2.7.1.2. Planar YUV formats

Planar formats split luma and chroma data in separate memory regions. They exist in two variants:

  • Semi-planar formats use two planes. The first plane is the luma plane and stores the Y components. The second plane is the chroma plane and stores the Cb and Cr components interleaved.
  • Fully planar formats use three planes to store the Y, Cb and Cr components separately.

Within a plane, components are stored in pixel order, which may be linear or tiled. Padding may be supported at the end of the lines, and the line stride of the chroma planes may be constrained by the line stride of the luma plane.

Some planar formats allow planes to be placed in independent memory locations. They are identified by an ‘M’ suffix in their name (such as in V4L2_PIX_FMT_NV12M). Those formats are intended to be used only in drivers and applications that support the multi-planar API, described in Single- and multi-planar APIs. Unless explicitly documented as supporting non-contiguous planes, formats require the planes to follow each other immediately in memory.

2.7.1.2.1. Semi-Planar YUV Formats

These formats are commonly referred to as NV formats (NV12, NV16, …). They use two planes, and store the luma components in the first plane and the chroma components in the second plane. The Cb and Cr components are interleaved in the chroma plane, with Cb and Cr always stored in pairs. The chroma order is exposed as different formats.

For memory contiguous formats, the number of padding pixels at the end of the chroma lines is identical to the padding of the luma lines. Without horizontal subsampling, the chroma line stride (in bytes) is thus equal to twice the luma line stride. With horizontal subsampling by 2, the chroma line stride is equal to the luma line stride. Vertical subsampling doesn’t affect the line stride.

For non-contiguous formats, no constraints are enforced by the format on the relationship between the luma and chroma line padding and stride.

All components are stored with the same number of bits per component.

Overview of Semi-Planar YUV Formats
Identifier Code Bits per component Subsampling Chroma order [1] Contiguous [2] Tiling [3]
V4L2_PIX_FMT_NV12 ‘NV12’ 8 4:2:0 Cb, Cr Yes Linear
V4L2_PIX_FMT_NV21 ‘NV21’ 8 4:2:0 Cr, Cr Yes Linear
V4L2_PIX_FMT_NV12M ‘NM12’ 8 4:2:0 Cb, Cr No Linear
V4L2_PIX_FMT_NV21M ‘NM21’ 8 4:2:0 Cr, Cr No Linear
V4L2_PIX_FMT_NV12MT ‘TM12’ 8 4:2:0 Cb, Cr No

64x32 macroblocks

Horizontal Z order

V4L2_PIX_FMT_NV12MT_16X16 ‘VM12’ 8 4:2:2 Cb, Cr No 16x16 macroblocks
V4L2_PIX_FMT_NV16 ‘NV16’ 8 4:2:2 Cb, Cr Yes Linear
V4L2_PIX_FMT_NV61 ‘NV61’ 8 4:2:2 Cr, Cr Yes Linear
V4L2_PIX_FMT_NV16M ‘NM16’ 8 4:2:2 Cb, Cr No Linear
V4L2_PIX_FMT_NV61M ‘NM61’ 8 4:2:2 Cr, Cr No Linear
V4L2_PIX_FMT_NV24 ‘NV24’ 8 4:4:4 Cb, Cr Yes Linear
V4L2_PIX_FMT_NV42 ‘NV42’ 8 4:4:4 Cr, Cr Yes Linear
[1]Order of chroma samples in the second plane
[2]Indicates if planes have to be contiguous in memory or can be disjoint
[3]Macroblock size in pixels

Color Sample Location: Chroma samples are interstitially sited horizontally.

2.7.1.2.1.1. NV12, NV21, NV12M and NV21M

Semi-planar YUV 4:2:0 formats. The chroma plane is subsampled by 2 in each direction. Chroma lines contain half the number of pixels and the same number of bytes as luma lines, and the chroma plane contains half the number of lines of the luma plane.

