Convert MP4 to AAC Online Free
Extract the AAC audio stream from your MP4 video file and save it as a standalone AAC file. Perfect for audio playback on streaming devices, automotive systems, and mobile apps.
ChangeThisFile extracts the audio from your MP4 video and saves it as AAC using FFmpeg on our secure servers. AAC delivers excellent audio quality at small file sizes, ideal for mobile and streaming. Files are auto-deleted after conversion, completely free with no signup needed.
Convert MP4 to AAC
Drop your MP4 file here to convert it instantly
Drag & drop your .mp4 file here, or click to browse
Convert to AAC instantly
MP4 vs AAC: Format Comparison
Key differences between the two formats
| Feature | MP4 | AAC |
|---|---|---|
| Type | Video container (audio + video) | Raw AAC audio bitstream |
| Audio codec | Usually AAC internally | AAC — Advanced Audio Coding |
| File size | Large (video included) | Small — efficient lossy audio compression |
| Compatibility | Universal video players | Streaming platforms, iOS, Android, automotive |
| Container | MPEG-4 container (.mp4) | Raw bitstream or ADTS container (.aac) |
| Quality vs size | Varies by video encoder settings | Excellent quality at 128–256 kbps |
| Use case | Video content delivery | Streaming, broadcast, in-car audio, mobile apps |
When to Convert
Common scenarios where this conversion is useful
Prepare audio for streaming platform upload
Many audio streaming platforms prefer AAC over MP3 for its superior quality-to-size ratio. Convert your MP4 recording to AAC before uploading to ensure optimal playback quality for listeners.
Extract audio for in-car entertainment systems
Many automotive infotainment systems support AAC natively via USB or Bluetooth. Extract audio from MP4 recordings to AAC so you can enjoy them in your vehicle without a video screen.
Create audio content for mobile apps
iOS and Android apps commonly use AAC for embedded audio because it balances quality and file size efficiently. Strip video from MP4 assets to get the AAC audio files needed for app development.
Extract conference call or webinar audio
Video conference recordings in MP4 format often only need their audio saved. Convert to AAC to create compact audio-only archives of meetings, webinars, or training sessions.
Reduce storage for video audio libraries
If you have a library of MP4 videos whose audio content is all you need, extracting to AAC dramatically reduces storage requirements while keeping quality high compared to MP3 at equivalent bitrates.
How to Convert MP4 to AAC
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1
Upload your MP4 file
Drag and drop your .mp4 file or click to browse and select it from your device. Files up to 500MB are supported.
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2
Server-side AAC extraction
Your file is uploaded over HTTPS and processed by FFmpeg. If the MP4 already contains AAC audio, it is stream-copied directly to the AAC output with no quality loss. Processing is typically complete in seconds.
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3
Download your AAC file
Click Download to save the .aac file. Both the original MP4 and the converted AAC are automatically deleted from our servers after download.
Frequently Asked Questions
An MP4 is a container that holds video, audio, and subtitle tracks. An AAC file contains only the raw AAC audio bitstream or an ADTS-wrapped audio stream — no video. Extracting the audio from MP4 to AAC removes the video component entirely.
If the MP4 already contains AAC audio (which is common), FFmpeg copies the audio stream directly without re-encoding, so there is zero quality loss. If the audio is a different codec like MP3 or AC-3, it will be re-encoded to AAC.
When stream-copying AAC from MP4, the bitrate matches the original. When re-encoding is required, FFmpeg uses a high-quality variable bitrate setting to preserve maximum audio fidelity.
AAC is a newer codec that generally sounds better than MP3 at the same file size. A 128 kbps AAC file sounds roughly equivalent to a 192 kbps MP3. AAC is the preferred format for Apple, YouTube, and most streaming services.
Yes. Android has supported AAC natively since Android 1.0. AAC files play in the default music app and all major third-party players including VLC and Poweramp.
Yes. AAC is supported by Windows Media Player, Groove Music, VLC, and most modern media players on Windows 10 and 11. iTunes on Windows also plays AAC natively.
If the MP4 file contains no audio stream (video-only), the conversion will fail or produce an empty file. Make sure your MP4 has an audio track before converting.
Yes. ChangeThisFile is completely free with no signup, no watermarks, and no per-conversion fees. Just upload your file and download the result.
Most conversions complete in under 10 seconds. When stream-copying (no re-encoding needed), it can be nearly instantaneous. Longer videos may take slightly more time but rarely exceed a minute.
Yes. All file transfers use HTTPS encryption. Files are automatically deleted from our servers immediately after conversion and are never shared or accessed by us.
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