Navigation Voice Prompt Triggering
(Compiled by Hardy 2013, reworked 2023-08)
Principle and Related Settings
- Prompts are triggered based on a lead distance threshold, derived by converting a specified lead time via the profile's Default speed. For close-up prompts this lead distance may then be adjusted based on the actual speed: increased to ensure the announcement is triggered early enough at high speeds, or decreased for more precision at low speeds.
- The profile's Default speed is user-adjustable, and changing it will hence affect the voice prompt trigger distances. Note: The Default speed also affects the calculated route time.
- Voice prompt timing my also be adjusted via the Arrival announcement setting. Check the 'Arrival Setting' column further below to see which voice prompts will be affected. The trigger distance will be multiplied by the following factor:
| Arrival announcement | Distance multiplier |
|---|---|
| Early | 1.5 |
| Normal | 1 |
| Late | 0.5 |
| Very late | 0.25 |
- In addition, there is a user-configurable overall Voice prompt delay (adjustable in the OsmAnd development plugin, Text voice prompts, button 11.2). This is particularly needed for output type Phone call audio, where we emulate a call to a car stereo which induces some delay, to avoid the beginning of the prompts being cut off. (All distances announced in the prompts will anticipate any Voice prompt delay.)
- We mute prompts immediately once they refer to outdated events, or if your direction of travel seems not in line with a current route.
Base Profile Default Speeds
While these can be user-adjusted, the defaults are
- Driving: 12.5 m/s (45 km/h)
- Cycling: 2.78 m/s (10 km/h)
- Walking: 1.11 m/s (4 km/h)
- Boat: 1.39 m/s (5 km/h)
- Ski: 1.39 m/s (5 km/h)
- Aircraft: 40 m/s (144 km/h)
Trigger Table
The triggers are here in the code. The corresponding values for OsmAnd's default settings are:
| Prompt Type | Lead Time [s]: Corresponding Lead Distance @ Default Speed [m] | Lead Distance Adjusted by Actual Speed? | Adjustable by Arrival Setting? | Comment |
|---|---|---|---|---|
| Turn now | 6.7 s / 3.2 s / 2 s: Driving: 83 m Cycling: 12(8) m Walking: 12(2) m | ✔️ (Proportional to actual speed / Default speed) | ✔️ | Lead time (heuristically) = max(8, sqrt(Default speed * 3.6)). The corresponding lead distance is floored at 12 m to allow for position inaccuracy. |
| Turn in X m | 22 s: Driving: 275 m Cycling: 61 m Walking: 24 m | ✔️ (Increase only) | Skipped if < 15 s before turn | |
| Prepare to turn in X m | 115 s: Driving: 1438 m Cycling: 319 m Walking: - | Skipped if < 150 m before "Turn in", skipped for Default speed < 8 km/h | ||
| Long Prepare to turn in X m | 300 s: Driving: - Cycling: - Walking: - | Skipped for Default speed < 108 km/h | ||
| Go Ahead | >300 s: Driving: 3750 m Cycling: 833 m Walking: 333 m | Plays after route calculation if no other prompt is due, or after a turn if the next turn is more than Long Prepare away | ||
| Arrive at destination or intermediate | 5 s: Driving: 63 m Cycling: 14 m Walking: 6(12) m | ✔️ | Minimum 12 m | |
| Approaching waypoint / favorite / POI | 60 s: Driving: 750 m Cycling: 167 m Walking: 67 m | ✔️ (Increase only) | ✔️ | Limited to max 1 point at a time |
| Passing waypoint / favorite / POI | 15 s: Driving: 188 m Cycling: 42 m Walking: 17 m | ✔️ (Increase only) | ✔️ | Limited to max 3 points at a time |
| Standard alarm | 12 s: Driving: 150 m Cycling: 33 m Walking: 13 m | ✔️ (Increase only) | ✔️ | |
| Close alarm | 7s: Driving: 88 m Cycling: 20 m Walking: 8 m | ✔️ (Increase only) | ✔️ | Traffic calming uses the Passing alarm for the approach prompt, and filters duplicates within this radius |
| Off-route announcement | 20 s: Driving: 250m Cycling: 56m Walking: 22m h | ✔️ | Can be disabled | |
| GPS signal lost | 20 s | Is played after the GPS signal has been lost for >= 20 s and this was not caused by user action. |