CODEWITHSUNDEEP
yuvcolor-spacev4l2
Raulp
Raulp

Reputation: 8176

YUVY format representation - v4l2 Specification?

This is the exerpt from the famous V4l2 Api specification.But I am not able to understand the YUYV also known as YUV422 format representation. Can some one plz explain this here.

Here is the excerpt : 

Example 2-1. V4L2_PIX_FMT_YUYV 4 × 4 pixel image

Byte Order. Each cell is one byte.

start + 0:  Y’00   Cb00   Y’01   Cr00   Y’02   Cb01   Y’03   Cr01
start + 8:  Y’10   Cb10   Y’11   Cr10   Y’12   Cb11   Y’13   Cr11
start + 16: Y’20   Cb20   Y’21   Cr20   Y’22   Cb21   Y’23   Cr21
start + 24: Y’30   Cb30   Y’31   Cr30   Y’32   Cb31   Y’33   Cr31

Each Y goes to one of the pixels, and the Cb and Cr belong to both pixels. What is the representation of Cell and Pixel here. How is the pixel being represented here. How we can represent it programmatically.

Plz explain. Rgds, Softy

Upvotes: 1

Views: 3396

Answers (1)

umläute
umläute

Reputation: 31304

YUV422 is an interleaved format that stores Y-information at a higher (double) resolution than the U&V (Cb&Cr) channels. each cell consists of 4 bytes, that stores Y/U/V vaLues for 2 pixels:

unsigned char*cell={127, 52, 139, 170};
unsigned char pixel0[3], pixel1[3];

pixel0[0]=cell[0]; // Y0
pixel0[1]=cell[1]; // U
pixel0[2]=cell[3]; // V

pixel1[0]=cell[2]; // Y1
pixel1[1]=cell[1]; // U
pixel1[2]=cell[3]; // V

as you can see, there is no direct representation of a single pixel.

Upvotes: 2

Related Questions