视频动态变速是什么意思，是否就是将一定帧拉长或缩短播放长度？那样要通过插值丢帧或补帧的，如果不是整数倍，插值不均匀，画面就要出现不正常的跳动。

新建一个composition设置新的速率，再把这个comp拿到老的comp里面试试，请guo兄指教

可以将你所需要编辑的视频切成两段。然后调整百分比。
比如前半段为50%，后半段为300%，就可实现如快进、慢放的效果了。
不知zhb是不是这意思

但是两段素材之间衔接会不平滑均匀

我试过，不太可能，变快是可以的，放慢不行，因为需要插帧，画面会有跳动。

缩放过程中发生的帧画面不均匀插补产生的抖动可以用开启该层的frame blending,AE产生介于两帧间的模糊帧来使这中跳动得到缓解。

Enhancing time-altered motion by blending frames
When you time-stretch footage to a slower frame rate or to a rate lower than that of its
composition, movement can appear jerky. This jerky appearance results because the layer now
has fewer frames per second than the composition. By default, After Effects fills in the missing frames in slow-motion footage by repeating the last frame shown. After Effects can create a more gradual transition between frames by interpolating new frames in between existing ones.When you time-stretch or time-remap footage to a frame rate that is faster than the original or higher than that of its composition, After Effects skips many of the original frames to achieve the new rate and, consequently, movement can appear jerky. Frame blending combines the remaining original frames to create smoother fast motion.Using frame blending
Use the Frame Blending switch when motion already exists in the source footage for a layer,
such as people moving in live-action video. You can apply frame blending to a sequence of still
images, but not to a single still image. If you are animating a layer—for example, moving a layer of type across the screen
Frame blending slows previewing and rendering, so you might want to apply frame blending
without displaying it. By selecting the Enable Frame Blending button at the top of the Time
Layout window, you can control whether layers that use frame blending affect redraw and
rendering. The Quality setting you choose also affects frame blending. When the layer is set to
Best Quality, frame blending results in smoother motion, but may take longer to render than
when set to Draft Quality. You can also enable frame blending for all compositions when you
render a movie.

看来这可能要在超级工作站上才能实现