FS-8204 add sprop-stereo also

html5/verto/js/src/jquery.FSRTC.js

@@ -181,10 +181,10 @@
 
         if (fmtpLineIndex === null) {
 	    // create an fmtp line
-	    sdpLines[opusIndex] = sdpLines[opusIndex] + '\r\na=fmtp:' + opusPayload.toString() + " stereo=1"
+	    sdpLines[opusIndex] = sdpLines[opusIndex] + '\r\na=fmtp:' + opusPayload.toString() + " stereo=1; sprop-stereo=1"
 	} else {
             // Append stereo=1 to fmtp line.
-            sdpLines[fmtpLineIndex] = sdpLines[fmtpLineIndex].concat('; stereo=1');
+            sdpLines[fmtpLineIndex] = sdpLines[fmtpLineIndex].concat('; stereo=1; sprop-stereo=1');
 	}
 
         sdp = sdpLines.join('\r\n');

src/mod/codecs/mod_opus/mod_opus.c

@@ -253,6 +253,7 @@ static char *gen_fmtp(opus_codec_settings_t *settings, switch_memory_pool_t *poo
 	}
 
 	if (settings->stereo) {
+		settings->sprop_stereo = settings->stereo;
 		snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "stereo=%d; ", settings->stereo);
 	}