lossyWAV 1.4.2, Copyright (C) 2007-2016 Nick Currie. Copyleft.

This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful,but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR APARTICULAR PURPOSE.  See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this program.  If not, see <http://www.gnu.org/licenses/>.

Process Description:

lossyWAV is a near lossless audio processor which dynamically reduces the
bitdepth of the signal on a block-by-block basis. Bitdepth reduction adds noiseto the processed output. The amount of permissible added noise is based on
analysis of the signal levels in the default frequency range 20Hz to 16kHz.

If signals above the upper limiting frequency are at an even lower level, they
can be swamped by the added noise. This is usually inaudible, but the behaviourcan be changed by specifying a different --limit (in the range 10kHz to 20kHz).
For many audio signals there is little content at very high frequencies and
forcing lossyWAV to keep the added noise level lower than the content at these
frequencies can increase the bitrate of the losslessly compressed output
dramatically for no perceptible benefit.

The noise added by the process is shaped using an adaptive method provided by
Sebastian Gesemann. This method, as implemented in lossyWAV, aims to use the
signal itself as the basis of the filter used for noise shaping. Adaptive noiseshaping is enabled by default.

Usage   : lossyWAV <input wav file> <options>

Example : lossyWAV musicfile.wav

Quality Options:

-q, --quality <t>    where t is one of the following (default = standard):
    I, insane        highest quality output, suitable for transcoding;
    E, extreme       higher quality output, suitable for transcoding;
    H, high          high quality output, suitable for transcoding;
    S, standard      default quality output, considered to be transparent;
    C, economic      intermediate quality output, likely to be transparent;
    P, portable      good quality output for DAP use, may not be transparent;
    X, extraportable lowest quality output, probably not transparent.

Standard Options:

-C, --correction     write correction file for processed WAV file; default=off.-f, --force          forcibly over-write output file if it exists; default=off.-h, --help           display help.
-L, --longhelp       display extended help.
-M, --merge          merge existing lossy.wav and lwcdf.wav files.
-o, --outdir <t>     destination directory for the output file(s).
-v, --version        display the lossyWAV version number.
-w, --writetolog     create (or add to) lossyWAV.log in the output directory.

Advanced Options:

-                    take WAV input from STDIN.
-c, --check          check if WAV file has already been processed; default=off.                     errorlevel=16 if already processed, 0 if not.
-q, --quality <n>    quality preset (-5.0<=n<=10.0); (-5=lowest, 10=highest;
                     default=2.5; I=10.0; E=7.5; H=5.0; S=2.5; C=0.0; P=-2.5;
                     X=-5.0.
--, --stdout         write WAV output to STDOUT.
    --stdinname <t>  pseudo filename to use when input from STDIN.

Advanced Quality Options:

