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/*
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 * Real Audio 1.0 (14.4K) encoder
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 * Copyright (c) 2010 Francesco Lavra <francescolavra@interfree.it>
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * Real Audio 1.0 (14.4K) encoder
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 * @author Francesco Lavra <francescolavra@interfree.it>
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 */
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#include <float.h>
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#include "avcodec.h"
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#include "put_bits.h"
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#include "celp_filters.h"
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#include "ra144.h"
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35

    
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static av_cold int ra144_encode_init(AVCodecContext * avctx)
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{
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    RA144Context *ractx;
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    int ret;
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41
    if (avctx->sample_fmt != AV_SAMPLE_FMT_S16) {
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        av_log(avctx, AV_LOG_ERROR, "invalid sample format\n");
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        return -1;
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    }
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    if (avctx->channels != 1) {
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        av_log(avctx, AV_LOG_ERROR, "invalid number of channels: %d\n",
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               avctx->channels);
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        return -1;
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    }
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    avctx->frame_size = NBLOCKS * BLOCKSIZE;
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    avctx->bit_rate = 8000;
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    ractx = avctx->priv_data;
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    ractx->lpc_coef[0] = ractx->lpc_tables[0];
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    ractx->lpc_coef[1] = ractx->lpc_tables[1];
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    ractx->avctx = avctx;
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    ret = ff_lpc_init(&ractx->lpc_ctx, avctx->frame_size, LPC_ORDER,
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                      AV_LPC_TYPE_LEVINSON);
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    return ret;
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}
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61

    
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static av_cold int ra144_encode_close(AVCodecContext *avctx)
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{
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    RA144Context *ractx = avctx->priv_data;
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    ff_lpc_end(&ractx->lpc_ctx);
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    return 0;
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}
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69

    
70
/**
71
 * Quantize a value by searching a sorted table for the element with the
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 * nearest value
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 *
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 * @param value value to quantize
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 * @param table array containing the quantization table
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 * @param size size of the quantization table
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 * @return index of the quantization table corresponding to the element with the
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 *         nearest value
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 */
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static int quantize(int value, const int16_t *table, unsigned int size)
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{
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    unsigned int low = 0, high = size - 1;
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84
    while (1) {
85
        int index = (low + high) >> 1;
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        int error = table[index] - value;
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88
        if (index == low)
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            return table[high] + error > value ? low : high;
90
        if (error > 0) {
91
            high = index;
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        } else {
93
            low = index;
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        }
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    }
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}
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98

    
99
/**
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 * Orthogonalize a vector to another vector
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 *
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 * @param v vector to orthogonalize
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 * @param u vector against which orthogonalization is performed
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 */
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static void orthogonalize(float *v, const float *u)
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{
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    int i;
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    float num = 0, den = 0;
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    for (i = 0; i < BLOCKSIZE; i++) {
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        num += v[i] * u[i];
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        den += u[i] * u[i];
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    }
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    num /= den;
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    for (i = 0; i < BLOCKSIZE; i++)
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        v[i] -= num * u[i];
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}
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119

