VFX & Film Production

Visual effects and film production involve massive file trees that move between facilities, departments, and drives every day. A single shot can contain hundreds of EXR frames, each one critical. C4 makes this manageable.

Verify a delivery

A VFX vendor sends you 2TB of shot composites. They also send a c4m file. Diff the manifest against what arrived on disk:

$ c4 diff delivery_v3.c4m /mnt/incoming/vendor_A/

If the output is empty, every file matches — the delivery is intact. If anything differs, the patch output shows exactly which entries don’t match. No more spot-checking. No more “can you re-send sh040?” after discovering corruption a week later.

Track what changed between versions

The vendor sends v4 a week later. What actually changed?

$ c4 diff delivery_v3.c4m delivery_v4.c4m
c41oRmNxBzJ4kLpQvW8sYdHf3gTe6UaCb5jX7nZwPq9iMrDuEvFy2hGtSxAl0KcOmBJN
-rw-r--r-- 2026-03-20T14:00:00Z  204800 shots/sh010/comp/sh010_comp_v4.1001-1048.exr c43nYt...
-rw-r--r-- 2026-03-20T14:00:00Z  204800 shots/sh010/comp/sh010_comp_v4.1049-1096.exr c48kPq...
-rw-r--r-- 2026-03-20T14:00:00Z  102400 shots/sh055/comp/sh055_comp_v1.1001-1024.exr c47mNq...
drwxr-xr-x 2026-03-20T14:00:00Z     ... shots/sh010/comp/                            c42qPn...
drwxr-xr-x 2026-03-20T14:00:00Z     ... shots/sh055/comp/                            c49xRw...
c45xZeXwKjQ2nMrBz7L1pYvWqRtN8sHfJd3g6CmAeU9kXoP4bG5hT0iVlDaSwFuO7yE

The patch shows exactly which entries changed between v3 and v4. You can see this before pulling a single frame.

Snapshot a workspace

Before a review session, capture the current state:

c4 id /mnt/show/project_x/shots/ > pre-review.c4m

After the review, artists make changes. Snapshot again:

c4 id /mnt/show/project_x/shots/ > post-review.c4m

Now you have an auditable record of what changed during the review:

c4 diff pre-review.c4m post-review.c4m

Multi-destination copy from camera cards

On set, a DIT needs to copy camera originals to three destinations simultaneously. Use c4sh’s cp command:

eval "$(c4sh shell-init)"
cp /mnt/card_A/ /mnt/shuttle/ /mnt/onset_backup/ /mnt/dit_workstation/

c4sh’s cp integrates identification with copying — content is verified by C4 ID as it’s written.

Why c4m files matter here

In film production, the question is never “do I have a file?” It’s “do I have the right file?” A filename like sh010_comp_v4.1001.exr tells you nothing about whether the content is correct. A C4 ID does.

The c4m file is the bridge between “I think this delivery is correct” and “I know it is.”