avformat/whip: skip the unmatch nack packet through ssrc

Signed-off-by: Jack Lau <jacklau1222gm@gmail.com>

Author: JackLau1222

libavformat/whip.c

@@ -1953,6 +1953,7 @@ static void handle_nack_rtx(AVFormatContext *s, int size)
     WHIPContext *whip = s->priv_data;
     uint8_t *buf = NULL;
     int rtcp_len, srtcp_len, header_len = 12/*RFC 4585 6.1*/;
+    uint32_t ssrc;
 
     /**
      * Refer to RFC 3550 6.4.1
@@ -1977,6 +1978,13 @@ static void handle_nack_rtx(AVFormatContext *s, int size)
         av_log(whip, AV_LOG_WARNING, "NACK packet decrypt failed: %d\n", ret);
         goto error;
     }
+    ssrc = AV_RB32(&buf[8]);
+    if (ssrc != whip->video_ssrc) {
+        av_log(whip, AV_LOG_TRACE,
+               "NACK packet SSRC: %"PRIu32" not match with video track SSRC: %"PRIu32"\n",
+               ssrc, whip->video_ssrc);
+        goto end;
+    }
     while (header_len + i + 4 <= rtcp_len) {
         /**
          * See https://datatracker.ietf.org/doc/html/rfc4585#section-6.1