yading@10: /* yading@10: * LPC utility code yading@10: * Copyright (c) 2006 Justin Ruggles yading@10: * yading@10: * This file is part of FFmpeg. yading@10: * yading@10: * FFmpeg is free software; you can redistribute it and/or yading@10: * modify it under the terms of the GNU Lesser General Public yading@10: * License as published by the Free Software Foundation; either yading@10: * version 2.1 of the License, or (at your option) any later version. yading@10: * yading@10: * FFmpeg is distributed in the hope that it will be useful, yading@10: * but WITHOUT ANY WARRANTY; without even the implied warranty of yading@10: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU yading@10: * Lesser General Public License for more details. yading@10: * yading@10: * You should have received a copy of the GNU Lesser General Public yading@10: * License along with FFmpeg; if not, write to the Free Software yading@10: * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA yading@10: */ yading@10: yading@10: #ifndef AVCODEC_LPC_H yading@10: #define AVCODEC_LPC_H yading@10: yading@10: #include yading@10: #include "libavutil/avassert.h" yading@10: yading@10: #define ORDER_METHOD_EST 0 yading@10: #define ORDER_METHOD_2LEVEL 1 yading@10: #define ORDER_METHOD_4LEVEL 2 yading@10: #define ORDER_METHOD_8LEVEL 3 yading@10: #define ORDER_METHOD_SEARCH 4 yading@10: #define ORDER_METHOD_LOG 5 yading@10: yading@10: #define MIN_LPC_ORDER 1 yading@10: #define MAX_LPC_ORDER 32 yading@10: yading@10: /** yading@10: * LPC analysis type yading@10: */ yading@10: enum FFLPCType { yading@10: FF_LPC_TYPE_DEFAULT = -1, ///< use the codec default LPC type yading@10: FF_LPC_TYPE_NONE = 0, ///< do not use LPC prediction or use all zero coefficients yading@10: FF_LPC_TYPE_FIXED = 1, ///< fixed LPC coefficients yading@10: FF_LPC_TYPE_LEVINSON = 2, ///< Levinson-Durbin recursion yading@10: FF_LPC_TYPE_CHOLESKY = 3, ///< Cholesky factorization yading@10: FF_LPC_TYPE_NB , ///< Not part of ABI yading@10: }; yading@10: yading@10: typedef struct LPCContext { yading@10: int blocksize; yading@10: int max_order; yading@10: enum FFLPCType lpc_type; yading@10: double *windowed_buffer; yading@10: double *windowed_samples; yading@10: yading@10: /** yading@10: * Apply a Welch window to an array of input samples. yading@10: * The output samples have the same scale as the input, but are in double yading@10: * sample format. yading@10: * @param data input samples yading@10: * @param len number of input samples yading@10: * @param w_data output samples yading@10: */ yading@10: void (*lpc_apply_welch_window)(const int32_t *data, int len, yading@10: double *w_data); yading@10: /** yading@10: * Perform autocorrelation on input samples with delay of 0 to lag. yading@10: * @param data input samples. yading@10: * constraints: no alignment needed, but must have have at yading@10: * least lag*sizeof(double) valid bytes preceding it, and yading@10: * size must be at least (len+1)*sizeof(double) if data is yading@10: * 16-byte aligned or (len+2)*sizeof(double) if data is yading@10: * unaligned. yading@10: * @param len number of input samples to process yading@10: * @param lag maximum delay to calculate yading@10: * @param autoc output autocorrelation coefficients. yading@10: * constraints: array size must be at least lag+1. yading@10: */ yading@10: void (*lpc_compute_autocorr)(const double *data, int len, int lag, yading@10: double *autoc); yading@10: } LPCContext; yading@10: yading@10: yading@10: /** yading@10: * Calculate LPC coefficients for multiple orders yading@10: */ yading@10: int ff_lpc_calc_coefs(LPCContext *s, yading@10: const int32_t *samples, int blocksize, int min_order, yading@10: int max_order, int precision, yading@10: int32_t coefs[][MAX_LPC_ORDER], int *shift, yading@10: enum FFLPCType lpc_type, int lpc_passes, yading@10: int omethod, int max_shift, int zero_shift); yading@10: yading@10: int ff_lpc_calc_ref_coefs(LPCContext *s, yading@10: const int32_t *samples, int order, double *ref); yading@10: yading@10: /** yading@10: * Initialize LPCContext. yading@10: */ yading@10: int ff_lpc_init(LPCContext *s, int blocksize, int max_order, yading@10: enum FFLPCType lpc_type); yading@10: void ff_lpc_init_x86(LPCContext *s); yading@10: yading@10: /** yading@10: * Uninitialize LPCContext. yading@10: */ yading@10: void ff_lpc_end(LPCContext *s); yading@10: yading@10: #ifdef LPC_USE_DOUBLE yading@10: #define LPC_TYPE double yading@10: #else yading@10: #define LPC_TYPE float yading@10: #endif yading@10: yading@10: /** yading@10: * Schur recursion. yading@10: * Produces reflection coefficients from autocorrelation data. yading@10: */ yading@10: static inline void compute_ref_coefs(const LPC_TYPE *autoc, int max_order, yading@10: LPC_TYPE *ref, LPC_TYPE *error) yading@10: { yading@10: int i, j; yading@10: LPC_TYPE err; yading@10: LPC_TYPE gen0[MAX_LPC_ORDER], gen1[MAX_LPC_ORDER]; yading@10: yading@10: for (i = 0; i < max_order; i++) yading@10: gen0[i] = gen1[i] = autoc[i + 1]; yading@10: yading@10: err = autoc[0]; yading@10: ref[0] = -gen1[0] / err; yading@10: err += gen1[0] * ref[0]; yading@10: if (error) yading@10: error[0] = err; yading@10: for (i = 1; i < max_order; i++) { yading@10: for (j = 0; j < max_order - i; j++) { yading@10: gen1[j] = gen1[j + 1] + ref[i - 1] * gen0[j]; yading@10: gen0[j] = gen1[j + 1] * ref[i - 1] + gen0[j]; yading@10: } yading@10: ref[i] = -gen1[0] / err; yading@10: err += gen1[0] * ref[i]; yading@10: if (error) yading@10: error[i] = err; yading@10: } yading@10: } yading@10: yading@10: /** yading@10: * Levinson-Durbin recursion. yading@10: * Produce LPC coefficients from autocorrelation data. yading@10: */ yading@10: static inline int compute_lpc_coefs(const LPC_TYPE *autoc, int max_order, yading@10: LPC_TYPE *lpc, int lpc_stride, int fail, yading@10: int normalize) yading@10: { yading@10: int i, j; yading@10: LPC_TYPE err; yading@10: LPC_TYPE *lpc_last = lpc; yading@10: yading@10: av_assert2(normalize || !fail); yading@10: yading@10: if (normalize) yading@10: err = *autoc++; yading@10: yading@10: if (fail && (autoc[max_order - 1] == 0 || err <= 0)) yading@10: return -1; yading@10: yading@10: for(i=0; i>1; j++) { yading@10: LPC_TYPE f = lpc_last[ j]; yading@10: LPC_TYPE b = lpc_last[i-1-j]; yading@10: lpc[ j] = f + r * b; yading@10: lpc[i-1-j] = b + r * f; yading@10: } yading@10: yading@10: if (fail && err < 0) yading@10: return -1; yading@10: yading@10: lpc_last = lpc; yading@10: lpc += lpc_stride; yading@10: } yading@10: yading@10: return 0; yading@10: } yading@10: yading@10: #endif /* AVCODEC_LPC_H */