concat.ts

import fs from "fs";
import path from "path";
import ffmpeg from "fluent-ffmpeg";

export default function concatenateAudioFiles() {
    const directoryPath = "./public/voice/";
    const silenceAudioFile = "./public/silence.mp3";

    if (!fs.existsSync("tmp/")) {
        fs.mkdirSync("tmp/");
    }

    const files = fs
        .readdirSync(directoryPath)
        .filter((file) => file.endsWith(".mp3") && !file.startsWith("silence"));

    files.sort((a, b) => {
        const numberA = parseInt(a.split("-")[1], 10);
        const numberB = parseInt(b.split("-")[1], 10);
        return numberA - numberB;
    });

    const command = ffmpeg();

    files.forEach((file, index) => {
        console.log("Adding file to ffmpeg:", file);
        command.input(path.join(directoryPath, file));
        if (index < files.length - 1) {
            console.log("Adding silence to ffmpeg");
            command.input(silenceAudioFile);
        }
    });

    command
        .on("start", (commandLine) => {
            console.log("Spawned Ffmpeg with command:", commandLine);
        })
        .on("error", (err) => {
            console.log("Error:", err.message);
        })
        .on("end", () => {
            console.log("Finished concatenating audio files!");
        })
        .mergeToFile(`./public/audio.mp3`, "tmp/");
}