Explain the process when you hit play on a video streaming platform. What happens in the background?

When a user hits play on a video streaming platform following steps take place

1) The subscription and entitlement service validate if the user is entitled to the content

2) If the user is entitled to the content, the DRM service sends a private key to the device

3) If the user is not entitled to the content, the entitlement service will prompt the user to buy the subscription or the content

4) Once the entitlement is confirmed, the video player will get a manifest from the CMS or from the SSAI server. The manifest will have details on the source of the content, the fidelity, ad playback details, captions etc. Usually content is packaged as HLS(HTTP Live Streaming) hence a playlist will also be provided. The playlist will break down the content each of 10 secs duration

5) The player will use these details and obtain the content using URL specified in the manifest. Mostly the content will be cached in the CDN

6) The content starts playing, if the player encounters an ad marker, it will send a VAST request to the SSAI server. The SSAI server will identify the ad to be placed, update the manifest and send it back to the video player. The video player plays the ad and then goes back the content once the ad playback is complete