private bool disposedValue = false;         // Для определения избыточных вызовов

        protected virtual void dispose(bool disposing)
        {
            if (!disposedValue)
            {
                if (disposing)
                {
                    try {
                        nvrPlayback_?.Dispose();
                    } finally {
                        nvrPlayback_ = null;
                    }
                }
                disposedValue = true;
            }
        }
 public PlaybackService()
 {
     nvrPlayback_ = new NvrPlayback(UserSessionService.GetInstance().NvrUserSession, true);
 }