Audio Channel Converter Online

An audio channel converter that upmixes stereo to 5.1, 7.1, 7.1.4 or 7.1.6 surround sound and downmixes surround back to stereo or mono. Four upmix algorithms — Simple, Matrix, Enhanced and Residual — plus standardized downmix coefficients, all running in your browser.

How to Convert Audio Channels

Choose your conversion direction: Upmix (stereo → surround) or Downmix (surround → stereo/mono)

Upload your audio file — MP3, WAV, FLAC, OGG, AAC, AC3, and more are supported

The tool auto-detects the number of channels in your file

For upmix: select target (5.1, 7.1, 7.1.4 or 7.1.6), choose algorithm (Simple, Matrix, Enhanced, or Residual), and pick output format

For downmix: select target (Stereo or Mono) and output format

Click "Convert" and wait for processing to complete

Download your converted file

Convert between stereo and surround sound formats instantly in your browser

Process

Drop your audio file here or browse

MP4, WEBM, MOV, MP3, WAV, M4A, OGG, FLAC, AAC, M4B, WMA, AIFF, OPUS, CAF, MKV, AVI, WMV, FLV, M4V, 3GP, TS, MTS, M2TS, VOB, MPG, MPEG, OGV, DSF, DFF ·

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Target Configuration

Upmix Algorithm how the surround channels are created

Output Format MP3 does not support more than 2 channels

Speaker Layout

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💡 How It Works

Target Configuration

Output Format

💡 How Downmixing Works

Downmixing combines multiple channels into fewer channels using standardized mixing coefficients. The center channel is distributed equally to left and right. Surround channels are mixed into the front at a reduced level (-3 dB). The LFE (subwoofer) channel is attenuated and added to the mix. This is the same algorithm used by professional audio software and hardware receivers.

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🎧 Per-channel monitor

Listen to each channel on its own — solo, mute, levels and waveform. No download.

FL/FR — front, C — center, LFE — subwoofer, SL/SR — surround, BL/BR — rear, T… — height.

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Immersive stereo (headphones)

Binaural 3D render of the channels for headphones. This is not Dolby Atmos.

🎧 Sounds best with headphones.

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Conversion Complete!

Key Features

Upmix stereo to 5.1 or 7.1 surround sound

Build a 6-channel home-theater layout or an 8-channel premium layout from a mono or stereo source.

Four algorithms: Simple, Matrix, Enhanced, Residual

Matrix steers the L+R common signal to the center and the L−R difference to the surrounds; Residual goes further, making the front L/R carry only what is left so the field is wider and more evenly distributed.

Downmix surround to stereo or mono

Folds 5.1 or 7.1 back to stereo with the standardized ISO/IEC 13818-7 coefficients used by hardware receivers.

LFE bass management and surround delay

Enhanced mode routes only sub-120 Hz frequencies to the LFE subwoofer channel and delays the surrounds by 15 ms for added depth.

Why Use This Channel Converter

No software to install and no registration. Process files of any length entirely in your browser. Supports all major audio formats for both input and output. Four upmix algorithms from a simple copy to a fully distributed spatial field. Professional downmix coefficients matching hardware receivers. The channel maths runs natively in your browser via Web Audio; FLAC and OGG are encoded with WebAssembly.

Frequently Asked Questions

Can I convert stereo to Dolby Atmos?

No — true Dolby Atmos is a licensed, object-based format that cannot be created in a browser, and calling an ordinary upmix Dolby Atmos would be inaccurate. What you can do is upmix to 5.1, 7.1 or 7.1.4 (with height channels), audition each channel right here, and turn on a binaural immersive mode for headphones.

Can I create real surround sound from stereo?

True surround requires recording with multiple microphones. However, Matrix Decode extracts genuine spatial information from stereo — the L-R difference signal contains reverb, ambience, and spatial effects that naturally belong in surround speakers. The result is noticeably more immersive than plain stereo, especially for well-mixed music and movie soundtracks.

Which upmix algorithm should I use?

Matrix Decode is the best balance of quality and compatibility. Enhanced adds proper bass management (LFE with 120 Hz lowpass) and surround delay for a more cinematic feel. Residual goes one step further — the front L/R carry only the residual after the center and ambience are extracted, giving the widest, most evenly distributed field while still folding back faithfully to stereo. Simple is fastest but just copies channels without spatial processing.

Why can't I save surround audio as MP3?

The MP3 specification only supports up to 2 channels (stereo). For multichannel audio, use FLAC (lossless, best quality), WAV (lossless, larger files), or OGG Vorbis (lossy but compact). All three fully support 5.1 and 7.1 channel layouts.

Will downmixing 5.1 to stereo lose quality?

Downmixing uses standardized mixing coefficients (ISO/IEC 13818-7) to combine all channels into stereo. You don't lose audio content — the center, surrounds, and LFE are blended into L/R at calibrated levels. The result sounds natural on headphones and stereo speakers.

What is the LFE channel?

LFE stands for Low Frequency Effects — it's the ".1" in 5.1 and 7.1. It carries only bass frequencies (below 120 Hz) intended for a subwoofer. In Enhanced upmix mode, bass is separated from the main mix using a lowpass filter and routed to the LFE channel.

Does this work with video files?

Yes — drop in a video file (MP4, WebM, MOV, MKV and more) and the tool extracts its audio track and converts the channels. The output is an audio file (FLAC, WAV, OGG or MP3), not a re-muxed video.

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Published 16 Feb 2026 Updated 03 Jun 2026 Authors: The Supreme