-A, --altspread [n]  disables 'old' sperading mechanism in favour of 'new'
                     mechanism (default spreading uses both 'old' and 'new'
                     mechanisms). Takes an optional parameter, n, which relates                     to the proportion of adjacent bins taken into account when                     calculating spread average for a particular bin (0<=n<=1;
                     default = 0.768544).
-a, --analyses <n>   set number of FFT analysis lengths, (2<=n<=7; default=3,
                     i.e. 32, 64 & 1024 samples. n = 2, remove 32 sample FFT;
                     n > 3 add 16; n > 4, add 128; n > 5, add 256, n > 6, add
                     512) n.b. FFT lengths stated are for 44.1/48kHz audio,
                     higher sample rates will automatically increase all FFT
                     lengths as required.
-D, --dynamic <n>    select minimum_bits_to_keep_dynamic to n bits (default
                     2.71 at -q X and 5.00 at -q I, 1.0 <= n <= 7.0.
    --feedback [n]   enable experimental bit removal / adaptive noise shaping
                     noise limiter. Tuning has been carried out at -q X and
                     should have a negligible effect at -q S. Optional setting
                     (0.0 <= n <= 10.0, default = 0.0) automatically selects
                     the following parameters (0 = least effect, 10 = most):
       r, round <n>  limit deviation from expected added noise due to rounding
                     (-2.0 <= n <= 2.0, default = 0.0).
       n, noise <n>  limit added noise due to adaptive noise shaping
                     (-2.5 <= n <= 7.5, default = 0.0).
       a, aclips <n> number of permissible exceedences of adaptive noise
                     shaping level limit (0 <= n <= 64, default = 32).
       A, alevel <n> adaptive noise shaping level limit (-2.0 <= n <= 2.5,
                     default = 0.0).
       V, verbose    enable more detailed feedback information in output.
-I, --ignore-chunk-sizes.
                     ignore 'RIFF' and 'data' chunk sizes in input.
-l, --limit <n>      set upper frequency limit to be used in analyses to n Hz;
                     (12500 <= n <= 20000*; default=16000).
                     *: for 44.1/48 kHz audio. Upper limit for audio of
                     other sampling rates is limited to sample-rate x 45.35%
    --linkchannels   revert to original single bits-to-remove value for all
                     channels rather than channel dependent bits-to-remove.
    --maxclips <n>   set max. number of acceptable clips per channel per block;                     (0 <= n <= 16; default = 3,3,3,3,3,2,2,2,2,2,1,1,1,0,0,0).-m, --midside        analyse 2 channel audio for mid/side content.
    --nodccorrect    disable DC correction of audio data prior to FFT analysis,                     default=on; (DC offset calculated per FFT data set).
-n, --noskew         disable application of low frequency level reduction prior                     to determination of bits-to-remove.
    --scale <n>      factor to scale audio by; (0.03125 < n <= 8.0; default=1).-s, --shaping        modify settings for noise shaping used in bit-removal:
       a, altfilter  enable alternative adaptive shaping filter method.
       A, average    set factor of shape modification above upper calculation
                     frequency limit (0.00000 <= n <= 1.00000)
       c, cubic      enable cubic interpolation when defining filter shape
       e, extra      additional white noise to add during creation of filter
       f, fixed      disable adaptive noise shaping (use fixed shaping)
       h, hybrid     enable hybrid alternative to default adaptive noise shaping
                     method. Uses all available calculated analyses to create
                     the desired noise filter shape rather than only those for
                     1.5ms and 20ms FFT analyses.
       n, nowarp     disable warped noise shaping (use linear frequency shaping)
       o, off        disable noise shaping altogether (use simple rounding)
       s, scale <n>  change effectiveness of noise shaping (0 < n <= 2; default                     = 1.0)
       t, taps <n>   select number of taps to use in FIR filter (8 <= n <= 256;                     default = 64)
       w, warp       enable cubic interpolation when creating warped filter
    --static <n>     set minimum-bits-to-keep-static to n bits (default=6;
                     3<=n<=28, limited to bits-per-sample - 3).
-U, --underlap <n>   enable underlap mode to increase number of FFT analyses
                     performed at each FFT length, (n = 2, 4 or 8, default=2).

Output Options:

    --bitdist        show distrubution of bits to remove.
    --blockdist      show distribution of lowest / highest significant bit of
                     input codec-blocks and bit-removed codec-blocks.
-d, --detail         enable per block per channel bits-to-remove data display.
-F, --freqdist [all] enable frequency analysis display of input data. Use of
                     'all' parameter displays all calculated analyses.
-H, --histogram      show sample value histogram (input, lossy and correction).    --perchannel     show selected distribution data per channel.
-p, --postanalyse    enable frequency analysis display of output and
                     correction data in addition to input data.
    --sampledist     show distribution of lowest / highest significant bit of
                     input samples and bit-removed samples.
    --spread [full]  show detailed [more detailed] results from the spreading/
                     averaging algorithm.
-W, --width <n>      select width of output options (79<=n<=255).

System Options:

-B, --below          set process priority to below normal.
    --low            set process priority to low.
-N, --nowarnings     suppress lossyWAV warnings.
-Q, --quiet          significantly reduce screen output.
-S, --silent         no screen output.

Special thanks go to:

David Robinson       for the publication of his lossyFLAC method, guidance, and                     the motivation to implement his method as lossyWAV.

Horst Albrecht       for ABX testing, valuable support in tuning the internal
                     presets, constructive criticism and all the feedback.

Sebastian Gesemann   for the adaptive noise shaping method and the amount of
                     help received in implementing it and also for the basis of                     the fixed noise shaping method.

Tyge Lovset          for the C++ translation initiative.

Matteo Frigo and     for libfftw3-3.dll contained in the FFTW distribution
Steven G Johnson     (v3.2.1 or v3.2.2).

Mark G Beckett       for the Delphi unit that provides an interface to the
(Univ. of Edinburgh) relevant fftw routines in libfftw3-3.dll.

Don Cross            for the Complex-FFT algorithm originally used.