Tiny 1.4 MB build
Uses a purpose-built audio-only FFmpeg WASM build instead of the standard 30 MB core. Much faster first load.
Video to Audio Converter
Extract the audio track from a video file and download it as MP3, AAC, WAV or Opus. The tool uses a compact audio-only FFmpeg WebAssembly build that is only 1.4 MB — much smaller than the full FFmpeg WASM. Everything runs locally in your browser.
Video to audio converter tool
Private by design. The conversion runs entirely in your browser using a WebAssembly build of FFmpeg. Your video never leaves your device. On first use, a small audio-only FFmpeg build (1.4 MB) is downloaded and cached.
Drop a video here
or click to browse — MP4, WebM, MOV, MKV and AVI are supported
Up to ~500 MB depending on your device's memory.
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Loading preview…
Conversion settings
MP3 is universally supported. Choose WAV or FLAC for lossless output.
Accepts seconds (15), MM:SS (1:30) or HH:MM:SS (0:01:30).
Source audio—
Output formatMP3 · 192 kbps
Estimated size—
Preparing…
0%
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Conversion complete
Your audio file is ready.
How it works
This tool runs a purpose-built audio-only FFmpeg build in your browser. It is only 1.4 MB, compared with the standard FFmpeg WASM build which is about 30 MB.
The build is downloaded on first use and cached by your browser, so subsequent conversions start instantly.
If the source audio codec matches the output format, the audio can be copied without re-encoding — lossless and very fast.
How to use the video to audio converter
- Upload a video. Drag an MP4, WebM, MOV, MKV or AVI file onto the drop zone, or click Choose video to browse.
- Preview the video. A built-in player shows the source file. You can scrub through it to find the part you want.
- Choose the output format. MP3, AAC, WAV, Opus, Vorbis or FLAC. Lossless formats skip the bitrate selector.
- Trim (optional). Enter a start and end time to export only part of the audio track.
- Convert and download. Click Convert to audio. The first run downloads the 1.4 MB FFmpeg build, then the audio is extracted and downloaded.
Key features and benefits
Six output formats
MP3, AAC, WAV, Opus, Vorbis and FLAC. Choose lossy for small files or lossless for perfect quality.
Trim before export
Set a start and end time to extract only the part of the audio track you need.
Fully private
Files are processed locally in your browser. Nothing is uploaded, stored, or logged anywhere.
Fast after first run
The build is cached by your browser after the first download, so later conversions start instantly.
Responsive layout
Works comfortably on phones, tablets and desktop screens.
Supported formats
The tool accepts any video container that your browser can play, and can output the following audio formats.
| Format | Extension | Type | Notes |
|---|---|---|---|
| MPEG Audio Layer III | .mp3 | Lossy | Universally supported |
| AAC | .aac | Lossy | Better quality than MP3 at the same bitrate |
| Waveform Audio | .wav | Lossless | Large files, perfect quality |
| Opus | .opus | Lossy | Best modern codec for speech and music |
| Ogg Vorbis | .ogg | Lossy | Open format, well supported |
| FLAC | .flac | Lossless | Lossless compression, smaller than WAV |
Privacy and limitations
- Fully client-side. The video is read via the File API and processed by a WebAssembly build of FFmpeg that runs in your browser. No content is transmitted to any server.
- No tracking. The tool does not record which videos you convert or what settings you choose. There is no analytics on file content.
- The FFmpeg build is downloaded on first use. A compact audio-only build (1.4 MB) is fetched from a CDN and cached by your browser. Later conversions load it from cache.
- Memory limits. Conversion happens in memory, so file size matters. WebAssembly has a hard limit of 2 GB per file, but practical limits are much lower on phones. Files up to a few hundred MB work well on desktop.
- Copy vs re-encode. If the source audio codec matches the output format, the tool copies the audio without re-encoding — lossless and very fast. Otherwise it re-encodes at the chosen bitrate.
- Videos without audio. If the source has no audio track, the conversion will fail with a clear error. This is common with AI-generated videos.
