25 #define LPC_USE_DOUBLE
44 c = 2.0 / (len - 1.0);
51 w_data[-i-1] = data[-i-1] * w;
52 w_data[+i ] = data[+i ] * w;
65 for(j=0; j<lag; j+=2){
66 double sum0 = 1.0, sum1 = 1.0;
68 sum0 += data[i] * data[i-j];
69 sum1 += data[i] * data[i-j-1];
77 for(i=j-1; i<
len; i+=2){
78 sum += data[i ] * data[i-j ]
79 + data[i+1] * data[i-j+1];
89 int32_t *lpc_out,
int *shift,
int max_shift,
int zero_shift)
97 qmax = (1 << (precision - 1)) - 1;
101 for(i=0; i<order; i++) {
102 cmax=
FFMAX(cmax, fabs(lpc_in[i]));
106 if(cmax * (1 << max_shift) < 1.0) {
108 memset(lpc_out, 0,
sizeof(
int32_t) * order);
114 while((cmax * (1 << sh) > qmax) && (sh > 0)) {
120 if(sh == 0 && cmax > qmax) {
121 double scale = ((double)qmax) / cmax;
122 for(i=0; i<order; i++) {
129 for(i=0; i<order; i++) {
130 error -= lpc_in[i] * (1 << sh);
131 lpc_out[i] = av_clip(
lrintf(error), -qmax, qmax);
142 for(i=max_order-1; i>=min_order-1; i--) {
152 const int32_t *samples,
int order,
double *ref)
170 const int32_t *samples,
int blocksize,
int min_order,
171 int max_order,
int precision,
174 int omethod,
int max_shift,
int zero_shift)
176 double autoc[MAX_LPC_ORDER+1];
182 assert(max_order >=
MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER &&
199 for(i=0; i<max_order; i++)
200 ref[i] = fabs(lpc[i][i]);
209 memset(var, 0,
FFALIGN(MAX_LPC_ORDER+1,4)*
sizeof(*var));
211 for(j=0; j<max_order; j++)
212 m[0].coeff[max_order-1][j] = -lpc[max_order-1][j];
214 for(; pass<lpc_passes; pass++){
218 for(i=max_order; i<blocksize; i++){
219 for(j=0; j<=max_order; j++)
220 var[j]= samples[i-j];
223 double eval, inv, rinv;
224 eval= m[pass&1].
evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
225 eval= (512>>
pass) + fabs(eval - var[0]);
228 for(j=0; j<=max_order; j++)
239 for(i=0; i<max_order; i++){
240 for(j=0; j<max_order; j++)
241 lpc[i][j]=-m[(pass-1)&1].
coeff[i][j];
242 ref[i]= sqrt(m[(pass-1)&1].variance[i] / weight) * (blocksize - max_order) / 4000;
244 for(i=max_order-1; i>0; i--)
245 ref[i] = ref[i-1] - ref[i];
247 opt_order = max_order;
252 quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
254 for(i=min_order-1; i<max_order; i++) {
255 quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
void(* update_lls)(struct LLSModel *m, double *var)
Take the outer-product of var[] with itself, and add to the covariance matrix.
Linear least squares model.
int ff_lpc_calc_coefs(LPCContext *s, const int32_t *samples, int blocksize, int min_order, int max_order, int precision, int32_t coefs[][MAX_LPC_ORDER], int *shift, enum FFLPCType lpc_type, int lpc_passes, int omethod, int max_shift, int zero_shift)
Calculate LPC coefficients for multiple orders.
static void lpc_compute_autocorr_c(const double *data, int len, int lag, double *autoc)
Calculate autocorrelation data from audio samples A Welch window function is applied before calculati...
void av_freep(void *arg)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc() and set the pointer ...
static void compute_ref_coefs(const LPC_TYPE *autoc, int max_order, LPC_TYPE *ref, LPC_TYPE *error)
Schur recursion.
av_cold void ff_lpc_init_x86(LPCContext *c)
int ff_lpc_calc_ref_coefs(LPCContext *s, const int32_t *samples, int order, double *ref)
void(* lpc_apply_welch_window)(const int32_t *data, int len, double *w_data)
Apply a Welch window to an array of input samples.
av_cold void avpriv_init_lls(LLSModel *m, int indep_count)
static int estimate_best_order(double *ref, int min_order, int max_order)
av_cold void ff_lpc_end(LPCContext *s)
Uninitialize LPCContext.
static void lpc_apply_welch_window_c(const int32_t *data, int len, double *w_data)
Apply Welch window function to audio block.
static av_always_inline av_const long int lrintf(float x)
void(* lpc_compute_autocorr)(const double *data, int len, int lag, double *autoc)
Perform autocorrelation on input samples with delay of 0 to lag.
static void quantize_lpc_coefs(double *lpc_in, int order, int precision, int32_t *lpc_out, int *shift, int max_shift, int zero_shift)
Quantize LPC coefficients.
void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order)
static int compute_lpc_coefs(const LPC_TYPE *autoc, int max_order, LPC_TYPE *lpc, int lpc_stride, int fail, int normalize)
Levinson-Durbin recursion.
Levinson-Durbin recursion.
double * windowed_samples
av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order, enum FFLPCType lpc_type)
Initialize LPCContext.
FFLPCType
LPC analysis type.
double(* evaluate_lls)(struct LLSModel *m, double *var, int order)
Inner product of var[] and the LPC coefs.
common internal and external API header
#define LOCAL_ALIGNED(a, t, v,...)
void * av_mallocz(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...