Sample 4x4 NV12 Image
start + 0: Y’00 Y’01 Y’02 Y’03
start + 4: Y’10 Y’11 Y’12 Y’13
start + 8: Y’20 Y’21 Y’22 Y’23
start + 12: Y’30 Y’31 Y’32 Y’33
start + 16: Cb00 Cr00 Cb01 Cr01
start + 20: Cb10 Cr10 Cb11 Cr11
Sample 4x4 NV12M Image
start0 + 0: Y’00 Y’01 Y’02 Y’03
start0 + 4: Y’10 Y’11 Y’12 Y’13
start0 + 8: Y’20 Y’21 Y’22 Y’23
start0 + 12: Y’30 Y’31 Y’32 Y’33
 
start1 + 0: Cb00 Cr00 Cb01 Cr01
start1 + 4: Cb10 Cr10 Cb11 Cr11

2.7.1.2.1.2. NV12MT and MV12MT_16X16

Semi-planar YUV 4:2:0 formats, using macroblock tiling. The chroma plane is subsampled by 2 in each direction. Chroma lines contain half the number of pixels and the same number of bytes as luma lines, and the chroma plane contains half the number of lines of the luma plane.

V4L2_PIX_FMT_NV12MT_16X16 stores pixel in 2D 16x16 macroblocks, and stores macroblocks linearly in memory. The line stride and image height must be aligned to a multiple of 16. The layouts of the luma and chroma planes are identical.

V4L2_PIX_FMT_NV12MT stores pixels in 2D 64x32 macroblocks, and stores 2x2 groups of macroblocks in Z-order in memory, alternating Z and mirrored Z shapes horizontally. The line stride must be a multiple of 128 pixels to ensure an integer number of Z shapes. The image height must be a multiple of 32 pixels. If the vertical resolution is an odd number of macroblocks, the last row of macroblocks is stored in linear order. The layouts of the luma and chroma planes are identical.

nv12mt.svg

V4L2_PIX_FMT_NV12MT macroblock Z shape memory layout

nv12mt_example.svg

Example V4L2_PIX_FMT_NV12MT memory layout of macroblocks

2.7.1.2.1.3. NV16, NV61, NV16M and NV61M

Semi-planar YUV 4:2:2 formats. The chroma plane is subsampled by 2 in the horizontal direction. Chroma lines contain half the number of pixels and the same number of bytes as luma lines, and the chroma plane contains the same number of lines as the luma plane.

Sample 4x4 NV16 Image
start + 0: Y’00 Y’01 Y’02 Y’03
start + 4: Y’10 Y’11 Y’12 Y’13
start + 8: Y’20 Y’21 Y’22 Y’23
start + 12: Y’30 Y’31 Y’32 Y’33
start + 16: Cb00 Cr00 Cb01 Cr01
start + 20: Cb10 Cr10 Cb11 Cr11
start + 24: Cb20 Cr20 Cb21 Cr21
start + 28: Cb30 Cr30 Cb31 Cr31
Sample 4x4 NV16M Image
start0 + 0: Y’00 Y’01 Y’02 Y’03
start0 + 4: Y’10 Y’11 Y’12 Y’13
start0 + 8: Y’20 Y’21 Y’22 Y’23
start0 + 12: Y’30 Y’31 Y’32 Y’33
 
start1 + 0: Cb00 Cr00 Cb02 Cr02
start1 + 4: Cb10 Cr10 Cb12 Cr12
start1 + 8: Cb20 Cr20 Cb22 Cr22
start1 + 12: Cb30 Cr30 Cb32 Cr32

2.7.1.2.1.4. NV24 and NV42

Semi-planar YUV 4:4:4 formats. The chroma plane is not subsampled. Chroma lines contain the same number of pixels and twice the number of bytes as luma lines, and the chroma plane contains the same number of lines as the luma plane.

