[PATCH v3] drm: drm_fourcc: add 10/12/16bit software decoder YCbCr formats
Robert Mader
robert.mader at collabora.com
Fri May 9 13:35:35 UTC 2025
This adds FOURCCs for 3-plane 10/12/16bit YCbCr formats used by software
decoders like ffmpeg, dav1d and libvpx. The intended use-case is buffer
sharing between decoders and GPUs by allocating buffers with e.g. udmabuf
or dma-heaps, avoiding unnecessary copies and format conversions in
various scenarios.
Unlike formats typically used by hardware decoders the 10/12bit formats
use a LSB alignment. In order to allow fast implementations in GL
and Vulkan the padding must contain only zeros, so the float
representation can be calculated by multiplying with 2^6=64 or 2^4=16
respectively.
MRs or branches for Mesa, Vulkan, Gstreamer, Weston and Mutter can be found at:
- https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34303
- https://github.com/rmader/Vulkan-Docs/commits/ycbcr-16bit-lsb-formats/
- https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8540
- https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/1753
- https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4348
The naming scheme follows the 'P' and 'Q' formats. The 'S' stands for
'software' and was selected in order to make remembering easy.
The 'Sx16' formats could as well be 'Qx16'. We stick with 'S' as 16bit software
decoders are likely much more common than hardware ones for the foreseeable
future. Note that these formats already have Vulkan equivalents:
- VK_FORMAT_G16_B16_R16_3PLANE_420_UNORM
- VK_FORMAT_G16_B16_R16_3PLANE_422_UNORM
- VK_FORMAT_G16_B16_R16_3PLANE_444_UNORM
Signed-off-by: Robert Mader <robert.mader at collabora.com>
---
Changes in v3:
- Changed x to z in the padding annotation to make it clear that the values
need to be 0. Also added that to the comments
- Added additional links to userspace MRs
- Added existing Vulkan formats to the commit message
Changes in v2:
- Added 16bit formats for completeness and because they are used by certain
ffmpeg decoders
- Changed the initial character to "S"
- Some minor changes to the commit message
---
drivers/gpu/drm/drm_fourcc.c | 27 ++++++++++++++++++++++++++
include/uapi/drm/drm_fourcc.h | 36 +++++++++++++++++++++++++++++++++++
2 files changed, 63 insertions(+)
diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
index 3a94ca211f9c..55ddd99fd7f6 100644
--- a/drivers/gpu/drm/drm_fourcc.c
+++ b/drivers/gpu/drm/drm_fourcc.c
@@ -346,6 +346,33 @@ const struct drm_format_info *__drm_format_info(u32 format)
{ .format = DRM_FORMAT_P030, .depth = 0, .num_planes = 2,
.char_per_block = { 4, 8, 0 }, .block_w = { 3, 3, 0 }, .block_h = { 1, 1, 0 },
.hsub = 2, .vsub = 2, .is_yuv = true},
+ { .format = DRM_FORMAT_S010, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 2, .vsub = 2, .is_yuv = true},
+ { .format = DRM_FORMAT_S210, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 2, .vsub = 1, .is_yuv = true},
+ { .format = DRM_FORMAT_S410, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 1, .vsub = 1, .is_yuv = true},
+ { .format = DRM_FORMAT_S012, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 2, .vsub = 2, .is_yuv = true},
+ { .format = DRM_FORMAT_S212, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 2, .vsub = 1, .is_yuv = true},
+ { .format = DRM_FORMAT_S412, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 1, .vsub = 1, .is_yuv = true},
+ { .format = DRM_FORMAT_S016, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 2, .vsub = 2, .is_yuv = true},
+ { .format = DRM_FORMAT_S216, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 2, .vsub = 1, .is_yuv = true},
+ { .format = DRM_FORMAT_S416, .depth = 0, .num_planes = 3,
+ .char_per_block = { 2, 2, 2 }, .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 },
+ .hsub = 1, .vsub = 1, .is_yuv = true},
};
unsigned int i;
diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index e41a3cec6a9e..add5cc6b1d94 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -377,6 +377,42 @@ extern "C" {
*/
#define DRM_FORMAT_Q401 fourcc_code('Q', '4', '0', '1')
+/*
+ * 3 plane YCbCr LSB aligned
+ * In order to use these formats in a similar fashion to MSB aligned ones
+ * implementation can multiply the values by 2^6=64. For that reason the padding
+ * must only contain zeros.
+ * index 0 = Y plane, [15:0] z:Y [6:10] little endian
+ * index 1 = Cr plane, [15:0] z:Cr [6:10] little endian
+ * index 2 = Cb plane, [15:0] z:Cb [6:10] little endian
+ */
+#define DRM_FORMAT_S010 fourcc_code('S', '0', '1', '0') /* 2x2 subsampled Cb (1) and Cr (2) planes 10 bits per channel */
+#define DRM_FORMAT_S210 fourcc_code('S', '2', '1', '0') /* 2x1 subsampled Cb (1) and Cr (2) planes 10 bits per channel */
+#define DRM_FORMAT_S410 fourcc_code('S', '4', '1', '0') /* non-subsampled Cb (1) and Cr (2) planes 10 bits per channel */
+
+/*
+ * 3 plane YCbCr LSB aligned
+ * In order to use these formats in a similar fashion to MSB aligned ones
+ * implementation can multiply the values by 2^4=16. For that reason the padding
+ * must only contain zeros.
+ * index 0 = Y plane, [15:0] z:Y [4:12] little endian
+ * index 1 = Cr plane, [15:0] z:Cr [4:12] little endian
+ * index 2 = Cb plane, [15:0] z:Cb [4:12] little endian
+ */
+#define DRM_FORMAT_S012 fourcc_code('S', '0', '1', '2') /* 2x2 subsampled Cb (1) and Cr (2) planes 12 bits per channel */
+#define DRM_FORMAT_S212 fourcc_code('S', '2', '1', '2') /* 2x1 subsampled Cb (1) and Cr (2) planes 12 bits per channel */
+#define DRM_FORMAT_S412 fourcc_code('S', '4', '1', '2') /* non-subsampled Cb (1) and Cr (2) planes 12 bits per channel */
+
+/*
+ * 3 plane YCbCr
+ * index 0 = Y plane, [15:0] Y little endian
+ * index 1 = Cr plane, [15:0] Cr little endian
+ * index 2 = Cb plane, [15:0] Cb little endian
+ */
+#define DRM_FORMAT_S016 fourcc_code('S', '0', '1', '6') /* 2x2 subsampled Cb (1) and Cr (2) planes 16 bits per channel */
+#define DRM_FORMAT_S216 fourcc_code('S', '2', '1', '6') /* 2x1 subsampled Cb (1) and Cr (2) planes 16 bits per channel */
+#define DRM_FORMAT_S416 fourcc_code('S', '4', '1', '6') /* non-subsampled Cb (1) and Cr (2) planes 16 bits per channel */
+
/*
* 3 plane YCbCr
* index 0: Y plane, [7:0] Y
--
2.49.0
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