← AlphaDCP

Guides

Working notes

Things that cost us a day to find out, written down so they cost you an afternoon. Mostly digital cinema packaging, subtitle standards and key delivery.

KDM delivery

What is inside a KDM, and why yours was refused

The 138-byte cipher block, the Recipient element, the validity window — and the four failure modes behind nearly every “key not valid” call from a booth.

Subtitling

Interop vs SMPTE DCP subtitling

Two specifications, not two dialects: different root elements, time models, font models and validation regimes — and which one a given delivery actually wants.

Subtitling

ST 428-7 quirks that break subtitles in the cinema

IssueDate time zones, EditRate vs TimeCodeRate, inverted Vposition, LoadFont UUIDs — the details a schema cannot protect you from.