Adaptive Video Transcoder

A video platform is only as good as its worst network condition. This project is a transcoding pipeline that takes a single uploaded master video and turns it into a ladder of renditions — so every viewer gets a smooth stream whether they are on fibre or a patchy mobile connection.

How it works

Uploads land in S3, which emits an event that enqueues a transcoding job on SQS. Serverless workers on AWS Lambda pick jobs off the queue, run FFmpeg to transcode the master into multiple bitrates, and segment the output into HLS playlists. Containerized services deployed on ECS (pulled from ECR) handle the longer, heavier jobs that outlive Lambda’s execution window.

Design decisions

• Event-driven over cron-driven — SQS decouples ingestion from processing, so spikes in uploads queue up instead of toppling the system.
• Serverless for the bursty part — Lambda scales to zero when idle and fans out under load without capacity planning.
• Adaptive Bitrate Streaming — FFmpeg produces a rendition ladder and HLS manifests, letting players switch quality mid-stream as network conditions change.
• Containers for the long tail — ECS absorbs transcoding jobs too heavy for Lambda’s limits, keeping the architecture heterogeneous but simple.

What I learned

Designing for failure at queue level changes everything: retries, dead-letter queues, and idempotent workers turned out to matter more than raw transcoding performance.