What is .aac?
.aac (Advanced Audio Coding) is a lossy audio compression format designed as the successor to MP3. It achieves similar or better perceived quality at lower bitrates, making it popular for streaming, downloads, and mobile use, especially in the MPEG-4 (MP4/M4A) ecosystem.
This quick guide explains when to use .aac files, how to open them on any device, and how to share them instantly with FileXhost.
When to use .aac files
- You are targeting streaming, mobile playback, or modern platforms like iOS and Android.
- You need smaller files than MP3 at the same perceived quality.
- You are encoding audio for services or devices that prefer AAC over MP3.
- You want a good balance of quality and bandwidth for music, podcasts, or video audio tracks.
How to open .aac files
AAC audio can be played by most modern devices and players, especially when stored in an .m4a or .mp4 container. Raw .aac files are supported by VLC, Foobar2000, iTunes (legacy), Apple Music apps, and many mobile players. On some systems you may need to rename or remux to .m4a or .mp4 for best compatibility. You can upload .aac files to FileXhost to share them as downloadable audio files or alongside other media.
Algorithm details
AAC is part of the MPEG-2 and MPEG-4 audio standards. It uses a filterbank based on the Modified Discrete Cosine Transform (MDCT), psychoacoustic modeling, temporal noise shaping, and advanced stereo coding tools to remove inaudible information and compress the remaining data efficiently. Profiles such as LC-AAC, HE-AAC (AAC+), and HE-AAC v2 target different bitrate and quality tradeoffs.
Browser & platform support
- Desktop: Widely supported in browsers via the HTML5 audio element when AAC is stored in an MP4 container.
- Mobile: Native support on iOS and Android for AAC in M4A/MP4; raw .aac may require specific apps.
- OS: Broad support across Windows, macOS, Linux, and embedded systems through system codecs or bundled players.
Format comparison
| Feature | Details |
|---|---|
| Quality vs Size | More efficient than MP3 at low to medium bitrates, especially with HE-AAC profiles. |
| Compatibility | Excellent on modern platforms, though MP3 still wins for sheer ubiquity and legacy support. |
| Use Case | Ideal for streaming, mobile listening, and as the audio layer in MP4 video files. |
| Containers | Frequently stored in .m4a or .mp4 files; raw .aac is less user-friendly. |
How to create aac files
- Audio Editors/DAWs: Export or render to AAC via built-in encoders or FFmpeg.
- Streaming Pipelines: Transcode audio to AAC for HLS/DASH delivery.
- Converters: Convert from WAV, FLAC, or MP3 to AAC using tools like FFmpeg or desktop apps.
- Rippers: Some CD ripping tools can encode directly to AAC or M4A.
How to convert aac files
- FileXhost: Upload AAC files for sharing or to accompany hosted video/audio content.
- Desktop: iTunes (legacy), Music app, dBpoweramp, XMedia Recode, Audacity with FFmpeg.
- CLI: FFmpeg (for example, ffmpeg -i input.wav -c:a aac -b:a 192k output.m4a).
- Online Tools: Web converters that transcode between AAC, MP3, FLAC, and other formats.
Advantages & disadvantages
Advantages
- Better efficiency than MP3 at many bitrates
- Widely used in streaming, mobile, and video platforms
- Good quality even at relatively low bitrates for voice and music
- Integrated with the MP4/M4A ecosystem for audio and video
Disadvantages
- Raw .aac files are less intuitive than MP3/M4A for end users
- Some older or niche devices may only support MP3
- Lossy compression permanently discards audio information
Tools & software
Players
VLC, iTunes/Apple Music, Windows Media Player (with codecs), Foobar2000, many mobile apps
Editors/DAWs
Audacity (with FFmpeg), Adobe Audition, Logic Pro, Reaper
Encoders/Converters
FFmpeg, dBpoweramp, XMedia Recode, many CD rippers and transcoders
Frequently asked questions
Is AAC better than MP3?
At the same bitrate, AAC typically sounds better than MP3, especially at lower bitrates used for streaming or mobile. For archival masters, use a lossless format like FLAC or WAV instead of any lossy codec.
Why are many audio files .m4a instead of .aac?
.m4a is a container format (MP4 audio) that usually holds AAC-encoded audio. It is more user-friendly and better supported in players and tag editors than raw .aac files, even though the underlying codec is the same.
Can I convert AAC to MP3 without losing quality?
No. Both AAC and MP3 are lossy codecs. Converting from AAC to MP3 involves another lossy step, which can slightly degrade quality. Whenever possible, convert from a lossless source instead.
Which bitrate should I use for AAC?
For music, 160–256 kbps AAC (or high-quality VBR) is a good balance. For podcasts or voice, 64–128 kbps is often enough, especially with HE-AAC profiles.
Technical specs
- File type
- Audio
- Extension
- .aac
- MIME type
- audio/aac, audio/mp4
- Compression
- Lossy
- Max file size on FileXhost
- Up to 25 MB per file on the free plan and up to 1 GB on Pro FileXhost accounts.
Share .aac files instantly
Upload your .aac file to FileXhost to get a clean, shareable URL in seconds. View the file in a modern browser, protect access with optional settings, and let others download it without any confusing ads or cluttered file pages.
Upload .aac file