private void PrePlay(object sender, RoutedEventArgs e)
        {
            minTime = int.Parse(startTimeBox.Text);
            maxTime = int.Parse(endTimeBox.Text);

            audioPlay audioPlay = new audioPlay();
            audioPlay.FilePath = FilePath;
            audioPlay.outputPath = outputPath;
            audioPlay.extension = extension;
            audioPlay.startTime = minTime;
            audioPlay.endTime = maxTime;
            audioPlay.isPreplay = true;
            audioPlay.ShowDialog();
        }
        private void start(object sender, RoutedEventArgs e)
        {
            int type=0;
            minTime = int.Parse(startTimeBox.Text);
            maxTime = int.Parse(endTimeBox.Text);

            audioPlay audioPlay = new audioPlay();

            if (extension == ".mp4")
                {
                    type = MP4_audio(FilePath, outputPath, minTime, maxTime);
                }
                if (extension == ".flv")
                {
                    type = FLV_audio(FilePath, outputPath, minTime, maxTime);
                }

            if (type == 1)
                generFile = outputPath + ".mp3";
            if (type == 2)
                generFile = outputPath + ".aac";
            audioPlay.isPreplay = false;
            audioPlay.generFile = generFile;
            MessageBox.Show("完成");
            audioPlay.ShowDialog();
        }