@deepwaterexploration/dwe-controls/lib/utils/driver.js

Web Based UVC Control Driver for the DeepWater Exploration exploreHD and HDCam

const path = require('path');
const config = require('./config.json');
const { execFile } = require('child_process');

const OPTION_NAMES = ['gop', 'bitrate', 'cvm'];

// invoke the driver executable directly with args
function invokeDriver(args) {
    return new Promise((resolve, reject) => {
        execFile(path.join(__dirname, config.DRIVER_EXECUTABLE), args, (error, stdout, stderr) => {
            if (error) {
                console.error(`error: ${error.message}`);
                reject(error);
            }
    
            if (stderr) {
                console.error(`stderr: ${stderr}`);
                reject(stderr);
            }

            let lines = stdout.split('\n');
            let res = {
                info: [ ], 
                output: { }
            };
            for (let line of lines) {
                if (line.startsWith('I: ')) res.info.push(line.split(': ')[1]);
                else if (line.startsWith('V: ')) {
                    let split = line.split(': ')[1].split('=');
                    let name = split[0];
                    let value = Number(split[1]);
                    res.output = { name, value };
                }
            }
            resolve(res);
        })
    })
}

function setOption(device, option, value) {
    return invokeDriver(['-d', device, '-s', option, value]);
}

function getOption(device, option) {
    return invokeDriver(['-d', device, '-g', option]);
}

async function getDriverOptions(device) {
    let rawOptions = { };
    for (let optionName of OPTION_NAMES) {
        let { output } = await getOption(device, optionName);
        rawOptions[optionName] = output.value;
    }
    let options = {
        bitrate: rawOptions.bitrate / 1000000, // convert to Mbps
        vbr: rawOptions.cvm == 2, // 1: cbr, 2: vbr
        h264: rawOptions.gop == 29 // 29: h264
    };
    return options;
}

async function setDriverOptions(device, newOptions) {
    let options = await getDriverOptions(device);
    newOptions = {...newOptions}; // make a copy of the original object
    newOptions = {
        bitrate: newOptions.bitrate * 1000000,
        gop: newOptions.h264 ? 29 : 0,
        cvm: newOptions.vbr ? 2 : 1
    }
    options = {
        bitrate: options.bitrate * 1000000,
        gop: options.h264 ? 29 : 0,
        cvm: options.vbr ? 2 : 1
    }
    for (let optionName of OPTION_NAMES) {
        // check if new option is different from current
        if (newOptions[optionName] != options[optionName]) {
            await setOption(device, optionName, newOptions[optionName]);
        }
    }
}

module.exports = {
    getOption, setOption, getDriverOptions, setDriverOptions
}