javascript - Node.js 音频播放器

Question

我基本上想依次播放一系列 mp3 文件。这不应该太难，但我正在努力让解码器和扬声器 channel 保持打开状态，以便在播放完一首歌曲后输入新的 mp3 数据。这是我目前使用的压缩版本，播放一个 mp3 文件。

var audioOptions = {channels: 2, bitDepth: 16, sampleRate: 44100};

// Create Decoder and Speaker
var decoder = lame.Decoder();
var speaker = new Speaker(audioOptions);

// My Playlist
var songs = ['samples/Piano11.mp3','samples/Piano12.mp3','samples/Piano13.mp3'];

// Read the first file
var inputStream = fs.createReadStream(songs[0]);

// Pipe the read data into the decoder and then out to the speakers
inputStream.pipe(decoder).pipe(speaker);

speaker.on('flush', function(){
  // Play next song
});

我正在使用 TooTallNate 的模块 node-lame (用于解码)和 node-speaker (用于通过扬声器输出音频)。

Answer 1

对您提到的模块没有任何经验，但我认为您每次想要播放歌曲时都需要重新打开扬声器(因为您将解码后的音频传输到扬声器，解码器完成后它将关闭)。

您可以将您的代码重写成这样(未经测试)；

var audioOptions = {channels: 2, bitDepth: 16, sampleRate: 44100};

// Create Decoder and Speaker
var decoder = lame.Decoder();

// My Playlist
var songs = ['samples/Piano11.mp3','samples/Piano12.mp3','samples/Piano13.mp3'];

// Recursive function that plays song with index 'i'.
function playSong(i) {
  var speaker     = new Speaker(audioOptions);
  // Read the first file
  var inputStream = fs.createReadStream(songs[i]);
  // Pipe the read data into the decoder and then out to the speakers
  inputStream.pipe(decoder).pipe(speaker);
  speaker.on('flush', function(){
    // Play next song, if there is one.
    if (i < songs.length - 1)
      playSong(i + 1);
  });
}

// Start with the first song.
playSong(0);

另一个解决方案(我更喜欢的一个)是使用非常好的 async模块:

var async = require('async');
...
async.eachSeries(songs, function(song, done) {
  var speaker     = new Speaker(audioOptions);
  var inputStream = fs.createReadStream(song);

  inputStream.pipe(decoder).pipe(speaker);

  speaker.on('flush', function() {
    // signal async that it should process the next song in the array  
    done();
  });
});