Node.js音频播放器

Question

我基本上想要播放一系列的mp3文件，一个接一个地播放。 这并不难，但是我正在努力保持解码器和扬声器通道打开，以便在播放完一首歌后提供新的mp3数据。 以下是我目前已经实现的播放单个mp3文件的简化版本。

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开发的模块node-lame（用于解码）和node-speaker（用于通过扬声器输出音频）。

- johnny

Answer 1

我完全没有使用你提到的模块的经验，但是我认为每次想播放一首歌曲时，您需要重新打开扬声器（因为您将解码后的音频传输到它，一旦解码器完成，它就会关闭）。

您可以重写您的代码，类似于以下内容（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);

另一种解决方案（我更喜欢的一种）是使用非常好用的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();
  });
});

- robertklep