00001
00022 #ifndef AVCODEC_LPC_H
00023 #define AVCODEC_LPC_H
00024
00025 #include <stdint.h>
00026 #include "dsputil.h"
00027
00028 #define ORDER_METHOD_EST 0
00029 #define ORDER_METHOD_2LEVEL 1
00030 #define ORDER_METHOD_4LEVEL 2
00031 #define ORDER_METHOD_8LEVEL 3
00032 #define ORDER_METHOD_SEARCH 4
00033 #define ORDER_METHOD_LOG 5
00034
00035 #define MIN_LPC_ORDER 1
00036 #define MAX_LPC_ORDER 32
00037
00038
00039 typedef struct LPCContext {
00040 int blocksize;
00041 int max_order;
00042 enum AVLPCType lpc_type;
00043 double *windowed_samples;
00044
00053 void (*lpc_apply_welch_window)(const int32_t *data, int len,
00054 double *w_data);
00068 void (*lpc_compute_autocorr)(const double *data, int len, int lag,
00069 double *autoc);
00070 } LPCContext;
00071
00072
00076 int ff_lpc_calc_coefs(LPCContext *s,
00077 const int32_t *samples, int blocksize, int min_order,
00078 int max_order, int precision,
00079 int32_t coefs[][MAX_LPC_ORDER], int *shift,
00080 enum AVLPCType lpc_type, int lpc_passes,
00081 int omethod, int max_shift, int zero_shift);
00082
00086 int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
00087 enum AVLPCType lpc_type);
00088 void ff_lpc_init_x86(LPCContext *s);
00089
00093 void ff_lpc_end(LPCContext *s);
00094
00095 #ifdef LPC_USE_DOUBLE
00096 #define LPC_TYPE double
00097 #else
00098 #define LPC_TYPE float
00099 #endif
00100
00105 static inline int compute_lpc_coefs(const LPC_TYPE *autoc, int max_order,
00106 LPC_TYPE *lpc, int lpc_stride, int fail,
00107 int normalize)
00108 {
00109 int i, j;
00110 LPC_TYPE err;
00111 LPC_TYPE *lpc_last = lpc;
00112
00113 if (normalize)
00114 err = *autoc++;
00115
00116 if (fail && (autoc[max_order - 1] == 0 || err <= 0))
00117 return -1;
00118
00119 for(i=0; i<max_order; i++) {
00120 LPC_TYPE r = -autoc[i];
00121
00122 if (normalize) {
00123 for(j=0; j<i; j++)
00124 r -= lpc_last[j] * autoc[i-j-1];
00125
00126 r /= err;
00127 err *= 1.0 - (r * r);
00128 }
00129
00130 lpc[i] = r;
00131
00132 for(j=0; j < (i+1)>>1; j++) {
00133 LPC_TYPE f = lpc_last[ j];
00134 LPC_TYPE b = lpc_last[i-1-j];
00135 lpc[ j] = f + r * b;
00136 lpc[i-1-j] = b + r * f;
00137 }
00138
00139 if (fail && err < 0)
00140 return -1;
00141
00142 lpc_last = lpc;
00143 lpc += lpc_stride;
00144 }
00145
00146 return 0;
00147 }
00148
00149 #endif