    
120
/**
121
 * Calculate match score and gain of an LPC-filtered vector with respect to
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 * input data, possibly othogonalizing it to up to 2 other vectors
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 *
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 * @param work array used to calculate the filtered vector
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 * @param coefs coefficients of the LPC filter
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 * @param vect original vector
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 * @param ortho1 first vector against which orthogonalization is performed
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 * @param ortho2 second vector against which orthogonalization is performed
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 * @param data input data
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 * @param score pointer to variable where match score is returned
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 * @param gain pointer to variable where gain is returned
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 */
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static void get_match_score(float *work, const float *coefs, float *vect,
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                            const float *ortho1, const float *ortho2,
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                            const float *data, float *score, float *gain)
136
{
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    float c, g;
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    int i;
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    ff_celp_lp_synthesis_filterf(work, coefs, vect, BLOCKSIZE, LPC_ORDER);
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    if (ortho1)
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        orthogonalize(work, ortho1);
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    if (ortho2)
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        orthogonalize(work, ortho2);
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    c = g = 0;
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    for (i = 0; i < BLOCKSIZE; i++) {
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        g += work[i] * work[i];
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        c += data[i] * work[i];
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    }
150
    if (c <= 0) {
151
        *score = 0;
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        return;
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    }
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    *gain = c / g;
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    *score = *gain * c;
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}
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/**
160
 * Create a vector from the adaptive codebook at a given lag value
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 *
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 * @param vect array where vector is stored
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 * @param cb adaptive codebook
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 * @param lag lag value
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 */
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static void create_adapt_vect(float *vect, const int16_t *cb, int lag)
167
{
168
    int i;
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170
    cb += BUFFERSIZE - lag;
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    for (i = 0; i < FFMIN(BLOCKSIZE, lag); i++)
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        vect[i] = cb[i];
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    if (lag < BLOCKSIZE)
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        for (i = 0; i < BLOCKSIZE - lag; i++)
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            vect[lag + i] = cb[i];
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}
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/**
180
 * Search the adaptive codebook for the best entry and gain and remove its
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 * contribution from input data
182
 *
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 * @param adapt_cb array from which the adaptive codebook is extracted
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 * @param work array used to calculate LPC-filtered vectors
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 * @param coefs coefficients of the LPC filter
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 * @param data input data
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 * @return index of the best entry of the adaptive codebook
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 */
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static int adaptive_cb_search(const int16_t *adapt_cb, float *work,
190
                              const float *coefs, float *data)
191
{
192
    int i, best_vect;
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    float score, gain, best_score, best_gain;
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    float exc[BLOCKSIZE];
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196
    gain = best_score = 0;
197
    for (i = BLOCKSIZE / 2; i <= BUFFERSIZE; i++) {
198
        create_adapt_vect(exc, adapt_cb, i);
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        get_match_score(work, coefs, exc, NULL, NULL, data, &score, &gain);
200
        if (score > best_score) {
201
            best_score = score;
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            best_vect = i;
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            best_gain = gain;
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        }
205
    }
206
    if (!best_score)
207
        return 0;
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209
    /**
210
     * Re-calculate the filtered vector from the vector with maximum match score
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     * and remove its contribution from input data.
212
     */
213
    create_adapt_vect(exc, adapt_cb, best_vect);
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    ff_celp_lp_synthesis_filterf(work, coefs, exc, BLOCKSIZE, LPC_ORDER);
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    for (i = 0; i < BLOCKSIZE; i++)
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        data[i] -= best_gain * work[i];
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    return (best_vect - BLOCKSIZE / 2 + 1);
218
}
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221
/**
222
 * Find the best vector of a fixed codebook by applying an LPC filter to
223
 * codebook entries, possibly othogonalizing them to up to 2 other vectors and
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 * matching the results with input data
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 *
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 * @param work array used to calculate the filtered vectors
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 * @param coefs coefficients of the LPC filter
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 * @param cb fixed codebook
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 * @param ortho1 first vector against which orthogonalization is performed
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 * @param ortho2 second vector against which orthogonalization is performed
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 * @param data input data
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 * @param idx pointer to variable where the index of the best codebook entry is
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 *        returned
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 * @param gain pointer to variable where the gain of the best codebook entry is
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 *        returned
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 */
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static void find_best_vect(float *work, const float *coefs,
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                           const int8_t cb[][BLOCKSIZE], const float *ortho1,
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                           const float *ortho2, float *data, int *idx,
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                           float *gain)
241
{
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    int i, j;
243
    float g, score, best_score;
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    float vect[BLOCKSIZE];
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246
    *idx = *gain = best_score = 0;
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    for (i = 0; i < FIXED_CB_SIZE; i++) {
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        for (j = 0; j < BLOCKSIZE; j++)
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            vect[j] = cb[i][j];
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        get_match_score(work, coefs, vect, ortho1, ortho2, data, &score, &g);
251
        if (score > best_score) {
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            best_score = score;
253
            *idx = i;
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            *gain = g;
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        }
256
    }
257
}
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260
/**
261
 * Search the two fixed codebooks for the best entry and gain
262
 *
263
 * @param work array used to calculate LPC-filtered vectors
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 * @param coefs coefficients of the LPC filter
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 * @param data input data
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 * @param cba_idx index of the best entry of the adaptive codebook
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 * @param cb1_idx pointer to variable where the index of the best entry of the
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 *        first fixed codebook is returned
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 * @param cb2_idx pointer to variable where the index of the best entry of the
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 *        second fixed codebook is returned
271
 */
272
static void fixed_cb_search(float *work, const float *coefs, float *data,
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                            int cba_idx, int *cb1_idx, int *cb2_idx)
274
{
275
    int i, ortho_cb1;
276
    float gain;
277
    float cba_vect[BLOCKSIZE], cb1_vect[BLOCKSIZE];
278
    float vect[BLOCKSIZE];
279

