javascript - SpeechSynthesis.speaking 从不真实

Question

我尝试用 javascript 实现一个小网页，允许从两个 mp3 之间的文本播放 specchsynthesis 部分。

至于无论出于何种原因，口语部分的 onend 语句不起作用，我想创建一个递归函数，这对我有帮助。为此，我使用了 SpeechSynthesis 的“说话”方法。但无论出于何种原因，说话永远不会是真的。

我调试并尝试了几个语句(见代码)，但它从来没有被证明是真的。代码有问题吗？否则，如何报告这个库的错误？

        function doSpeech() {
            var synth = window.speechSynthesis;

            var utterance1 = new SpeechSynthesisUtterance('How about we say this now? This is quite a long sentence to say.');
            var utterance2 = new SpeechSynthesisUtterance('We should say another sentence too, just to be on the safe side.');
            synth.speak(utterance1);
            if(synth.speaking){
                doNothing();
            }else{
                playEnd();
            }

playEnd() 仅在合成器说话时播放 mp3。请注意，当我将 playEnd() 放在 if 语句中时，它不会播放。我可以把任何代码放在那里，它永远不会到达，因为 synth.speaking 永远不会是真的。此示例接近 Mozilla 基础文档的示例 (https://developer.mozilla.org/en-US/docs/Web/API/SpeechSynthesis/speaking)。我想测试它，因为递归从未起作用。

编辑:递归在我的特定编码中仍然不会这样做。我在这里遗漏了什么吗？

  function doSpeech() {
            var synth = window.speechSynthesis;
            var speech = new SpeechSynthesisUtterance();
            speech.text = getText();
            speech.lang = "en-US";
            speech.voice = speechSynthesis.getVoices().filter(function(voice) { return voice.name == 'Google UK English Male'; })[0];

            speech.addEventListener('start', function(){
                speechEndLoop(synth);
            });


            synth.speak(speech);
    }

   function speechEndLoop(x) {
          if (x.speaking) {
               speechEndLoop(x);  
            } else {
               playEnd(); 
            }
        }

Answer 1

它工作得很好，问题是根据您的代码，您正在立即验证状态。这可能是一个问题，因为它取决于 API 如何将文本转换为音频(使用本地文本到操作系统的语音或使用谷歌服务器):

function doSpeech() {
    var synth = window.speechSynthesis;

    var utterance1 = new SpeechSynthesisUtterance('How about we say this now? This is quite a long sentence to say. Make it longer !');
    var utterance2 = new SpeechSynthesisUtterance('We should say another sentence too, just to be on the safe side. even longer !');

    synth.speak(utterance1);

    // If you check immediately (js code executed in less than ms) the
    // status won't be true
    if (synth.speaking) {
        console.log("This is usually printed, if the utterance uses the default voice of the browser (native)");
    }

    // Wait 500ms to check for the status of the utterance
    setTimeout(function(){
        if (synth.speaking) {
            console.log("This will be printed if starts after 500ms :)");
        }
    }, 500);
}

doSpeech();

在我的例子中，两个 console.log 语句都被打印出来了。但是如果在你的情况下它没有被打印出来，那么只在话语的开始事件之后执行你的代码:

function doSpeech() {
    var synth = window.speechSynthesis;
    var msg = new SpeechSynthesisUtterance();
    msg.text = "We should say another sentence too, just to be on the safe side. even longer !";

    msg.addEventListener('start', function () {
        if(synth.speaking){
            console.log("This will be printed !");
        }
    });

    synth.speak(msg);
} 

doSpeech();

自己使用普通 API 非常好，但是如果您想要更强大的东西来解决文本到语音的问题，我建议您使用 use the JS Library Artyom.js ，它为语音合成 API 提供了一个非常好的包装器。即使使用这个库，您也会看到相同的行为:

function doSpeech() {
    let assistant = new Artyom();

    assistant.say('How about we say this now? This is quite a long sentence to say. Make it longer !', {
        onStart: function() {
            if(assistant.isSpeaking()){
                console.log("This will be shown");
            }
        }
    });

    if(assistant.isSpeaking()){
        console.log("This won't appear !");
    }
} 

doSpeech();