sbr_fbt.c

wince下著名的视频播放器源码

/*
** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
** Copyright (C) 2003-2004 M. Bakker, Ahead Software AG, http://www.nero.com
**  
** 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 2 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 A PARTICULAR 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, write to the Free Software 
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
** Any non-GPL usage of this software or parts of this software is strictly
** forbidden.
**
** Commercial non-GPL licensing of this software is possible.
** For more info contact Ahead Software through [e-mail].
**
** $Id: sbr_fbt.c,v 1.17 2004/09/08 09:43:11 gcp Exp $
**/

/* Calculate frequency band tables */

#include "common.h"
#include "structs.h"

#ifdef SBR_DEC

#include <stdlib.h>

#include "sbr_syntax.h"
#include "sbr_fbt.h"

/* static function declarations */
static int32_t find_bands(uint8_t warp, uint8_t bands, uint8_t a0, uint8_t a1);


/* calculate the start QMF channel for the master frequency band table */
/* parameter is also called k0 */
uint8_t qmf_start_channel(uint8_t bs_start_freq, uint8_t bs_samplerate_mode,
                           uint32_t sample_rate)
{
    static const uint8_t startMinTable[12] = { 7, 7, 10, 11, 12, 16, 16,
        17, 24, 32, 35, 48 };
    static const uint8_t offsetIndexTable[12] = { 5, 5, 4, 4, 4, 3, 2, 1, 0,
        6, 6, 6 };
    static const int8_t offset[7][16] = {
        { -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7 },
        { -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13 },
        { -5, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16 },
        { -6, -4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16 },
        { -4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20 },
        { -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20, 24 },
        { 0, 1, 2, 3, 4, 5, 6, 7, 9, 11, 13, 16, 20, 24, 28, 33 }
    };
    uint8_t startMin = startMinTable[get_sr_index(sample_rate)];
    uint8_t offsetIndex = offsetIndexTable[get_sr_index(sample_rate)];

#if 0 /* replaced with table (startMinTable) */
    if (sample_rate >= 64000)
    {
        startMin = (uint8_t)((5000.*128.)/(float)sample_rate + 0.5);
    } else if (sample_rate < 32000) {
        startMin = (uint8_t)((3000.*128.)/(float)sample_rate + 0.5);
    } else {
        startMin = (uint8_t)((4000.*128.)/(float)sample_rate + 0.5);
    }
#endif

    if (bs_samplerate_mode)
    {
        return startMin + offset[offsetIndex][bs_start_freq];

#if 0 /* replaced by offsetIndexTable */ 
        switch (sample_rate)
        {
        case 16000:
            return startMin + offset[0][bs_start_freq];
        case 22050:
            return startMin + offset[1][bs_start_freq];
        case 24000:
            return startMin + offset[2][bs_start_freq];
        case 32000:
            return startMin + offset[3][bs_start_freq];
        default:
            if (sample_rate > 64000)
            {
                return startMin + offset[5][bs_start_freq];
            } else { /* 44100 <= sample_rate <= 64000 */
                return startMin + offset[4][bs_start_freq];
            }
        }
#endif
    } else {
        return startMin + offset[6][bs_start_freq];
    }
}

static int __cdecl longcmp(const void *a, const void *b)
{
    return ((int)(*(int32_t*)a - *(int32_t*)b));
}

/* calculate the stop QMF channel for the master frequency band table */
/* parameter is also called k2 */
uint8_t qmf_stop_channel(uint8_t bs_stop_freq, uint32_t sample_rate,
                          uint8_t k0)
{
    if (bs_stop_freq == 15)
    {
        return min(64, k0 * 3);
    } else if (bs_stop_freq == 14) {
        return min(64, k0 * 2);
    } else {
        static const uint8_t stopMinTable[12] = { 13, 15, 20, 21, 23,
            32, 32, 35, 48, 64, 70, 96 };
        static const int8_t offset[12][14] = {
            { 0, 2, 4, 6, 8, 11, 14, 18, 22, 26, 31, 37, 44, 51 },
            { 0, 2, 4, 6, 8, 11, 14, 18, 22, 26, 31, 36, 42, 49 },
            { 0, 2, 4, 6, 8, 11, 14, 17, 21, 25, 29, 34, 39, 44 },
            { 0, 2, 4, 6, 8, 11, 14, 17, 20, 24, 28, 33, 38, 43 },
            { 0, 2, 4, 6, 8, 11, 14, 17, 20, 24, 28, 32, 36, 41 },
            { 0, 2, 4, 6, 8, 10, 12, 14, 17, 20, 23, 26, 29, 32 },
            { 0, 2, 4, 6, 8, 10, 12, 14, 17, 20, 23, 26, 29, 32 },
            { 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 20, 23, 26, 29 },
            { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16 },
            { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
            { 0, -1, -2, -3, -4, -5, -6, -6, -6, -6, -6, -6, -6, -6 },
            { 0, -3, -6, -9, -12, -15, -18, -20, -22, -24, -26, -28, -30, -32 }
        };
#if 0
        uint8_t i;
        int32_t stopDk[13], stopDk_t[14], k2;
#endif
        uint8_t stopMin = stopMinTable[get_sr_index(sample_rate)];

