[Flac] flac -- exhaustive model search vs. -A <*>?

[Martin Leese]

"Linda A. Walsh" <flac at tlinx.org> wrote:

> what does the exhaustive model search do?

I am not an expert on the guts of FLAC, but
there is some information about this at:
http://flac.sourceforge.net/documentation_format_overview.html

and scroll down to "MODELING".

> Does it try all of the functions listed under "-A" to find the 'best',
> i.e. bartlett, bartlett_hann, blackman, blackman_har-
>      ris_4term_92db, connes, flattop, gauss(STDDEV),  hamming,  hann,
>      kaiser_bessel, nuttall, rectangle, triangle, tukey(P), welch.
>
> Or is that something else?

That is something else.

> I've been using the -e option for a while in my flac encoding,
> but for something that sounds like it should be slow I wonder
> if it is testing all the models or if it might not be
> working correctly?

At:
http://flac.sourceforge.net/documentation_tools_flac.html#flac_options_exhaustive_model_search

it states, "If the max LPC order is high this
can significantly increase the encode time."
This suggest that if the max LPC order is low
then using -e will not be slow.

The max LPC order is set explicitly using the
-l option or, more usually, by setting a
compression level.  Compression levels are
described at:
http://flac.sourceforge.net/documentation_tools_flac.html#flac_options_level_0

Note that compression levels 7 and 8 also set
the -e option.

I have not attempted to explain what the LPC
order actually is because I do not understand
it well enough

Regards,
Martin.
-- 
Martin J Leese
E-mail: martin.leese  stanfordalumni.org
Web: http://members.tripod.com/martin_leese/