ffmpeg / libavcodec / ra144enc.c @ d36beb3f
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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 FFmpeg.

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*

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* FFmpeg 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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* FFmpeg 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 FFmpeg; if not, write to the Free Software

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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 021101301 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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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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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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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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/**

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* 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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while (1) { 
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int index = (low + high) >> 1; 
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int error = table[index]  value;

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if (index == low)

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return table[high] + error > value ? low : high;

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if (error > 0) { 
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high = index; 
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} else {

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low = index; 
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} 
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} 
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} 
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/**

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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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/**

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* Calculate match score and gain of an LPCfiltered 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) 
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{ 
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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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} 
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if (c <= 0) { 
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*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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/**

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* 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) 
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{ 
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int i;

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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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/**

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* Search the adaptive codebook for the best entry and gain and remove its

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* contribution from input data

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*

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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 LPCfiltered 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, 
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const float *coefs, float *data) 
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{ 
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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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gain = best_score = 0;

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for (i = BLOCKSIZE / 2; i <= BUFFERSIZE; i++) { 
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create_adapt_vect(exc, adapt_cb, i); 
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get_match_score(work, coefs, exc, NULL, NULL, data, &score, &gain); 
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if (score > best_score) {

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best_score = score; 
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best_vect = i; 
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best_gain = gain; 
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} 
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} 
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if (!best_score)

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return 0; 
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/**

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* Recalculate the filtered vector from the vector with maximum match score

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* and remove its contribution from input data.

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*/

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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); 
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} 
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/**

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* Find the best vector of a fixed codebook by applying an LPC filter to

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* 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)

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{ 
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int i, j;

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float g, score, best_score;

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float vect[BLOCKSIZE];

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*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); 
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if (score > best_score) {

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best_score = score; 
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*idx = i; 
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*gain = g; 
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} 
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} 
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} 
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/**

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* Search the two fixed codebooks for the best entry and gain

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*

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* @param work array used to calculate LPCfiltered 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

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*/

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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) 
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{ 
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int i, ortho_cb1;

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float gain;

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float cba_vect[BLOCKSIZE], cb1_vect[BLOCKSIZE];

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float vect[BLOCKSIZE];

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/**

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* The filtered vector from the adaptive codebook can be retrieved from

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* work, because this function is called just after adaptive_cb_search().

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*/

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if (cba_idx)

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memcpy(cba_vect, work, sizeof(cba_vect));

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find_best_vect(work, coefs, ff_cb1_vects, cba_idx ? cba_vect : NULL, NULL, 
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data, cb1_idx, &gain); 
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/**

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* Recalculate the filtered vector from the vector with maximum match score

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* and remove its contribution from input data.

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*/

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if (gain) {

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for (i = 0; i < BLOCKSIZE; i++) 
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vect[i] = ff_cb1_vects[*cb1_idx][i]; 
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ff_celp_lp_synthesis_filterf(work, coefs, vect, BLOCKSIZE, LPC_ORDER); 
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if (cba_idx)

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orthogonalize(work, cba_vect); 
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for (i = 0; i < BLOCKSIZE; i++) 
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data[i] = gain * work[i]; 
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memcpy(cb1_vect, work, sizeof(cb1_vect));

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ortho_cb1 = 1;

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} else

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ortho_cb1 = 0;

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find_best_vect(work, coefs, ff_cb2_vects, cba_idx ? cba_vect : NULL,

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ortho_cb1 ? cb1_vect : NULL, data, cb2_idx, &gain);

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} 
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/**

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* Encode a subblock of the current frame

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*

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* @param ractx encoder context

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* @param sblock_data input data of the subblock

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* @param lpc_coefs coefficients of the LPC filter

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* @param rms RMS of the reflection coefficients

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* @param pb pointer to PutBitContext of the current frame

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*/

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static void ra144_encode_subblock(RA144Context *ractx, 
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const int16_t *sblock_data,

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const int16_t *lpc_coefs, unsigned int rms, 
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PutBitContext *pb) 
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{ 
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float data[BLOCKSIZE], work[LPC_ORDER + BLOCKSIZE];

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float coefs[LPC_ORDER];

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float zero[BLOCKSIZE], cba[BLOCKSIZE], cb1[BLOCKSIZE], cb2[BLOCKSIZE];

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int16_t cba_vect[BLOCKSIZE]; 
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int cba_idx, cb1_idx, cb2_idx, gain;

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int i, n, m[3]; 
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float g[3]; 
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float error, best_error;

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for (i = 0; i < LPC_ORDER; i++) { 
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work[i] = ractx>curr_sblock[BLOCKSIZE + i]; 
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coefs[i] = lpc_coefs[i] * (1/4096.0); 
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} 
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/**

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* Calculate the zeroinput response of the LPC filter and subtract it from

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* input data.

