KEYKODE and film scan identifiers

Keep the five identities separate.

A film scan can have a physical edge number, camera-roll name, timecode label, image filename and position in a delivered sequence. They answer different questions. A reliable turnover connects them explicitly rather than treating any one as a universal frame address.

Kodak describes KEYKODE numbers as machine-readable edge barcodes corresponding to human-readable key numbers, used to correlate film with transfer timecode. KEYKODE is Kodak’s trademark. “Edge code” is a broader description; identify the actual system on the material.

A roll named A007 is a production choice, not a transcription of its film-manufacturing prefix. Likewise, two scans can reuse 01:00:00:00. Neither roll name nor timecode alone proves that two files depict the same physical frame.

Read the reference mark before the offset.

Kodak’s Essential Reference Guide, printed pages 149–151, distinguishes the film-identification letters, roll prefix, footage count and zero-frame reference mark. Its barcode diagram also identifies perforation-offset and checksum information. The marked reference and its offset locate an individual picture; a footage number alone is incomplete.

Keep the units attached. A frame offset counts pictures; a perforation offset counts perforation intervals. For 35 mm, advancing one picture by two, three or four perforations changes that relationship. Do not apply a generic “16 frames per foot” rule to every 35 mm negative. In particular, 3-perf picture boundaries do not repeat at every nominal foot: the reference relationship must travel with the code.

Autodesk’s Flame documentation illustrates why the software convention matters: it distinguishes frame and perforation offsets and documents an additional 3-perf reference-foot value. Confirm the receiving system’s supported representation with the lab before converting it.

Retain the full physical prefix when a scan crosses a splice or joins material. Do not continue a footage arithmetic sequence across a source boundary without a new mapping. Film-stock identification describes the emulsion; it does not change the camera’s frame advance. Use the separate film footage and runtime guide for nominal length calculations.

Map a 240-picture scan without an off-by-one error.

This original example assumes a continuous, forward scan with exactly one file per physical picture, no repeated or missing pictures, and assigned 24 fps timecode. The names and timecode are hypothetical. The physical reference must be supplied and checked by the lab.

The range contains ten seconds of pictures. Subtracting the first picture’s label from the last gives only 239 frame periods, because those labels describe picture starts. For duration, subtract the start from the exclusive end. For an inclusive selection, add one frame after subtracting the endpoints. State which convention the turnover uses.

Validate the sequence and its metadata independently.

The SMPTE DPX specification, ST 268:2014, defines individual image files and header fields for film-edge information, sequence position, sequence length and timecode. These fields are distinct. The specification permits undefined values for non-core information when the correct value is unknown.

A .dpx extension therefore does not establish correct timecode, populated KEYKODE fields or an accurate film-to-file mapping. Read the supplied metadata with suitable inspection software and compare it with the lab report and representative images. A valid file format and a valid source identification are separate checks.

For the example, enumerate all 240 files, check numeric continuity and inspect the first and last images. Then compare intermediate anchors, particularly around splices, scanner restarts and damaged material. A filename gap may mean a missing picture, an intentional omission or a naming error; determine which before calculating a span.

Record whether the first scan ordinal is zero or one. Renaming 1001 to 0000 changes a filename, not the photographed frame. Preserve a before-and-after mapping whenever files are renamed, trimmed or split.

Deliver the mapping with the pictures.

A useful scan turnover includes the original lab report or sidecar, logical roll names, complete physical references, gauge and perforations per picture, scan direction, file pattern, delivered count, first/last pictures and assigned timecode rate. State any unknown values explicitly. Add checksums when the delivery workflow uses them to verify file integrity; matching hashes do not validate a misidentified film frame.

1. Agree the counted range. Specify whether leader, slates, flash frames and extra camera heads are included. Cropping the image area can hide the edge code; keep the associated identification evidence.
2. Record exceptions. Identify missing, repeated, held, replaced or reversed pictures and every discontinuity in the mapping.
3. Preserve versions. Keep original scan filenames and metadata alongside any editorial renaming or proxy mapping.
4. Test the return path. Ask editorial or finishing to locate selected head, middle and tail pictures from the turnover data before committing to a full reconform.

A new scan may include additional heads or use a different numbering start. Reusing the old reel name without updating the source relationship can move every selected picture. If dailies used pulldown or speed changes, document that transformation too; see pulldown and inverse telecine and film-to-digital workflows.

Use arithmetic to check the handoff.

Use the free timecode calculator to check assigned label offsets and the duration calculator to compare a start with an exclusive end. Keep the scan’s actual rate beside each calculation. These checks can expose an inconsistent count, but cannot establish the physical anchor.

Timecode Pro supports timecode, footage and frame-count arithmetic for production notes. It does not read KEYKODE barcodes, inspect DPX headers, manage scan manifests or perform a negative conform. Preserve the lab’s source evidence and verify the mapping in the systems handling the media.