uvideo_payload_header_t
uvideo_payload_header_t *uvchdr;
uvchdr = (uvideo_payload_header_t *)buf;
uvideo_payload_header_t *hdr;
if (len < sizeof(uvideo_payload_header_t)) {
hdr = (uvideo_payload_header_t *)buf;
hdr->bHeaderLength < sizeof(uvideo_payload_header_t))