g722_encode.c

/*
 * g722_encode.c - The ITU G.722 codec, encode part.
 *
 * Written by Steve Underwood <steveu@coppice.org>
 *
 * Copyright (C) 2005 Steve Underwood
 *
 * All rights reserved.
 *
 *  Despite my general liking of the GPL, I place my own contributions 
 *  to this code in the public domain for the benefit of all mankind -
 *  even the slimy ones who might try to proprietize my work and use it
 *  to my detriment.
 *
 * Based on a single channel 64kbps only G.722 codec which is:
 *
 *****    Copyright (c) CMU    1993      *****
 * Computer Science, Speech Group
 * Chengxiang Lu and Alex Hauptmann
 *
 * The Carnegie Mellon ADPCM program is Copyright (c) 1993 by Carnegie Mellon
 * University. Use of this program, for any research or commercial purpose, is
 * completely unrestricted. If you make use of or redistribute this material,
 * we would appreciate acknowlegement of its origin.
 *****
 */

/*! \file */

#include <stdio.h>
#include <inttypes.h>
#include <memory.h>
#include <stdlib.h>

#include "g722_private.h"
#include "g722_common.h"
#include "g722_encoder.h"

G722_ENC_CTX *
g722_encoder_new(int rate, int options)
{
    G722_ENC_CTX *s;

    if ((s = (G722_ENC_CTX *) malloc(sizeof(*s))) == NULL)
        return NULL;
    memset(s, 0, sizeof(*s));
    if (rate == 48000)
        s->bits_per_sample = 6;
    else if (rate == 56000)
        s->bits_per_sample = 7;
    else
        s->bits_per_sample = 8;
    if ((options & G722_SAMPLE_RATE_8000))
        s->eight_k = TRUE;
    if ((options & G722_PACKED)  &&  s->bits_per_sample != 8)
        s->packed = TRUE;
    else
        s->packed = FALSE;
    s->band[0].det = 32;
    s->band[1].det = 8;
    return s;
}
/*- End of function --------------------------------------------------------*/

int g722_encoder_destroy(G722_ENC_CTX *s)
{
    free(s);
    return 0;
}
/*- End of function --------------------------------------------------------*/

int g722_encode(G722_ENC_CTX *s, const int16_t amp[], int len, uint8_t g722_data[])
{
    static const int q6[32] =
    {
           0,   35,   72,  110,  150,  190,  233,  276,
         323,  370,  422,  473,  530,  587,  650,  714,
         786,  858,  940, 1023, 1121, 1219, 1339, 1458,
        1612, 1765, 1980, 2195, 2557, 2919,    0,    0
    };
    static const int iln[32] =
    {
         0, 63, 62, 31, 30, 29, 28, 27,
        26, 25, 24, 23, 22, 21, 20, 19,
        18, 17, 16, 15, 14, 13, 12, 11,
        10,  9,  8,  7,  6,  5,  4,  0
    };
    static const int ilp[32] =
    {
         0, 61, 60, 59, 58, 57, 56, 55,
        54, 53, 52, 51, 50, 49, 48, 47,
        46, 45, 44, 43, 42, 41, 40, 39,
        38, 37, 36, 35, 34, 33, 32,  0
    };
    static const int wl[8] =
    {
        -60, -30, 58, 172, 334, 538, 1198, 3042
    };
    static const int rl42[16] =
    {
        0, 7, 6, 5, 4, 3, 2, 1, 7, 6, 5, 4, 3, 2, 1, 0
    };
    static const int ilb[32] =
    {
        2048, 2093, 2139, 2186, 2233, 2282, 2332,
        2383, 2435, 2489, 2543, 2599, 2656, 2714,
        2774, 2834, 2896, 2960, 3025, 3091, 3158,
        3228, 3298, 3371, 3444, 3520, 3597, 3676,
        3756, 3838, 3922, 4008
    };
    static const int qm4[16] =
    {
             0, -20456, -12896, -8968,
         -6288,  -4240,  -2584, -1200,
         20456,  12896,   8968,  6288,
          4240,   2584,   1200,     0
    };
    static const int qm2[4] =
    {
        -7408,  -1616,   7408,   1616
    };
    static const int qmf_coeffs[12] =
    {
           3,  -11,   12,   32, -210,  951, 3876, -805,  362, -156,   53,  -11,
    };
    static const int ihn[3] = {0, 1, 0};
    static const int ihp[3] = {0, 3, 2};
    static const int wh[3] = {0, -214, 798};
    static const int rh2[4] = {2, 1, 2, 1};

