ssrc切换时间改为3秒:#899

src/Rtsp/RtpReceiver.cpp

@@ -61,7 +61,7 @@ bool RtpReceiver::handleOneRtp(int index, TrackType type, int sample_rate, uint8
         _ssrc_alive[index].resetTime();
     } else {
         //ssrc错误
-        if (_ssrc_alive[index].elapsedTime() < 10 * 1000) {
+        if (_ssrc_alive[index].elapsedTime() < 3 * 1000) {
             //接受正确ssrc的rtp在10秒内，那么我们认为存在多路rtp,忽略掉ssrc不匹配的rtp
             WarnL << "ssrc不匹配,rtp已丢弃:" << ssrc << " != " << _ssrc[index];
             return false;