AAC 转 M4A - 在线免费转换
在浏览器里直接把 .aac 转成 .m4a。文件不上传，免登录，转完即下载。
What is AAC?
Advanced Audio Coding (.aac) — AAC is the successor to MP3, offering better sound quality at similar bitrates. It is the default audio format for Apple devices, YouTube, and many streaming services.
What is M4A?
MPEG-4 Audio (.m4a) — M4A is an audio-only MPEG-4 container, typically containing AAC-encoded audio. It is Apple's preferred audio format and supports both lossy and lossless compression (Apple Lossless).
AAC vs M4A
| Feature | AAC | M4A |
|---|---|---|
| Full Name | Advanced Audio Coding | MPEG-4 Audio |
| Compression | Lossy | Lossy |
| Typical Bitrate | 128-256 kbps | 128-256 kbps |
| Best For | Apple devices, streaming services, mobile audio | Apple Music, iTunes, iPhone/iPad audio |
| File Extension | .aac | .m4a |
Frequently Asked Questions
Is converting AAC to M4A free?
Yes, completely free. The conversion runs entirely in your browser using WebAssembly — your files never leave your device and no sign-up is required.
Will I lose audio quality converting AAC to M4A?
Both AAC and M4A use lossy compression. There may be a slight quality loss from re-encoding. If possible, convert from the original lossless source.
What is the maximum file size?
You can convert audio files up to 100MB. Since the conversion happens in your browser, processing speed depends on your device's performance.
Is my audio file uploaded to a server?
No. All format conversion is processed locally in your browser using FFmpeg WebAssembly. Your files never leave your device, ensuring complete privacy.