🎵 M4A 转 OGGM4A to OGG Converter

使用说明与常见问题How-to & FAQ

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

把 M4A（AAC，iPhone 录音、iTunes 音乐、语音备忘录等）转换为 OGG（Ogg Vorbis）：可选音质、采样率和单声道，并可截取片段；在浏览器本地解码和编码，文件不上传。受 DRM 保护的 iTunes 歌曲无法转换。Convert M4A (AAC — iPhone recordings, iTunes music, Voice Memos and so on) to OGG (Ogg Vorbis), with a choice of quality, sample rate and mono plus optional trimming. Decoding and encoding run locally in your browser and nothing is uploaded. DRM-protected iTunes songs can't be converted.

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

在「M4A 转 OGG」中，选择或拖入文件，按需设置「音质」、「采样率」、「声道」、「开始（秒或 分:秒）」、「结束」等选项，然后点击「转换为 OGG」按钮即可。In the M4A to OGG Converter: Choose or drop your files, set "Quality", "Sample rate", "Channels", "Start (s or m:ss)", "End", then click "Convert to OGG".

哪些 M4A 可以转换？Which M4A files can be converted?

普通的 AAC 编码 M4A（iPhone 语音备忘录、录音、自己导出或购买的无 DRM 音乐）和 .m4b 有声书都可以。早期 iTunes 商店带 FairPlay DRM 的 .m4p 歌曲浏览器无法解码。ALAC（Apple 无损）编码的 M4A 只有 Safari 能解码，其他浏览器会提示无法读取音轨。Regular AAC M4A files (iPhone Voice Memos, recordings, DRM-free music you exported or bought) and .m4b audiobooks work. Early iTunes Store .m4p songs with FairPlay DRM can't be decoded by browsers. ALAC (Apple Lossless) M4A can only be decoded by Safari; other browsers will say the audio track can't be read.

输出的 OGG 是什么编码？能在哪里播放？Which codec is used, and where does the OGG play?

输出为 Ogg Vorbis（.ogg），这是最常见、兼容性最好的 OGG 格式：Chrome、Edge、Firefox、Android、VLC、foobar2000，以及 Unity、Godot 等游戏引擎都能直接使用。新版 Safari / iOS 也能播放 Vorbis，老版本 iPhone 可能需要 VLC 等播放器。The output is Ogg Vorbis (.ogg), the most common and most widely supported OGG flavour: Chrome, Edge, Firefox, Android, VLC, foobar2000 and game engines such as Unity and Godot use it directly. Recent Safari / iOS versions play Vorbis too; on older iPhones you may need a player such as VLC.

音质该怎么选？Which quality should I pick?

Vorbis 使用可变码率，选项里的 kbps 是立体声 44.1 kHz 下的大致平均值，实际大小取决于内容。音乐用“标准”通常已听不出差别，想保留更多细节可选“高”或“很高”；语音、播客用“最小”或“较小”加单声道能大幅减小体积。M4A本身已是有损格式时，选比原文件高很多的音质不会让声音变好，只会让文件变大。Vorbis uses variable bitrate; the kbps in the menu is a rough average for 44.1 kHz stereo, and the real size depends on the content. For music, Standard is usually transparent; pick High or Very high to keep more detail. For speech and podcasts, Smallest or Smaller plus Mono saves a lot of space. Because M4A is already lossy, choosing a much higher quality than the source won't improve the sound, it only makes the file bigger.

会保留歌曲名、歌手等标签和封面吗？Are tags (title, artist) and cover art kept?

不会。转换只处理音频本身，原文件里的标签和封面不会写入 OGG，转换后可以用 Mp3tag、foobar2000 等软件补上。No. Only the audio is converted; tags and cover art from the source aren't written to the OGG. You can add them afterwards with Mp3tag, foobar2000 or similar.

文件会上传吗？有大小限制吗？Is the file uploaded? Is there a size limit?

不会上传，解码和编码都在你的浏览器里完成（编码器是 libvorbis 的 WebAssembly 版本）。单个文件最大 512 MB；很长的音频解码后会占用较多内存，手机上建议分段（填写开始和结束时间）转换。No. Decoding and encoding happen in your browser (the encoder is libvorbis compiled to WebAssembly). Files up to 512 MB are supported; very long audio uses a lot of memory once decoded, so on phones convert it in parts using Start and End.

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

「M4A 转 OGG」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 OGG 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.