V4L2_PIX_FMT_YUV420M — Variation of V4L2_PIX_FMT_YUV420 with planes non contiguous in memory.


This is a multi-planar format, as opposed to a packed format. The three components are separated into three sub- images or planes. The Y plane is first. The Y plane has one byte per pixel. The Cb data constitutes the second plane which is half the width and half the height of the Y plane (and of the image). Each Cb belongs to four pixels, a two-by-two square of the image. For example, Cb0 belongs to Y'00, Y'01, Y'10, and Y'11. The Cr data, just like the Cb plane, is in the third plane.

If the Y plane has pad bytes after each row, then the Cb and Cr planes have half as many pad bytes after their rows. In other words, two Cx rows (including padding) is exactly as long as one Y row (including padding).

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”.

Example 2.21. V4L2_PIX_FMT_YVU420M 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:Cb00Cb01  
start1 + 2:Cb10Cb11  
start2 + 0:Cr00Cr01  
start2 + 2:Cr10Cr11  

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