修复nack/rtx发送时相关bug

webrtc/Nack.cpp

@@ -58,7 +58,7 @@ uint32_t NackList::get_cache_ms() {
     }
     }
     uint32_t back = _nack_cache_pkt[_nack_cache_seq.back()]->getStampMS();
     uint32_t back = _nack_cache_pkt[_nack_cache_seq.back()]->getStampMS();
     uint32_t front = _nack_cache_pkt[_nack_cache_seq.front()]->getStampMS();
     uint32_t front = _nack_cache_pkt[_nack_cache_seq.front()]->getStampMS();
-    if (back > front) {
+    if (back >= front) {
         return back - front;
         return back - front;
     }
     }
     //很有可能回环了
     //很有可能回环了