2.7.26. V4L2_PIX_FMT_NV12M (‘NM12’), V4L2_PIX_FMT_NV21M (‘NM21’), V4L2_PIX_FMT_NV12MT_16X16

V4L2_PIX_FMT_NV21M V4L2_PIX_FMT_NV12MT_16X16 Variation of V4L2_PIX_FMT_NV12 and V4L2_PIX_FMT_NV21 with planes non contiguous in memory.

2.7.26.1. Description

This is a multi-planar, two-plane version of the YUV 4:2:0 format. The three components are separated into two sub-images or planes. V4L2_PIX_FMT_NV12M differs from V4L2_PIX_FMT_NV12 in that the two planes are non-contiguous in memory, i.e. the chroma plane do not necessarily immediately follows the luma plane. The luminance data occupies the first plane. The Y plane has one byte per pixel. In the second plane there is a chrominance data with alternating chroma samples. The CbCr plane is the same width, in bytes, as the Y plane (and of the image), but is half as tall in pixels. Each CbCr pair belongs to four pixels. For example, Cb0/Cr0 belongs to Y’00, Y’01, Y’10, Y’11. V4L2_PIX_FMT_NV12MT_16X16 is the tiled version of V4L2_PIX_FMT_NV12M with 16x16 macroblock tiles. Here pixels are arranged in 16x16 2D tiles and tiles are arranged in linear order in memory. V4L2_PIX_FMT_NV21M is the same as V4L2_PIX_FMT_NV12M except the Cb and Cr bytes are swapped, the CrCb plane starts with a Cr byte.

V4L2_PIX_FMT_NV12M is intended to be used only in drivers and applications that support the multi-planar API, described in Single- and multi-planar APIs.

If the Y plane has pad bytes after each row, then the CbCr plane has as many pad bytes after its rows.

Byte Order. Each cell is one byte.

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

Color Sample Location:

0

1

2

3

0

Y

Y

Y

Y

C

C

1

Y

Y

Y

Y

2

Y

Y

Y

Y

C

C

3

Y

Y

Y

Y