Videos

Question 1

What do you is ABR

Answer 1

Adaptive Bitrate Stream - dynamically adjust the quality of a video based on the viewer’s internet speed, device, and available bandwidth.

Multiple Video Versions:

The video is encoded at different resolutions and bitrates (e.g., 360p, 720p, 1080p, 4K).
Each version is split into small chunks (segments), usually a few seconds long.

Manifest File:

A manifest file (.m3u8 for HLS, .mpd for DASH) contains the available video qualities and their URLs.
The player reads this file to decide which quality to play.
Real-Time Adaptation:

If the internet speed is fast, the player selects a higher resolution (e.g., 1080p).

If the connection slows down, it switches to a lower resolution (e.g., 480p) to prevent buffering.

This happens seamlessly between video segments, so users don’t notice sudden quality drops.

Question 2

What controls the switching for abr?

Answer 2

This is a propriety algorithm which continuously monitors network conditions, buffer levels, and device performance to decide the best video quality to play.

Question 3

What kind of streaming protocol is used by youtube?

Answer 3

DASH - .mpd - manifest - most browsers except safari

HLS - .m3u8

Question 4

Where are video chunks stored for a streaming service like youtube?

Answer 4

Typically on a CDN for access by the client, also redundantly in blob storage.