From c815f35f8825288ef32518a6fbb7637b761a6909 Mon Sep 17 00:00:00 2001
From: Richard Fuchs <rfuchs@sipwise.com>
Date: Wed, 12 Oct 2022 13:37:14 -0400
Subject: [PATCH] MT#55447 add dedicated format printing function

Change-Id: I19485a331afa4c1bee98317ca4b8a73b0e3deeae
---
 daemon/sdp.c   | 21 ++++++++++++++++++++-
 lib/codeclib.h |  3 +++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/daemon/sdp.c b/daemon/sdp.c
index 5ce06fa33..61a24dca2 100644
--- a/daemon/sdp.c
+++ b/daemon/sdp.c
@@ -1864,11 +1864,30 @@ static void insert_codec_parameters(GString *s, struct call_media *cm) {
 		g_string_append_printf(s, "a=rtpmap:%u " STR_FORMAT "\r\n",
 				pt->payload_type,
 				STR_FMT(&pt->encoding_with_params));
-		if (pt->format_parameters.len) {
+
+		bool check_format = true;
+		if (pt->codec_def && pt->codec_def->format_print) {
+			gsize prev_len = s->len;
+			g_string_append_printf(s, "a=fmtp:%u ", pt->payload_type);
+			gsize fmtp_len = s->len;
+			bool success = pt->codec_def->format_print(s, pt);
+			if (!success)
+				g_string_truncate(s, prev_len); // backtrack
+			else {
+				check_format = false; // done with this
+				// anything printed?
+				if (s->len == fmtp_len)
+					g_string_truncate(s, prev_len); // backtrack
+				else
+					g_string_append(s, "\r\n");
+			}
+		}
+		if (check_format && pt->format_parameters.len) {
 			g_string_append_printf(s, "a=fmtp:%u " STR_FORMAT "\r\n",
 					pt->payload_type,
 					STR_FMT(&pt->format_parameters));
 		}
+
 		for (GList *l = pt->rtcp_fb.head; l; l = l->next) {
 			str *fb = l->data;
 			g_string_append_printf(s, "a=rtcp-fb:%u " STR_FORMAT "\r\n",
diff --git a/lib/codeclib.h b/lib/codeclib.h
index 3b9e3a05d..3a039d542 100644
--- a/lib/codeclib.h
+++ b/lib/codeclib.h
@@ -40,6 +40,7 @@ INLINE enum media_type codec_get_type(const str *type) {
 // 1:  a is compatible with b (not necessarily the other way around)
 // -1: a is not compatible with b
 typedef int format_cmp_f(const struct rtp_payload_type *a, const struct rtp_payload_type *b);
+typedef bool format_print_f(GString *, const struct rtp_payload_type *);
 
 
 #ifndef WITHOUT_CODECLIB
@@ -143,6 +144,7 @@ struct codec_def_s {
 	const char *default_fmtp;
 	format_parse_f * const format_parse;
 	format_cmp_f * const format_cmp;
+	format_print_f * const format_print;
 	packetizer_f * const packetizer;
 	const int bits_per_sample;
 	const enum media_type media_type;
@@ -402,6 +404,7 @@ struct codec_def_s {
 	int dtmf;
 	int supplemental;
 	format_cmp_f * const format_cmp;
+	format_print_f * const format_print;
 	const str silence_pattern;
 };
 struct packet_sequencer_s {