Using youtube_dl.YoutubeDL to download audio only (options help)

[heyitswither]

Please follow the guide below

• You will be asked some questions and requested to provide some information, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your issue (like this: [x])
• Use the Preview tab to see what your issue will actually look like

---

Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2018.07.29. If it's not, read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2018.07.29

Before submitting an issue make sure you have:

• At least skimmed through the README, most notably the FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones
• Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)
• Site support request (request for adding support for a new site)
• Feature request (request for a new functionality)
• Question
• Other

---

The following sections concretize particular purposed issues, you can erase any section (the contents between triple ---) not applicable to your issue

---

Description of your issue, suggested solution and other information

I am trying to use youtube_dl.YoutubeDL to download the audio track of a video.

{
    "default_search": "ytsearch",
    "quiet": true,
    "restrictfilenames": true,
    "format": "bestaudio",
    "postprocessors": [{
        "key": "FFmpegExtractAudio",
        "preferredcodec": "wav",
        "preferredquality": "48000",
    }]
}

I believe the options are the only thing causing my problem, the video is downloaded fine. See ffprobe of the downloaded file below.

Input #0, matroska,webm, from 'Electric_Light_Orchestra___Mr__Blue_Sky__Audio.wav':
  Metadata:
    encoder         : google/video-file
  Duration: 00:05:04.10, start: -0.007000, bitrate: 129 kb/s
    Stream #0:0(eng): Audio: opus, 48000 Hz, stereo, fltp (default)

The .wav was added by me.

[dstftw]

Post the complete verbose output.