www.pudn.com > CryptoPhone-src-031122.zip > acb_code.c

/* Copyright 2001,2002,2003 NAH6 
 * All Rights Reserved 
 * 
 * Parts Copyright DoD, Parts Copyright Starium 
 * 
 */ 
          /*LINTLIBRARY*/ 
          /*PROTOLIB1*/ 
#include  
#include "main.h" 
#include "acb_code.h" 
 
static float ACBGainTable[32] = 
{ 
  -0.993, -0.831, -0.693, -0.555, -0.414, -0.229,    0.0,  0.139, 
   0.255,  0.368,  0.457,  0.531,  0.601,  0.653,  0.702,  0.745, 
   0.780,  0.816,  0.850,  0.881,  0.915,  0.948,  0.983,  1.020,  
   1.062,  1.117,  1.193,  1.289,  1.394,  1.540,  1.765,  1.991 
}; 
 
/************************************************************************** 
* 
* ROUTINE 
*		ACBGainEncode 
* 
* FUNCTION 
* 
*		encode and quantize ACB gain for various 
*		quantizer types. 
* 
* SYNOPSIS 
*		ACBGainEncode(UGain, *QGain) 
* 
*   formal 
* 
*                       data    I/O 
*       name            type    type    function 
*       ------------------------------------------------------------------- 
*	UGain		float	i	pitch gain input (true value) 
*	QGain		int	o	encoded pitch gain index 
* 
*	ACBGainEncode	float	fun	encoded pitch gain 
* 
*************************************************************************** 
* 
* DESCRIPTION 
* 
*	This funtion uses output level data obtained by Max's minimum 
*	distortion quantization priciples and quantizes to the nearest 
*	level (L1 norm).  (Using level data only was found superior to 
*	using both of Max's level and boundry data.) 
* 
*************************************************************************** 
* 
* CALLED BY 
* 
*	AdaptiveAnalysis Encode Decode 
* 
*************************************************************************** 
* 
* REFERENCES 
* 
*	Quantizing for Minimum Distorion 
*	J. Max 
*	IRE Trans. Inform. Theory, vol. IT-6, pp.7-12, Mar. 1960 
* 
**************************************************************************/ 
float ACBGainEncode( 
float 	UGain,  
int 	*QGain) 
{ 
  int i; 
  float dist, low; 
   
  low = dist = fabs(UGain - *ACBGainTable); 
  *QGain = 0; 
  for (i = 1; i < 32; i++) 
  { 
    dist = fabs(UGain - ACBGainTable[i]); 
    if (dist < low) 
    { 
      low = dist; 
      *QGain = i; 
    } 
  } 
  return (ACBGainTable[*QGain]); 
} 
/* 
 
************************************************************************* 
* 
* ROUTINE 
*		ACBGainDecode 
* 
* FUNCTION 
* 
*		decode ACB gain from table  
* 
* SYNOPSIS 
*		ACBGainDecode(QGain, UGain) 
* 
*   formal 
* 
*                       data    I/O 
*       name            type    type    function 
*       ------------------------------------------------------------------- 
*	QGain		int	i	Quantized ACB Gain 
*	UGain		float	o	Unquantized ACB Gain 
* 
*************************************************************************** 
* 
*	The data used in the table generation is from 3m3f.spd. 
* 
*************************************************************************** 
* 
* REFERENCES 
* 
*	Quantizing for Minimum Distorion 
*	J. Max 
*	IRE Trans. Inform. Theory, vol. IT-6, pp.7-12, Mar. 1960 
* 
**************************************************************************/ 
void ACBGainDecode( 
int 	QGain,  
float 	*UGain) 
{ 
  *UGain = ACBGainTable[QGain]; 
}