--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sip-manual-out/rtp_tx.c	Fri Mar 17 13:45:31 2023 -0800
@@ -0,0 +1,48 @@
+/*
+ * In this module we implement outgoing RTP stream generation.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <unistd.h>
+#include "../include/tmgw_const.h"
+#include "../include/rtp_defs.h"
+
+extern struct sockaddr_in rtp_local_addr, rtp_remote_addr;
+extern int rtp_udp_fd, rtcp_udp_fd, pcma_selected;
+extern struct timeval cur_event_time;
+
+static uint32_t rtp_ssrc;
+static uint32_t rtp_out_ts;
+static uint16_t rtp_out_seq;
+
+void
+assign_rtpout_ssrc()
+{
+	rtp_ssrc = cur_event_time.tv_sec ^ cur_event_time.tv_usec ^ getpid();
+}
+
+void
+generate_rtp_packet()
+{
+	struct rtp_packet pkt;
+	socklen_t addrlen;
+
+	pkt.v_p_x_cc = 0x80;
+	pkt.m_pt = pcma_selected ? PSTN_CODEC_PCMA : PSTN_CODEC_PCMU;
+	pkt.seq = htons(rtp_out_seq++);
+	pkt.tstamp = htonl(rtp_out_ts);
+	rtp_out_ts += 160;
+	pkt.ssrc = rtp_ssrc;
+	memset(pkt.payload, pcma_selected ? 0xD5 : 0xFF, RTP_MAX_PAYLOAD);
+	addrlen = sizeof(struct sockaddr_in);
+	sendto(rtp_udp_fd, &pkt, RTP_PACKET_SIZE_PSTN, 0,
+		(struct sockaddr *) &rtp_remote_addr, addrlen);
+}