An MP4 is a container. It holds a video track, an audio track, and sometimes subtitles. Extracting the audio means pulling that track out — copied as-is, or converted to MP3, AAC, WAV, or FLAC.
The same steps work on MOV, WebM, MKV, AVI, WMV, and TS. Most people search for MP4 because that is what their phone or recorder wrote.
Method 1: Browser (nothing to install)
- Go to convertyard.com/extract-audio.
- Drop one file, several files, or the folder itself onto the dropzone. Mixed containers are fine.
- Pick an output:
- MP3 — plays everywhere. Default 192 kbps is enough for listening. See bitrate if you want a different number.
- AAC / M4A — smaller than MP3 at the same quality. The browser tool re-encodes; it does not copy the original AAC packet-for-packet.
- WAV or FLAC — if you will edit it. Bitrate is ignored; these are lossless.
- Extract. One file downloads directly. Several come back as a ZIP.
ffmpeg runs in the tab as WebAssembly. The video is not uploaded. You can confirm that in the Network tab the same way as in the no-upload video guide.
Use this when the file is on disk, you do not want to install anything, or you would not upload the video to a random site (calls, lectures, kids, internal recordings).
Method 2: ffmpeg command line
ffmpeg is a free, open-source tool that handles almost every audio and video format. It gives precise control over extraction parameters.
Install ffmpeg:
- macOS:
brew install ffmpeg - Windows: download from ffmpeg.org, add to PATH
- Linux:
sudo apt install ffmpegor equivalent
Extract audio without re-encoding (highest quality):
ffmpeg -i input.mp4 -vn -acodec copy output.aac
-vn drops the video stream. -acodec copy copies the audio stream as-is, with no re-encoding. The output format is determined by the extension — use .aac if the MP4 contains AAC (it usually does), .mp3 if it contains MP3 audio.
Extract and convert to MP3:
ffmpeg -i input.mp4 -vn -acodec libmp3lame -q:a 2 output.mp3
-q:a 2 sets variable bitrate quality — 0 is highest, 9 is lowest. -q:a 2 corresponds to roughly 190 kbps VBR, which is excellent quality.
Extract and convert to WAV (lossless):
ffmpeg -i input.mp4 -vn -acodec pcm_s16le output.wav
This produces an uncompressed WAV at 16-bit depth, suitable for audio editing.
Batch extract from a folder:
for f in *.mp4; do ffmpeg -i "$f" -vn -acodec copy "${f%.mp4}.aac"; done
This processes every MP4 in the current directory.
When to use ffmpeg: You need exact control over codec, bitrate, or sample rate. You're batch processing dozens or hundreds of files. You're working in a script or automation pipeline.
Method 3: Desktop apps
For occasional one-off extractions, several desktop apps include audio extraction as a feature:
VLC (free, all platforms): Media → Convert/Save → select input file → choose Audio - MP3 (or any audio codec) → convert. VLC is reliable but slower than ffmpeg and less flexible.
HandBrake (free, all platforms): Primarily a video transcoder, but can output audio-only by setting the video track to none. Slightly more setup than ffmpeg but has a GUI.
Audacity (free, all platforms): Can open MP4 files (requires the ffmpeg library plugin) and export audio in various formats. Best if you want to edit the audio after extracting it — trim, normalize, add effects.
When to use a desktop app: You want a GUI. You plan to edit the audio immediately after extracting it (Audacity). You already have one of these installed.
Choosing the right output format
| Format | Best for | Notes |
|---|---|---|
| MP3 | Listening, sharing | Universal compatibility. Slight quality loss vs. original AAC. |
| AAC | Listening, Apple devices | Matches the native format in most MP4s. Smaller than MP3 at same quality. |
| WAV | Editing, archiving | Lossless, large files. Import into any DAW or editor. |
| FLAC | Archiving | Lossless and compressed (~50% smaller than WAV). Not as universally supported as WAV. |
| OGG | Web delivery | Open format, good quality. Less widely supported on mobile. |
The re-encoding question: A bit-perfect extract is ffmpeg -vn -acodec copy. ConvertYard re-encodes so you can pick MP3, a bitrate, or WAV/FLAC. For listening, 192 kbps MP3 is inaudible as a generation loss. If you will edit and export again, extract to WAV or FLAC first so you only re-encode once.
Checking what audio format is inside your MP4
Before extracting, it's worth knowing what you're working with:
With ffmpeg:
ffmpeg -i input.mp4
Look for the line starting with Audio: — it will show the codec (aac, mp3, ac3, etc.), sample rate, and channel count.
With VLC: Open the file → Tools → Codec Information → look at the Audio track entry.
With MediaInfo (free): Shows complete technical details including codec, bitrate, sample rate, and channel layout.
Most MP4 files from cameras, screen recorders, and social platforms contain AAC audio at 44.1 kHz or 48 kHz stereo. MP4 files from older tools occasionally contain MP3.
Common problems
"No audio stream found": The MP4 has a video track but no audio track. This happens with screen recordings of silent content, some converted files, and certain camera modes. Check with ffmpeg -i input.mp4 — if there's no Audio: line, there's nothing to extract.
Extracted audio is out of sync: If you're extracting from a file that was previously edited or re-muxed, the audio stream may have a timing offset. Fix with: ffmpeg -i input.mp4 -vn -acodec copy -avoid_negative_ts make_zero output.aac.
File won't open after extraction: The container extension and codec don't match. If you extracted a Dolby AC-3 stream but named it .aac, media players may reject it. Use -acodec copy and check the codec first, or convert explicitly to MP3/AAC/WAV.
Quality sounds worse than the original video: You re-encoded from a lossy source. Minimize re-encoding steps: extract to AAC (matching the source) or WAV, then convert once to your final format.