diff --git a/markdown/RTC 4.x/custom video source/ custom_video_source_android_ng.md b/markdown/RTC 4.x/custom video source/ custom_video_source_android_ng.md
index dd08289d057..ae13050595c 100644
--- a/markdown/RTC 4.x/custom video source/ custom_video_source_android_ng.md	
+++ b/markdown/RTC 4.x/custom video source/ custom_video_source_android_ng.md	
@@ -209,6 +209,7 @@ private void pushVideoFrameByTexture(int textureId, VideoFrame.TextureBuffer.Typ
 
    // 获取 SDK 当前的 Monotonic Time
    long currentMonotonicTimeInMs = engine.getCurrentMonotonicTimeInMs();
+   // 创建一个 VideoFrame 对象，传入要推送的 Texture 视频帧和视频帧的 Monotonic Time (单位为纳秒)
    VideoFrame videoFrame = new VideoFrame(frameBuffer, 0, currentMonotonicTimeInMs * 1000000);
    
    // 通过视频轨道将视频帧推送到 SDK