No audio/sound recording after pause and resume

[oney]

class MyViewController: CameraBaseViewController {
  var writer: GPUImageMovieWriter
  override func pauseRecording() {
    writer.isPaused = true
  }

  override func resumeRecording() {
    writer.isPaused = false
  }
}

Recording video and audio is fine if no pause. However, if I pause and then resume, the audio disappears, but the video is fine. Can someone help? Thanks!