FFmpeg AV_PIX_FMT_YUVJ420P advantage
For RGB, saving a pixel requires 8 bytes and 24 bits, but for YUV, it is possible to achieve four adjacent points and share UV components, except that four points have separate Y components, that is, four points, only 4 bytes of Y component + 1 byte U component + 1 byte V component, so on average, one pixel has 1.5 bytes of pixel content. Saved half the space.
