Currently am using this command but the quality was decreasing so suggest me how to merge without losing the quality
"-y", "-i", path_real, "-i", outputfile4, "-strict", "experimental", "-filter_complex",
"[0:v]scale=480x640,setsar=1:1[v0];[1:v]scale=480x640,setsar=1:1[v1];[v0][0:a][v1][1:a] concat=n=2:v=1:a=1",
"-ab", "48000", "-ac", "2", "-ar", "22050", "-s", "480x640", "-vcodec", "libx264", "-crf", "27", "-q", "4", "-preset", "ultrafast", (...)