I've been chasing this issue down for a few long (long) days and can now 100% reproduce but not sure actually whats causing the issue. This used to work 100% under jessie but not stretch (ive re-checked at I am right it works). Let me explain how to reproduce as it shows what I need to do (mixing tracks at the end for a smooth music transition - part of my project). 2 terminal ssh windows to your stretch raspberry pi 3B+ first window: sudo /usr/bin/mpg123 -q -a hw:0,0 /media/musicfile1.mp3 #(now hear music ok)
second window: sudo /usr/bin/mpg123 -q -a hw:0,0 /media/musicfile2.mp3 #(now hear music ok)
Now stop the first window music and try restarting it. The music jumps, buffers, clicks and basically goes wrong. You could have restarted the 2nd window all day long with no issues. As I say this works really well under jessie. This solution is out of the box (i.e. not changed alsa configurations / asource etc). Can anyone else easily reproduce? Anyone any ideas? I know the issue is also with mplayer so it must be alsa related right (since pulseaudio is not in stretch by default). This is command line PI only (no GUI).
HELP, you could be my hero, I know you are out there!