如何通过视频播放进行语音识别？

Question

我目前有一个应用程序可以根据https://www.youtube.com/watch?v=AB9lfHDOe5U

上的教程检测我的语音

在此表单的load事件中，我有以下内容

//Global Variable
SpeechRecognitionEngine recEngine = new SpeechRecognitionEngine();

            private void frmMain_Load(object sender, EventArgs e)
            {
                //hide border to prevent screen burnout
                this.FormBorderStyle = FormBorderStyle.None;

                Choices commands = new Choices();
                commands.Add(new string[] { "stock", "news", "percent", "down" }); //need to read company list from db
                GrammarBuilder gBuilder = new GrammarBuilder();
                gBuilder.Append(commands);
                Grammar grammar = new Grammar(gBuilder);


                recEngine.LoadGrammarAsync(grammar);

                //THIS IS PROBABLY WHERE I NEED HELP-----------
                recEngine.SetInputToDefaultAudioDevice();
                recEngine.SpeechRecognized += recEngine_SpeechRecognized;
            }

    //Event called when a word is recognized
    private void recEngine_SpeechRecognized(object sender, SpeechRecognizedEventArgs e)
    {
        switch (e.Result.Text)
        {
            case "stock":
            MessageBox.Show(e.Result.Text);
            break;

            case "news":
            MessageBox.Show(e.Result.Text);
            break;

            case "percent":
            MessageBox.Show(e.Result.Text);
            break;

            case "down":
            MessageBox.Show(e.Result.Text);
            break;
        }
    }

    //Used to enable the recognition to start
    private void btnEnableAudio_Click(object sender, EventArgs e)
    {
        recEngine.RecognizeAsync(RecognizeMode.Multiple);
    }

我想从扬声器而不是麦克风中读取音频，所以如果我正在播放视频，我希望能够检测到这些词。

有没有人有任何想法如何将输入设备设置到输出设备？