MT#55283 fix random seq under DTX

Skip initialisation of seq_out to a random number and track its init
state with a dedicated flag. Initialise it to the first received seq.

Change-Id: Iecdd3d28c5d6fe36d0a7488dd231767ff788942e
(cherry picked from commit 154f2b8927)
(cherry picked from commit c43a067b91)

daemon/codec.c

@@ -3391,6 +3391,11 @@ static bool __buffer_dtx(struct dtx_buffer *dtxb, struct codec_ssrc_handler *dec
 
 	unsigned long ts = packet ? packet->ts : 0;
 
+	if (!mp->ssrc_out->seq_set) {
+		mp->ssrc_out->seq_set = true;
+		mp->ssrc_out->seq_out = packet->p.seq;
+	}
+
 	// allocate packet object
 	struct dtx_packet *dtxp = g_new0(__typeof(*dtxp), 1);
 	dtxp->packet = packet;

daemon/ssrc.c

@@ -37,11 +37,8 @@ static struct ssrc_entry *create_ssrc_entry_call(void *uptr) {
 	payload_tracker_init(&ent->tracker);
 	while (!ent->ssrc_map_out)
 		ent->ssrc_map_out = ssl_random();
-	ent->seq_out = ssl_random();
 	atomic64_set_na(&ent->last_sample, rtpe_now);
 	ent->stats = bufferpool_alloc0(shm_bufferpool, sizeof(*ent->stats));
-	//ent->seq_out = ssl_random();
-	//ent->ts_out = ssl_random();
 	ent->lost_bits = -1;
 	return &ent->h;
 }

include/ssrc.h

@@ -67,6 +67,7 @@ struct ssrc_entry_call {
 	uint32_t ssrc_map_out;
 	uint16_t seq_out;
 	unsigned long ts_out;
+	bool seq_set;
 
 	// RTCP stats
 	struct ssrc_stats *stats;