Concatenate multiple files using FFmpeg
Use the concat filter:

ffmpeg -y -i a.mp4 -ss 2 -t 22 -i x.wma -ss 00:01:22 -t 19 -i y.mp3 -ss 29 -t 124 -i z.mp3 -filter_complex "[1:a][2:a][3:a]concat=n=3:v=0:a=1[a]" -map 0:v -map "[a]" -shortest output.mp4


Alternatively, instead of -ss/-t you can use the atrim and asetpts filters.