Fix findRtpSource for non-primary ssrc's.

Author: JonathanLennox

jitsi-media-transform/src/main/kotlin/org/jitsi/nlj/MediaSourceDesc.kt

@@ -115,6 +115,7 @@ class MediaSourceDesc
      * @return the last "stable" bitrate (bps) of the encoding with a non-zero rate
      * at or below the specified index.
      */
+    @Synchronized
     fun getBitrate(nowMs: Long, idx: Int): Bandwidth {
         for (entry in layersByIndex.headMap(idx, true).descendingMap()) {
             val bitrate = entry.value.getBitrate(nowMs)
@@ -180,14 +181,20 @@ class MediaSourceDesc
     /**
      * Checks whether the given SSRC matches this source's [primarySSRC].
      * This is mostly useful only for determining quickly whether two source
-     * descriptions describe the same source; other functions should be used
+     * descriptions describe the same source; other functions (probably [hasSsrc]) should be used
      * to match received media packets.
      *
      * @param ssrc the SSRC to match.
      * @return `true` if the specified `ssrc` is the primary SSRC
      * for this source.
      */
     fun matches(ssrc: Long) = rtpEncodings.getOrNull(0)?.primarySSRC == ssrc
+
+    /**
+     * Checks whether any encoding of this source has this [ssrc]
+     */
+    @Synchronized
+    fun hasSsrc(ssrc: Long) = rtpEncodings.any { it.matches(ssrc) }
 }
 
 /**
@@ -199,10 +206,14 @@ fun Array<MediaSourceDesc>.findRtpLayerDescs(packet: VideoRtpPacket): Collection
     return this.flatMap { it.findRtpLayerDescs(packet) }
 }
 
-fun Array<MediaSourceDesc>.findRtpSource(ssrc: Long): MediaSourceDesc? {
+fun Array<MediaSourceDesc>.findRtpSourceByPrimary(ssrc: Long): MediaSourceDesc? {
     return this.find { it.matches(ssrc) }
 }
 
+fun Array<MediaSourceDesc>.findRtpSource(ssrc: Long): MediaSourceDesc? {
+    return this.find { it.hasSsrc(ssrc) }
+}
+
 fun Array<MediaSourceDesc>.findRtpSource(packet: RtpPacket): MediaSourceDesc? = findRtpSource(packet.ssrc)
 
 fun Array<MediaSourceDesc>.findRtpEncodingId(packet: VideoRtpPacket): Int? {

jitsi-media-transform/src/main/kotlin/org/jitsi/nlj/transform/node/incoming/VideoParser.kt

@@ -20,6 +20,7 @@ import org.jitsi.nlj.MediaSourceDesc
 import org.jitsi.nlj.PacketInfo
 import org.jitsi.nlj.SetMediaSourcesEvent
 import org.jitsi.nlj.findRtpSource
+import org.jitsi.nlj.findRtpSourceByPrimary
 import org.jitsi.nlj.format.Vp8PayloadType
 import org.jitsi.nlj.format.Vp9PayloadType
 import org.jitsi.nlj.rtp.ParsedVideoPacket
@@ -228,7 +229,7 @@ class VideoParser(
     }
 
     private fun resetSource(source: MediaSourceDesc) {
-        val signaledSource = signaledSources.findRtpSource(source.primarySSRC)
+        val signaledSource = signaledSources.findRtpSourceByPrimary(source.primarySSRC)
         if (signaledSource == null) {
             logger.warn("Unable to find signaled source corresponding to ${source.primarySSRC}")
             return