umd/ffmpeg-core.js",
          });
        }
        const { name } = files[0];
        await ffmpeg.writeFile(name, await fetchFile(files[0]));
        message.innerHTML = 'Start transcoding';
        console.time('exec');
        await ffmpeg.exec(['-i', name,  'output.mp4']);
        console.timeEnd('exec');
        message.innerHTML = 'Complete transcoding';
        const data = await ffmpeg.readFile('output.mp4');

        const video = document.getElementById('output-video');
        video.src = URL.c