diff --git a/lib/render.js b/lib/render.js
index 8bc7df0..aa1df1b 100644
--- a/lib/render.js
+++ b/lib/render.js
@@ -1,4 +1,5 @@
 var spawn = require('child_process').spawn
+var fs = require('fs')
 //var Canvas = require('canvas')
 
 var defaultSetting = {
@@ -32,6 +33,10 @@ function getPcmData (filename, options, sampleCallback, endCallback) {
     sampleRate = options.sampleRate
   }
 
+  if (!fs.existsSync(filename)) {
+    throw `File doesn't exist: ${filename}`
+  }
+
   var ffmpeg = spawn('ffmpeg', ['-i', filename, '-f', 's16le', '-ac', channels,
     '-acodec', 'pcm_s16le', '-ar', sampleRate, '-y', 'pipe:1'])
 
@@ -161,7 +166,7 @@ module.exports = function render (url, options, cb) {
       //canvasContext.fillStyle = options.baselineColor
       //canvasContext.fillRect(0, options.baseline - (options.baselineWidth / 2), options.width, options.baselineWidth)
     }
-    cb(null, canvas.toBuffer())
+    //cb(null, canvas.toBuffer())
 
     if (options.normalizedValuesCallback) {
       options.normalizedValuesCallback(normalizedVals);