replace web-audio-api to ffmpeg

drone1 · Feb 9, 2017 · 282e539 · 282e539
1 parent f951924
commit 282e539
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Showing 3 changed files with 126 additions and 67 deletions.
diff --git a/lib/render.js b/lib/render.js
@@ -1,5 +1,4 @@
-var AudioContext = require('web-audio-api').AudioContext
-var fs = require('fs')
+var spawn = require('child_process').spawn
 var Canvas = require('canvas')
 
 var defaultSetting = {
@@ -16,9 +15,64 @@ var defaultSetting = {
   baselineWidth: 0,
   baselineColor: 'white'
 }
+//https://github.com/jhurliman/node-pcm
+function getPcmData (filename, options, sampleCallback, endCallback) {
+  var outputStr = ''
+  var oddByte = null
+  var channel = 0
+  var gotData = false
+
+  options = options || {}
+  var channels = 2
+  if (typeof options.stereo !== 'undefined') {
+    channels = (options.stereo) ? 2 : 1
+  }
+  var sampleRate = 44100
+  if (typeof options.sampleRate !== 'undefined') {
+    sampleRate = options.sampleRate
+  }
+
+  var ffmpeg = spawn('ffmpeg', ['-i', filename, '-f', 's16le', '-ac', channels,
+    '-acodec', 'pcm_s16le', '-ar', sampleRate, '-y', 'pipe:1'])
+
+  ffmpeg.stdout.on('data', function (data) {
+    gotData = true
+
+    var value
+    var i = 0
+    var dataLen = data.length
+
+    // If there is a leftover byte from the previous block, combine it with the
+    // first byte from this block
+    if (oddByte !== null) {
+      value = ((data.readInt8(i++, true) << 8) | oddByte) / 32767.0
+      sampleCallback(value, channel)
+      channel = ++channel % 2
+    }
+
+    for (; i < dataLen; i += 2) {
+      value = data.readInt16LE(i, true) / 32767.0
+      sampleCallback(value, channel)
+      channel = ++channel % 2
+    }
+
+    oddByte = (i < dataLen) ? data.readUInt8(i, true) : null
+  })
+
+  ffmpeg.stderr.on('data', function (data) {
+    outputStr += data.toString()
+  })
+
+  ffmpeg.stderr.on('end', function () {
+    if (gotData) {
+      endCallback(null, outputStr)
+    } else {
+      endCallback(outputStr, null)
+    }
+  })
+}
 
 module.exports = function render (url, options, cb) {
-  var audioContext = new AudioContext()
   if (typeof options === 'function') {
     cb = options
     options = {}
@@ -35,70 +89,76 @@ module.exports = function render (url, options, cb) {
 
   var canvas = new Canvas(options.width, options.height)
   var canvasContext = canvas.getContext('2d')
-  fs.readFile(url, function (err, buffer) {
-    if (err) return cb(err)
-
-    audioContext.decodeAudioData(buffer, function (result) {
-      var data = result.getChannelData(0)
-      var step = Math.floor(data.length / options.width)
-      var ratio = options.baseline / options.height
-      var vals = []
-
-      canvasContext.fillStyle = options.backgroundColor
-      canvasContext.fillRect(0, 0, options.width, options.height)
-
-      canvasContext.fillStyle = options.waveColor
-
-      for (var i = 0; i < options.width; i += options.barWidth) {
-        var position = i * step
-        var sum = 0.0
-        for (var j = position; j <= (position + step) - 1; j++) {
-          sum += Math.pow(data[j], 2)
-        }
-        vals.push(Math.sqrt(sum / data.length) * 10000)
+  var data = []
+
+  getPcmData(url, null, function (sample, channel) {
+    if (channel === 0) {
+      data.push(sample)
+    }
+  }, function (err) {
+
+    if (err) {
+      return cb(err)
+    }
+
+    var step = Math.floor(data.length / options.width)
+    var ratio = options.baseline / options.height
+    var vals = []
+
+    canvasContext.fillStyle = options.backgroundColor
+    canvasContext.fillRect(0, 0, options.width, options.height)
+
+    canvasContext.fillStyle = options.waveColor
+
+    for (var i = 0; i < options.width; i += options.barWidth) {
+      var position = i * step
+      var sum = 0.0
+      for (var j = position; j <= (position + step) - 1; j++) {
+        sum += Math.pow(data[j], 2)
       }
+      vals.push(Math.sqrt(sum / data.length) * 10000)
+    }
+
+    var maxValue = Math.max.apply(null, vals)
 
