How do I extend Strapi admin panel API controller to update a field

System Information
  • Strapi Version: 3.6.1
  • Operating System: Windows
  • Database: MongoDB
  • Node Version: v14.17.3
  • NPM Version: 6.14.13
  • Yarn Version:

I have a requirement where I need to fetch duration of a video which comes from a third party API.

I have a videos collection type in Strapi, whenever a video is updated in Strapi admin panel, I want to fetch the duration from third party API and update the duration field.

I have written a controller in api>videos but it is not being called on admin panel update.

Please tell me how can I achieve this requirement.