#if 0 /* replaced by table lookup */
        if (sample_rate >= 64000)
        {
            stopMin = (uint8_t)((10000.*128.)/(float)sample_rate + 0.5);
        } else if (sample_rate < 32000) {
            stopMin = (uint8_t)((6000.*128.)/(float)sample_rate + 0.5);
        } else {
            stopMin = (uint8_t)((8000.*128.)/(float)sample_rate + 0.5);
        }
#endif

#if 0 /* replaced by table lookup */
        /* diverging power series */
        for (i = 0; i <= 13; i++)
        {
            stopDk_t[i] = (int32_t)(stopMin*pow(64.0/stopMin, i/13.0) + 0.5);
        }
        for (i = 0; i < 13; i++)
        {
            stopDk[i] = stopDk_t[i+1] - stopDk_t[i];
        }

        /* needed? */
        qsort(stopDk, 13, sizeof(stopDk[0]), longcmp);

        k2 = stopMin;
        for (i = 0; i < bs_stop_freq; i++)
        {
            k2 += stopDk[i];
        }
        return min(64, k2);
#endif
        /* bs_stop_freq <= 13 */
        return min(64, stopMin + offset[get_sr_index(sample_rate)][min(bs_stop_freq, 13)]);
    }

    return 0;
}

/* calculate the master frequency table from k0, k2, bs_freq_scale
   and bs_alter_scale

   version for bs_freq_scale = 0
*/
uint8_t master_frequency_table_fs0(sbr_info *sbr, uint8_t k0, uint8_t k2,
                                   uint8_t bs_alter_scale)
{
    int8_t incr;
    uint8_t k;
    uint8_t dk;
    uint32_t nrBands, k2Achieved;
    int32_t k2Diff, vDk[64] = {0};

    /* mft only defined for k2 > k0 */
    if (k2 <= k0)
    {
        sbr->N_master = 0;
        return 1;
    }

    dk = bs_alter_scale ? 2 : 1;

#if 0 /* replaced by float-less design */
    nrBands = 2 * (int32_t)((float)(k2-k0)/(dk*2) + (-1+dk)/2.0f);
#else
    if (bs_alter_scale)
    {
        nrBands = (((k2-k0+2)>>2)<<1);
    } else {
        nrBands = (((k2-k0)>>1)<<1);
    }
#endif
    nrBands = min(nrBands, 63);
    if (nrBands <= 0)
        return 1;

    k2Achieved = k0 + nrBands * dk;
    k2Diff = k2 - k2Achieved;
    for (k = 0; k < nrBands; k++)
        vDk[k] = dk;

    if (k2Diff)
    {
        incr = (k2Diff > 0) ? -1 : 1;
        k = (uint8_t) ((k2Diff > 0) ? (nrBands-1) : 0);

        while (k2Diff != 0)
        {
            vDk[k] -= incr;
            k += incr;
            k2Diff += incr;
        }
    }

    sbr->f_master[0] = k0;
    for (k = 1; k <= nrBands; k++)
        sbr->f_master[k] = (uint8_t)(sbr->f_master[k-1] + vDk[k-1]);

    sbr->N_master = (uint8_t)nrBands;
    sbr->N_master = (min(sbr->N_master, 64));

