修复NTP时间戳计算精度不足导致误差累积问题 (#2576 #2570 )

ntp时间戳计算精度由毫秒调整为微秒，解决误差累积问题。

src/Common/Stamp.cpp

@@ -236,68 +236,68 @@ void NtpStamp::setNtpStamp(uint32_t rtp_stamp, uint64_t ntp_stamp_ms) {
         WarnL << "Invalid sender report rtcp, ntp_stamp_ms = " << ntp_stamp_ms << ", rtp_stamp = " << rtp_stamp;
         return;
     }
-    update(rtp_stamp, ntp_stamp_ms);
+    update(rtp_stamp, ntp_stamp_ms * 1000);
 }
 
-void NtpStamp::update(uint32_t rtp_stamp, uint64_t ntp_stamp_ms) {
+void NtpStamp::update(uint32_t rtp_stamp, uint64_t ntp_stamp_us) {
     _last_rtp_stamp = rtp_stamp;
-    _last_ntp_stamp_ms = ntp_stamp_ms;
+    _last_ntp_stamp_us = ntp_stamp_us;
 }
 
 uint64_t NtpStamp::getNtpStamp(uint32_t rtp_stamp, uint32_t sample_rate) {
     if (rtp_stamp == _last_rtp_stamp) {
-        return _last_ntp_stamp_ms;
+        return _last_ntp_stamp_us / 1000;
     }
-    return getNtpStamp_l(rtp_stamp, sample_rate);
+    return getNtpStampUS(rtp_stamp, sample_rate) / 1000;
 }
 
-uint64_t NtpStamp::getNtpStamp_l(uint32_t rtp_stamp, uint32_t sample_rate) {
-    if (!_last_ntp_stamp_ms) {
+uint64_t NtpStamp::getNtpStampUS(uint32_t rtp_stamp, uint32_t sample_rate) {
+    if (!_last_ntp_stamp_us) {
         // 尚未收到sender report rtcp包，那么赋值为本地系统时间戳吧
-        update(rtp_stamp, getCurrentMillisecond(true));
+        update(rtp_stamp, getCurrentMicrosecond(true));
     }
 
     // rtp时间戳正增长
     if (rtp_stamp >= _last_rtp_stamp) {
-        auto diff = static_cast<int>((rtp_stamp - _last_rtp_stamp) / (sample_rate / 1000.0f));
-        if (diff < MAX_DELTA_STAMP) {
+        auto diff_us = static_cast<int64_t>((rtp_stamp - _last_rtp_stamp) / (sample_rate / 1000000.0f));
+        if (diff_us < MAX_DELTA_STAMP * 1000) {
             // 时间戳正常增长
-            update(rtp_stamp, _last_ntp_stamp_ms + diff);
-            return _last_ntp_stamp_ms;
+            update(rtp_stamp, _last_ntp_stamp_us + diff_us);
+            return _last_ntp_stamp_us;
         }
 
         // 时间戳大幅跳跃
-        uint64_t loop_delta = STAMP_LOOP_DELTA * sample_rate / 1000;
-        if (_last_rtp_stamp < loop_delta && rtp_stamp > UINT32_MAX - loop_delta) {
+        uint64_t loop_delta_hz = STAMP_LOOP_DELTA * sample_rate / 1000;
+        if (_last_rtp_stamp < loop_delta_hz && rtp_stamp > UINT32_MAX - loop_delta_hz) {
             // 应该是rtp时间戳溢出+乱序
-            uint64_t max_rtp_ms = uint64_t(UINT32_MAX) * 1000 / sample_rate;
-            return _last_ntp_stamp_ms + diff - max_rtp_ms;
+            uint64_t max_rtp_us = uint64_t(UINT32_MAX) * 1000000 / sample_rate;
+            return _last_ntp_stamp_us + diff_us - max_rtp_us;
         }
         // 不明原因的时间戳大幅跳跃，直接返回上次值
         WarnL << "rtp stamp abnormal increased:" << _last_rtp_stamp << " -> " << rtp_stamp;
-        update(rtp_stamp, _last_ntp_stamp_ms);
-        return _last_ntp_stamp_ms;
+        update(rtp_stamp, _last_ntp_stamp_us);
+        return _last_ntp_stamp_us;
     }
 
     // rtp时间戳负增长
-    auto diff = static_cast<int>((_last_rtp_stamp - rtp_stamp) / (sample_rate / 1000.0f));
-    if (diff < MAX_DELTA_STAMP) {
+    auto diff_us = static_cast<int64_t>((_last_rtp_stamp - rtp_stamp) / (sample_rate / 1000000.0f));
+    if (diff_us < MAX_DELTA_STAMP * 1000) {
         // 正常范围的时间戳回退，说明收到rtp乱序了
-        return _last_ntp_stamp_ms - diff;
+        return _last_ntp_stamp_us - diff_us;
     }
 
     // 时间戳大幅度回退
-    uint64_t loop_delta = STAMP_LOOP_DELTA * sample_rate / 1000;
-    if (rtp_stamp < loop_delta && _last_rtp_stamp > UINT32_MAX - loop_delta) {
+    uint64_t loop_delta_hz = STAMP_LOOP_DELTA * sample_rate / 1000;
+    if (rtp_stamp < loop_delta_hz && _last_rtp_stamp > UINT32_MAX - loop_delta_hz) {
         // 确定是时间戳溢出
-        uint64_t max_rtp_ms = uint64_t(UINT32_MAX) * 1000 / sample_rate;
-        update(rtp_stamp, _last_ntp_stamp_ms + (max_rtp_ms - diff));
-        return _last_ntp_stamp_ms;
+        uint64_t max_rtp_us = uint64_t(UINT32_MAX) * 1000000 / sample_rate;
+        update(rtp_stamp, _last_ntp_stamp_us + (max_rtp_us - diff_us));
+        return _last_ntp_stamp_us;
     }
     // 不明原因的时间戳回退，直接返回上次值
     WarnL << "rtp stamp abnormal reduced:" << _last_rtp_stamp << " -> " << rtp_stamp;
-    update(rtp_stamp, _last_ntp_stamp_ms);
-    return _last_ntp_stamp_ms;
+    update(rtp_stamp, _last_ntp_stamp_us);
+    return _last_ntp_stamp_us;
 }
 
 } // namespace mediakit

src/Common/Stamp.h

@@ -125,12 +125,12 @@ public:
     uint64_t getNtpStamp(uint32_t rtp_stamp, uint32_t sample_rate);
 
 private:
-    void update(uint32_t rtp_stamp, uint64_t ntp_stamp_ms);
-    uint64_t getNtpStamp_l(uint32_t rtp_stamp, uint32_t sample_rate);
+    void update(uint32_t rtp_stamp, uint64_t ntp_stamp_us);
+    uint64_t getNtpStampUS(uint32_t rtp_stamp, uint32_t sample_rate);
 
 private:
     uint32_t _last_rtp_stamp = 0;
-    uint64_t _last_ntp_stamp_ms = 0;
+    uint64_t _last_ntp_stamp_us = 0;
 };
 
 }//namespace mediakit