V4L2_PIX_FMT_NV12M, 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.


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 the section called “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.

Example 2.32. V4L2_PIX_FMT_NV12M 4 × 4 pixel image

Byte Order. Each cell is one byte.

start0 + 0:Y'00Y'01Y'02Y'03
start0 + 4:Y'10Y'11Y'12Y'13
start0 + 8:Y'20Y'21Y'22Y'23
start0 + 12:Y'30Y'31Y'32Y'33
start1 + 0:Cb00Cr00Cb01Cr01
start1 + 4:Cb10Cr10Cb11Cr11

Color Sample Location. 

 0 1 2 3
0Y Y Y Y
  C   C 
1Y Y Y Y
2Y Y Y Y
  C   C 
3Y Y Y Y