Convert Advanced Audio Coding (.aac) to MPEG-4 Audio (.m4a) online for free. Fast, secure audio conversion with no watermarks or registration.
Conversion settings — add a file to adjust
Upload your .aac file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .m4a file when it's ready.
AAC and M4A are intimately related — M4A is simply the file extension Apple uses for MPEG-4 containers that hold AAC audio. A raw AAC stream (ADTS format) lacks metadata support, chapter markers, and album art embedding. Converting to M4A wraps the AAC audio in a proper MPEG-4 container, enabling full metadata, gapless playback tags, and compatibility with iTunes, Apple Music, and every media player that expects the M4A format.
Raw AAC files (.aac extension) use the ADTS transport format, which streams audio but cannot store ID3 tags, album artwork, chapter markers, or gapless playback information. M4A containers add all of this while keeping the audio data identical. Many music players and library managers (iTunes, MusicBee, Plex) handle M4A better than raw AAC, displaying proper metadata and enabling features like bookmarking and chapter navigation.
FFmpeg copies the AAC bitstream directly into an M4A (MPEG-4 Part 14) container without re-encoding. This is a pure remux operation — the audio data is byte-for-byte identical. The M4A container adds proper atoms for metadata (udta/meta), chapter markers (chpl), and gapless playback (iTunSMPB). The moov atom is placed at the file start for streaming compatibility.
Since the AAC audio stream is copied without re-encoding, quality is 100% identical to the source. This is a container change, not a transcoding operation. Not a single sample is modified.
| Device | AAC | M4A |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Native | Native |
| iPhone/iPad | Native | Native |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Resolution: N/A
Bitrate: 256 kbps
AAC format required
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
AAC to M4A is the simplest conversion on this list — a lossless container swap that adds metadata support and Apple ecosystem compatibility without touching the audio data.
Безпечна передача
Завантаження зашифровані через HTTPS
Конфіденційність передусім
Файли автоматично видаляються після обробки
Без реєстрації
Почніть конвертацію миттєво
Працює всюди
Будь-який браузер, будь-який пристрій
| No |
| Характеристика | AAC | M4A |
|---|---|---|
| Повна назва | Advanced Audio Coding | MPEG-4 Audio |
| Розширення | .aac | .m4a |
| Найкраще для | Superior to MP3 | Better than MP3 |