Takes an audio or video file and changes its tempo by a factor from 0.5 (half sp
Takes an audio or video file and changes its tempo by a factor from 0.5 (half speed) to 2.0 (double speed) while keeping the pitch, using the Rubber Band time-stretching library through ffmpeg — good for faster listening, language learning at reduced speed, or fitting a voice-over into a slot. The new running time is measured and returned. All timestamps of the original scale by 1/factor. Runs locally with ffmpeg; nothing leaves this machine and nothing is stored.
Answeringour last check, 2026-10-31
1 of 1checks answered this week
1032 msmedian answer time
$0.003listed price per call
$0.003price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://medien.halowerk.com/v1/speed-change
| Category | Image and media |
|---|---|
| Provider host | medien.halowerk.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 1 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-10-31 | valid payment request | 402 | $0.003 | 1032 ms |
Example input (from the provider)
{
"body": {
"duration_minutes": 1,
"factor": 1.25,
"source": {
"url": "https://static.deepgram.com/examples/Bueller-Life-moves-pretty-fast.wav"
}
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"additionalProperties": false,
"properties": {
"duration_minutes": {
"description": "Length in started minutes \u2014 this is what you are billed for.",
"maximum": 60,
"minimum": 1,
"type": "integer"
},
"factor": {
"default": 1.25,
"maximum": 2,
"minimum": 0.5,
"type": "number"
},
"output_format": {
"default": "mp3",
"enum": [
"opus",
"mp3",
"wav",
"flac"
],
"type": "string"
},
"source": {
"additionalProperties": false,
"description": "The recording. Either url or content_base64.",
"properties": {
"content_base64": {
"description": "The file inline, base64. Larger files by url.",
"maxLength": 12000000,
"type": "string"
},
"filename": {
"maxLength": 260,
"type": "string"
},
"url": {
"description": "Public http(s) URL of the file.",
"maxLength": 2048,
"type": "string"
}
},
"type": "object"
}
},
"required": [
"source",
"duration_minutes",
"factor"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST",
"PUT",
"PATCH"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}