-      var maxValue = Math.max.apply(null, vals)
-
-      vals.forEach(function (val, index) {
-        var scale = options.height / maxValue
-        val *= scale
-        var w = options.barWidth
-        if (options.barGap !== 0) {
-          w *= Math.abs(1 - options.barGap)
-        }
-        var x = index * options.barWidth + (w / 2)
-
-        var lowerHeight = val * ratio
-
-        if (lowerHeight < options.padding) {
-          lowerHeight = 1
-        } else {
-          lowerHeight -= options.padding
-        }
-
-        var upperHeight = val * (1 - ratio)
-
-        if (upperHeight < options.padding) {
-          upperHeight = 1
-        } else {
-          upperHeight -= options.padding
-        }
-
-        if (options.waveAlpha < 1) {
-          canvasContext.clearRect(x, options.baseline, w, upperHeight)
-          canvasContext.clearRect(x, options.baseline, w, -lowerHeight)
-          canvasContext.globalAlpha = options.waveAlpha
-        }
-        canvasContext.fillRect(x, options.baseline, w, upperHeight)
-        canvasContext.fillRect(x, options.baseline, w, -lowerHeight)
-      })
-
-      if (options.baselineWidth >= 1) {
-        canvasContext.fillStyle = options.baselineColor
-        canvasContext.fillRect(0, options.baseline - (options.baselineWidth / 2), options.width, options.baselineWidth)
+    vals.forEach(function (val, index) {
+      var scale = options.height / maxValue
+      val *= scale
+      var w = options.barWidth
+      if (options.barGap !== 0) {
+        w *= Math.abs(1 - options.barGap)
       }
-      cb(null, canvas.toBuffer())
+      var x = index * options.barWidth + (w / 2)
+
+      var lowerHeight = val * ratio
+
+      if (lowerHeight < options.padding) {
+        lowerHeight = 1
+      } else {
+        lowerHeight -= options.padding
+      }
+
+      var upperHeight = val * (1 - ratio)
+
+      if (upperHeight < options.padding) {
+        upperHeight = 1
+      } else {
+        upperHeight -= options.padding
+      }
+
+      if (options.waveAlpha < 1) {
+        canvasContext.clearRect(x, options.baseline, w, upperHeight)
+        canvasContext.clearRect(x, options.baseline, w, -lowerHeight)
+        canvasContext.globalAlpha = options.waveAlpha
+      }
+      canvasContext.fillRect(x, options.baseline, w, upperHeight)
+      canvasContext.fillRect(x, options.baseline, w, -lowerHeight)
     })
+
+    if (options.baselineWidth >= 1) {
+      canvasContext.fillStyle = options.baselineColor
+      canvasContext.fillRect(0, options.baseline - (options.baselineWidth / 2), options.width, options.baselineWidth)
+    }
+    cb(null, canvas.toBuffer())
   })
 }
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "node-wave",
-  "version": "0.0.3",
+  "version": "0.0.4",
   "description": "Render waveform image like SoundCloud",
   "main": "index.js",
   "scripts": {
@@ -19,8 +19,7 @@
     "url": "git+https://github.com/trquoccuong/node-wave.git"
   },
   "dependencies": {
-    "canvas": "^1.6.2",
-    "web-audio-api": "^0.2.2"
+    "canvas": "^1.6.2"
   },
   "devDependencies": {
     "mocha": "^3.2.0",

diff --git a/test/out.png b/test/out.png