优化国标规范，参考国标文档中-点播外域设备媒体流SSRC处理方式，上级点播时自定义ssrc，不适用上级携带的ssrc，也避免上级兼容性差，不携带ssrc的问题，可通过配置关闭此特性

src/main/java/com/genersoft/iot/vmp/media/zlm/ZLMHttpHookListener.java

@@ -8,6 +8,7 @@ import com.genersoft.iot.vmp.conf.exception.SsrcTransactionNotFoundException;
 import com.genersoft.iot.vmp.gb28181.bean.*;
 import com.genersoft.iot.vmp.gb28181.event.EventPublisher;
 import com.genersoft.iot.vmp.gb28181.event.subscribe.catalog.CatalogEvent;
+import com.genersoft.iot.vmp.gb28181.session.SSRCFactory;
 import com.genersoft.iot.vmp.gb28181.session.VideoStreamSessionManager;
 import com.genersoft.iot.vmp.gb28181.transmit.callback.DeferredResultHolder;
 import com.genersoft.iot.vmp.gb28181.transmit.callback.RequestMessage;
@@ -105,6 +106,9 @@ public class ZLMHttpHookListener {
     @Autowired
     private AssistRESTfulUtils assistRESTfulUtils;
 
+    @Autowired
+    private SSRCFactory ssrcFactory;
+
     @Qualifier("taskExecutor")
     @Autowired
     private ThreadPoolTaskExecutor taskExecutor;
@@ -666,6 +670,7 @@ public class ZLMHttpHookListener {
             if (sendRtpItems.size() > 0) {
                 for (SendRtpItem sendRtpItem : sendRtpItems) {
                     ParentPlatform parentPlatform = storager.queryParentPlatByServerGBId(sendRtpItem.getPlatformId());
+                    ssrcFactory.releaseSsrc(sendRtpItem.getMediaServerId(), sendRtpItem.getSsrc());
                     try {
                         commanderFroPlatform.streamByeCmd(parentPlatform, sendRtpItem.getCallId());
                     } catch (SipException | InvalidArgumentException | ParseException e) {