retime_video

ffmpeg

Make a video last an exact number of seconds. New in-between frames are synthesised by motion interpolation, so a stretched clip still moves smoothly instead of stuttering on held frames; audio is tempo-stretched at its original pitch.

When to use: The user states a duration — 'make this 8-second clip run for 40 seconds', 'fit this into a 15-second slot' — or a speed multiplier.
Not for: Cutting a clip down to length by removing footage (trim_video). Simply changing the frame rate (ffmpeg_command).
Returns: A signed download URL for the retimed mp4, alongside the source, target and actual durations.
Runtime: Slow — a large input can take minutes. The call is synchronous, so the request simply stays open until the file comes back.

Parameters

Name	Type	Required	Description
file_url	string	no	Public http(s) URL of the input file (preferred — fetched server-side, so the bytes never pass through your context). Private, loopback and cloud-metadata addresses are blocked.
file_base64	string	no	Base64 of a small inline input file (up to about 15MB). Provide "filename" too.
filename	string	no	Original filename including its extension, e.g. "report.pdf". The extension is how the source format is detected.
target_duration	number	no	How many seconds the finished video should last. Give this OR speed.
speed	number	no	Speed multiplier instead of a duration: 0.5 is half speed, 2 is double.
output_filename	string	no	Desired output filename.

Example call

JSON-RPC tools/call body (sent to https://convertfleet.com/api/mcp):

{
  "jsonrpc": "2.0", "id": 1, "method": "tools/call",
  "params": { "name": "retime_video", "arguments": {
               "file_url": "https://example.com/input"
             } }
}

Connect first

curl -sN https://convertfleet.com/api/mcp \
  -H "Authorization: Bearer flt_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}'

See the quickstarts for Hermes, Claude, Cursor, OpenClaw, n8n, Zapier and Make.