那啥，youtube我是拿火狐的插件下的：Video DownloadHelper

引用:

原帖由 美女 于 2015-10-13 20:12 发表
posted by wap, platform: iPad
youtube现在解决了，现在的问题是twitter

推分两种，gif存下来也是mp4，正好问下怎么才能再变成gif？
另外就是视频，可以自动播放的一小段视频这种，有声音，不能右键保存，不知道 ...

现在twitter 上好像没有真正的gif，都是mp4，即便是你上传gif也会自动转换成mp4，我看你还是去找mp4->gif的软件吧。

quote：“mp4 They’re MP4s, embedded with the HTML5 video tag. Even if you upload a GIF, it’s converted into an MP4.”

“andypiperTwitter StaffDec '14
Hi, thanks for the question. We've been working to enable this (animated GIFs in extended entities) for a while but we're not quite ready to provide it in the API yet - it is coming very soon! Hold tight, and we'll certainly announce here when the animated GIF entities are ready for general consumption. Thanks for your patience, and we apologise for the delay in bringing this to you all.”

It appears that on upload, Twitter is converting the GIF to an MP4 and embedding the video instead. Why would they do such a crazy thing? Well, size and control.

Size

GIFs are terrible at compression. The original GIF above is 500kb while the mp4 version is only 100kb. A GIF is literally a sequence of independent images squeezed into the same file. An mp4 video can take advantage of all kinds of fancy compression techniques like keyframes and forward-predictive frames.

If most of your users are on mobile, this is a huge win. Even desktop users will notice better performance on a page with many GIFs.

Control

Pausing a GIF isn’t really possible. There are some tricks to swap out the gif with a static frame, but it’s not built into the browser. Videos allow Twitter to leverage the browser. This means play, pause, and seek, but also cool things like slow-motion. Think your GIF is funny now? Wait til you see it in slow motion.

Cool story, so why is this important?

Now you don’t have to wait an hour for a GIF to load on your phone. Hopefully this technique catches on and we’ll have faster GIF sharing all around.

Specifically for Twitter, I think this leads to future video sharing directly through the app.  Twitter seemed late to the GIF game, but they’re ahead of us all.

Long live the VIF.