PCM reader

lib/pcm.js

@@ -0,0 +1,54 @@
+var spawn = require("child_process").spawn,
+    stream = require("stream");
+
+// Forked from https://github.com/jhurliman/node-pcm
+module.exports = function(filename, options) {
+  var sampleStream = new stream.Stream(),
+      channels = 2,
+      output = "",
+      channel = 0,
+      oddByte;
+
+  sampleStream.readable = true;
+
+  if (options && options.channels) channels = options.channels;
+
+  var args = ["-i", filename, "-f", "s16le", "-ac", channels, "-acodec", "pcm_s16le"];
+
+  if (options && options.sampleRate) {
+    args.push("-ar", options.sampleRate);
+  }
+
+  args.push("-y", "pipe:1");
+
+  var spawned = spawn("ffmpeg", args);
+
+  spawned.stdout.on("data", function(data) {
+
+    var len = data.length;
+
+    if (oddByte != null) {
+      sampleStream.emit("data", ((data.readInt8(i++, true) << 8) | oddByte) / 32767.0, channel);
+      channel = ++channel % channels;
+    }
+
+    for (var i = 0; i < len; i += 2) {
+      sampleStream.emit("data", data.readInt16LE(i, true) / 32767.0, channel);
+      channel = ++channel % channels;
+    }
+
+    oddByte = (i < len) ? data.readUInt8(i, true) : null;
+
+  });
+
+  spawned.stderr.on("data", function(data) {
+    output += data.toString();
+  });
+
+  spawned.stderr.on("end", function() {
+    sampleStream.emit(oddByte !== undefined ? "end" : "error", output);
+  });
+
+  return sampleStream;
+
+};