QUOTE (floyd @ Mar 8 2003 - 04:51 PM)
I did some searching and indeed mpeg1-layer3 doesn't support lower than 32khz. In that case I'd probably use lame or fhg at around 48kbps for 32khz mono audio. Also, setting the lowpass to 10khz or something close could help alot.
Probably not necessary to cut things off quite that low, as most audiobook programs shouldn't suffer from a slightly extended spectrum. But here's a fairly reasonable line, if you would like to try it:
CODE
--alt-preset cbr 48 -a --lowpass 15 -t
In this example, L.A.M.E. matches the default cutoff frequency for
--alt-preset cbr 96 (stereo), downmixes and automatically resamples to 32kHz. That's nice, since a few audiobooks include written songs, and if the reader chooses to sing them (Robert Inglis' dramatic readings of Tolkien's
The Hobbit and
Lord of the Rings trilogy spring to mind) the more generous cutoff will allow a little musical "breathing room."
For audiobooks I prefer CBR, but this is an arbitrary decision... leave it in or out, as you please. (I'll only note that in some cases, despite the fact that all MP3 players should support VBR, CBR is a more reliable option.) Also, since I object to the inclusion of extraneous tags (unrelated to the program material, that is) I use the
-t switch to turn off the L.A.M.E./Xing tag. This is generally frowned upon if you are trading MP3s; I am not, so I don't particulary care that it's frowned upon. Again, do as you please.
- M.