Chrome 语音合成具有较长的文本

我在 Chrome 33 中尝试使用语音合成 API 时遇到问题。它可以完美地处理较短的文本，但如果我尝试较长的文本，它就会停在中间。一旦停止后，语音合成将无法在 Chrome 中的任何地方工作，直到浏览器重新启动。

示例代码（http://jsfiddle.net/Mdm47/1/ http://jsfiddle.net/Mdm47/1/):

function speak(text) {
    var msg = new SpeechSynthesisUtterance();
    var voices = speechSynthesis.getVoices();
    msg.voice = voices[10];
    msg.voiceURI = 'native';
    msg.volume = 1;
    msg.rate = 1;
    msg.pitch = 2;
    msg.text = text;
    msg.lang = 'en-US';

    speechSynthesis.speak(msg);
}

speak('Short text');
speak('Collaboratively administrate empowered markets via plug-and-play networks. Dynamically procrastinate B2C users after installed base benefits. Dramatically visualize customer directed convergence without revolutionary ROI. Efficiently unleash cross-media information without cross-media value. Quickly maximize timely deliverables for real-time schemas. Dramatically maintain clicks-and-mortar solutions without functional solutions.');
speak('Another short text');

它在第二个文本中间停止说话，此后我无法让任何其他页面说话。

这是浏览器错误还是某种安全限制？

我在使用 Google Chrome 语音合成时遇到这个问题已经有一段时间了。经过一番调查，我发现了以下几点：

• 言语的断裂仅当声音不是母语时才会发生,
• 切断通常发生在200-300 个字符,
• 当它确实损坏时，您可以通过执行以下操作来解冻它speechSynthesis.cancel();
• The 'onend' 事件有时会决定不触发。一个奇怪的解决方法是在说出话语对象之前使用 console.log() 输出它。我还发现将发言调用包装在 setTimeout 回调中有助于解决这些问题。

为了解决这些问题，我编写了一个克服字符限制的函数，将文本分成更小的话语，然后一个接一个地播放它们。显然，有时你会听到一些奇怪的声音，因为句子可能会被分成两个单独的话语，每个话语之间有一个小的时间延迟，however代码将尝试在标点符号处分割这些点，以使声音的中断不那么明显。

Update

我已将此解决方法公开发布于https://gist.github.com/woollsta/2d146f13878a301b36d7#file-chunkify-js https://gist.github.com/woollsta/2d146f13878a301b36d7#file-chunkify-js。非常感谢布雷特·扎米尔 https://gist.github.com/brettz9感谢他的贡献。

功能：

var speechUtteranceChunker = function (utt, settings, callback) {
    settings = settings || {};
    var newUtt;
    var txt = (settings && settings.offset !== undefined ? utt.text.substring(settings.offset) : utt.text);
    if (utt.voice && utt.voice.voiceURI === 'native') { // Not part of the spec
        newUtt = utt;
        newUtt.text = txt;
        newUtt.addEventListener('end', function () {
            if (speechUtteranceChunker.cancel) {
                speechUtteranceChunker.cancel = false;
            }
            if (callback !== undefined) {
                callback();
            }
        });
    }
    else {
        var chunkLength = (settings && settings.chunkLength) || 160;
        var pattRegex = new RegExp('^[\\s\\S]{' + Math.floor(chunkLength / 2) + ',' + chunkLength + '}[.!?,]{1}|^[\\s\\S]{1,' + chunkLength + '}$|^[\\s\\S]{1,' + chunkLength + '} ');
        var chunkArr = txt.match(pattRegex);

        if (chunkArr[0] === undefined || chunkArr[0].length <= 2) {
            //call once all text has been spoken...
            if (callback !== undefined) {
                callback();
            }
            return;
        }
        var chunk = chunkArr[0];
        newUtt = new SpeechSynthesisUtterance(chunk);
        var x;
        for (x in utt) {
            if (utt.hasOwnProperty(x) && x !== 'text') {
                newUtt[x] = utt[x];
            }
        }
        newUtt.addEventListener('end', function () {
            if (speechUtteranceChunker.cancel) {
                speechUtteranceChunker.cancel = false;
                return;
            }
            settings.offset = settings.offset || 0;
            settings.offset += chunk.length - 1;
            speechUtteranceChunker(utt, settings, callback);
        });
    }

    if (settings.modifier) {
        settings.modifier(newUtt);
    }
    console.log(newUtt); //IMPORTANT!! Do not remove: Logging the object out fixes some onend firing issues.
    //placing the speak invocation inside a callback fixes ordering and onend issues.
    setTimeout(function () {
        speechSynthesis.speak(newUtt);
    }, 0);
};

如何使用它...

//create an utterance as you normally would...
var myLongText = "This is some long text, oh my goodness look how long I'm getting, wooooohooo!";

var utterance = new SpeechSynthesisUtterance(myLongText);

//modify it as you normally would
var voiceArr = speechSynthesis.getVoices();
utterance.voice = voiceArr[2];

//pass it into the chunking function to have it played out.
//you can set the max number of characters by changing the chunkLength property below.
//a callback function can also be added that will fire once the entire text has been spoken.
speechUtteranceChunker(utterance, {
    chunkLength: 120
}, function () {
    //some code to execute when done
    console.log('done');
});

希望人们发现这很有用。