🎵 M4A 转 MP3M4A to MP3 Converter

使用说明与常见问题How-to & FAQ

「M4A 转 MP3」是什么？What is the M4A to MP3 Converter tool?

把 M4A（AAC）音频转换成兼容性最好的 MP3：iPhone 录音、语音备忘录、iTunes 歌曲和播客下载都适用，可选 128–320 kbps（单声道最高 160 kbps）、单声道/立体声、截取片段并写入标题和歌手，全部在浏览器本地完成。Convert M4A (AAC) audio — iPhone recordings, Voice Memos, iTunes tracks and podcast downloads — into universally compatible MP3 at 128–320 kbps (mono up to 160 kbps), mono or stereo, with optional trimming and title/artist tags. Everything runs locally in your browser.

如何使用「M4A 转 MP3」？How do I use the M4A to MP3 Converter tool?

在「M4A 转 MP3」中，按需设置「码率」、「声道」、「开始（秒或 分:秒）」、「结束」、「标题」等选项，然后点击「转换为 MP3」按钮即可。支持拖放文件。In the M4A to MP3 Converter: Set "Bitrate", "Channels", "Start (s or m:ss)", "End", "Title", then click "Convert to MP3". Drag-and-drop files is supported.

M4A 和 MP3 有什么区别？How do M4A and MP3 differ?

M4A 通常是 AAC 编码，同码率下音质略好于 MP3，是苹果设备的默认格式；MP3 的兼容性更好，老车载音响、MP3 播放器、部分剪辑和网站只接受 MP3。M4A usually holds AAC audio, which sounds slightly better than MP3 at the same bitrate and is Apple's default; MP3 is more compatible — older car stereos, MP3 players and some editors and websites accept only MP3.

转换会损失音质吗？Will quality drop?

会有轻微损失，因为是从一种有损格式重新编码到另一种。建议选择不低于原文件的码率：原文件的码率可以在大多数播放器的文件信息里看到；作为参考，语音录音用 128 kbps 一般足够，音乐可选 192–256 kbps。Slightly, since it re-encodes one lossy format into another. Pick a bitrate at least as high as the source: most players show the source bitrate in the file info. As a guide, 128 kbps is usually enough for speech recordings, and 192–256 kbps suits music.

单声道和立体声怎么选？Mono or stereo?

立体声保留左右声道；单声道把两个声道混合成一个，文件更小，适合语音和录音。单声道 MP3 最高 160 kbps，选择更高码率时会按 160 kbps 输出；原文件本身是单声道时，即使选择立体声，输出也是单声道。这两种情况在控件下方和完成提示里都会说明。Stereo keeps the left and right channels; mono mixes them into one for a smaller file, which suits speech and recordings. Mono MP3 is capped at 160 kbps, so a higher setting is output at 160 kbps; and when the source itself is mono, the output is mono even if Stereo is selected. Both cases are shown under the controls and in the done message.

受 DRM 保护的 M4P/有声书能转吗？Can DRM-protected M4P or audiobooks be converted?

不能。浏览器无法解码受 DRM 保护的文件（旧版 iTunes 的 .m4p、Audible 的 .aax），会提示无法读取音轨。普通 M4A、M4B 有声书（无 DRM）可以转换。No. Browsers cannot decode DRM-protected files such as old iTunes .m4p or Audible .aax, so you will see a cannot-read-audio message. Ordinary M4A and DRM-free M4B audiobooks work.

文件会上传吗？Is my file uploaded?

不会。音频用浏览器内置解码器解码，再用 lamejs（LGPL）在后台线程编码为 MP3，文件不会离开你的设备。No. The audio is decoded by the browser's built-in decoder and encoded to MP3 with lamejs (LGPL) in a background thread; the file never leaves your device.

「M4A 转 MP3」免费吗？需要注册吗？Is the M4A to MP3 Converter free? Do I need an account?

「M4A 转 MP3」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The M4A to MP3 Converter is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.