export-runner
Exports a video by splitting it at keyframes, encoding the segments in parallel with FFmpeg, retrying only the segments that fail, and reporting progress from finished segments. An idempotency key means a retried or resumed job is never charged twice. Every number below was measured. Nothing is estimated except the dollar conversion.
How it works
Two pieces of durable state: a per-job manifest (which pieces are done, so a crashed job resumes) and a shared ledger (whether the job was charged, keyed by idempotency key, under a cross-process file lock).
Parallelism
Speed-up versus one worker, with 10 s segments and 1 thread per ffmpeg process.
Table view
Segment length
Wall time at 10 workers. Short segments mean more processes and more joins. Long segments leave workers idle at the end, waiting for the last piece.
Table view
Retries under injected failures
Deterministic fault injection kills or fails a share of encode attempts. A failed piece is retried on its own; the rest of the job keeps going.
Table view
Crash, resume, replay
The same job three times: killed halfway, run again (it resumes from the manifest), then run a third time (the ledger already has the key, so nothing is encoded and nothing is charged).