M4B音频文件与M4A文件几乎相同。它们通常用AAC编解码器编码。M4A文件包含有声书籍，文件格式支持章节和书签。iTunes或VLC支持这些文件。
M4B audio files are nearly identical to M4A files. They are usually encoded with the AAC codec. M4A files contain audio books and the file format supports chapters and bookmarking. These files is supported by iTunes or VLC.
