How do I change a video's resolution over an API?

Q: How do I change a video's resolution over an API?

Use the scale filter with a fixed height and -2 for the width: -vf scale=-2:720. The -2 keeps the aspect ratio and rounds the width to an even number, which H.264 requires.

Resize a video with an API

Use the scale filter with a fixed height and -2 for the width: -vf scale=-2:720. The -2 keeps the aspect ratio and rounds the width to an even number, which H.264 requires.

The ffmpeg command

What you would run locally, for reference.

ffmpeg -i input.mp4 \
  -vf scale=-2:720 \
  -c:v libx264 -crf 23 -c:a copy \
  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": [
        "-vf",
        "scale=-2:720",
        "-c:v",
        "libx264",
        "-crf",
        "23",
        "-c:a",
        "copy"
      ]
    }
  ]
}

Worth knowing

Use -2 and not -1: -1 can land on an odd width, which libx264 rejects outright.
-c:a copy passes the audio through untouched — faster, cheaper, and no generation loss, since resizing has nothing to do with the audio track.

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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