# Racing engine recording

`engine-idle.wav`: domasx2, "racing car engine sound loops", CC0.
https://opengameart.org/content/racing-car-engine-sound-loops
https://creativecommons.org/publicdomain/zero/1.0/

Downloaded 2026-09-07. The author states the files were remade from a public-domain sample. The runtime changes playback rate and layers original intake, exhaust, tire, turbo, wind and collision synthesis. No game audio was extracted from Need for Speed, Burnout or Yakuza.


## Toyosu Routes recording additions (2026-09-08)

- `engine-load.wav`: **qubodup**, *Car Engine Loop 96kHz, 4s*, CC BY 3.0. https://opengameart.org/content/car-engine-loop-96khz-4s — converted from the normalized WAV to mono 44.1 kHz. Used under CC BY 3.0, https://creativecommons.org/licenses/by/3.0/ . Runtime pitch, gain and filters vary with engine RPM and load.
- `tire-squeal.wav`: **audible-edge (Tom Haigh)**, loop edit by **qubodup**, *Car tire squeal skid loop*, CC BY 3.0. https://opengameart.org/content/car-tire-squeal-skid-loop — converted to mono 44.1 kHz. License: https://creativecommons.org/licenses/by/3.0/ . Runtime gain/pitch vary with slip and speed.
- `traffic-pass.wav`: **Yaroslav_Novikov**, *Car 1*, CC0. https://opengameart.org/content/car-1-1 — converted to mono 44.1 kHz, excerpts used for passing cars. https://creativecommons.org/publicdomain/zero/1.0/

Engine, skid, and passing-car recordings are separate sources. They are not recordings of the exact four playable car models. Original synthesis remains for quiet mechanical reinforcement, road/wind layers, rail joints, impacts, and UI. Music now starts muted and can be enabled in Setup.

## Tokyo Overdrive harmonic processing

The idle and loaded engine recordings are analyzed once into phase-aligned periodic harmonic voices. These derivatives retain their original authors and licenses above; frequency is driven by the simulated drivetrain instead of replaying the source recordings’ rev fluctuations.

## Engine families (2026-09-09)

- `engine-saloon.wav`: Dmitry_mansurev64, **Sedan engine loop**, CC0. https://freesound.org/people/Dmitry_mansurev64/sounds/748027/ . Excerpt 2–5 seconds of the public HQ preview, converted to mono 22.05 kHz and band limited.
- `engine-three.wav`: rodrigocswm, **Starting car engine**, CC0. https://freesound.org/people/rodrigocswm/sounds/584878/ . Excerpt 25–28 seconds of the public HQ preview, converted to mono 22.05 kHz and band limited.
- CC0: https://creativecommons.org/publicdomain/zero/1.0/

The player engine now retains overlapping loops of the recordings, with RPM-driven playback and load crossfades. The four credited engine sources above are processed into distinct fictional engine families; these are not recordings of each exact depicted vehicle. Both new source pages and licenses were checked on 2026-09-09.