * - byte 2 > + - Y'\ :sub:`1:6` > + - Y'\ :sub:`1:7` > + - Y'\ :sub:`1:8` > + - Y'\ :sub:`1:9` > + - Y'\ :sub:`2:0` > + - Y'\ :sub:`2:1` > + - Y'\ :sub:`2:2` > + - Y'\ :sub:`2:3` > + * - byte 3 > + - Y'\ :sub:`2:4` > + - Y'\ :sub:`2:5` > + - Y'\ :sub:`2:6` > + - Y'\ :sub:`2:7` > + - Y'\ :sub:`2:8` > + - Y'\ :sub:`2:9` > + - Y'\ :sub:`3:0` > + - Y'\ :sub:`3:1` > + * - byte 4 > + - Y'\ :sub:`3:2` > + - Y'\ :sub:`3:3` > + - Y'\ :sub:`3:4` > + - Y'\ :sub:`3:5` > + - Y'\ :sub:`3:6` > + - Y'\ :sub:`3:7` > + - Y'\ :sub:`3:8` > + - Y'\ :sub:`3:9` > + > +``V4L2_PIX_FMT_NV15_4L4`` stores pixels in 4x4 tiles, and stores tiles linearly > +in memory. > > ``V4L2_PIX_FMT_NV12M_10BE_8L128`` is similar to ``V4L2_PIX_FMT_NV12M`` but stores > 10 bits pixels in 2D 8x128 tiles, and stores tiles linearly in memory. > @@ -385,13 +449,6 @@ The image height must be aligned to a multiple of 128. > The layouts of the luma and chroma planes are identical. > Note the tile size is 8bytes multiplied by 128 bytes, > it means that the low bits and high bits of one pixel may be in different tiles. > -The 10 bit pixels are packed, so 5 bytes contain 4 10-bit pixels layout like > -this (for luma): > -byte 0: Y0(bits 9-2)
...here it says byts 9-2? Is it a mistake or are you cleaning up the doc and the table above is the correct version?
Regards,
Andrzej
> -byte 1: Y0(bits 1-0) Y1(bits 9-4) > -byte 2: Y1(bits 3-0) Y2(bits 9-6) > -byte 3: Y2(bits 5-0) Y3(bits 9-8) > -byte 4: Y3(bits 7-0) > > ``V4L2_PIX_FMT_NV12_10BE_8L128`` is similar to ``V4L2_PIX_FMT_NV12M_10BE_8L128`` but stores > two planes in one memory.
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