[FFmpeg-devel] about check_pack_header, pls do me a favor

[Mark Yin]

hi all

I'm a newcomer for ffmpeg. I can not understand this function.pls do me  a
favor.

static int check_pack_header(const uint8_t *buf) {
 return (buf[1] & 0xC0) == 0x40 || (buf[1] & 0xF0) == 0x20;
}

1> can this function check the header of mepg ps(0x000001BA)?
2> why use the 0xC0 and 0xF0?

thanks in advance
Br/York