    
280
    /**
281
     * The filtered vector from the adaptive codebook can be retrieved from
282
     * work, because this function is called just after adaptive_cb_search().
283
     */
284
    if (cba_idx)
285
        memcpy(cba_vect, work, sizeof(cba_vect));
286

    
287
    find_best_vect(work, coefs, ff_cb1_vects, cba_idx ? cba_vect : NULL, NULL,
288
                   data, cb1_idx, &gain);
289

    
290
    /**
291
     * Re-calculate the filtered vector from the vector with maximum match score
292
     * and remove its contribution from input data.
293
     */
294
    if (gain) {
295
        for (i = 0; i < BLOCKSIZE; i++)
296
            vect[i] = ff_cb1_vects[*cb1_idx][i];
297
        ff_celp_lp_synthesis_filterf(work, coefs, vect, BLOCKSIZE, LPC_ORDER);
298
        if (cba_idx)
299
            orthogonalize(work, cba_vect);
300
        for (i = 0; i < BLOCKSIZE; i++)
301
            data[i] -= gain * work[i];
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        memcpy(cb1_vect, work, sizeof(cb1_vect));
303
        ortho_cb1 = 1;
304
    } else
305
        ortho_cb1 = 0;
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307
    find_best_vect(work, coefs, ff_cb2_vects, cba_idx ? cba_vect : NULL,
308
                   ortho_cb1 ? cb1_vect : NULL, data, cb2_idx, &gain);
309
}
310

    
311

    
312
/**
313
 * Encode a subblock of the current frame
314
 *
315
 * @param ractx encoder context
316
 * @param sblock_data input data of the subblock
317
 * @param lpc_coefs coefficients of the LPC filter
318
 * @param rms RMS of the reflection coefficients
319
 * @param pb pointer to PutBitContext of the current frame
320
 */
321
static void ra144_encode_subblock(RA144Context *ractx,
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                                  const int16_t *sblock_data,
323
                                  const int16_t *lpc_coefs, unsigned int rms,
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                                  PutBitContext *pb)
325
{
326
    float data[BLOCKSIZE], work[LPC_ORDER + BLOCKSIZE];
327
    float coefs[LPC_ORDER];
328
    float zero[BLOCKSIZE], cba[BLOCKSIZE], cb1[BLOCKSIZE], cb2[BLOCKSIZE];
329
    int16_t cba_vect[BLOCKSIZE];
330
    int cba_idx, cb1_idx, cb2_idx, gain;
331
    int i, n, m[3];
332
    float g[3];
333
    float error, best_error;
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335
    for (i = 0; i < LPC_ORDER; i++) {
336
        work[i] = ractx->curr_sblock[BLOCKSIZE + i];
337
        coefs[i] = lpc_coefs[i] * (1/4096.0);
338
    }
339

    
340
    /**
341
     * Calculate the zero-input response of the LPC filter and subtract it from
342
     * input data.
343
     */
344
    memset(data, 0, sizeof(data));
345
    ff_celp_lp_synthesis_filterf(work + LPC_ORDER, coefs, data, BLOCKSIZE,
346
                                 LPC_ORDER);
347
    for (i = 0; i < BLOCKSIZE; i++) {
348
        zero[i] = work[LPC_ORDER + i];
349
        data[i] = sblock_data[i] - zero[i];
350
    }
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352
    /**
353
     * Codebook search is performed without taking into account the contribution
354
     * of the previous subblock, since it has been just subtracted from input
355
     * data.
356
     */
357
    memset(work, 0, LPC_ORDER * sizeof(*work));
358

    
359
    cba_idx = adaptive_cb_search(ractx->adapt_cb, work + LPC_ORDER, coefs,
360
                                 data);
361
    if (cba_idx) {
362
        /**
363
         * The filtered vector from the adaptive codebook can be retrieved from
364
         * work, see implementation of adaptive_cb_search().
365
         */
366
        memcpy(cba, work + LPC_ORDER, sizeof(cba));
367

