使用ffmpeg驱动程序合并n个.mp3（相同比特率）文件

I have 3 .mp3 files of 128 kbps. I want to merge these files using ffmpeg driver. Is this possible?

I have tried this code:

shell_exec("ffmpeg -i 1490103690_128_1.mp3 -i 1490103714_128_2.mp3 -i 1490103734_128_3.mp3 \
-filter_complex '[0:0][1:0][2:0]concat=n=3:v=0:a=1[out]' \
-map '[out]' output.mp3");