How do I concatenate several videos into one over an API?

Q: How do I concatenate several videos into one over an API?

Pass every clip as its own entry in inputs and join them in the output with the concat filter. Set n to the number of inputs and map the two labels it produces.

Join videos with an API

Pass every clip as its own entry in inputs and join them in the output with the concat filter. Set n to the number of inputs and map the two labels it produces.

The ffmpeg command

What you would run locally, for reference.

ffmpeg -i first.mp4 -i second.mp4 \
  -filter_complex "[0:v:0][0:a:0][1:v:0][1:a:0]concat=n=2:v=1:a=1[outv][outa]" \
  -map "[outv]" -map "[outa]" \
  output.mp4

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/first.mp4"
    },
    {
      "input_source": "https://example.com/second.mp4"
    }
  ],
  "outputs": [
    {
      "filename": "output.mp4",
      "options": [
        "-filter_complex",
        "[0:v:0][0:a:0][1:v:0][1:a:0]concat=n=2:v=1:a=1[outv][outa]",
        "-map",
        "[outv]",
        "-map",
        "[outa]"
      ]
    }
  ]
}

Worth knowing

The concat filter is the way to do this here — the concat demuxer (-f concat) reads a playlist file from disk and is rejected with a 400.
The filter re-encodes, so clips with different resolutions or frame rates join fine. Bump n and add another [i:v:0][i:a:0] pair for each extra clip.
Every input needs an audio track. Joining a clip that has none makes the filter fail — give it a silent track first.

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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