xref: /frameworks/av/media/libstagefright/codecs/amrwbenc/src/q_gain2.c

/*
 ** Copyright 2003-2010, VisualOn, Inc.
 **
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 **
 **     http://www.apache.org/licenses/LICENSE-2.0
 **
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 */

/**************************************************************************
*  File: q_gain2.c                                                         *
*                                                                          *
*  Description:                                                            *
* Quantization of pitch and codebook gains.                                *
* MA prediction is performed on the innovation energy (in dB with mean     *
* removed).                                                                *
* An initial predicted gain, g_0, is first determined and the correction   *
* factor     alpha = gain / g_0    is quantized.                           *
* The pitch gain and the correction factor are vector quantized and the    *
* mean-squared weighted error criterion is used in the quantizer search.   *
****************************************************************************/

#include "typedef.h"
#include "basic_op.h"
#include "oper_32b.h"
#include "math_op.h"
#include "log2.h"
#include "acelp.h"
#include "q_gain2.tab"

#define MEAN_ENER    30
#define RANGE        64
#define PRED_ORDER   4


/* MA prediction coeff ={0.5, 0.4, 0.3, 0.2} in Q13 */
static Word16 pred[PRED_ORDER] = {4096, 3277, 2458, 1638};


void Init_Q_gain2(
		Word16 * mem                          /* output  :static memory (2 words)      */
		)
{
	Word32 i;

	/* 4nd order quantizer energy predictor (init to -14.0 in Q10) */
	for (i = 0; i < PRED_ORDER; i++)
	{
		mem[i] = -14336;                     /* past_qua_en[i] */
	}

	return;
}

Word16 Q_gain2(                            /* Return index of quantization.          */
		Word16 xn[],                          /* (i) Q_xn: Target vector.               */
		Word16 y1[],                          /* (i) Q_xn: Adaptive codebook.           */
		Word16 Q_xn,                          /* (i)     : xn and y1 format             */
		Word16 y2[],                          /* (i) Q9  : Filtered innovative vector.  */
		Word16 code[],                        /* (i) Q9  : Innovative vector.           */
		Word16 g_coeff[],                     /* (i)     : Correlations <xn y1> <y1 y1> */
		/*           Compute in G_pitch().        */
		Word16 L_subfr,                       /* (i)     : Subframe lenght.             */
		Word16 nbits,                         /* (i)     : number of bits (6 or 7)      */
		Word16 * gain_pit,                    /* (i/o)Q14: Pitch gain.                  */
		Word32 * gain_cod,                    /* (o) Q16 : Code gain.                   */
		Word16 gp_clip,                       /* (i)     : Gp Clipping flag             */
		Word16 * mem                          /* (i/o)   : static memory (2 words)      */
	      )
{
	Word16 index, *p, min_ind, size;
	Word16 exp, frac, gcode0, exp_gcode0, e_max, exp_code, qua_ener;
	Word16 g_pitch, g2_pitch, g_code, g_pit_cod, g2_code, g2_code_lo;
	Word16 coeff[5], coeff_lo[5], exp_coeff[5];
	Word16 exp_max[5];
	Word32 i, j, L_tmp, dist_min;
	Word16 *past_qua_en, *t_qua_gain;

	past_qua_en = mem;

	/*-----------------------------------------------------------------*
	 * - Find the initial quantization pitch index                     *
	 * - Set gains search range                                        *
	 *-----------------------------------------------------------------*/
	if (nbits == 6)
	{
		t_qua_gain = t_qua_gain6b;
		min_ind = 0;
		size = RANGE;

		if(gp_clip == 1)
		{
			size = size - 16;          /* limit gain pitch to 1.0 */
		}
	} else
	{
		t_qua_gain = t_qua_gain7b;

		p = t_qua_gain7b + RANGE;            /* pt at 1/4th of table */

		j = nb_qua_gain7b - RANGE;

		if (gp_clip == 1)
		{
			j = j - 27;                /* limit gain pitch to 1.0 */
		}
		min_ind = 0;
		g_pitch = *gain_pit;

		for (i = 0; i < j; i++, p += 2)
		{
			if (g_pitch > *p)
			{
				min_ind = min_ind + 1;
			}
		}
		size = RANGE;
	}

	/*------------------------------------------------------------------*
	 *  Compute coefficient need for the quantization.                  *
	 *                                                                  *
	 *  coeff[0] =    y1 y1                                             *
	 *  coeff[1] = -2 xn y1                                             *
	 *  coeff[2] =    y2 y2                                             *
	 *  coeff[3] = -2 xn y2                                             *
	 *  coeff[4] =  2 y1 y2                                             *
	 *                                                                  *
	 * Product <y1 y1> and <xn y1> have been compute in G_pitch() and   *
	 * are in vector g_coeff[].                                         *
	 *------------------------------------------------------------------*/

	coeff[0] = g_coeff[0];
	exp_coeff[0] = g_coeff[1];
	coeff[1] = negate(g_coeff[2]);                    /* coeff[1] = -2 xn y1 */
	exp_coeff[1] = g_coeff[3] + 1;

