Analize your GoPro footage and animate your content

After Effects Expression.js

function analize(file, yMin, yMax){
	eval("var gopro=" + footage(file).sourceText);
	// (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min
	outMax = yMax; // Y max
	outMin = yMin; // Y min
	inMax = parseFloat(gopro.streams.GPS5.min_alt);
	inMin = parseFloat(gopro.streams.GPS5.max_alt);

	samplesDuration = parseInt(gopro.streams.GPS5.duration);
	samplesCount = gopro.streams.GPS5.samples.length;
	sampleDuration = samplesDuration / samplesCount;

	timeMillis = time * 1000;

	var currentItemIndex = parseInt(timeMillis/sampleDuration);
	var item = gopro.streams.GPS5.samples[currentItemIndex];
	itemAlt = item.alt;
	itemLat = item.lat;
	itemLon = item.lon;
	y = (itemAlt - inMin) * (outMax - outMin) / (inMax - inMin) + outMin;
	return {
		y: y,
		alt: itemAlt,
		lat: itemLat,
		lon: itemLon
	};
}

var result = analize("out.json", 0, 635);

dependencies.sh

npm install gopro-telemetry
npm install gpmf-extract

extractor.js

const gpmfExtract = require('gpmf-extract');
const goproTelemetry = require('gopro-telemetry');
const fs = require('fs');
const readline = require("readline");

const { promisify } = require('util');
const writeFileAsync = promisify(fs.writeFile);

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

async function toJSON(data) {
    try {
        const result = goproTelemetry(
            { rawData: data },
            {
                stream: 'GPS5',
                repeatSticky: true,
                repeatHeaders: true,
                GPS5Fix: 2,
                GPSPrecision: 500
            }
        );
        var res = result["1"];
        res.device_name = res["device name"];
        delete res["device name"];
        var str = JSON.stringify(res);
        str = str.replace(/altitude system/g, "alt_system");
        str = str.replace(/GPS \(Lat.\) \[deg\]/g, "lat");
        str = str.replace(/GPS \(Long.\) \[deg\]/g, "lon");
        str = str.replace(/GPS \(Alt.\) \[m\]/g, "alt");
        str = str.replace(/GPS \(2D speed\) \[m\/s\]/g, "2d_speed");
        str = str.replace(/GPS \(3D speed\) \[m\/s\]/g, "3d_speed");
        res = JSON.parse(str);

        var maxAlt = 0;
        var minAlt = 10000;
        const samples = res.streams.GPS5.samples;
        for (let i = 0; i < samples.length; i++) {
            const item = samples[i];
            const alt = item.alt;
            if (alt > maxAlt)
                maxAlt = alt;
            if (alt < minAlt)
                minAlt = alt;
        }
        const firstFrameTime = Date.parse(samples[0].date);
        const lastFrameTime = Date.parse(samples[samples.length - 1].date);
        const duration = lastFrameTime - firstFrameTime;

        res.streams.GPS5["max_alt"] = maxAlt.toString();
        res.streams.GPS5["min_alt"] = minAlt.toString();
        res.streams.GPS5["duration"] = duration.toString();
        await writeFileAsync('./out-new.json', JSON.stringify(res));
        console.log('File saved');
    } catch (error) {
        console.log(error);
    } finally {
        rl.close();
    }
}

rl.question("Please, type the filename:", function (name) {
    const file = fs.readFileSync(name);
    gpmfExtract(file)
        .then(result => {
            console.log('Length of data received:', result.rawData.length);
            console.log('Framerate of data received:', result.timing.frameDuration);
            toJSON(result.rawData);
        })
        .catch(error => console.log(error));
});

rl.on("close", function () {
    console.log("\nBYE BYE !!!");
    process.exit(0);
});