使用转置滤镜。
ffmpeg -i input.mp3 -filter_complex "[0:a]showspectrum=color=fiery:saturation=2:slide=scroll:scale=log:win_func=gauss:overlap=1:s=960x1080,pad=1920:1080[vs]; [0:a]showspectrum=color=fiery:saturation=2:slide=rscroll:scale=log:win_func=gauss:overlap=1:s=960x1080[ss]; [0:a]showwaves=s=1080x540:colors=B80000|950000|690000:mode=p2p,inflate,transpose=cclock[sw]; [vs][ss]overlay=w[out]; [out][sw]overlay=(W-w)/2:0[out]" -map "[out]" -map 0:a -c:v libx264 -preset fast -crf 18 -c:a copy output.mkv