修复录制突然声音消失的bug

MusicGradeExam/MusicGradeExam/UI/RecordAction/KSVideoRecordViewController.m

@@ -186,6 +186,7 @@
     
     // 初始化设备输出对象
     _captureMovieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
+    _captureMovieFileOutput.movieFragmentInterval = kCMTimeInvalid;
     //将设备输入添加到会话中
     if ([_captureSession canAddInput:_videoCaptureDeviceInput]) {
         [_captureSession addInput:_videoCaptureDeviceInput];
@@ -385,6 +386,7 @@
     }
     
 }
+
 #pragma mark --------  AVCaptureFileOutputRecordingDelegate  ----------
 - (void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections {
     NSLog(@"开始录制");