Video Overlay on Background Image

////////////////////
// ENCODING LIBRARY
////////////////////

class Encoding {

    constructor(){
        this.error = null;
        this.in_path = null;
        this.out_path = null;
        this.options = ["-loop 1", "-movflags faststart","-c:v libx264","-crf 21","-preset medium", "-r 30","-c:a aac","-ac 2","-strict -2", "-f mp4", '-af volume=6.0','-map [out]', '-map 1:a'];
        this.input_options = ["-sseof -4"];
        this.debug_mode = false;
        this.backgroundFile = false;
        this.watermarkFile = false;
    }

    logging(value){
        this.debug_mode = value;
    }

    getError(){
        return this.error;
    }

    setPaths(in_path, out_path){
        this.in_path = in_path;
        this.out_path = out_path;
    };

    setOptions(value){
        this.options = value;
    }

    setBackground(backgroundFile){
        this.backgroundFile = backgroundFile;
    }

    setWatermark(watermarkFile){
        this.watermarkFile = watermarkFile;
    }

    async convert(){
        return new Promise((resolve, reject)=>{
            if(this.debug_mode){
                console.log("Starting File Conversion");
                console.log(this.in_path);
                console.log(this.out_path);
            }
            if(this.watermarkFile){
                ffmpeg()
                .input(this.backgroundFile)
                .input(this.in_path)
                .complexFilter([
                    "[1]scale=640:480[inner];[0][inner]overlay=0:120:shortest=1[out]"
                ])
                .outputOptions(this.options)
                .saveToFile(this.out_path)
                .on('end', () => {
                    if(this.debug_mode){console.log("Conversion Complete");}
                    resolve(true);
                })
                .on('error',(err)=>{
                    if(this.debug_mode){console.log("Conversion Error");}
                    if(this.debug_mode){console.log(err);}
                    resolve(err);
                });
            } else {
                ffmpeg()
                .input(this.backgroundFile)
                .input(this.in_path)
                .complexFilter([
                    "[1]scale=640:480[inner];[0][inner]overlay=0:120:shortest=1[out]"
                ])
                .outputOptions(this.options)
                .saveToFile(this.out_path)
                .on('end', () => {
                    if(this.debug_mode){console.log("Conversion Complete");}
                    resolve(true);
                })
                .on('error',(err)=>{
                    if(this.debug_mode){console.log("Conversion Error");}
                    if(this.debug_mode){console.log(err);}
                    resolve(err);
                });
            }
        });
    }
}

////////////////////
// MAIN FUNCTION
////////////////////

(async()=>{
    let encoder = new Encoding();
    encoder.logging(true);
    encoder.setPaths("./overlay.mp4", "./output.mp4");
    encoder.setWatermark(false);
    encoder.setBackground("./background.png");
    await encoder.convert();
})();

////////////////////
// FILES
////////////////////
/*
  overlay.mp4  ->  https://storage.googleapis.com/clipdrop-prod/videos/test/overlay.mp4
  background.png -> https://storage.googleapis.com/clipdrop-prod/videos/test/background.png
*/