FFmpeg/libavcodec/ra288.c

/*
 * RealAudio 2.0 (28.8K)
 * Copyright (c) 2003 the ffmpeg project
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "avcodec.h"
#define ALT_BITSTREAM_READER_LE
#include "bitstream.h"
#include "ra288.h"

typedef struct {
    float history[8];
    float output[40];
    float pr1[36];
    float pr2[10];
    int   phase, phasep;

    float st1a[111], st1b[37], st1[37];
    float st2a[38], st2b[11], st2[11];
    float sb[41];
    float lhist[10];
} Real288_internal;

/* initial decode */
static void unpack(unsigned short *tgt, const unsigned char *src,
                   unsigned int len)
{
    int i = 0;
    GetBitContext gb;

    init_get_bits(&gb, src, len * 8);

    while (get_bits_count(&gb) + 9 + (i&1) <= len*8) {
        tgt[i] = get_bits(&gb, 9 + (i&1));
        i++;
    }
}

/* Decode and produce output */
static void decode(Real288_internal *glob, unsigned int input)
{
    unsigned int x, y;
    float f;
    double sum, sumsum;
    float *p1, *p2;
    float buffer[5];
    const float *table;

    for (x=36; x--; glob->sb[x+5] = glob->sb[x]);

    for (x=5; x--;) {
        p1 = glob->sb+x;
        p2 = glob->pr1;
        for (sum=0, y=36; y--; sum -= (*(++p1))*(*(p2++)));

        glob->sb[x] = sum;
    }

    f = amptable[input & 7];
    table = codetable + (input >> 3) * 5;

    /* convert log and do rms */
    for (sum=32, x=10; x--; sum -= glob->pr2[x] * glob->lhist[x]);

    if (sum < 0)
        sum = 0;
    else if (sum > 60)
        sum = 60;

    sumsum = exp(sum * 0.1151292546497) * f;    /* pow(10.0,sum/20)*f */

    for (sum=0, x=5; x--;) {
        buffer[x] = table[x] * sumsum;
        sum += buffer[x] * buffer[x];
    }

    if ((sum /= 5) < 1)
        sum = 1;

    /* shift and store */
    for (x=10; --x; glob->lhist[x] = glob->lhist[x-1]);

    *glob->lhist = glob->history[glob->phase] = 10 * log10(sum) - 32;

    for (x=1; x < 5; x++)
        for (y=x; y--; buffer[x] -= glob->pr1[x-y-1] * buffer[y]);

    /* output */
    for (x=0; x < 5; x++) {
        f = glob->sb[4-x] + buffer[x];

        if (f > 4095)
            f = 4095;
        else if (f < -4095)
            f = -4095;

        glob->output[glob->phasep+x] = glob->sb[4-x] = f;
    }
}

/* column multiply */
static void colmult(float *tgt, float *m1, const float *m2, int n)
{
    while (n--)
        *(tgt++) = (*(m1++)) * (*(m2++));
}

static int pred(float *in, float *tgt, int n)
{
    int x, y;
    float *p1, *p2;
    double f0, f1, f2;
    float temp;

    if (in[n] == 0)
        return 0;

    if ((f0 = *in) <= 0)
        return 0;

    for (x=1 ; ; x++) {
        if (n < x)
            return 1;

        p1 = in + x;
        p2 = tgt;
        f1 = *(p1--);
        for (y=x; --y; f1 += (*(p1--))*(*(p2++)));

        p1 = tgt + x - 1;
        p2 = tgt;
        *(p1--) = f2 = -f1/f0;
        for (y=x >> 1; y--;) {
            temp = *p2 + *p1 * f2;
            *(p1--) += *p2 * f2;
            *(p2++) = temp;
        }
        if ((f0 += f1*f2) < 0)
            return 0;
    }
}

/* product sum (lsf) */
static void prodsum(float *tgt, float *src, int len, int n)
{
    unsigned int x;
    float *p1, *p2;
    double sum;

    while (n >= 0) {
        p1 = (p2 = src) - n;
        for (sum=0, x=len; x--; sum += (*p1++) * (*p2++));
        tgt[n--] = sum;
    }
}

static void co(int n, int i, int j, float *in, float *out, float *st1,
               float *st2, const float *table)
{
    int a, b, c;
    unsigned int x;
    float *fp;
    float buffer1[37];
    float buffer2[37];
    float work[111];

    /* rotate and multiply */
    c = (b = (a = n + i) + j) - i;
    fp = st1 + i;
    for (x=0; x < b; x++) {
        if (x == c)
            fp=in;
        work[x] = *(table++) * (*(st1++) = *(fp++));
    }

    prodsum(buffer1, work + n, i, n);
    prodsum(buffer2, work + a, j, n);

    for (x=0;x<=n;x++) {
        *st2 = *st2 * (0.5625) + buffer1[x];
        out[x] = *(st2++) + buffer2[x];
    }
    *out *= 1.00390625; /* to prevent clipping */
}

static void update(Real288_internal *glob)
{
    int x,y;
    float buffer1[40], temp1[37];
    float buffer2[8], temp2[11];

    for (x=0, y=glob->phasep+5; x < 40; buffer1[x++] = glob->output[(y++)%40]);

    co(36, 40, 35, buffer1, temp1, glob->st1a, glob->st1b, table1);

    if (pred(temp1, glob->st1, 36))
        colmult(glob->pr1, glob->st1, table1a, 36);

    for (x=0, y=glob->phase + 1; x < 8; buffer2[x++] = glob->history[(y++) % 8]);

    co(10, 8, 20, buffer2, temp2, glob->st2a, glob->st2b, table2);

    if (pred(temp2, glob->st2, 10))
        colmult(glob->pr2, glob->st2, table2a, 10);
}

static void * decode_block(AVCodecContext * avctx, const unsigned char *in,
                           signed short int *out, unsigned len)
{
    int x, y;
    Real288_internal *glob = avctx->priv_data;
    unsigned short int buffer[len];

    unpack(buffer, in, len);

    for (x=0; x < 32; x++) {
        glob->phasep = (glob->phase = x & 7) * 5;
        decode(glob, buffer[x]);

        for (y=0; y<5; *(out++) = 8 * glob->output[glob->phasep+(y++)]);

        if (glob->phase == 3)
            update(glob);
    }

    return out;
}

/* Decode a block (celp) */
static int ra288_decode_frame(AVCodecContext * avctx, void *data,
                              int *data_size, const uint8_t * buf,
                              int buf_size)
{
    void *datao;

    if (buf_size < avctx->block_align) {
        av_log(avctx, AV_LOG_ERROR,
               "Error! Input buffer is too small [%d<%d]\n",
               buf_size, avctx->block_align);
        return 0;
    }

    datao = data;
    data = decode_block(avctx, buf, (signed short *)data, avctx->block_align);

    *data_size = (char *)data - (char *)datao;
    return avctx->block_align;
}

AVCodec ra_288_decoder =
{
    "real_288",
    CODEC_TYPE_AUDIO,
    CODEC_ID_RA_288,
    sizeof(Real288_internal),
    NULL,
    NULL,
    NULL,
    ra288_decode_frame,
    .long_name = NULL_IF_CONFIG_SMALL("RealAudio 2.0 (28.8K)"),
};