au能否打开m4a文件
A file with the .m4v file extension is an MPEG-4 Video (M4V) container file format, also known as an iTunes video file. This is the primary type of file used when purchasing or renting any video from the iTunes store.
具有.m4v文件扩展名的文件是MPEG-4视频(M4V)容器文件格式，也称为iTunes视频文件。 这是从iTunes商店购买或租借任何视频时使用的主要文件类型。
什么是M4V文件？ (What Is an M4V File?)Developed by Apple, M4V files are very similar to the MP4 format, which are both based on the MPEG-4 video container format. The main reason behind creating it was to put a level of security, which adds Apple’s FairPlay DRM protection, on anything from the iTunes Store. This prevents anyone attempting to view or copy these files on a device that isn’t made by Apple, such as iPhone, iPad, iPod, etc.
由Apple开发的M4V文件与MP4格式非常相似，它们均基于MPEG-4视频容器格式。 创建它的主要原因是在iTunes Store中的任何内容上都设置了一定程度的安全性，从而增加了Apple的FairPlay DRM保护。 这样可以防止任何人尝试在非Apple制造的设备(例如iPhone，iPad，iPod等)上查看或复制这些文件。
Other than the use of DRM, the other differences are that M4V files use the H.264 video codec exclusively, allow the storage of chapter information, and can deal with AC3 (Dolby Digital) audio files.
除了使用DRM之外，其他区别是M4V文件仅使用H.264视频编解码器，允许存储章节信息，并且可以处理AC3(杜比数字)音频文件。
如何打开M4V文件？ (How Do I Open an M4V File?)To open a DRM protected M4V file, your computer—or device— must be authorized using iTunes and the AppleID that was used to purchase/rent the video. Assuming it doesn’t have any DRM associated with it, let’s look at how you can open one up.
要打开受DRM保护的M4V文件，您的计算机(或设备)必须使用iTunes和用于购买/租赁视频的AppleID进行授权。 假设它没有任何关联的DRM，让我们看看如何打开一个DRM。
To open any M4V file without DRM, just double-click the video you wish to open. It’s as simple as that.
要打开任何没有DRM的M4V文件，只需双击您要打开的视频。 就这么简单。
Due to the similarities between M4V and MP4 files, Windows can open them natively in Windows Media Player just the same as in QuickTime on macOS.
由于M4V和MP4文件之间的相似性，Windows可以在Windows Media Player中本机打开它们，就像在macOS上的QuickTime中一样。
If, however, you prefer a different video player, changing the association of a file is a simple process on either Windows or macOS. And you most likely won’t even have to do that. When you install a new video playback app, the chances are high that the new app will claim the association with M4V files during installation, unless specified otherwise.
但是，如果您希望使用其他视频播放器，则在Windows或macOS上更改文件的关联都是一个简单的过程。 而且您很可能甚至不必这样做。 当您安装新的视频播放应用程序时，除非另有说明，否则新应用程序很有可能会在安装过程中声明与M4V文件的关联。
Because M4V is based on the MPEG-4 container format, if you have a file and it isn’t DRM protected, you can simply change the extension from .m4v to .mp4 and open it on any device that already supports MP4 file formats. So if for some reason the file isn’t playing on your Windows machine, simply change the file extension and it opens the video as an MP4 instead.
因为M4V基于MPEG-4容器格式，所以如果您有文件且不受DRM保护，则只需将扩展名从.m4v更改为.mp4，然后在任何已支持MP4文件格式的设备上将其打开。 因此，如果由于某种原因该文件无法在Windows计算机上播放，则只需更改文件扩展名，它就会以MP4格式打开视频。
翻译自: https://www.howtogeek.com/368307/what-is-an-m4v-file-and-how-do-i-open-one/
au能否打开m4a文件