minimum_masking_threshold.m

这是一个包含对MPEG视频各种变换处理的Matlab程序包

function  LTmin = Minimum_masking_threshold(LTg, Map)
%LTmin = Minimum_masking_threshold(LTg, Map)
%
%   Find the minimum of the global masking threshold for each subband.
%   [1, pp. 114]
%
%   See also Global_masking_threshold
   
%   Author: Fabien A. P. Petitcolas
%           Computer Laboratory
%           University of Cambridge
%
%   Copyright (c) 1998--2001 by Fabien A. P. Petitcolas
%   $Header: /Matlab MPEG/Minimum_masking_threshold.m 3     7/07/01 1:27 Fabienpe $
%   $Id: Minimum_masking_threshold.m,v 1.2 1998-06-22 17:47:56+01 fapp2 Exp $

%   References:
%    [1] Information technology -- Coding of moving pictures and associated
%        audio for digital storage media at up to 1,5 Mbits/s -- Part3: audio.
%        British standard. BSI, London. October 1993. Implementation of ISO/IEC
%        11172-3:1993. BSI, London. First edition 1993-08-01.
%
%   Legal notice:
%    This computer program is based on ISO/IEC 11172-3:1993, Information
%    technology -- Coding of moving pictures and associated audio for digital
%    storage media at up to about 1,5 Mbit/s -- Part 3: Audio, with the
%    permission of ISO. Copies of this standards can be purchased from the
%    British Standards Institution, 389 Chiswick High Road, GB-London W4 4AL, 
%    Telephone:+ 44 181 996 90 00, Telefax:+ 44 181 996 74 00 or from ISO,
%    postal box 56, CH-1211 Geneva 20, Telephone [phone], Telefax
%    [phone]. Copyright remains with ISO.
%-------------------------------------------------------------------------------
Common;

Subband_size = FFT_SIZE / 2 / N_SUBBAND;

for n = 1:N_SUBBAND, % For each subband
   
   LTmin(n) = LTg(Map((n - 1) * Subband_size + 1));
   
   for j = 2:Subband_size, % Try all the samples in this subband
      if (LTg(Map((n - 1) * Subband_size + j)) < LTmin(n))
         LTmin(n) = LTg(Map((n - 1) * Subband_size + j));
      end
   end
end