The recipe
A recipe is a small text file that lists every change a tuner made to a car's
engine file. Its file extension is .remap.
That is the whole idea, and it is worth reading why it matters.
Note
A recipe is a list, not a copy. It says "at this spot, these bytes become those bytes". On its own it is useless: it can only be applied to the file it was made from. That is not a weakness — it is exactly what makes it safe to read, keep and hand to someone else.
What it looks like
Every line is one change. Here is a real instruction from a real recipe, with the long surrounding bytes shortened:
{
"offset": 2251283,
"offset_hex": "225A13",
"size": 1,
"ob": "01",
"mb": "00",
"ctx": "0000080008730700…",
"context_after": "0028070102000306…",
"description": "Byte at 0x225A13: 0x01 -> 0x00",
"region": "calibration",
"flags": []
}
In plain words: at address 0x225A13, one byte changes from 01 to 00; the
bytes around it are these, so we can find the spot again; this change sits in the
calibration data, not in the program; nothing is worth flagging.
A whole tune is a list of these — 79 of them in the file above.
Why this format, and not something else
| If it were… | What you would lose |
|---|---|
| a photo of a screen | you cannot re-apply it, check it, or prove what changed |
| a binary patch blob | you cannot read it, review it, or see what it does |
| a replacement file | it is a whole firmware copy — the size of the file, and someone else's data |
| a recipe | nothing: it is small, readable, checkable, and applies only where it belongs |
The five things that follow from being "just a list":
- You can read it before you trust it. Any text editor. No special tool, no vendor, no licence.
- It proves itself. A recipe carries a fingerprint of its own contents, so a single edited byte makes it fail loudly instead of applying the wrong thing.
- It carries its own evidence. Every change has the surrounding bytes that locate it — which is what lets the tool say "this is not the file you think it is" instead of writing into the wrong car.
- It travels. A few hundred kilobytes at most, compared with several megabytes for a firmware file.
- It ages. The format has a version number, and an old recipe is refused with a clear message rather than misread.
The pages in this section
| Page | What it covers |
|---|---|
| Inside a recipe | every part of the file, field by field, in plain words |
| Why it matters | the five promises above, and the one thing it deliberately does not store |
| Sharing and copyright | what a recipe is not, what you can hand over, and where the limits are |
| Format reference | the exact 5.0 fields, for people who read schemas |
Where recipes come from, and where they go
stock file ─┐
├─→ cook-strict / cook-forced ─→ recipe (.remap)
tuned file ─┘ │
▼
another file of the same software ─────→ tune-strict … tune-any ─→ patched copy
Making one is cook-strict; using one is
tune-strict and its three looser siblings.