How do I reduce a video's file size over an API?

Q: How do I reduce a video's file size over an API?

Re-encode with a higher -crf value. CRF is a quality target, not a size target: 23 is ffmpeg's default, 28 is noticeably smaller and still fine for most footage, and anything past 30 starts to show. Each +6 roughly halves the file.

Compress a video with an API

Re-encode with a higher -crf value. CRF is a quality target, not a size target: 23 is ffmpeg's default, 28 is noticeably smaller and still fine for most footage, and anything past 30 starts to show. Each +6 roughly halves the file.

The ffmpeg command

What you would run locally, for reference.

ffmpeg -i input.mp4 \
  -c:v libx264 -crf 28 -preset medium \
  -c:a aac -b:a 128k \
  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/input.mp4"
    }
  ],
  "outputs": [
    {
      "filename": "output.mp4",
      "options": [
        "-c:v",
        "libx264",
        "-crf",
        "28",
        "-preset",
        "medium",
        "-c:a",
        "aac",
        "-b:a",
        "128k"
      ]
    }
  ]
}

Worth knowing

-preset trades CPU time for compression: slow gives a smaller file than medium at the same CRF, but takes longer — and here CPU time is what you pay for.
There is no quality to recover: compressing an already-compressed file degrades it again. Always re-encode from the highest-quality source you have.

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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