ffmpeg -loop 1 -i input.jpg -i input.mp3 -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:-1:-1:color=black,setsar=1,format=yuv420p" -shortest -fflags +shortest output.mp4
ffmpeg -loop 1 -i image.png -i audio.mp3 -vf "scale=1920:1080:force_original_aspect_ratio=decrease:-1:-1" -shortest -fflags +shortest analog2.mp4
That's tighter. Learning ffmpeg on the fly; love this program.