The nine, in rough order of frequency
- Wrong EXR compression. One artist's render preset quietly set DWAA; the spec says lossless only. The whole shot bounces.
- Missing frames. A farm render died mid-sequence and restarted unevenly. Frame 1049, 1051 - and a hole at 1050 nobody played through.
- Short of handles. The shot covers the cut exactly, but the contract says +8 frames each side. Cut-length renders are the subtle version of "missing".
- Wrong bit depth. 32-bit float where 16-bit half was specified (double the size, same look) - or half where float was required for a utility pass.
- Wrong ProRes flavour. The review QT went out as 422 Proxy because that was the last export preset used. The spec says 4444. They are very different files.
- Naming drift. A space in a file name, three-digit padding in one sequence, an unannounced task token - anything the client's parser does not expect.
- Mixed versions. v002 frames 1001-1050 and v003 frames 1051-1088 in the same folder after a partial re-render - a package that LOOKS complete by count.
- Wrong start frame. Renders from 1 or 101 when the spec says 1001. Trivial to fix, embarrassing to be told.
- Wrong resolution or frame rate. A proxy-resolution render promoted by accident, or a 24 fps QT against a 23.976 spec - ingest systems treat those as different numbers because they are.
Why the round trip costs so much
None of these take long to FIX. The cost is the discovery latency: a multi-hour upload, a day in the client's queue, the rejection email, the re-render, the re-upload - and a little note in the relationship ledger. A vendor who bounces twice gets checked harder the third time, which slows every future delivery.
The fix is a ten-second habit
Every item on the list is detectable from file headers and file names - no pixel inspection, no human judgement. Big facilities run in-house Python for exactly this. Shot Delivery Preflight is that script with a UI: pick the spec, scan the delivery folder in the browser, and the fix list tells you what would have bounced - before anything uploads.
Scope honesty: a mechanical preflight cannot catch creative rejections - a comp the supe dislikes sails through any header check. It catches the rejections that were never about the work.