The best Opus Codec commands in DOS/Windows Command would be:
For lib 1.3, smallest filesize (tape quality):
Opusenc a.wav a.opus --bitrate 24 --framesize 40 --discard-comments --discard-pictures
You will:
a- at 24kbits still have a 16kHz (32kHz stereo) sonic output, on a super small size. Any smaller, and Sonic output will drop to 11kHz
b- Increase framesize (save a few bits of data (about 6%), without perceivable loss in quality)
c- Discard unnecessary TAG info, and cover pictures that will only enlarge file size.
For lib 1.3, streaming (near CD quality) use '--bitrate 52' instead of '24'.
The default in 1.2 is 48kbits, but using 52 in 1.3, with 'framesize' set to 40, your file size is equal, but there are much less artifacts audible.
52 kbits with framesize 40, is arguably equal in quality to 160kbits MP3, at less than 1/3rd the size; while 48kbits on 1.2 equals 128kbits MP3, or only 2.5x smaller in size.
For near identical quality, you'll need between 80 to 96kbits. I hardly ever use this, as I want my audio as small as possible.
Over 96kbits, is only good for editing, and one can't audibly hear the difference between the original and the Opus encoded file.
That being said, I don't yet know how it all works in Linux.
3You did not mention your OS. – llogan – 2012-12-09T17:48:36.113