Node.js使用setTimeout（）暂停和恢复流

Question

I'm working with Node.js (v4.4.7) and have written a few lines to play a sound ...

const Speaker = require('audio-speaker/stream');
const Generator = require('audio-generator/stream');

const speaker = new Speaker({
        channels: 1,          // 1 channel 
        bitDepth: 16,         // 16-bit samples 
        sampleRate: 44100     // 44,100 Hz sample rate 
      });

// Streams sample values...
const sound = new Generator(
        //Generator function, returns sample values
        function (time) {
               return Math.sin(Math.PI * 2 * time * 2000);
        },
        {
        //Duration of generated stream, in seconds, after which stream will end. 
        duration: Infinity,

        //Periodicity of the time. 
        period: Infinity
       });

// Pipe value stream to speaker
sound.pipe(speaker);

...hurray, it works! Now, let's try to pause the sound and resume it after 3 seconds ...

sound.pause();

setTimeout(()=>{
        sound.resume();
        console.log(sound.isPaused());   //  => false
}, 3000);

... brilliant, that works as well! And now, let's try the opposite and pause the sound after 3 seconds ...

setTimeout(()=>{
        sound.pause();
        console.log(sound.isPaused()); // => true / although sound is still playing 
}, 3000);

... wait, why is this not working? And why does sound.isPaused() shows "true" although sound is still playing. Is it bug or am I doing something wrong?

I went through the Node.js documentation and a couple of tutorials about streams in Node.js and could not find an explanation.In this tutorials they only use setTimout() to resume streams, but they never say anything about why you can not pause a stream this way.

Answer 1

For now, I don't know why calling .pause()/.resume() on the readable stream is not working as expected. I ended up calling .cork()/.uncork() on the writable stream, that achieves the desired result.

setTimeout(()=>{
    speaker.cork();
}, 3000);

setTimeout(()=>{
    speaker.uncork();
}, 3000);

I will update this answer as soon I have an explanation for this behaviour.