CDFbin Editor (Project CARS) — cdf_editor.py

A small definition-driven editor + hex viewer/editor for Project CARS CDFbin files.

• Scans a binary .cdf / .cdfbin file for known marker bytes
• Decodes the following payload scalar types: byte, float, int32, uint32
• Lets you edit values in-place only (the payload size must not change)
• Includes a hex viewer with click-to-select and in-place overwrite tooling
• Performs a CDF header byte-count register sanity check on open/save-as and can apply a conservative repair

⚠️ This tool modifies binary files. Always keep backups.

Features

Definition-driven field browser

• Fields are defined in CDF_DEFS as CdfFieldDef entries:
  • section, name, marker, layout, notes
• The app scans for all occurrences of each marker, decodes its payload, and lists them in a Treeview grouped by section.
• A filter box allows quick narrowing by section/name/occurrence.

Scalar editor (safe path)

• When you select a field, the right panel shows:
  • marker bytes & offsets
  • payload offset
  • raw payload bytes
  • decoded value tuple
• You can edit via typed scalar inputs.
• Edits are applied in-place (exact same byte count as original payload).

Hex viewer/editor (verification + unknowns)

• Bottom pane shows a classic hex dump.
• Selecting a field jumps to its marker and highlights:
  • marker bytes
  • payload bytes
• Clicking a byte in the hex view selects the corresponding field in the tree (where known).
• You can overwrite the selected payload bytes by pasting space-separated hex.
• Revert options exist for both scalar edits and hex overwrites.

Byte Count Registers check (header validation / repair)

On open and before “Save As…”, the tool checks common CDF header “byte count registers”:

• R0 @ 0x0008 should match file length
• R1 @ 0x0014 should match (R3 - 0x0028) (if R3 >= 0x0028)
• R2 @ 0x0020 should be end-length
• R3 @ 0x0024 should be end-start
• Consistency: R3 + R2 == file_len

If inconsistent, the app will show problems and may offer an automatic conservative repair.

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Requirements

• Python 3.10+ (recommended)
• Standard library only (tkinter ships with most Python installs on Windows)

Windows DPI awareness is enabled when available via ctypes.

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Run

python cdf_editor.py