Stereo to Mid-Side Converter

Convert stereo audio files to Mid-Side format and back. Perfect for audio mastering, width adjustment, and stereo enhancement. Everything runs 100% offline in your browser.

Drop audio file here or click to browse

Supports WAV, MP3, OGG, FLAC, AAC (browser dependent)

Processing Mode

Output Format

Understanding Mid-Side Processing

Mid-Side (M/S) processing is a powerful technique for stereo manipulation where audio is split into:

Mid (M): The center channel - sum of left and right (L+R)
Side (S): The difference channel - difference between left and right (L-R)

Common Use Cases

Scenario	Benefit
Stereo Width Adjustment	Increase/decrease side channel for width control
Vocal Enhancement	Process mid channel separately from sides
Mono Compatibility	Check how mix collapses to mono

Step-by-Step Instructions

Upload a stereo audio file using the drag-and-drop area
Choose conversion direction (Stereo→M/S or M/S→Stereo)
Select output format (WAV for quality, WebM for size)
Preview the result and download when satisfied

A-B Comparison

Original

Processed

Frequently Asked Questions

What audio formats are supported?

This tool supports any format your browser can decode, typically including WAV, MP3, OGG, FLAC, and AAC/M4A. Output is always WAV or WebM Opus.

Does this work offline?

Yes, all processing happens locally in your browser. No audio data is sent to any server.

When should I use WAV vs WebM Opus?

Use WAV for maximum quality and professional work. Use WebM Opus for smaller file sizes when quality loss is acceptable.

What if my file is mono?

Mono files will be converted to stereo first when processing to Mid-Side format.

How It Works

Audio is decoded using Web Audio API's AudioContext
Processing happens via OfflineAudioContext with sample-by-sample math
For M/S conversion: Mid = (L+R)/2, Side = (L-R)/2
For stereo conversion: L = Mid+Side, R = Mid-Side
WAV files are encoded manually using RIFF PCM format
WebM Opus uses MediaRecorder API when available

For informational and educational purposes only. Processing occurs locally in your browser and depends on device codecs. Audio quality and compatibility may vary. For professional work verify loudness levels formats and legal rights before publishing.

References: W3C Web Audio API, MediaRecorder API, RIFF WAV file format, Opus Audio Codec overview

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Convert Stereo to Mid Side and Back

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