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*/

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memset(data, 0, sizeof(data)); 
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ff_celp_lp_synthesis_filterf(work + LPC_ORDER, coefs, data, BLOCKSIZE, 
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LPC_ORDER); 
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for (i = 0; i < BLOCKSIZE; i++) { 
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zero[i] = work[LPC_ORDER + i]; 
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data[i] = sblock_data[i]  zero[i]; 
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} 
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/**

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* Codebook search is performed without taking into account the contribution

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* of the previous subblock, since it has been just subtracted from input

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* data.

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*/

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memset(work, 0, LPC_ORDER * sizeof(*work)); 
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cba_idx = adaptive_cb_search(ractx>adapt_cb, work + LPC_ORDER, coefs, 
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data); 
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if (cba_idx) {

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/**

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* The filtered vector from the adaptive codebook can be retrieved from

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* work, see implementation of adaptive_cb_search().

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*/

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memcpy(cba, work + LPC_ORDER, sizeof(cba));

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ff_copy_and_dup(cba_vect, ractx>adapt_cb, cba_idx + BLOCKSIZE / 2  1); 
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m[0] = (ff_irms(cba_vect) * rms) >> 12; 
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} 
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fixed_cb_search(work + LPC_ORDER, coefs, data, cba_idx, &cb1_idx, &cb2_idx); 
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for (i = 0; i < BLOCKSIZE; i++) { 
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cb1[i] = ff_cb1_vects[cb1_idx][i]; 
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cb2[i] = ff_cb2_vects[cb2_idx][i]; 
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} 
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ff_celp_lp_synthesis_filterf(work + LPC_ORDER, coefs, cb1, BLOCKSIZE, 
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LPC_ORDER); 
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memcpy(cb1, work + LPC_ORDER, sizeof(cb1));

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m[1] = (ff_cb1_base[cb1_idx] * rms) >> 8; 
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ff_celp_lp_synthesis_filterf(work + LPC_ORDER, coefs, cb2, BLOCKSIZE, 
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LPC_ORDER); 
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memcpy(cb2, work + LPC_ORDER, sizeof(cb2));

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m[2] = (ff_cb2_base[cb2_idx] * rms) >> 8; 
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best_error = FLT_MAX; 
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gain = 0;

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for (n = 0; n < 256; n++) { 
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g[1] = ((ff_gain_val_tab[n][1] * m[1]) >> ff_gain_exp_tab[n]) * 
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(1/4096.0); 
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g[2] = ((ff_gain_val_tab[n][2] * m[2]) >> ff_gain_exp_tab[n]) * 
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(1/4096.0); 
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error = 0;

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if (cba_idx) {

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g[0] = ((ff_gain_val_tab[n][0] * m[0]) >> ff_gain_exp_tab[n]) * 
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(1/4096.0); 
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for (i = 0; i < BLOCKSIZE; i++) { 
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data[i] = zero[i] + g[0] * cba[i] + g[1] * cb1[i] + 
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g[2] * cb2[i];

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error += (data[i]  sblock_data[i]) * 
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(data[i]  sblock_data[i]); 
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} 
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} else {

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for (i = 0; i < BLOCKSIZE; i++) { 
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data[i] = zero[i] + g[1] * cb1[i] + g[2] * cb2[i]; 
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error += (data[i]  sblock_data[i]) * 
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(data[i]  sblock_data[i]); 
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} 
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} 
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if (error < best_error) {

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best_error = error; 
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gain = n; 
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} 
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} 
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put_bits(pb, 7, cba_idx);

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put_bits(pb, 8, gain);

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put_bits(pb, 7, cb1_idx);

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put_bits(pb, 7, cb2_idx);

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ff_subblock_synthesis(ractx, lpc_coefs, cba_idx, cb1_idx, cb2_idx, rms, 
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gain); 
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} 
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static int ra144_encode_frame(AVCodecContext *avctx, uint8_t *frame, 
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int buf_size, void *data) 
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{ 
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static const uint8_t sizes[LPC_ORDER] = {64, 32, 32, 16, 16, 8, 8, 8, 8, 4}; 
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static const uint8_t bit_sizes[LPC_ORDER] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2}; 
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RA144Context *ractx; 
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PutBitContext pb; 
429 
int32_t lpc_data[NBLOCKS * BLOCKSIZE]; 
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int32_t lpc_coefs[LPC_ORDER][MAX_LPC_ORDER]; 
431 
int shift[LPC_ORDER];

432 
int16_t block_coefs[NBLOCKS][LPC_ORDER]; 
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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;

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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; 
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/**

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* Since the LPC coefficients are calculated on a frame centered over the

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* 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

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* 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++) { 
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lpc_data[i] = *((int16_t *)data + i  2 * BLOCKSIZE  BLOCKSIZE / 2) >> 
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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, 
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CODEC_ID_RA_144, 
516 
sizeof(RA144Context),

517 
ra144_encode_init, 
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ra144_encode_frame, 
519 
ra144_encode_close, 
520 
.long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K) encoder"),

521 
}; 