[MPlayer-dev-eng] question about mov_check_file in demux_mov.c

[cckuo]

Dear All:
I tried to trace the H.264 path in mplayer.
In mov-check_file in demux_mov.c, we need len and id to determine the format
of file like below.
	off_t len=stream_read_dword(demuxer->stream);
	unsigned int id=stream_read_dword(demuxer->stream);
	switch(id){
	case MOV_FOURCC('f','t','y','p'): {
	  unsigned int tmp;
...................
Where can I get the parsing rule used in the following switch case? 
Appreciate your help,
cckuo