JR LocalLab
Processed on your device

Extract Audio from Video

Yes. You can extract high-fidelity audio from your MP4, WebM, and MOV videos directly in your browser without uploading your files. Using client-side WebCodecs and mp4box.js, extraction runs locally on your hardware.

Browse files or drag & drop

Files never leave your browser. Zero cloud uploads.

Supports MP4, M4V, MOV, or WebM video (up to 1 GB)

Your files are processed in your browser and are not uploaded by our code. You can confirm this in your browser's Network tab. Third-party ad scripts load on the page, outside the tool area, and are not given your files.

How does it work locally?

1

Select Video File

Drag your MP4, WebM, or MOV video into the drop zone. The file is read locally using File.slice streaming.

2

Inspect & Demux Stream

The tool inspects the video container atoms. If an AAC track is detected, direct stream-copy isolates the sound losslessly.

3

Export Audio File

Save your audio as an original M4A stream copy, an uncompressed 16-bit PCM WAV, or an MP3 file at up to 320 kbps.

Tips for Best Results

  • If your video contains an AAC audio track, choose M4A for instantaneous extraction with zero re-encoding loss.
  • For universal playback in older car stereos and media players, select MP3 at 192 kbps or 320 kbps.
  • Choose uncompressed WAV when importing the extracted audio into video editing software or DAWs.
  • You can verify that your video never uploads by watching the Network tab in your browser Developer Tools.

Format Comparison

FormatCompression TypeQuality FidelityBest For
M4A (AAC)Lossy (Stream Copy)Exact Source Match (No Loss)Original Apple & Web MP4 files
WAVUncompressed PCMStudio Master (Lossless)Audio editing and DAW production
MP3Lossy (LAME)High (Selectable kbps)Universal playback on legacy devices

Limits and Technical Specifications

  • Maximum video file size: 1 GB (processed in streaming chunks to protect browser RAM).
  • Supported video containers: MP4, M4V, MOV, and WebM.
  • Encrypted, DRM-protected, or streaming URL sources are strictly not supported.

Frequently Asked Questions

Are my video files uploaded to a remote server?

No. All demuxing and audio extraction happens entirely within your web browser using WebAssembly and client-side decoders.

What is lossless direct AAC stream copy?

When your MP4 or MOV contains an AAC audio track, our tool copies the exact compressed stream into an M4A container without re-encoding.

Can I extract audio from large video files?

Yes. Files up to 1 GB are read incrementally in small chunks via File.slice so your browser tab does not run out of memory.

What audio formats can I download?

You can download direct M4A stream copies, 16-bit uncompressed WAV files, or MP3 files at your choice of bitrate up to 320 kbps.

Why is the first audio extraction run slower?

The initial extraction loads the client-side parsing libraries into browser memory. Subsequent conversions run much faster.

Related In-Browser Tools

MP4 to MP3 Converter

Dedicated in-browser MP4 to MP3 audio converter.

Open Tool →

Audio Extraction Guide

Learn how video demuxing and stream copy work.

Open Tool →

MP3 vs M4A vs WAV

Detailed comparison of audio formats and bitrates.

Open Tool →

Suggested Tools & Resources

Independent Recommendations

Audacity

Free

Open-source multitrack audio editor and recording suite with spectral analysis and effects.

Best for: Desktop podcast recording, audio cleanup, and sound effect mixing
Visit Official Site →

Descript

Freemium

Text-based video and podcast editor with voice cloning and automatic filler word removal.

Best for: Editing video and podcast audio like a text document
Visit Official Site →

CapCut Web

Freemium

Cloud-enabled video editor with auto-captions, visual templates, and background removal.

Best for: Short-form video creation for social media channels
Visit Official Site →
Also on JR LocalLab:
MP4 to MP3Image ConverterAudio Extraction Guide