Extract Audio from AVI to MP3 — Free Online Tool
Extract the audio track from an AVI file and save it as an MP3 using the LAME encoder. AVI files commonly store audio as MP3 (libmp3lame) already, but this tool re-encodes at your chosen bitrate to produce a clean, standalone MP3 file compatible with virtually every device and media player.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your AVI file here
or click to browse
Free — no uploads, no signups. Your files never leave your browser.
Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
AVI is a container format that interleaves audio and video data into a single file. Extracting audio to MP3 means the video stream is completely discarded (using the -vn flag), and the audio stream is re-encoded using the LAME MP3 encoder (libmp3lame) at the target bitrate. Even if the AVI's audio is already MP3-encoded, the stream is not simply copied — it is decoded and re-encoded to ensure a clean, standards-compliant MP3 output file with proper ID3 tag support. The result is a standalone .mp3 file with no video data, substantially smaller than the original AVI.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool. In the browser-based version of this tool, FFmpeg runs via WebAssembly (ffmpeg.wasm) entirely within your browser — no files leave your device. |
-i input.avi
|
Specifies the input AVI file. FFmpeg reads the RIFF/AVI container, identifies the interleaved audio and video streams, and prepares them for processing or discard. |
-vn
|
Disables video output entirely. Since we are extracting only the audio track and MP3 cannot contain video, this flag tells FFmpeg to ignore all video streams in the AVI and not attempt to encode them into the output file. |
-c:a libmp3lame
|
Specifies the LAME MP3 encoder for the audio output stream. LAME (libmp3lame) is the industry-standard open-source MP3 encoder, producing widely compatible MP3 files recognized by virtually every device, browser, and media player. |
-b:a 128k
|
Sets the audio output bitrate to 128 kilobits per second, a common baseline for MP3 files that balances file size and perceptual audio quality. Increase to 192k or 320k for music where fine detail matters, or reduce to 96k for voice-only content. |
output.mp3
|
Defines the output filename and format. The .mp3 extension tells FFmpeg to write an MPEG Audio Layer III file. The resulting file contains only the re-encoded audio stream from the original AVI, with no video data. |
Common Use Cases
- Ripping the audio from an old AVI music video or concert recording to add to your MP3 music library
- Extracting the narration or voiceover track from an AVI screen recording or tutorial video for use in a podcast or audio course
- Pulling the soundtrack from a legacy AVI film or home video to preserve the audio before the video file degrades or becomes unplayable
- Extracting dialogue or commentary from an AVI sports or news clip to create a standalone audio file for transcription
- Separating audio from an AVI game recording or walkthrough to use as background audio or commentary in another project
- Archiving the audio content of large AVI files as compact MP3s to free up disk space while retaining the audio
Frequently Asked Questions
Yes, there will be some quality loss because MP3 is a lossy format and the audio is being decoded and re-encoded regardless of the source codec. If the AVI's audio track was already MP3-encoded, this re-encoding is a second generation of lossy compression, which can introduce minor additional artifacts. To minimize quality loss, choose the highest bitrate (320k) when audio fidelity is important. For archival purposes, consider extracting to a lossless format instead if your workflow supports it.
AVI files commonly contain audio encoded as MP3 (libmp3lame), AAC, or Vorbis. For this conversion to MP3, the source codec does not change the process — the audio is always decoded to PCM internally by FFmpeg and then re-encoded to MP3 using LAME. Whether the original is AAC, Vorbis, or already MP3, you will get the same type of MP3 output. The main practical difference is that converting from a lossy format like AAC or Vorbis introduces a second generation of lossy encoding.
Change the value after the -b:a flag. For example, to export at 320 kbps for maximum MP3 quality, use: ffmpeg -i input.avi -vn -c:a libmp3lame -b:a 320k output.mp3. The default in this tool is 128k, which is a common streaming bitrate. For voice recordings or podcasts, 96k or 128k is usually sufficient; for music, 192k to 320k is recommended to preserve detail.
FFmpeg will attempt to copy any metadata embedded in the AVI file's audio stream to the output MP3 as ID3 tags. However, AVI has limited and inconsistently implemented metadata support compared to MP3's ID3 standard, so most AVI files carry little or no metadata. You will likely need to add or edit ID3 tags manually after conversion using a tag editor such as Mp3tag or MusicBrainz Picard.
By default, FFmpeg selects the first audio stream it finds in the AVI file, which is typically the primary audio track. AVI does support multiple audio streams, though this is uncommon. If you need to extract a specific track, add the -map flag to your command — for example, ffmpeg -i input.avi -vn -map 0:a:1 -c:a libmp3lame -b:a 128k output.mp3 would extract the second audio stream (index 1).
Yes. On Linux or macOS you can use a shell loop: for f in *.avi; do ffmpeg -i "$f" -vn -c:a libmp3lame -b:a 128k "${f%.avi}.mp3"; done. On Windows Command Prompt, use: for %f in (*.avi) do ffmpeg -i "%f" -vn -c:a libmp3lame -b:a 128k "%~nf.mp3". This is especially useful for large collections that exceed the 1GB per-file limit of the browser-based tool.
Technical Notes
AVI (Audio Video Interleave) stores audio and video in an interleaved RIFF-based structure, which means the audio data is not stored as a clean, contiguous stream — FFmpeg must read and demux the entire container to extract it. The -vn flag explicitly disables video output, preventing FFmpeg from attempting to encode any video stream into the MP3 container (which MP3 does not support). The libmp3lame encoder produces MPEG Audio Layer III files compliant with the ISO/IEC 11172-3 standard and supports bitrates from 32k to 320k. MP3 does not support chapters, multiple audio tracks, or embedded subtitles, so any such data in the AVI source is silently dropped. AVI's theoretical support for up to 99 audio streams is largely academic — real-world AVI files almost always carry a single audio track. One known AVI limitation is that files larger than 2GB using the original AVI specification can have sync issues; FFmpeg handles OpenDML AVI extensions to support larger files, but very old or malformed AVI files may produce audio with timing drift in the output.