Sample 4x4 NV24 Image
start + 0: Y’00 Y’01 Y’02 Y’03
start + 4: Y’10 Y’11 Y’12 Y’13
start + 8: Y’20 Y’21 Y’22 Y’23
start + 12: Y’30 Y’31 Y’32 Y’33
start + 16: Cb00 Cr00 Cb01 Cr01 Cb02 Cr02 Cb03 Cr03
start + 24: Cb10 Cr10 Cb11 Cr11 Cb12 Cr12 Cb13 Cr13
start + 32: Cb20 Cr20 Cb21 Cr21 Cb22 Cr22 Cb23 Cr23
start + 40: Cb30 Cr30 Cb31 Cr31 Cb32 Cr32 Cb33 Cr33

2.7.1.2.2. Fully Planar YUV Formats

These formats store the Y, Cb and Cr components in three separate planes. The luma plane comes first, and the order of the two chroma planes varies between formats. The two chroma planes always use the same subsampling.

For memory contiguous formats, the number of padding pixels at the end of the chroma lines is identical to the padding of the luma lines. The chroma line stride (in bytes) is thus equal to the luma line stride divided by the horizontal subsampling factor. Vertical subsampling doesn’t affect the line stride.

For non-contiguous formats, no constraints are enforced by the format on the relationship between the luma and chroma line padding and stride.

All components are stored with the same number of bits per component.

Overview of Fully Planar YUV Formats
Identifier Code Bits per component Subsampling Planes order [4] Contiguous [5]
V4L2_PIX_FMT_YUV410 ‘YUV9’ 8 4:1:0 Y, Cb, Cr Yes
V4L2_PIX_FMT_YVU410 ‘YVU9’ 8 4:1:0 Y, Cr, Cb Yes
V4L2_PIX_FMT_YUV411P ‘411P’ 8 4:1:1 Y, Cb, Cr Yes
V4L2_PIX_FMT_YUV420M ‘YM12’ 8 4:2:0 Y, Cb, Cr No
V4L2_PIX_FMT_YVU420M ‘YM21’ 8 4:2:0 Y, Cr, Cb No
V4L2_PIX_FMT_YUV420 ‘YU12’ 8 4:2:0 Y, Cb, Cr Yes
V4L2_PIX_FMT_YVU420 ‘YV12’ 8 4:2:0 Y, Cr, Cb Yes
V4L2_PIX_FMT_YUV422P ‘422P’ 8 4:2:2 Y, Cb, Cr Yes
V4L2_PIX_FMT_YUV422M ‘YM16’ 8 4:2:2 Y, Cb, Cr No
V4L2_PIX_FMT_YVU422M ‘YM61’ 8 4:2:2 Y, Cr, Cb No
V4L2_PIX_FMT_YUV444M ‘YM24’ 8 4:4:4 Y, Cb, Cr No
V4L2_PIX_FMT_YVU444M ‘YM42’ 8 4:4:4 Y, Cr, Cb No
[4]Order of luma and chroma planes
[5]Indicates if planes have to be contiguous in memory or can be disjoint

Color Sample Location: Chroma samples are interstitially sited horizontally.

2.7.1.2.2.1. YUV410 and YVU410

Planar YUV 4:1:0 formats. The chroma planes are subsampled by 4 in each direction. Chroma lines contain a quarter of the number of pixels and bytes of the luma lines, and the chroma planes contain a quarter of the number of lines of the luma plane.

Sample 4x4 YUV410 Image
start + 0: Y’00 Y’01 Y’02 Y’03
start + 4: Y’10 Y’11 Y’12 Y’13
start + 8: Y’20 Y’21 Y’22 Y’23
start + 12: Y’30 Y’31 Y’32 Y’33
start + 16: Cr00
start + 17: Cb00

2.7.1.2.2.2. YUV411P

Planar YUV 4:1:1 formats. The chroma planes are subsampled by 4 in the horizontal direction. Chroma lines contain a quarter of the number of pixels and bytes of the luma lines, and the chroma planes contain the same number of lines as the luma plane.

