Requirements

Functional Requirements:

for such a video source website, I believe we should definitely start with the basic functions first. I can list a few functions, we can then discuss and let me know what you think on these items:

1. Uploading video for YouTuber
2. User to watch a pre-saved video
3. User to watch a streaming video
4. User to talk with other users, like a comment session
5. prossible search bar is required

Non-Functional Requirements:

We will definitely need some low-latency play-back mechanism, and since this is YouTube, I assume the global users would be huge, so high-availability is a must, as well as scalability.

Capacity Estimation

Estimate the scale of the system. Consider daily active users, read/write ratio, storage requirements, bandwidth, and any relevant QPS calculations...

API Design

We will need the following RESTful control services:

1. POST: uploading a new video, fetch the assigned uploading URL
2. POST: posting a signal that put an end of the video
3. GET: playback segment API for user to retrieve the correct data from the Data Plane
4. GET: metadata for a video, like title, description, others
5. GET: search for video/uploader/etc...
6. POST: probably need a heartbeat signal

Additionally we need a Data Plane services:

1. Raw source Object Bucket, segment/manifest bucket
2. CDN in front of the segment bucket

High-Level Design

So basically like what I have drawn in the Diagram section:

A client is talking to two basic data plane. One is the control plane, the other is the object bucket (some said blob storage), now the control plane is holding metadata services, providing all APIs that I listed above.

Then for the Data Plane, we need an Object Bucket, like my diagram shown, but once the raw data or let's say the origin copy is stored, we start processing with the transcoding services, which handles by a transcoding message queue, and then a distributor (depending on how many different encoding version we need to do) then writes to the Object Bucket again.

Database Design

Define the data model. Identify the main entities, their attributes, and relationships. Consider the choice of database type (SQL vs NoSQL) and justify your decision based on access patterns...

Detailed Component Design

Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.