    
368
        ff_copy_and_dup(cba_vect, ractx->adapt_cb, cba_idx + BLOCKSIZE / 2 - 1);
369
        m[0] = (ff_irms(cba_vect) * rms) >> 12;
370
    }
371
    fixed_cb_search(work + LPC_ORDER, coefs, data, cba_idx, &cb1_idx, &cb2_idx);
372
    for (i = 0; i < BLOCKSIZE; i++) {
373
        cb1[i] = ff_cb1_vects[cb1_idx][i];
374
        cb2[i] = ff_cb2_vects[cb2_idx][i];
375
    }
376
    ff_celp_lp_synthesis_filterf(work + LPC_ORDER, coefs, cb1, BLOCKSIZE,
377
                                 LPC_ORDER);
378
    memcpy(cb1, work + LPC_ORDER, sizeof(cb1));
379
    m[1] = (ff_cb1_base[cb1_idx] * rms) >> 8;
380
    ff_celp_lp_synthesis_filterf(work + LPC_ORDER, coefs, cb2, BLOCKSIZE,
381
                                 LPC_ORDER);
382
    memcpy(cb2, work + LPC_ORDER, sizeof(cb2));
383
    m[2] = (ff_cb2_base[cb2_idx] * rms) >> 8;
384
    best_error = FLT_MAX;
385
    gain = 0;
386
    for (n = 0; n < 256; n++) {
387
        g[1] = ((ff_gain_val_tab[n][1] * m[1]) >> ff_gain_exp_tab[n]) *
388
               (1/4096.0);
389
        g[2] = ((ff_gain_val_tab[n][2] * m[2]) >> ff_gain_exp_tab[n]) *
390
               (1/4096.0);
391
        error = 0;
392
        if (cba_idx) {
393
            g[0] = ((ff_gain_val_tab[n][0] * m[0]) >> ff_gain_exp_tab[n]) *
394
                   (1/4096.0);
395
            for (i = 0; i < BLOCKSIZE; i++) {
396
                data[i] = zero[i] + g[0] * cba[i] + g[1] * cb1[i] +
397
                          g[2] * cb2[i];
398
                error += (data[i] - sblock_data[i]) *
399
                         (data[i] - sblock_data[i]);
400
            }
401
        } else {
402
            for (i = 0; i < BLOCKSIZE; i++) {
403
                data[i] = zero[i] + g[1] * cb1[i] + g[2] * cb2[i];
404
                error += (data[i] - sblock_data[i]) *
405
                         (data[i] - sblock_data[i]);
406
            }
407
        }
408
        if (error < best_error) {
409
            best_error = error;
410
            gain = n;
411
        }
412
    }
413
    put_bits(pb, 7, cba_idx);
414
    put_bits(pb, 8, gain);
415
    put_bits(pb, 7, cb1_idx);
416
    put_bits(pb, 7, cb2_idx);
417
    ff_subblock_synthesis(ractx, lpc_coefs, cba_idx, cb1_idx, cb2_idx, rms,
418
                          gain);
419
}
420

    
421

    
422
static int ra144_encode_frame(AVCodecContext *avctx, uint8_t *frame,
423
                              int buf_size, void *data)
424
{
425
    static const uint8_t sizes[LPC_ORDER] = {64, 32, 32, 16, 16, 8, 8, 8, 8, 4};
426
    static const uint8_t bit_sizes[LPC_ORDER] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};
427
    RA144Context *ractx;
428
    PutBitContext pb;
429
    int32_t lpc_data[NBLOCKS * BLOCKSIZE];
430
    int32_t lpc_coefs[LPC_ORDER][MAX_LPC_ORDER];
431
    int shift[LPC_ORDER];
432
    int16_t block_coefs[NBLOCKS][LPC_ORDER];
433
    int lpc_refl[LPC_ORDER];    /**< reflection coefficients of the frame */
434
    unsigned int refl_rms[NBLOCKS]; /**< RMS of the reflection coefficients */
435
    int energy = 0;
436
    int i, idx;
437

    
438
    if (buf_size < FRAMESIZE) {
439
        av_log(avctx, AV_LOG_ERROR, "output buffer too small\n");
440
        return 0;
441
    }
442
    ractx = avctx->priv_data;
443

