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YUV 4:2:0 is a specific encoding for digital representation of the YUV color space.
In YUV 4:2:0, the basic unit (or macropixel) is composed of four pixels, and occupies six bytes of space. Each pixel has an individual 8 bit Y channel.
Interlaced version (YUV 420, fourcc's NV12/NV21)
In the interlaced version, the Y, U, and V components are mixed together.
Planar version (YUV 420P, fourcc's I420 and YV12)
In the planar version of YUV 4:2:0, all the Y components are given first, then the U components (1 sample per 2x2 pixels), then the V components (1 sample per 2x2 pixels).
Thus, the layout for a 4x4 image is:
Y01 Y02 Y03 Y04 Y05 Y06 Y07 Y08 Y09 Y10 Y11 Y12 Y13 Y14 Y15 Y16
U1 U2 U3 U4
V1 V2 V3 V4
The components map onto the image as follows:
[Y01 U1 V1] [Y02 U1 V1] [Y03 U2 V2] [Y04 U2 V2]
[Y05 U1 V1] [Y06 U1 V1] [Y07 U2 V2] [Y08 U2 V2]
[Y09 U3 V3] [Y10 U3 V3] [Y11 U4 V4] [Y12 U4 V4]
[Y13 U3 V3] [Y14 U3 V3] [Y15 U4 V4] [Y16 U4 V4]
Note that in the image data,
- The Y component takes up Width × Height bytes. This group of bytes forms the Y plane.
- The U component plane takes only Width × Height / 4 bytes.
- The V component plane is the same size as the U plane.
See also
YUV
YUV 4:4:4 - higher quality YUV encoding
External link
http://www.fourcc.org/
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