blackshirt convert log

$ \cat convert.log
$ date +%s; opus.book Michael\ Parenti\ -\ Blackshirts\ and\ Reds\ Audiobook.mp3; date +%s
1646055550
[1] 2563140
mediaduration mp3 05:28:45
mediaduration opus
size=   39782kB time=05:28:45.23 bitrate=  16.5kbits/s speed=47.8x
mediaduration mp3 05:28:45
mediaduration opus 05:28:45
1646055994

#1646055994-1646055550 = 4440
#4400/60 = 7.4 = 07:24 mm:ss

$ ll
.rw-rw-r-- 157,903,023 deluge 28 Feb 07:44 Michael Parenti - Blackshirts and Reds Audiobook.mp3
.rw-rw-r--  40,736,781 deluge 28 Feb 08:46 Michael Parenti - Blackshirts and Reds Audiobook.opus

#157903023-40736781 = 117166242
#117166242/157903023 = 0.742= 74.2% reduction