Constant rsmpeg::ffi::AVPixelFormat_AV_PIX_FMT_RGB4

pub const AVPixelFormat_AV_PIX_FMT_RGB4: i32 = 21;

< packed RGB 1:2:1 bitstream, 4bpp, (msb)1R 2G 1B(lsb), a byte contains two pixels, the first pixel in the byte is the one composed by the 4 msb bits