忽略非法的rtcp ntp时间戳

有些设备在发送sender report rtcp时，其rtp和ntp时间戳一直为0，将导致zlmediakit计算出的ntp时间戳异常

src/Common/Stamp.cpp

@@ -231,14 +231,15 @@ bool DtsGenerator::getDts_l(uint64_t pts, uint64_t &dts) {
 }
 
 void NtpStamp::setNtpStamp(uint32_t rtp_stamp, uint64_t ntp_stamp_ms) {
+    if (!ntp_stamp_ms || !rtp_stamp) {
+        // 实测发现有些rtsp服务器发送的rtp时间戳和ntp时间戳一直为0
+        WarnL << "Invalid sender report rtcp, ntp_stamp_ms = " << ntp_stamp_ms << ", rtp_stamp = " << rtp_stamp;
+        return;
+    }
     update(rtp_stamp, ntp_stamp_ms);
 }
 
 void NtpStamp::update(uint32_t rtp_stamp, uint64_t ntp_stamp_ms) {
-    if (ntp_stamp_ms == 0) {
-        // 实测发现有些rtsp服务器发送的rtp时间戳和ntp时间戳一直为0
-        return;
-    }
     _last_rtp_stamp = rtp_stamp;
     _last_ntp_stamp_ms = ntp_stamp_ms;
 }