Video transcoding pipeline

Design the transcoding pipeline behind a UGC video platform ingesting 500 hours of new video per minute. Each upload must be fanned out into ~8 renditions (multiple resolutions + codecs) plus a thumbnail set, and the median upload must be playable within 60s while a 4-hour 4K upload may take much longer. Cost-sensitive: you run a fleet of mixed GPU and CPU workers and want >70% utilization. Design the job graph, scheduling, and how you keep p50 latency low without starving long jobs.