sv-p56.c

Reference Implementation of G.711 standard and other voice codecs

/*                                                             v2.3 19.MAY.05
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                   ========================================
                    ITU-T - USER'S GROUP ON SOFTWARE TOOLS
                   ========================================

       =============================================================
       COPYRIGHT NOTE: This source code, and all of its derivations,
       is subject to the "ITU-T General Public License". Please have
       it  read  in    the  distribution  disk,   or  in  the  ITU-T
       Recommendation G.191 on "SOFTWARE TOOLS FOR SPEECH AND  AUDIO 
       CODING STANDARDS".
       =============================================================


MODULE:         SV-P56.C, FUNCTIONS RELATED TO ACTIVE LEVEL CALCULATIONS

ORIGINAL BY:    
   Simao Ferraz de Campos Neto   CPqD/Telebras Brazil

DATE:           19/May/2005

RELEASE:        2.00

PROTOTYPES:     see sv-p56.h.

FUNCTIONS:

init_speech_voltmeter ......... initialization of the speech voltmeter state
                                variables in a structure of type SVP56_state.

speech_voltmeter .............. measurement of the active speech level of
                                data in a buffer according to P.56. Other 
				relevant statistics are also available.

HISTORY:

   07.Oct.91 v1.0 Release of 1st version to UGST.
   28.Feb.92 v2.0 Correction of bug in speech_voltmeter; inclusion of test
                  for extremes in bin_interp; use of structure to keep  
                  state variables.   <[e-mail]>
   18.May.92 v2.1 Creation of init_speech_voltmeter and consequent changes;
                  speech_voltmeter changed to operate with float data in the 
                  normalized range. <[e-mail]>
   01.Sep.95 v2.2 Added very small constant to avoid problems first detected
                  in a DEC Alpha VMS workstation with log(0) by
                  <[e-mail]>; generalized to all
		  platforms <[e-mail]>
   19.May.05 v2.3 Bug correction in bin_interp() routine, based on changes 
				  suggested by Mr Kabal. 
				  Upper and lower bounds are updated during the interpolation.
						<Cyril Guillaum