media_header_box = full_box(b'smhd', 0, 0, smhd_payload) # Sound Media Header
else:
vmhd_payload = u16.pack(0) # graphics mode
media_header_box = full_box(b'smhd', 0, 0, smhd_payload) # Sound Media Header
else:
vmhd_payload = u16.pack(0) # graphics mode