#if 0
    printf("f_master[%d]: ", nrBands);
    for (k = 0; k <= nrBands; k++)
    {
        printf("%d ", sbr->f_master[k]);
    }
    printf("\n");
#endif

    return 0;
}

/*
   This function finds the number of bands using this formula:
    bands * log(a1/a0)/log(2.0) + 0.5
*/
static int32_t find_bands(uint8_t warp, uint8_t bands, uint8_t a0, uint8_t a1)
{
#ifdef FIXED_POINT
    /* table with log2() values */
    static const real_t log2Table[65] = {
        COEF_CONST(0.0), COEF_CONST(0.0), COEF_CONST(1.0000000000), COEF_CONST(1.5849625007),
        COEF_CONST(2.0000000000), COEF_CONST(2.3219280949), COEF_CONST(2.5849625007), COEF_CONST(2.8073549221),
        COEF_CONST(3.0000000000), COEF_CONST(3.1699250014), COEF_CONST(3.3219280949), COEF_CONST(3.4594316186),
        COEF_CONST(3.5849625007), COEF_CONST(3.7004397181), COEF_CONST(3.8073549221), COEF_CONST(3.9068905956),
        COEF_CONST(4.0000000000), COEF_CONST(4.0874628413), COEF_CONST(4.1699250014), COEF_CONST(4.2479275134),
        COEF_CONST(4.3219280949), COEF_CONST(4.3923174228), COEF_CONST(4.4594316186), COEF_CONST(4.5235619561),
        COEF_CONST(4.5849625007), COEF_CONST(4.6438561898), COEF_CONST(4.7004397181), COEF_CONST(4.7548875022),
        COEF_CONST(4.8073549221), COEF_CONST(4.8579809951), COEF_CONST(4.9068905956), COEF_CONST(4.9541963104),
        COEF_CONST(5.0000000000), COEF_CONST(5.0443941194), COEF_CONST(5.0874628413), COEF_CONST(5.1292830169),
        COEF_CONST(5.1699250014), COEF_CONST(5.2094533656), COEF_CONST(5.2479275134), COEF_CONST(5.2854022189),
        COEF_CONST(5.3219280949), COEF_CONST(5.3575520046), COEF_CONST(5.3923174228), COEF_CONST(5.4262647547),
        COEF_CONST(5.4594316186), COEF_CONST(5.4918530963), COEF_CONST(5.5235619561), COEF_CONST(5.5545888517),
        COEF_CONST(5.5849625007), COEF_CONST(5.6147098441), COEF_CONST(5.6438561898), COEF_CONST(5.6724253420),
        COEF_CONST(5.7004397181), COEF_CONST(5.7279204546), COEF_CONST(5.7548875022), COEF_CONST(5.7813597135),
        COEF_CONST(5.8073549221), COEF_CONST(5.8328900142), COEF_CONST(5.8579809951), COEF_CONST(5.8826430494),
        COEF_CONST(5.9068905956), COEF_CONST(5.9307373376), COEF_CONST(5.9541963104), COEF_CONST(5.9772799235),
        COEF_CONST(6.0)
    };
    real_t r0 = log2Table[a0]; /* coef */
    real_t r1 = log2Table[a1]; /* coef */
    real_t r2 = (r1 - r0); /* coef */

    if (warp)
        r2 = MUL_C(r2, COEF_CONST(1.0/1.3));

    /* convert r2 to real and then multiply and round */
    r2 = (r2 >> (COEF_BITS-REAL_BITS)) * bands + (1<<(REAL_BITS-1));

    return (r2 >> REAL_BITS);
#else
    real_t div = (real_t)log(2.0);
    if (warp) div *= (real_t)1.3;

