Container Format

What this is about

Think of the container as the box and the codec as what is packed inside. The box determines how many audio tracks fit, whether timecode survives, how subtitles travel and which software opens the file at all. Broadcasters lean on MXF because it carries strict metadata; post houses use MOV for its track flexibility; anything meant for a website ends up as MP4. Delivery specs almost always name both — container and codec — and rejecting a master over the wrong wrapper is common even when the picture itself is perfect.

A term only helps when everyone on set means the same thing by it — so what follows is how it is used, not a dictionary definition.

What runs differently here

In planning terms, that means:

• MXF for broadcast, MOV for post, MP4 for web — each container answers a different delivery question
• The wrapper decides how many audio tracks, which timecode and what metadata survive the handover
• Renaming an extension changes nothing inside the file and usually breaks playback instead

With TillyGen

Delivery requirements captured in TillyGen travel with the project, so the export at the end matches the wrapper the client agreed to at the start.

Change one constraint and the consequences travel through the whole plan: affected shots are flagged, the call sheet is regenerated, and nobody keeps working from yesterday's version.