append a string to a modified line

[Axel_Erfurt]

This is very different from the first post.

in_text = '''#EXTINF:137,Choir - When Johnny Comes Marching Home
#EXTINF:191,Glenn Miller - When Johnny Comes Marching Home
#EXTINF:308,Chad Mitchell Trio - Johnnie
#EXTINF:205,Joan Baez - Johnny, I Hardly Knew Yeh
#EXTINF:213,Clancy Brothers & Tommy Makem - Johnny I Hardly Knew You
'''

for line in in_text.splitlines():
    if line.startswith("#EXTINF"):
        print(line)
        name = line.split(",")[1]
        print(f'{name}.mp3')

Output:
#EXTINF:137,Choir - When Johnny Comes Marching Home
Choir - When Johnny Comes Marching Home.mp3
#EXTINF:191,Glenn Miller - When Johnny Comes Marching Home
Glenn Miller - When Johnny Comes Marching Home.mp3
#EXTINF:308,Chad Mitchell Trio - Johnnie
Chad Mitchell Trio - Johnnie.mp3
#EXTINF:205,Joan Baez - Johnny, I Hardly Knew Yeh
Joan Baez - Johnny.mp3
#EXTINF:213,Clancy Brothers & Tommy Makem - Johnny I Hardly Knew You
Clancy Brothers & Tommy Makem - Johnny I Hardly Knew You.mp3