    return (int32_t)(bands * log((float)a1/(float)a0)/div + 0.5);
#endif
}

static real_t find_initial_power(uint8_t bands, uint8_t a0, uint8_t a1)
{
#ifdef FIXED_POINT
    /* table with log() values */
    static const real_t logTable[65] = {
        COEF_CONST(0.0), COEF_CONST(0.0), COEF_CONST(0.6931471806), COEF_CONST(1.0986122887),
        COEF_CONST(1.3862943611), COEF_CONST(1.6094379124), COEF_CONST(1.7917594692), COEF_CONST(1.9459101491),
        COEF_CONST(2.0794415417), COEF_CONST(2.1972245773), COEF_CONST(2.3025850930), COEF_CONST(2.3978952728),
        COEF_CONST(2.4849066498), COEF_CONST(2.5649493575), COEF_CONST(2.6390573296), COEF_CONST(2.7080502011),
        COEF_CONST(2.7725887222), COEF_CONST(2.8332133441), COEF_CONST(2.8903717579), COEF_CONST(2.9444389792),
        COEF_CONST(2.9957322736), COEF_CONST(3.0445224377), COEF_CONST(3.0910424534), COEF_CONST(3.1354942159),
        COEF_CONST(3.1780538303), COEF_CONST(3.2188758249), COEF_CONST(3.2580965380), COEF_CONST(3.2958368660),
        COEF_CONST(3.3322045102), COEF_CONST(3.3672958300), COEF_CONST(3.4011973817), COEF_CONST(3.4339872045),
        COEF_CONST(3.4657359028), COEF_CONST(3.4965075615), COEF_CONST(3.5263605246), COEF_CONST(3.5553480615),
        COEF_CONST(3.5835189385), COEF_CONST(3.6109179126), COEF_CONST(3.6375861597), COEF_CONST(3.6635616461),
        COEF_CONST(3.6888794541), COEF_CONST(3.7135720667), COEF_CONST(3.7376696183), COEF_CONST(3.7612001157),
        COEF_CONST(3.7841896339), COEF_CONST(3.8066624898), COEF_CONST(3.8286413965), COEF_CONST(3.8501476017),
        COEF_CONST(3.8712010109), COEF_CONST(3.8918202981), COEF_CONST(3.9120230054), COEF_CONST(3.9318256327),
        COEF_CONST(3.9512437186), COEF_CONST(3.9702919136), COEF_CONST(3.9889840466), COEF_CONST(4.0073331852),
        COEF_CONST(4.0253516907), COEF_CONST(4.0430512678), COEF_CONST(4.0604430105), COEF_CONST(4.0775374439),
        COEF_CONST(4.0943445622), COEF_CONST(4.1108738642), COEF_CONST(4.1271343850), COEF_CONST(4.1431347264),
        COEF_CONST(4.158883083)
    };
    /* standard Taylor polynomial coefficients for exp(x) around 0 */
    /* a polynomial around x=1 is more precise, as most values are around 1.07,
       but this is just fine already */
    static const real_t c1 = COEF_CONST(1.0);
    static const real_t c2 = COEF_CONST(1.0/2.0);
    static const real_t c3 = COEF_CONST(1.0/6.0);
    static const real_t c4 = COEF_CONST(1.0/24.0);

    real_t r0 = logTable[a0]; /* coef */
    real_t r1 = logTable[a1]; /* coef */
    real_t r2 = (r1 - r0) / bands; /* coef */
    real_t rexp = c1 + MUL_C((c1 + MUL_C((c2 + MUL_C((c3 + MUL_C(c4,r2)), r2)), r2)), r2);

    return (rexp >> (COEF_BITS-REAL_BITS)); /* real */
#else
    return (real_t)pow((real_t)a1/(real_t)a0, 1.0/(real_t)bands);
#endif
}

/*
   version for bs_freq_scale > 0
*/
uint8_t master_frequency_table(sbr_info *sbr, uint8_t k0, uint8_t k2,
                               uint8_t bs_freq_scale, uint8_t bs_alter_scale)
{
    uint8_t k, bands, twoRegions;
    uint8_t k1;
    uint8_t nrBand0, nrBand1;
    int32_t vDk0[64] = {0}, vDk1[64] = {0};
    int32_t vk0[64] = {0}, vk1[64] = {0};
    uint8_t temp1[] = { 6, 5, 4 };
    real_t q, qk;
    int32_t A_1;
#ifdef FIXED_POINT
    real_t rk2, rk0;
#endif

    /* mft only defined for k2 > k0 */
    if (k2 <= k0)
    {
        sbr->N_master = 0;
        return 1;
    }

    bands = temp1[bs_freq_scale-1];

#ifdef FIXED_POINT
    rk0 = (real_t)k0 << REAL_BITS;
    rk2 = (real_t)k2 << REAL_BITS;
    if (rk2 > MUL_C(rk0, COEF_CONST(2.2449)))
#else
    if ((float)k2/(float)k0 > 2.2449)
#endif
    {
        twoRegions = 1;
        k1 = k0 << 1;
    } else {