Video Streaming & Media Delivery Flashcards

What is 'origin shield' and how does it benefit high-traffic video delivery?

Answer: A designated intermediate CDN tier that reduces origin fetch requests by consolidating cache misses

An origin shield is a centralized caching layer between CDN edge nodes and origin, ensuring origin receives far fewer requests by serving most cache misses from the shield.

Which video codec is most commonly used for high-quality streaming at lower bitrates compared to H.264?

Answer: H.265 (HEVC)

H.265/HEVC achieves roughly 50% better compression than H.264 at the same quality level, making it preferred for bandwidth-efficient high-quality streaming.

A CDN edge node receives a request for a live segment that has not yet been generated by the encoder. What should the CDN do?

Answer: Hold the request open and deliver the segment as soon as it arrives from origin (long polling)

CDNs supporting low-latency live streaming hold requests open using long polling or blocking requests, delivering the segment to waiting clients the moment origin has it.

What does 'per-title encoding' optimize in video streaming delivery?

Answer: Generates a custom bitrate ladder per video title based on its complexity rather than a one-size-fits-all ladder

Per-title encoding analyzes each video's visual complexity and generates a content-specific bitrate ladder, achieving better quality at lower bitrates than a universal ladder.

In the context of CDN video delivery, what is 'byte-range serving' used for?

Answer: Allows players to request specific byte ranges of a file, enabling mid-file seeking without downloading the entire asset

HTTP byte-range requests (using the Range header) let video players jump to any point in a file and download only the needed portion, enabling fast seeking in progressive download.

Which factor most significantly determines the optimal segment duration for a live HLS stream?

Answer: The tradeoff between latency (shorter = lower latency) and stability (longer = more buffer for network jitter)

Shorter segments reduce end-to-end latency but increase the number of HTTP requests and sensitivity to network jitter, while longer segments do the opposite.

What is the primary purpose of using a CDN 'multi-CDN' strategy for premium video streaming?

Answer: Improves resilience and global coverage by routing viewers to the best-performing CDN in real time

A multi-CDN strategy uses real-time performance data to route each viewer's stream to the CDN delivering the best quality, providing redundancy and global reach.