	/* Compute scalar product <y2[],y2[]> */
#ifdef ASM_OPT                   /* asm optimization branch */
	coeff[2] = extract_h(Dot_product12_asm(y2, y2, L_subfr, &exp));
#else
	coeff[2] = extract_h(Dot_product12(y2, y2, L_subfr, &exp));
#endif
	exp_coeff[2] = (exp - 18) + (Q_xn << 1);     /* -18 (y2 Q9) */

	/* Compute scalar product -2*<xn[],y2[]> */
#ifdef ASM_OPT                  /* asm optimization branch */
	coeff[3] = extract_h(L_negate(Dot_product12_asm(xn, y2, L_subfr, &exp)));
#else
	coeff[3] = extract_h(L_negate(Dot_product12(xn, y2, L_subfr, &exp)));
#endif

	exp_coeff[3] = (exp - 8) + Q_xn;  /* -9 (y2 Q9), +1 (2 xn y2) */

	/* Compute scalar product 2*<y1[],y2[]> */
#ifdef ASM_OPT                 /* asm optimization branch */
	coeff[4] = extract_h(Dot_product12_asm(y1, y2, L_subfr, &exp));
#else
	coeff[4] = extract_h(Dot_product12(y1, y2, L_subfr, &exp));
#endif
	exp_coeff[4] = (exp - 8) + Q_xn;  /* -9 (y2 Q9), +1 (2 y1 y2) */

	/*-----------------------------------------------------------------*
	 *  Find energy of code and compute:                               *
	 *                                                                 *
	 *    L_tmp = MEAN_ENER - 10log10(energy of code/ L_subfr)         *
	 *          = MEAN_ENER - 3.0103*log2(energy of code/ L_subfr)     *
	 *-----------------------------------------------------------------*/
#ifdef ASM_OPT                 /* asm optimization branch */
	L_tmp = Dot_product12_asm(code, code, L_subfr, &exp_code);
#else
	L_tmp = Dot_product12(code, code, L_subfr, &exp_code);
#endif
	/* exp_code: -18 (code in Q9), -6 (/L_subfr), -31 (L_tmp Q31->Q0) */
	exp_code = (exp_code - (18 + 6 + 31));

	Log2(L_tmp, &exp, &frac);
	exp += exp_code;
	L_tmp = Mpy_32_16(exp, frac, -24660);  /* x -3.0103(Q13) -> Q14 */

	L_tmp += (MEAN_ENER * 8192)<<1; /* + MEAN_ENER in Q14 */

	/*-----------------------------------------------------------------*
	 * Compute gcode0.                                                 *
	 *  = Sum(i=0,1) pred[i]*past_qua_en[i] + mean_ener - ener_code    *
	 *-----------------------------------------------------------------*/
	L_tmp = (L_tmp << 10);              /* From Q14 to Q24 */
	L_tmp += (pred[0] * past_qua_en[0])<<1;      /* Q13*Q10 -> Q24 */
	L_tmp += (pred[1] * past_qua_en[1])<<1;      /* Q13*Q10 -> Q24 */
	L_tmp += (pred[2] * past_qua_en[2])<<1;      /* Q13*Q10 -> Q24 */
	L_tmp += (pred[3] * past_qua_en[3])<<1;      /* Q13*Q10 -> Q24 */

	gcode0 = extract_h(L_tmp);             /* From Q24 to Q8  */

	/*-----------------------------------------------------------------*
	 * gcode0 = pow(10.0, gcode0/20)                                   *
	 *        = pow(2, 3.321928*gcode0/20)                             *
	 *        = pow(2, 0.166096*gcode0)                                *
	 *-----------------------------------------------------------------*/

	L_tmp = vo_L_mult(gcode0, 5443);          /* *0.166096 in Q15 -> Q24     */
	L_tmp = L_tmp >> 8;               /* From Q24 to Q16             */
	VO_L_Extract(L_tmp, &exp_gcode0, &frac);  /* Extract exponent of gcode0  */

	gcode0 = (Word16)(Pow2(14, frac));    /* Put 14 as exponent so that  */
	/* output of Pow2() will be:   */
	/* 16384 < Pow2() <= 32767     */
	exp_gcode0 -= 14;

