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Audio Time Stretch & Pitch

Change speed without pitch, or pitch without speed

Uses FFmpeg atempo for time-stretching and asetrate+atempo for pitch shifting.

Click to upload file or drag and drop file here

Maximum file size: 200MB Supported formats: audio/*

Key Facts

Category
Media
Input Types
file, select, number
Output Type
file
Sample Coverage
4
API Ready
Yes

Overview

This tool lets you adjust audio speed without changing pitch or shift pitch without altering speed, using FFmpeg's atempo and asetrate filters for precise control.

When to Use

  • •When you need to speed up or slow down audio for efficient listening or editing without pitch distortion.
  • •When transposing music to a different key for practice, performance, or compatibility.
  • •When creating audio effects that require independent speed and pitch adjustments, such as for video synchronization.

How It Works

  • •Upload your audio file in a supported format like MP3, WAV, or AAC.
  • •Select the operation mode: time-stretch to change speed or pitch-shift to change pitch.
  • •Set the tempo factor (0.25 to 4) or semitone shift (-12 to 12) as needed.
  • •Choose the output format and download the processed file.

Use Cases

Adjusting podcast or audiobook playback speed for time-efficient listening without voice distortion.
Transposing musical tracks to match vocal or instrumental ranges during practice or recording.
Synchronizing audio with slow-motion or fast-forward video sequences while maintaining clarity.

Examples

1. Speed Up a Podcast Episode

Commuter
Background
A user wants to listen to a 90-minute podcast during a 45-minute commute.
Problem
Standard playback is too slow, and speeding up in media players often distorts speech pitch.
How to Use
Upload the podcast MP3 file, select 'Time Stretch' mode, set tempo factor to 2.0, and output as MP3.
Outcome
The podcast plays in half the time with clear, natural-sounding voices.

2. Transpose a Song for Guitar Practice

Musician
Background
A guitarist needs to practice a song recorded in A major but requires it in F major for easier chord shapes.
Problem
The original key is too high, and manual transposition is error-prone and time-consuming.
How to Use
Upload the audio file, choose 'Pitch Shift' mode, set semitones to -4 (from A to F), and output as WAV for high fidelity.
Outcome
The track is shifted down by 4 semitones, making it playable in the desired key without tempo change.

3. Create Slow-Motion Audio for Video

Video Editor
Background
Editing a sports highlight reel with a slow-motion replay that needs matching audio.
Problem
Slowing down the video also slows the audio, lowering the pitch and making it sound unnatural.
How to Use
Upload the audio clip, select 'Time Stretch', set tempo factor to 0.5, and output in AAC format for video integration.
Example Config
{"mode": "time-stretch", "tempoFactor": 0.5, "outputFormat": "aac"}
Outcome
Audio is slowed to half speed while preserving the original pitch, ideal for slow-motion effects.

Try with Samples

audio, file
WebRTC Real-Time Communication Samples
Comprehensive WebRTC samples for peer-to-peer audio/video communication, data channels, screen sharing, and signaling server implementation
title token time
audio
Copyright-Free AAC Audio Samples
High-quality AAC encoded audio samples for testing and development, featuring nature sounds and meditation music with excellent compression
title token audio
audio
Copyright-Free MP3 Audio Samples
Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio
title token audio
audio
Copyright-Free WAV Audio Samples
Uncompressed PCM WAV audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music
title token audio
audio

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FAQ

What audio formats can I upload?

Any audio format supported by FFmpeg, such as MP3, WAV, AAC, OGG, FLAC, and more.

How does time-stretching preserve pitch?

It uses FFmpeg's atempo filter to adjust speed while keeping the original pitch unchanged.

Can I process multiple files at once?

No, the tool handles one audio file per session to maintain processing quality.

What is the maximum file size allowed?

Audio files must be under 200 MB.

Is there a limit on tempo or pitch adjustment?

Tempo factor ranges from 0.25 to 4, and pitch shift from -12 to 12 semitones.

API Documentation

Request Endpoint

POST /en/api/tools/audio-time-stretch-pitch

Request Parameters

Parameter Name Type Required Description
audioFile file (Upload required) Yes -
mode select No -
tempoFactor number No -
semitones number No -
outputFormat select No -

File type parameters need to be uploaded first via POST /upload/audio-time-stretch-pitch to get filePath, then pass filePath to the corresponding file field.

Response Format

{
  "filePath": "/public/processing/randomid.ext",
  "fileName": "output.ext",
  "contentType": "application/octet-stream",
  "size": 1024,
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}
File: File

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-audio-time-stretch-pitch": {
      "name": "audio-time-stretch-pitch",
      "description": "Change speed without pitch, or pitch without speed",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=audio-time-stretch-pitch",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

Supports URL file links or Base64 encoding for file parameters.

If you encounter any issues, please contact us at [email protected]