The process of video annotation does not differ significantly. However, there are a few crucial features available when working with video materials only.
Keyframe
Video is a sequence of images annotated in a row. The interpolation function allows users to annotate every 5/10/... frame instead of annotating every single frame Stacking order. To find out more about interpolation go here.
Frames where any action was performed (creating/editing/moving), are called keyframes. You can move between 
keyframes with the help of 
buttons or shortcuts 
are images where no actions were performed. You can also delete the keyframe by clicking on the keyframe icon 
(
keyframes with the help of buttons or shortcuts Up and Down . Non-key frames are images where no actions were performed. You can also delete the keyframe by clicking on the keyframe icon (X).In the object toolbox and next to each attribute in the attributes form, on (prev keyframe) and (next keyframe) buttons, tooltips include the frame number of the prev./next keyframe.
(prev keyframe) and (next keyframe) buttons, tooltips include the frame number of the prev./next keyframe.On frames where there is no keyframe, clicking the button 
will preserve the current interpolated value as a keyframe.When multiple objects are selected, the keyframe indicator will show an empty diamond to indicate that none of the selected objects has a keyframe on the current frame, a full diamond to indicate that all the selected objects have a keyframe on the current frame, or a half-full diamond 
to indicate that only some of the selected objects have a keyframe on the current frame.
will preserve the current interpolated value as a keyframe.When multiple objects are selected, the keyframe indicator will show an empty diamond to indicate that none of the selected objects has a keyframe on the current frame, a full diamond to indicate that all the selected objects have a keyframe on the current frame, or a half-full diamond to indicate that only some of the selected objects have a keyframe on the current frame.Clicking the keyframe indication will create keyframes for all the objects that are missing a keyframe on the current frame, or if all the selected objects have a keyframe on the current frame, will delete the current keyframe for all of the selected objects.
Object visibility
The platform allows to manage object's visibility. When an annotated object disappears from the video you can turn it off by clicking 
or
or O . If you turn the object off in one frame but it is annotated on the subsequent frames, the platform will offer you to make the object not visible from now on or only to the next keyframe.You can make an object visible onwards at any moment by clicking 
or
or O .Merge and split
If one object was annotated with two masks you can merge them into one without the need of redrawing and deleting instances. The function merges two objects by taking all instances of one up to the current frame and all instances of the other from the current frame onwards and joining them into one.
For example, you have a 100-frame video. A car was annotated as Car_1 from Frame 9 to Frame 23, and the same car was annotated as Car_2 from Frame 25 to Frame 89. You can merge Car_1 and Car_2 into one object. To do so:
- Select the object from an object list
(i) or right-click it.
- Click
and then click the other object in the list.
If you merge object 1 with object 2 on Frame 20, all the instances of object 2 will be discarded in the subsequent frames.
You can also split 
an object at the current frame, making the selected object invisible from the current frame onwards, while creating a new object that takes up all instances that have been removed from the selected object if, for example, two objects have been annotated with one mask.
an object at the current frame, making the selected object invisible from the current frame onwards, while creating a new object that takes up all instances that have been removed from the selected object if, for example, two objects have been annotated with one mask.
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