    
444
    /**
445
     * Since the LPC coefficients are calculated on a frame centered over the
446
     * fourth subframe, to encode a given frame, data from the next frame is
447
     * needed. In each call to this function, the previous frame (whose data are
448
     * saved in the encoder context) is encoded, and data from the current frame
449
     * are saved in the encoder context to be used in the next function call.
450
     */
451
    for (i = 0; i < (2 * BLOCKSIZE + BLOCKSIZE / 2); i++) {
452
        lpc_data[i] = ractx->curr_block[BLOCKSIZE + BLOCKSIZE / 2 + i];
453
        energy += (lpc_data[i] * lpc_data[i]) >> 4;
454
    }
455
    for (i = 2 * BLOCKSIZE + BLOCKSIZE / 2; i < NBLOCKS * BLOCKSIZE; i++) {
456
        lpc_data[i] = *((int16_t *)data + i - 2 * BLOCKSIZE - BLOCKSIZE / 2) >>
457
                      2;
458
        energy += (lpc_data[i] * lpc_data[i]) >> 4;
459
    }
460
    energy = ff_energy_tab[quantize(ff_t_sqrt(energy >> 5) >> 10, ff_energy_tab,
461
                                    32)];
462

    
463
    ff_lpc_calc_coefs(&ractx->lpc_ctx, lpc_data, NBLOCKS * BLOCKSIZE, LPC_ORDER,
464
                      LPC_ORDER, 16, lpc_coefs, shift, AV_LPC_TYPE_LEVINSON,
465
                      0, ORDER_METHOD_EST, 12, 0);
466
    for (i = 0; i < LPC_ORDER; i++)
467
        block_coefs[NBLOCKS - 1][i] = -(lpc_coefs[LPC_ORDER - 1][i] <<
468
                                        (12 - shift[LPC_ORDER - 1]));
469

    
470
    /**
471
     * TODO: apply perceptual weighting of the input speech through bandwidth
472
     * expansion of the LPC filter.
473
     */
474

    
475
    if (ff_eval_refl(lpc_refl, block_coefs[NBLOCKS - 1], avctx)) {
476
        /**
477
         * The filter is unstable: use the coefficients of the previous frame.
478
         */
479
        ff_int_to_int16(block_coefs[NBLOCKS - 1], ractx->lpc_coef[1]);
480
        ff_eval_refl(lpc_refl, block_coefs[NBLOCKS - 1], avctx);
481
    }
482
    init_put_bits(&pb, frame, buf_size);
483
    for (i = 0; i < LPC_ORDER; i++) {
484
        idx = quantize(lpc_refl[i], ff_lpc_refl_cb[i], sizes[i]);
485
        put_bits(&pb, bit_sizes[i], idx);
486
        lpc_refl[i] = ff_lpc_refl_cb[i][idx];
487
    }
488
    ractx->lpc_refl_rms[0] = ff_rms(lpc_refl);
489
    ff_eval_coefs(ractx->lpc_coef[0], lpc_refl);
490
    refl_rms[0] = ff_interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);
491
    refl_rms[1] = ff_interp(ractx, block_coefs[1], 2,
492
                            energy <= ractx->old_energy,
493
                            ff_t_sqrt(energy * ractx->old_energy) >> 12);
494
    refl_rms[2] = ff_interp(ractx, block_coefs[2], 3, 0, energy);
495
    refl_rms[3] = ff_rescale_rms(ractx->lpc_refl_rms[0], energy);
496
    ff_int_to_int16(block_coefs[NBLOCKS - 1], ractx->lpc_coef[0]);
497
    put_bits(&pb, 5, quantize(energy, ff_energy_tab, 32));
498
    for (i = 0; i < NBLOCKS; i++)
499
        ra144_encode_subblock(ractx, ractx->curr_block + i * BLOCKSIZE,
500
                              block_coefs[i], refl_rms[i], &pb);
501
    flush_put_bits(&pb);
502
    ractx->old_energy = energy;
503
    ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];
504
    FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);
505
    for (i = 0; i < NBLOCKS * BLOCKSIZE; i++)
506
        ractx->curr_block[i] = *((int16_t *)data + i) >> 2;
507
    return FRAMESIZE;
508
}
509

    
510

    
511
AVCodec ff_ra_144_encoder =
512
{
513
    "real_144",
514
    AVMEDIA_TYPE_AUDIO,
515
    CODEC_ID_RA_144,
516
    sizeof(RA144Context),
517
    ra144_encode_init,
518
    ra144_encode_frame,
519
    ra144_encode_close,
520
    .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K) encoder"),
521
};