How Spotify Streams Audio and Builds Discover Weekly

Short summary

Spotify's playback system uses CDN edge caching, adaptive bitrate chunking, and aggressive prefetching to deliver audio with sub-second startup and no rebuffering. Its Discover Weekly engine runs as a weekly batch pipeline using collaborative filtering via matrix factorization, blended with content-based signals to solve cold-start for new tracks. The core architectural lesson: isolate the fast synchronous path (playback) from the heavy asynchronous one (personalization).

• •Playback relies on CDN edge caching, adaptive bitrate segments, and device-level prefetching to minimize latency and rebuffering
• •Recommendations use batch collaborative filtering with matrix factorization plus content signals for cold-start tracks
• •Key pattern: separate millisecond-response synchronous paths from hours-long asynchronous batch pipelines

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