sox_and_ffmpeg.ipynb

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    "[&larr; Back to Index](index.html)"
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  {
   "cell_type": "markdown",
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   "source": [
    "# SoX"
   ]
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   "source": [
    "[SoX](http://sox.sourceforge.net/) is a command-line utility for audio processing, e.g. convert file format, convert sample rate, remix, trim, pad, normalize, etc."
   ]
  },
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   "source": [
    "To install, for Mac:\n",
    "\n",
    "    brew install sox"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "skip"
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   },
   "source": [
    "To play or record audio from the command line:"
   ]
  },
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   "source": [
    "    rec test.wav\n",
    "    \n",
    "    play test.wav"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Resample to 22050 Hz:\n",
    "\n",
    "    sox in.wav -r 22050 out.wav"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Normalize gain, e.g. to avoid clipping:\n",
    "\n",
    "    sox in.wav --norm out.wav"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Down-mix all input channels to mono:\n",
    "\n",
    "    sox in.wav out.wav remix -"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Convert to 16-bit signed integer:\n",
    "\n",
    "    sox in.wav -b 16 -e signed-integer out.wav"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Trim the audio file starting at 1 min 15 sec and ending at 1 min 45 sec:\n",
    "\n",
    "    sox in.wav out.wav trim 1:15 =1:45\n",
    "    sox in.wav out.wav trim 1:15 0:30\n",
    "    sox in.wav out.wav trim 75 30"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Pad 1 second of silence to the beginning and 2 seconds of silence to the end:\n",
    "\n",
    "    sox in.wav out.wav pad 1 2"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# ffmpeg"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "[ffmpeg](https://www.ffmpeg.org/) is a framework to convert among different audio and video file formats. Use `ffmpeg` if you want to convert WAV to MP3."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "To install on MacOS:\n",
    "\n",
    "    brew install ffmpeg"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Convert a WAV file to MP3:\n",
    "\n",
    "    ffmpeg -i in.wav out.mp3 "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Down-mix all input channels to mono with a bitrate of 128k:\n",
    "\n",
    "    ffmpeg -i in.wav -ac 1 -ab 128k out.mp3"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "To do the above command for all wav files in a directory:\n",
    "\n",
    "    for i in wav/*; do ffmpeg -y -i \"$i\" -ac 1 -ab 128k mp3/`basename \"$i\" .wav`.mp3; done\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "[&larr; Back to Index](index.html)"
   ]
  }
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