M4A 转 Opus - 在线免费转换
在浏览器里直接把 .m4a 转成 .opus。文件不上传，免登录，转完即下载。
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).
What is Opus?
Opus Interactive Audio Codec (.opus) — Opus is a modern, open-source audio codec designed for the internet. It excels at both voice and music, and is the standard codec for WebRTC, Discord, and WhatsApp calls.
M4A vs Opus
| Feature | M4A | Opus |
|---|---|---|
| Full Name | MPEG-4 Audio | Opus Interactive Audio Codec |
| Compression | Lossy | Lossy |
| Typical Bitrate | 128-256 kbps | 32-128 kbps |
| Best For | Apple Music, iTunes, iPhone/iPad audio | Voice calls, VoIP, real-time audio, low-bandwidth streaming |
| File Extension | .m4a | .opus |
Frequently Asked Questions
Is converting M4A to Opus 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 M4A to Opus?
Both M4A and Opus 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.