How to add the border-radius in my image?

Video demo

I need to make this type of video with dynamic image and username like Emily’s Wardrobe
so how to create this type of video with same animations and dynamic images and photos
please make one demo JSON for this video

You can create a mask using a luma matte. Use the luma asset type to create a mask of a video or image. Here are the API docs: Shotstack v1 API Reference Documentation.

Here is a guide to using the luma asset to create mask transitions: How to create transitions using luma mattes — Shotstack. The same approach can be used to create a mask for an image. Just make sure the luma is in the same track as the image being masked.

Also here is a template example where a circle image is used to mask a video clip, same approach can be used for an image: Circle mask video template — Shotstack

The only thing to bear in mind with luma mattes is that they will stretch to the shape of the asset they are masking. This means that all your images must be the same shape. We are building a service to resize and crop images if you can not do this at your end. Should be public in the next 2-4 weeks.