GPX fake timer

Create timestamps for every trackpoint in a GPX file.

npm install @mikaello/gpxfaketimer

Example

import { createTimestampsEvenly } from "@mikaello/gpxfaketimer";

const exampleGpx = `
<?xml version="1.0" encoding="UTF-8"?>
<gpx xmlns="http://www.topografix.com/GPX/1/1" version="1.0">
  <name>Example gpx</name>
  <trk>
    <name>Example gpx</name>
    <number>1</number>
    <trkseg>
      <trkpt lat="46.57608333" lon="8.89241667">
        <ele>2376</ele>
      </trkpt>
      <trkpt lat="46.57619444" lon="8.89252778">
        <ele>2375</ele>
      </trkpt>
      <trkpt lat="46.57661111" lon="8.89344444">
        <ele>2376</ele>
      </trkpt>
    </trkseg>
  </trk>
</gpx>
`;

console.log(createTimestampsEvenly(exampleGpx, 0, 100000));
// => will return the same GPX file, only with <time>date here</time> inside every trkpt:

/*
<?xml version="1.0" encoding="UTF-8"?>
<gpx xmlns="http://www.topografix.com/GPX/1/1" version="1.0">
  <name>Example gpx</name>
  <trk>
    <name>Example gpx</name>
    <number>1</number>
    <trkseg>
      <trkpt lat="46.57608333" lon="8.89241667">
        <ele>2376</ele>
        <time>1970-01-01T00:00:00.000Z</time>
      </trkpt>
      <trkpt lat="46.57619444" lon="8.89252778">
        <ele>2375</ele>
        <time>1970-01-01T00:00:50.000Z</time>
      </trkpt>
      <trkpt lat="46.57661111" lon="8.89344444">
        <ele>2376</ele>
        <time>1970-01-01T00:01:40.000Z</time>
      </trkpt>
    </trkseg>
  </trk>
</gpx>
*/

API

• createTimestampsEvenly(gpxContent: string, startTime: number, endTime: number) => string: returns the incoming gpxContent enriched with timestamps in every trkpt element. startTime and endTime are milliseconds since epoch.

• createTimestampsFromSpeed(gpxContent: string, startTime: number, speed: number, unit?: "kmh" | "mph") => string: returns the incoming gpxContent enriched with timestamps calculated from the GPS distance between each track point at the given speed. unit defaults to "kmh".

CLI

npx @mikaello/gpxfaketimer input.gpx --output output.gpx

Options:

| Flag | Description | |------|-------------| | --output, -o | Output file (default: stdout) | | --start | Start time as ISO 8601 or Unix ms (default: now) | | --end | End time for evenly distributed mode | | --speed | Speed value for distance-based timing | | --unit | Speed unit: kmh or mph (default: kmh, requires --speed) | | --help, -h | Show help |

When --speed is provided, timestamps are calculated from GPS distances at that speed. Otherwise, timestamps are evenly distributed between --start and --end (default duration: 1 hour).

Utility functions

Not specific for GPX, but just as helper functions

getUniformDistribution(count: number, intervalStart: number, intervalEnd: number) => number[]: returns an array of length count with first element intervalStart and last element intervalEnd, all elements in between is evenly distributed between these extremeties.

Develop

You can use the ./example project to ease developing. Run npm run dev from that folder to start a Vite dev server that loads the code from this module with hot module replacement.

Contributions are welcome :-)