How do I get the audio track out of a video over an API?

Q: How do I get the audio track out of a video over an API?

Drop the video stream with -vn and encode what's left. -c:a libmp3lame -q:a 2 gives a ~190 kbps VBR MP3, which is the usual choice when the file has to play everywhere.

Extract audio from a video with an API

Drop the video stream with -vn and encode what's left. -c:a libmp3lame -q:a 2 gives a ~190 kbps VBR MP3, which is the usual choice when the file has to play everywhere.

The ffmpeg command

What you would run locally, for reference.

ffmpeg -i input.mp4 -vn -c:a libmp3lame -q:a 2 output.mp3

The API request

The same flags, sent as JSON. Authenticate with Authorization: Token <your-api-token>.

POST /api/ffmpeg/job/

{
  "global_options": [
    "-y"
  ],
  "inputs": [
    {
      "input_source": "https://example.com/input.mp4"
    }
  ],
  "outputs": [
    {
      "filename": "output.mp3",
      "options": [
        "-vn",
        "-c:a",
        "libmp3lame",
        "-q:a",
        "2"
      ]
    }
  ]
}

Worth knowing

To avoid re-encoding entirely, use -vn -c:a copy and name the output for whatever codec is already inside — usually .m4a for AAC. It is faster, cheaper and lossless, but you don't get to pick the format.
-q:a runs backwards from CRF: 0 is the best quality, 9 the worst.

What it costs

Jobs bill in processing seconds — the CPU time this one actually uses — with a floor of 25 seconds per GB pulled out of storage to run it, so a stream-copy still counts. Uploading the output and downloading it afterwards are free. See the plans.

Related guides

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