diff --git a/libavformat/rtcenc.c b/libavformat/rtcenc.c
index 3abc85f52a246..d68ad1a713d3d 100644
--- a/libavformat/rtcenc.c
+++ b/libavformat/rtcenc.c
@@ -58,7 +58,11 @@ typedef struct RTCContext {
     /* The ICE username and pwd from remote server. */
     char *ice_ufrag_remote;
     char *ice_pwd_remote;
-    /* The ICE candidate protocol, priority, host and port. */
+    /**
+     * The ICE candidate protocol, priority, host and port. Note that only
+     * support one candidate for now. We will choose the first udp candidate.
+     * We will support multiple candidates in the future.
+     */
     char *ice_protocol;
     int ice_priority;
     char *ice_host;
@@ -372,9 +376,7 @@ static int parse_answer(AVFormatContext *s)
     int i;
     RTCContext *rtc = s->priv_data;
 
-    pb = avio_alloc_context(
-        (unsigned char *)rtc->sdp_answer, (int)strlen(rtc->sdp_answer),
-        AVIO_FLAG_READ, NULL, NULL, NULL, NULL);
+    pb = avio_alloc_context(rtc->sdp_answer, strlen(rtc->sdp_answer), AVIO_FLAG_READ, NULL, NULL, NULL, NULL);
     if (!pb) {
         av_log(s, AV_LOG_ERROR, "Failed to alloc AVIOContext for answer: %s", rtc->sdp_answer);
         ret = AVERROR(ENOMEM);
@@ -383,13 +385,11 @@ static int parse_answer(AVFormatContext *s)
 
     for (i = 0; !avio_feof(pb); i++) {
         ff_get_chomp_line(pb, line, sizeof(line));
-        if (av_strstart(line, "a=ice-ufrag:", &ptr)) {
-            av_freep(&rtc->ice_ufrag_remote);
+        if (av_strstart(line, "a=ice-ufrag:", &ptr) && !rtc->ice_ufrag_remote) {
             rtc->ice_ufrag_remote = av_strdup(ptr);
-        } else if (av_strstart(line, "a=ice-pwd:", &ptr)) {
-            av_freep(&rtc->ice_pwd_remote);
+        } else if (av_strstart(line, "a=ice-pwd:", &ptr) && !rtc->ice_pwd_remote) {
             rtc->ice_pwd_remote = av_strdup(ptr);
-        } else if (av_strstart(line, "a=candidate:", &ptr)) {
+        } else if (av_strstart(line, "a=candidate:", &ptr) && !rtc->ice_protocol) {
             ptr = av_stristr(ptr, "udp");
             if (ptr && av_stristr(ptr, "host")) {
                 char protocol[17], host[129];
@@ -403,14 +403,13 @@ static int parse_answer(AVFormatContext *s)
                 }
 
                 if (av_strcasecmp(protocol, "udp")) {
-                    av_log(s, AV_LOG_ERROR, "Protocol %s is not supported by RTC, choose udp", protocol);
+                    av_log(s, AV_LOG_ERROR, "Protocol %s is not supported by RTC, choose udp, line %d %s of %s",
+                        protocol, i, line, rtc->sdp_answer);
                     ret = AVERROR(EINVAL);
                     goto end;
                 }
 
-                av_freep(&rtc->ice_protocol);
                 rtc->ice_protocol = av_strdup(protocol);
-                av_freep(&rtc->ice_host);
                 rtc->ice_host = av_strdup(host);
                 rtc->ice_priority = priority;
                 rtc->ice_port = port;