Frequently asked questions
Are my videos uploaded to a server?
No. The entire conversion process runs locally in your browser using WebAssembly. Your video files never leave your device and are not uploaded, stored, or logged anywhere.
Why does the first conversion take longer?
On first use, a compact audio-only FFmpeg WebAssembly build is downloaded. It is about 1.4 MB, which is much smaller than the full FFmpeg WASM build (about 30 MB). After the first use, the build is cached by your browser and later conversions start instantly.
Which video and audio formats are supported?
The tool accepts any video format that your browser can decode, including MP4, WebM, MOV, MKV and AVI. On the audio side, you can extract to MP3, AAC, WAV, Opus, Vorbis or FLAC.
Can I trim the audio before exporting?
Yes. You can set a start and end time in seconds, and the exported audio will contain only that portion of the original video's audio track.
Is the conversion quality lossless?
If the source audio codec matches the output format, the tool can copy the audio stream without re-encoding, which is lossless and very fast. Otherwise, the audio is re-encoded at the chosen bitrate, which is lossy.
What is the size limit?
The tool works well with files up to a few hundred megabytes, depending on your available memory. WebAssembly has a hard limit of 2 GB per file.
A practical guide to extracting audio from video
Extracting audio from a video is a common task with many use cases: saving a lecture or interview as a podcast, pulling the music from a concert recording, or turning a presentation into an audio-only file you can listen to on the go. Doing it in the browser means you do not have to install anything, and it can be done without uploading your files to a server.
Why a browser-based converter
Desktop tools like the command-line FFmpeg are powerful, but they require installation and a bit of familiarity with the terminal. Online services are convenient but typically upload your file to a remote server, which is a problem for anything confidential. A browser-based converter that runs entirely on the client gives you the best of both worlds: the convenience of a website and the privacy of a desktop application.
The technology that makes this possible is WebAssembly, a binary instruction format that runs at near-native speed inside the browser. FFmpeg — the industry-standard tool for audio and video processing — has been compiled to WebAssembly, so the same code that powers professional video pipelines can run entirely in your browser.
The size problem, and how this tool solves it
The standard FFmpeg WASM build is around 30 MB, which is a lot to download just to extract an audio track. It includes encoders and decoders for video, subtitles, and dozens of codecs you will never need for audio extraction. That is why this tool uses a purpose-built audio-only build that comes in at just 1.4 MB — about 1/20th the size.
The audio-only build supports all the common audio codecs (MP3, AAC, WAV, Opus, Vorbis, FLAC) but none of the video ones. Since we only need to extract audio, the video codecs are unnecessary. The result is a much faster first load and a smaller memory footprint.
Copy vs. re-encode
When you extract audio, there are two approaches. The first is stream copy, which takes the compressed audio data out of the video container and writes it into a new file without decoding it. This is lossless and extremely fast. The second is re-encoding, which decodes the audio and re-encodes it in the target format. This is slower and lossy, but it is necessary when the source and target formats differ.
A good converter picks the right approach automatically. If you ask for MP3 output from a video that already contains MP3 audio, stream copy is used. If you ask for WAV output from a video that contains AAC audio, re-encoding is necessary because the formats are fundamentally different.
Common pitfalls
- Videos with no audio track. Some videos — particularly those generated by AI tools — have no audio at all. The converter will report this clearly instead of failing silently.
- Mobile browser memory. WebAssembly runs in a sandboxed memory space that is more limited on phones than on desktops. Very large videos may run out of memory on older devices.
- Codec support. The browser must be able to decode the source video before FFmpeg can process it. Modern browsers handle all the common formats, but very old or exotic codecs may not work.
- Lossy sources. Extracting audio from a lossy source and re-encoding to another lossy format loses a little quality. For the best result, use a lossless output format like WAV or FLAC.
About this tool
This video to audio converter is part of the TempScript free online tools collection. It runs entirely in your browser, requires no account, and never sends your files anywhere. If you work with media regularly, you may also find our audio trimmer and image compressor useful.
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