	/*-------------------------------------------------------------------------*
	 * Find the best quantizer                                                 *
	 * ~~~~~~~~~~~~~~~~~~~~~~~                                                 *
	 * Before doing the computation we need to aling exponents of coeff[]      *
	 * to be sure to have the maximum precision.                               *
	 *                                                                         *
	 * In the table the pitch gains are in Q14, the code gains are in Q11 and  *
	 * are multiply by gcode0 which have been multiply by 2^exp_gcode0.        *
	 * Also when we compute g_pitch*g_pitch, g_code*g_code and g_pitch*g_code  *
	 * we divide by 2^15.                                                      *
	 * Considering all the scaling above we have:                              *
	 *                                                                         *
	 *   exp_code = exp_gcode0-11+15 = exp_gcode0+4                            *
	 *                                                                         *
	 *   g_pitch*g_pitch  = -14-14+15                                          *
	 *   g_pitch          = -14                                                *
	 *   g_code*g_code    = (2*exp_code)+15                                    *
	 *   g_code           = exp_code                                           *
	 *   g_pitch*g_code   = -14 + exp_code +15                                 *
	 *                                                                         *
	 *   g_pitch*g_pitch * coeff[0]  ;exp_max0 = exp_coeff[0] - 13             *
	 *   g_pitch         * coeff[1]  ;exp_max1 = exp_coeff[1] - 14             *
	 *   g_code*g_code   * coeff[2]  ;exp_max2 = exp_coeff[2] +15+(2*exp_code) *
	 *   g_code          * coeff[3]  ;exp_max3 = exp_coeff[3] + exp_code       *
	 *   g_pitch*g_code  * coeff[4]  ;exp_max4 = exp_coeff[4] + 1 + exp_code   *
	 *-------------------------------------------------------------------------*/

	exp_code = (exp_gcode0 + 4);
	exp_max[0] = (exp_coeff[0] - 13);
	exp_max[1] = (exp_coeff[1] - 14);
	exp_max[2] = (exp_coeff[2] + (15 + (exp_code << 1)));
	exp_max[3] = (exp_coeff[3] + exp_code);
	exp_max[4] = (exp_coeff[4] + (1 + exp_code));

	/* Find maximum exponant */

	e_max = exp_max[0];
	for (i = 1; i < 5; i++)
	{
		if(exp_max[i] > e_max)
		{
			e_max = exp_max[i];
		}
	}

	/* align coeff[] and save in special 32 bit double precision */

	for (i = 0; i < 5; i++)
	{
		j = add1(vo_sub(e_max, exp_max[i]), 2);/* /4 to avoid overflow */
		L_tmp = L_deposit_h(coeff[i]);
		L_tmp = L_shr(L_tmp, j);
		VO_L_Extract(L_tmp, &coeff[i], &coeff_lo[i]);
		coeff_lo[i] = (coeff_lo[i] >> 3);   /* lo >> 3 */
	}

	/* Codebook search */
	dist_min = MAX_32;
	p = &t_qua_gain[min_ind << 1];

	index = 0;
	for (i = 0; i < size; i++)
	{
		g_pitch = *p++;
		g_code = *p++;

		g_code = ((g_code * gcode0) + 0x4000)>>15;
		g2_pitch = ((g_pitch * g_pitch) + 0x4000)>>15;
		g_pit_cod = ((g_code * g_pitch) + 0x4000)>>15;
		L_tmp = (g_code * g_code)<<1;
		VO_L_Extract(L_tmp, &g2_code, &g2_code_lo);

		L_tmp = (coeff[2] * g2_code_lo)<<1;
		L_tmp =  (L_tmp >> 3);
		L_tmp += (coeff_lo[0] * g2_pitch)<<1;
		L_tmp += (coeff_lo[1] * g_pitch)<<1;
		L_tmp += (coeff_lo[2] * g2_code)<<1;
		L_tmp += (coeff_lo[3] * g_code)<<1;
		L_tmp += (coeff_lo[4] * g_pit_cod)<<1;
		L_tmp =  (L_tmp >> 12);
		L_tmp += (coeff[0] * g2_pitch)<<1;
		L_tmp += (coeff[1] * g_pitch)<<1;
		L_tmp += (coeff[2] * g2_code)<<1;
		L_tmp += (coeff[3] * g_code)<<1;
		L_tmp += (coeff[4] * g_pit_cod)<<1;

		if(L_tmp < dist_min)
		{
			dist_min = L_tmp;
			index = i;
		}
	}

	/* Read the quantized gains */
	index = index + min_ind;
	p = &t_qua_gain[(index + index)];
	*gain_pit = *p++;                       /* selected pitch gain in Q14 */
	g_code = *p++;                          /* selected code gain in Q11  */

	L_tmp = vo_L_mult(g_code, gcode0);             /* Q11*Q0 -> Q12 */
	L_tmp = L_shl(L_tmp, (exp_gcode0 + 4));   /* Q12 -> Q16 */

	*gain_cod = L_tmp;                       /* gain of code in Q16 */

	/*---------------------------------------------------*
	 * qua_ener = 20*log10(g_code)                       *
	 *          = 6.0206*log2(g_code)                    *
	 *          = 6.0206*(log2(g_codeQ11) - 11)          *
	 *---------------------------------------------------*/

	L_tmp = L_deposit_l(g_code);
	Log2(L_tmp, &exp, &frac);
	exp -= 11;
	L_tmp = Mpy_32_16(exp, frac, 24660);   /* x 6.0206 in Q12 */

	qua_ener = (Word16)(L_tmp >> 3); /* result in Q10 */

	/* update table of past quantized energies */

	past_qua_en[3] = past_qua_en[2];
	past_qua_en[2] = past_qua_en[1];
	past_qua_en[1] = past_qua_en[0];
	past_qua_en[0] = qua_ener;

	return (index);
}