    int dlow;
    int dhigh;
    int el;
    int wd;
    int wd1;
    int ril;
    int wd2;
    int il4;
    int ih2;
    int wd3;
    int eh;
    int mih;
    int i;
    int j;
    /* Low and high band PCM from the QMF */
    int xlow;
    int xhigh;
    int g722_bytes;
    /* Even and odd tap accumulators */
    int sumeven;
    int sumodd;
    int ihigh;
    int ilow;
    int code;

    g722_bytes = 0;
    xhigh = 0;
    for (j = 0;  j < len;  )
    {
        if (s->itu_test_mode)
        {
            xlow =
            xhigh = amp[j++] >> 1;
        }
        else
        {
            if (s->eight_k)
            {
                xlow = amp[j++] >> 1;
            }
            else
            {
                /* Apply the transmit QMF */
                /* Shuffle the buffer down */
                for (i = 0;  i < 22;  i++)
                    s->x[i] = s->x[i + 2];
                s->x[22] = amp[j++];
                s->x[23] = amp[j++];
    
                /* Discard every other QMF output */
                sumeven = 0;
                sumodd = 0;
                for (i = 0;  i < 12;  i++)
                {
                    sumodd += s->x[2*i]*qmf_coeffs[i];
                    sumeven += s->x[2*i + 1]*qmf_coeffs[11 - i];
                }
                xlow = (sumeven + sumodd) >> 14;
                xhigh = (sumeven - sumodd) >> 14;
            }
        }
        /* Block 1L, SUBTRA */
        el = saturate(xlow - s->band[0].s);

        /* Block 1L, QUANTL */
        wd = (el >= 0)  ?  el  :  -(el + 1);

        for (i = 1;  i < 30;  i++)
        {
            wd1 = (q6[i]*s->band[0].det) >> 12;
            if (wd < wd1)
                break;
        }
        ilow = (el < 0)  ?  iln[i]  :  ilp[i];

        /* Block 2L, INVQAL */
        ril = ilow >> 2;
        wd2 = qm4[ril];
        dlow = (s->band[0].det*wd2) >> 15;

        /* Block 3L, LOGSCL */
        il4 = rl42[ril];
        wd = (s->band[0].nb*127) >> 7;
        s->band[0].nb = wd + wl[il4];
        if (s->band[0].nb < 0)
            s->band[0].nb = 0;
        else if (s->band[0].nb > 18432)
            s->band[0].nb = 18432;

        /* Block 3L, SCALEL */
        wd1 = (s->band[0].nb >> 6) & 31;
        wd2 = 8 - (s->band[0].nb >> 11);
        wd3 = (wd2 < 0)  ?  (ilb[wd1] << -wd2)  :  (ilb[wd1] >> wd2);
        s->band[0].det = wd3 << 2;

        block4(&s->band[0], dlow);
        
        if (s->eight_k)
        {
            /* Just leave the high bits as zero */
            code = (0xC0 | ilow) >> (8 - s->bits_per_sample);
        }
        else
        {
            /* Block 1H, SUBTRA */
            eh = saturate(xhigh - s->band[1].s);

            /* Block 1H, QUANTH */
            wd = (eh >= 0)  ?  eh  :  -(eh + 1);
            wd1 = (564*s->band[1].det) >> 12;
            mih = (wd >= wd1)  ?  2  :  1;
            ihigh = (eh < 0)  ?  ihn[mih]  :  ihp[mih];

            /* Block 2H, INVQAH */
            wd2 = qm2[ihigh];
            dhigh = (s->band[1].det*wd2) >> 15;

            /* Block 3H, LOGSCH */
            ih2 = rh2[ihigh];
            wd = (s->band[1].nb*127) >> 7;
            s->band[1].nb = wd + wh[ih2];
            if (s->band[1].nb < 0)
                s->band[1].nb = 0;
            else if (s->band[1].nb > 22528)
                s->band[1].nb = 22528;

            /* Block 3H, SCALEH */
            wd1 = (s->band[1].nb >> 6) & 31;
            wd2 = 10 - (s->band[1].nb >> 11);
            wd3 = (wd2 < 0)  ?  (ilb[wd1] << -wd2)  :  (ilb[wd1] >> wd2);
            s->band[1].det = wd3 << 2;

            block4(&s->band[1], dhigh);
            code = ((ihigh << 6) | ilow) >> (8 - s->bits_per_sample);
        }

        if (s->packed)
        {
            /* Pack the code bits */
            s->out_buffer |= (code << s->out_bits);
            s->out_bits += s->bits_per_sample;
            if (s->out_bits >= 8)
            {
                g722_data[g722_bytes++] = (uint8_t) (s->out_buffer & 0xFF);
                s->out_bits -= 8;
                s->out_buffer >>= 8;
            }
        }
        else
        {
            g722_data[g722_bytes++] = (uint8_t) code;
        }
    }
    return g722_bytes;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/