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26 #define LPC_USE_DOUBLE
47 c = 2.0 / (
len - 1.0);
79 for(j=0; j<lag; j+=2){
80 double sum0 = 1.0, sum1 = 1.0;
104 int max_shift,
int zero_shift)
112 qmax = (1 << (precision - 1)) - 1;
116 for(
i=0;
i<order;
i++) {
121 if(cmax * (1 << max_shift) < 1.0) {
123 memset(lpc_out, 0,
sizeof(
int32_t) * order);
129 while((cmax * (1 << sh) > qmax) && (sh > min_shift)) {
135 if(sh == 0 && cmax > qmax) {
137 for(
i=0;
i<order;
i++) {
144 for(
i=0;
i<order;
i++) {
145 error -= lpc_in[
i] * (1 << sh);
157 for(
i=max_order-1;
i>=min_order-1;
i--) {
171 s->lpc_apply_welch_window(
samples,
s->blocksize,
s->windowed_samples);
172 s->lpc_compute_autocorr(
s->windowed_samples,
s->blocksize, order, autoc);
179 int order,
double *
ref)
182 double signal = 0.0f, avg_err = 0.0f;
184 const double a = 0.5f,
b = 1.0f -
a;
187 for (
i = 0;
i <=
len / 2;
i++) {
193 s->lpc_compute_autocorr(
s->windowed_samples,
len, order, autoc);
196 for (
i = 0;
i < order;
i++)
197 avg_err = (avg_err +
error[
i])/2.0f;
198 return avg_err ? signal/avg_err :
NAN;
209 int max_order,
int precision,
212 int omethod,
int min_shift,
int max_shift,
int zero_shift)
225 if (blocksize !=
s->blocksize || max_order !=
s->max_order ||
226 lpc_type !=
s->lpc_type) {
235 s->lpc_apply_welch_window(
samples, blocksize,
s->windowed_samples);
237 s->lpc_compute_autocorr(
s->windowed_samples, blocksize, max_order, autoc);
241 for(
i=0;
i<max_order;
i++)
253 for(j=0; j<max_order; j++)
254 m[0].
coeff[max_order-1][j] = -lpc[max_order-1][j];
260 for(
i=max_order;
i<blocksize;
i++){
261 for(j=0; j<=max_order; j++)
265 double eval, inv, rinv;
267 eval= (512>>
pass) +
fabs(eval - var[0]);
270 for(j=0; j<=max_order; j++)
281 for(
i=0;
i<max_order;
i++){
282 for(j=0; j<max_order; j++)
284 ref[
i]= sqrt(m[(
pass-1)&1].variance[
i] /
weight) * (blocksize - max_order) / 4000;
286 for(
i=max_order-1;
i>0;
i--)
290 opt_order = max_order;
296 min_shift, max_shift, zero_shift);
298 for(
i=min_order-1;
i<max_order;
i++) {
300 min_shift, max_shift, zero_shift);
310 s->blocksize = blocksize;
311 s->max_order = max_order;
312 s->lpc_type = lpc_type;
315 sizeof(*
s->windowed_samples));
316 if (!
s->windowed_buffer)
318 s->windowed_samples =
s->windowed_buffer +
FFALIGN(max_order, 4);
static void error(const char *err)
Linear least squares model.
FFLPCType
LPC analysis type.
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
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 min_shift, int max_shift, int zero_shift)
Calculate LPC coefficients for multiple orders.
av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order, enum FFLPCType lpc_type)
Initialize LPCContext.
static void lpc_apply_welch_window_c(const int32_t *data, ptrdiff_t len, double *w_data)
Apply Welch window function to audio block.
@ FF_LPC_TYPE_CHOLESKY
Cholesky factorization.
static int AAC_RENAME() compute_lpc_coefs(const LPC_TYPE *autoc, int max_order, LPC_TYPE *lpc, int lpc_stride, int fail, int normalize)
Levinson-Durbin recursion.
static av_always_inline float scale(float x, float s)
#define LOCAL_ALIGNED(a, t, v,...)
#define av_assert0(cond)
assert() equivalent, that is always enabled.
static __device__ float fabs(float a)
av_cold void ff_lpc_end(LPCContext *s)
Uninitialize LPCContext.
av_cold void avpriv_init_lls(LLSModel *m, int indep_count)
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
static int weight(int i, int blen, int offset)
void(* update_lls)(struct LLSModel *m, const double *var)
Take the outer-product of var[] with itself, and add to the covariance matrix.
static int shift(int a, int b)
void ff_lpc_init_x86(LPCContext *s)
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len, int order, double *ref)
double(* evaluate_lls)(struct LLSModel *m, const double *var, int order)
Inner product of var[] and the LPC coefs.
static int estimate_best_order(double *ref, int min_order, int max_order)
static void quantize_lpc_coefs(double *lpc_in, int order, int precision, int32_t *lpc_out, int *shift, int min_shift, int max_shift, int zero_shift)
Quantize LPC coefficients.
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
#define i(width, name, range_min, range_max)
static void lpc_compute_autocorr_c(const double *data, ptrdiff_t len, int lag, double *autoc)
Calculate autocorrelation data from audio samples A Welch window function is applied before calculati...
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
static void compute_ref_coefs(const LPC_TYPE *autoc, int max_order, LPC_TYPE *ref, LPC_TYPE *error)
Schur recursion.
double coeff[32][MAX_VARS]
static int ref[MAX_W *MAX_W]
Filter the word “frame” indicates either a video frame or a group of audio samples
int ff_lpc_calc_ref_coefs(LPCContext *s, const int32_t *samples, int order, double *ref)
static const double coeff[2][5]
@ FF_LPC_TYPE_LEVINSON
Levinson-Durbin recursion.
void avpriv_solve_lls(LLSModel *m, double threshold, unsigned short min_order)
@ FF_LPC_TYPE_FIXED
fixed LPC coefficients