MP4 to AAC Converter
Convert MP4 to AAC free — no upload, no signup
To convert MP4 to AAC, drop your MP4 video into the box below and click Convert. Fylo converts with ffmpeg running inside your browser, so nothing is uploaded and there's no signup or watermark. Extract the raw AAC stream from MP4 without re-encoding.
Drop audio files here
or tap to browse · paste with Ctrl+V · add many at once
Your files never leave your device
Advanced
How to convert MP4 to AAC
Add your MP4 videos
Drag and drop MP4 files into the box or tap to choose them. The converter engine (about 31 MB) downloads once, the first time you convert.
Pick a bitrate
192 kbps suits music and 128 kbps or less suits speech. Sample rate and mono/stereo are under Advanced.
Convert and download
Click Convert, then download each AAC file or all of them as one ZIP.
Why convert MP4 to AAC?
Broadcast tools, streaming encoders and some audio apps need a raw AAC (ADTS) stream.
What happens when you convert MP4 to AAC?
MP4 AAC audio is copied into an ADTS .aac file with no quality loss. Other codecs are encoded to AAC.
How does Fylo convert MP4 to AAC?
Fylo decodes the soundtrack of the MP4 (usually AAC) with ffmpeg compiled to WebAssembly and encodes it with FFmpeg's AAC encoder at 160 kbps, written as a raw ADTS stream. The video stream is skipped entirely, which is why extraction is fast — the AAC is a fraction of the video's size. The original sample rate and channel layout are kept unless you change them under Advanced.
What's the difference between MP4 and AAC?
MP4 (MPEG-4 Part 14) is a container format standardised in 2001 and based on Apple's QuickTime file structure. A container holds separately compressed video and audio streams plus metadata such as subtitles, chapters and cover art. Most MP4s use H.264 video and AAC audio; newer files may use H.265 (HEVC) or AV1.
AAC (Advanced Audio Coding) was standardised in 1997 as part of MPEG-2 and later MPEG-4, designed to replace MP3. It achieves better quality at the same bitrate, especially below 128 kbps. A .aac file is usually a raw ADTS stream; the same audio inside an MP4 container is called M4A.
Learn more: MP4 format guide · AAC format guide
| Property | MP4 | AAC |
|---|---|---|
| Type | Video | Audio |
| Contains | Video (H.264, H.265/HEVC, AV1) + audio (AAC, MP3) | Audio only, lossy |
| Developed by | MPEG (ISO/IEC 14496-14) | MPEG (Dolby, Fraunhofer, AT&T, Sony, Nokia) |
| Introduced | 2001 | 1997 |
| Compatibility | Universal: phones, TVs, editors, social media | Very wide: Apple, Android, YouTube, browsers |
| Best for | Sharing, uploading, streaming, editing | Efficient music and video soundtracks |
Frequently asked questions
AAC or M4A?
M4A supports tags and accurate seeking; raw AAC is for tools that require it.
Is it lossless?
Yes when the audio is already AAC.
Is my MP4 file uploaded to a server?
No. Fylo runs ffmpeg, the same engine used by professional video tools, compiled to WebAssembly inside your browser. Your MP4 file is read directly from your device and never sent anywhere.
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