ffmpeg filter_complex [0:v] in video-filter: refused, labels fine

Do not write [0:v] in a Sume video-filter graph. The server wraps your filters as [0:v]...[vout] itself, so a stream specifier is refused as invalid_filtergraph. Internal labels you invent, such as split[a][b], are fine.

This is from the Video filter docs, read 2026-10-01. If an assistant ported an ffmpeg command after the Resolve 21.1 announcement, the leading [0:v] is the line to delete.

Why is [0:v] refused?

A filter_complex string normally names its inputs and outputs. Here the request has exactly one clip, supplied as video_url, so there is nothing to select. The client supplies filters only; the server wraps [0:v] in front and [vout] behind.

Which labels are allowed?

Labels that start and end inside your graph. The docs give split[a][b] as the example.

What does the refusal look like?

The code is invalid_filtergraph; the free check returns it as a diagnostic, so nothing is billed. This sample is refused on its leading label.

curl -X POST https://api.sume.com/v1/video-filter/check \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/talk.mp4",
    "filtergraph": "[0:v]hflip"
  }'

What should I use instead?

Write the same chain without the outer labels. For a first look at the allowlist, see the filter allowlist post. Clients also cannot send vf, ffmpeg or cmd fields.