Regarding "--adapt-thres-type" and "--adapt-thres-level", there is
an old message describing the functions you mentioned:

http://www.mail-archive.com/[email protected]/msg02484.html

Since that message was written, some things have changed.
While the option "--adapt-thres-type" still primarily selects the
loudness approximation routine used to compute adaptive threshold 
compensation, "--adapt-thres-type 2" became default in LAME 3.89b.
Instead of the flat loudness approximation used in 3.88b (still
available with "--adapt-thres-type 1"), an equal loudness curve is
now used to compute the loudness.  The only trouble that has been
reported with the now default "--adapt-thres-type 2" was a limited
maximum adjustment range, but that has been fixed in the LAME 3.90
alpha in the CVS repository since late July.

Note too that "--adapt-thres-type 0" disables the adaptive
adjustment, and only yields a lower VBR bit rate for encodings
where auto-adjustment would normally be active.  A better
compromise to cut bits might use "--adapt-thres-level" with
negative values, keeping the adaptive threshold adjustment 
inactive for all but the audio that needs it the most.

I have not heard from anyone who claimed a benefit by using a
positive number with "--adapt-thres-level" since LAME 3.89beta.
If there is a benefit with positive "--adapt-thres-level" values,
it will likely be found in combination with a more aggressive ATH
curve like "--athtype 3".  Note that the internal default offset
for "--adapt-thres-level" is primarily tuned for combination
with the default "--adapt-thres-type 2", and should include just
enough margin to cover "--athtype 3".  The internal default level
probably has roughly 1 dB of margin when used with "--athtype 2".
Again, this margin can be cut by using "--adapt-thres-level" with
negative values.

I really should insert a somewhat meaningful tidbit for
"--adapt-thres-level" into LAME's --longhelp,  Ironically, this
task has been lingering on my backlogged TO-DO list for some time.
That's my lame excuse anyway.  (Oh no!  Did I just make a bad pun?
Somebody shoot me with a water pistol until I stop this drivel!)

BTW, LAME 3.90 has been at alpha7 since mid-August.  Hopefully,
we are still making progress...

Kind regards,

- John


jp wrote:
> 
>                           Hello John
> 
>  I tested the new fonction --adapt-thres-type (n)
>  I use version alpha7, sep 29 2001 with win 95 osr2
>  and very little describe for this new fonction!
>  So i trying in use, but i not see one 'hear <>'
>  This is a 'next' fonction not implemented ?
>  (I have make one error in use ?)
>  I testing in VBR-New format in Q0 and v4
>  I see so one associed (?) fonction not described
>  named --adapt-thres-level but here 'nothing' with use
>  the longhelp??
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