If you click on "Settings" when exporting your recording you can adjustI've got some field recordings that I'm editing minimally in their native .wav format and then exporting as .mp3s. The resulting mp3 files are very large--as big as commercial .flac files (over 20 MB). This seems to be especially true after I add metadata (song title, track number, artist name and art) even though the art is only about half a MB. My 13 minute song is 23 MB, and the 9-minute song is over 20. I've had this issue in the past but haven't followed up on why or how to make them smaller. I'd like them to be around 5-7 MB max, like the standard commercial recordings in my iTunes library.
all the parameters for the Mp3 encoder. If you are aiming for a specific size,
I would recommend to set the encoding type to ABR and then adjust the bitrate
as desired. The standard bitrate for iTunes recordings is 256kbps, so a 13-minute
recording would end up being even slightly above 23MB in size:
13min * 60sec/min *256kb/sec / (8000 MB/kb) = 24.9MB
(One megabyte (MB) equals 8000 kilobit (kb) since one byte has 8 bits.)
In my iTunes library for example, "Honesty" by Billy Joel which I purchased from
Apple's music store is almost exactly 4minutes in length and weighs in at 8.2MB which
is consistent with this.
If you want your 13 minutes recording to get down to 6MB you'll have to encode
it at 64kbps at which stage you'll probably have audible quality degradation, depending
on the quality of your recordings. In any case, I would then recommend using either
AAC or Ogg Vorbis which perform much better than Mp3 at lower bitrates. Best,