Sample 4x4 YUV411P Image
start + 0: Y’00 Y’01 Y’02 Y’03
start + 4: Y’10 Y’11 Y’12 Y’13
start + 8: Y’20 Y’21 Y’22 Y’23
start + 12: Y’30 Y’31 Y’32 Y’33
start + 16: Cb00
start + 17: Cb10
start + 18: Cb20
start + 19: Cb30
start + 20: Cr00
start + 21: Cr10
start + 22: Cr20
start + 23: Cr30

2.7.1.2.2.3. YUV420, YVU420, YUV420M and YVU420M

Planar YUV 4:2:0 formats. The chroma planes are subsampled by 2 in each direction. Chroma lines contain half of the number of pixels and bytes of the luma lines, and the chroma planes contain half of the number of lines of the luma plane.

Sample 4x4 YUV420 Image
start + 0: Y’00 Y’01 Y’02 Y’03
start + 4: Y’10 Y’11 Y’12 Y’13
start + 8: Y’20 Y’21 Y’22 Y’23
start + 12: Y’30 Y’31 Y’32 Y’33
start + 16: Cr00 Cr01
start + 18: Cr10 Cr11
start + 20: Cb00 Cb01
start + 22: Cb10 Cb11
Sample 4x4 YUV420M Image
start0 + 0: Y’00 Y’01 Y’02 Y’03
start0 + 4: Y’10 Y’11 Y’12 Y’13
start0 + 8: Y’20 Y’21 Y’22 Y’23
start0 + 12: Y’30 Y’31 Y’32 Y’33
 
start1 + 0: Cb00 Cb01
start1 + 2: Cb10 Cb11
 
start2 + 0: Cr00 Cr01
start2 + 2: Cr10 Cr11

2.7.1.2.2.4. YUV422P, YUV422M and YVU422M

Planar YUV 4:2:2 formats. The chroma planes are subsampled by 2 in the horizontal direction. Chroma lines contain half of the number of pixels and bytes of the luma lines, and the chroma planes contain the same number of lines as the luma plane.

Sample 4x4 YUV422P Image
start + 0: Y’00 Y’01 Y’02 Y’03
start + 4: Y’10 Y’11 Y’12 Y’13
start + 8: Y’20 Y’21 Y’22 Y’23
start + 12: Y’30 Y’31 Y’32 Y’33
start + 16: Cb00 Cb01
start + 18: Cb10 Cb11
start + 20: Cb20 Cb21
start + 22: Cb30 Cb31
start + 24: Cr00 Cr01
start + 26: Cr10 Cr11
start + 28: Cr20 Cr21
start + 30: Cr30 Cr31
Sample 4x4 YUV422M Image
start0 + 0: Y’00 Y’01 Y’02 Y’03
start0 + 4: Y’10 Y’11 Y’12 Y’13
start0 + 8: Y’20 Y’21 Y’22 Y’23
start0 + 12: Y’30 Y’31 Y’32 Y’33
 
start1 + 0: Cb00 Cb01
start1 + 2: Cb10 Cb11
start1 + 4: Cb20 Cb21
start1 + 6: Cb30 Cb31
 
start2 + 0: Cr00 Cr01
start2 + 2: Cr10 Cr11
start2 + 4: Cr20 Cr21
start2 + 6: Cr30 Cr31

2.7.1.2.2.5. YUV444M and YVU444M

Planar YUV 4:4:4 formats. The chroma planes are no subsampled. Chroma lines contain the same number of pixels and bytes of the luma lines, and the chroma planes contain the same number of lines as the luma plane.

Sample 4x4 YUV444M Image
start0 + 0: Y’00 Y’01 Y’02 Y’03
start0 + 4: Y’10 Y’11 Y’12 Y’13
start0 + 8: Y’20 Y’21 Y’22 Y’23
start0 + 12: Y’30 Y’31 Y’32 Y’33
 
start1 + 0: Cb00 Cb01 Cb02 Cb03
start1 + 4: Cb10 Cb11 Cb12 Cb13
start1 + 8: Cb20 Cb21 Cb22 Cb23
start1 + 12: Cb20 Cb21 Cb32 Cb33
 
start2 + 0: Cr00 Cr01 Cr02 Cr03
start2 + 4: Cr10 Cr11 Cr12 Cr13
start2 + 8: Cr20 Cr21 Cr22 Cr23
start2 + 12: Cr30 Cr31 Cr32 Cr33