文档不完整。在ffmpeg/libavformat/unix.c,
static const AVOption unix_options[] = {
{ "listen", "Open socket for listening", OFFSET(listen), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, ED },
{ "timeout", "Timeout in ms", OFFSET(timeout), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, ED },
{ "type", "Socket type", OFFSET(type), AV_OPT_TYPE_INT, { .i64 = SOCK_STREAM }, INT_MIN, INT_MAX, ED, "type" },
{ "stream", "Stream (reliable stream-oriented)", 0, AV_OPT_TYPE_CONST, { .i64 = SOCK_STREAM }, INT_MIN, INT_MAX, ED, "type" },
{ "datagram", "Datagram (unreliable packet-oriented)", 0, AV_OPT_TYPE_CONST, { .i64 = SOCK_DGRAM }, INT_MIN, INT_MAX, ED, "type" },
{ "seqpacket", "Seqpacket (reliable packet-oriented", 0, AV_OPT_TYPE_CONST, { .i64 = SOCK_SEQPACKET }, INT_MIN, INT_MAX, ED, "type" },
{ NULL }
};
它处理stream=1、datagram=1、seqpacket=1或type=#,其中#是所需套接字类型的整数值(SOCK_STREAM=1、SOCK_DGRAM=2、SOCK_SEQPACKET=5)。