diff --git a/src/Record/MP4Recorder.cpp b/src/Record/MP4Recorder.cpp
index b775da13..7576ba6a 100644
--- a/src/Record/MP4Recorder.cpp
+++ b/src/Record/MP4Recorder.cpp
@@ -123,11 +123,15 @@ bool MP4Recorder::inputFrame(const Frame::Ptr &frame) {
     if (!(_have_video && frame->getTrackType() == TrackAudio)) {
         // 如果有视频且输入的是音频，那么应该忽略切片逻辑  [AUTO-TRANSLATED:fbb15d93]
         // If there is video and the input is audio, then the slice logic should be ignored
-        if (_last_dts == 0 || _last_dts > frame->dts()) {
+        if (_last_dts == 0) {
+            // first frame assign dts
+            _last_dts = frame->dts();
+        } else if (_last_dts > frame->dts()) {
             // b帧情况下dts时间戳可能回退  [AUTO-TRANSLATED:1de38f77]
             // In the case of b-frames, the dts timestamp may regress
             _last_dts = MIN(frame->dts(), _last_dts);
         }
+        
         auto duration = 5u; // 默认至少一帧5ms
         if (frame->dts() > 0 && frame->dts() > _last_dts) {
             duration = MAX(duration, frame->dts() - _last_dts);