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codec2/misc/vq_binary_switch.c
Author Name ac7c48b4de shallow zip-file copy from codec2 e9d726bf20
2023-07-07 12:29:06 +09:30

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/*
vq_binary_switch.c
David Rowe Dec 2021
C implementation of [1], that re-arranges VQ indexes so they are robust to single
bit errors.
[1] Pseudo Gray Coding, Zeger & Gersho 1990
*/
#include <assert.h>
#include <getopt.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include "mbest.h"
#define MAX_DIM 20
#define MAX_ENTRIES 4096
// equation (33) of [1], total cost of all hamming distance 1 vectors of vq index k
float cost_of_distance_one(float *vq, int n, int dim, float *prob, int k, int st, int en, int verbose) {
int log2N = log2(n);
float c = 0.0;
for (int b=0; b<log2N; b++) {
unsigned int index_neighbour = k ^ (1<<b);
float dist = 0.0;
for(int i=st; i<=en; i++)
dist += pow(vq[k*dim+i] - vq[index_neighbour*dim+i], 2.0);
c += prob[k]*dist;
if (verbose)
printf("k: %d b: %d index_neighbour: %d dist: %f prob: %f c: %f \n", k, b, index_neighbour, dist, prob[k], c);
}
return c;
}
// equation (39) of [1]
float distortion_of_current_mapping(float *vq, int n, int dim, float *prob, int st, int en) {
float d = 0.0;
for(int k=0; k<n; k++)
d += cost_of_distance_one(vq, n, dim, prob, k, st, en, 0);
return d;
}
// we sort the cost array c[], returning the indexes of sorted elements
float c[MAX_ENTRIES];
/* Note how the compare function compares the values of the
* array to be sorted. The passed value to this function
* by `qsort' are actually the `idx' array elements.
*/
int compare_increase (const void * a, const void * b) {
int aa = *((int *) a), bb = *((int *) b);
if (c[aa] < c[bb]) {
return 1;
} else if (c[aa] == c[bb]) {
return 0;
} else {
return -1;
}
}
void sort_c(int *idx, const size_t n) {
for (size_t i=0; i<n; i++) idx[i] = i;
qsort(idx, n, sizeof(int), compare_increase);
}
void swap(float *vq, int dim, float *prob, int index1, int index2) {
float tmp[dim];
for(int i=0; i<dim; i++) tmp[i] = vq[index1*dim+i];
for(int i=0; i<dim; i++) vq[index1*dim+i] = vq[index2*dim+i];
for(int i=0; i<dim; i++) vq[index2*dim+i] = tmp[i];
tmp[0] = prob[index1];
prob[index1] = prob[index2];
prob[index2] = tmp[0];
}
int main(int argc, char *argv[]) {
float vq[MAX_DIM*MAX_ENTRIES];
int dim = MAX_DIM;
int max_iter = INT_MAX;
int st = -1;
int en = -1;
int verbose = 0;
int n = 0;
int fast_en = 0;
char prob_fn[80]="";
int o = 0; int opt_idx = 0;
while (o != -1) {
static struct option long_opts[] = {
{"prob", required_argument, 0, 'p'},
{"st", required_argument, 0, 't'},
{"en", required_argument, 0, 'e'},
{0, 0, 0, 0}
};
o = getopt_long(argc,argv,"hd:m:vt:e:n:fp:",long_opts,&opt_idx);
switch (o) {
case 'd':
dim = atoi(optarg);
assert(dim <= MAX_DIM);
break;
case 'm':
max_iter = atoi(optarg);
break;
case 't':
st = atoi(optarg);
break;
case 'e':
en = atoi(optarg);
break;
case 'f':
fast_en = 1;
break;
case 'n':
n = atoi(optarg);
break;
case 'p':
strcpy(prob_fn,optarg);
break;
case 'v':
verbose = 1;
break;
help:
fprintf(stderr, "\n");
fprintf(stderr, "usage: %s -d dimension [-m max_iterations -v --st Kst --en Ken -n nVQ] vq_in.f32 vq_out.f32\n", argv[0]);
fprintf(stderr, "\n");
fprintf(stderr, "-n nVQ Run with just the first nVQ entries of the VQ\n");
fprintf(stderr, "--st Kst Start vector element for error calculation (default 0)\n");
fprintf(stderr, "--en Ken End vector element for error calculation (default K-1)\n");
fprintf(stderr, "--prob probFile f32 file of probabilities for each VQ element (default 1.0)\n");
fprintf(stderr, "-v verbose\n");
exit(1);
}
}
int dx = optind;
if ((argc - dx) < 2) {
fprintf(stderr, "Too few arguments\n");
goto help;
}
if (dim == 0) goto help;
/* default to measuring error on entire vector */
if (st == -1) st = 0;
if (en == -1) en = dim-1;
/* load VQ quantiser file --------------------*/
fprintf(stderr, "loading %s ... ", argv[dx]);
FILE *fq=fopen(argv[dx], "rb");
if (fq == NULL) {
fprintf(stderr, "Couldn't open: %s\n", argv[dx]);
exit(1);
}
if (n==0) {
/* count how many entries m of dimension k are in this VQ file */
float dummy[dim];
while (fread(dummy, sizeof(float), dim, fq) == (size_t)dim)
n++;
assert(n <= MAX_ENTRIES);
fprintf(stderr, "%d entries of vectors width %d\n", n, dim);
rewind(fq);
}
/* load VQ into memory */
int nrd = fread(vq, sizeof(float), n*dim, fq);
assert(nrd == n*dim);
fclose(fq);
/* set probability of each vector to 1.0 as default */
float prob[n];
for(int l=0; l<n; l++) prob[l] = 1.0;
if (strlen(prob_fn)) {
fprintf(stderr, "Reading probability file: %s\n", prob_fn);
FILE *fp = fopen(prob_fn,"rb");
assert(fp != NULL);
int nrd = fread(prob, sizeof(float), n, fp);
assert(nrd == n);
fclose(fp);
float sum = 0.0;
for(int l=0; l<n; l++) sum += prob[l];
fprintf(stderr, "sum = %f\n", sum);
}
int iteration = 0;
int i = 0;
int finished = 0;
int switches = 0;
int log2N = log2(n);
float distortion0 = distortion_of_current_mapping(vq, n, dim, prob, st, en);
fprintf(stderr, "distortion0: %f\n", distortion0);
while(!finished) {
// generate a list A(i) of which vectors have the largest cost of bit errors
for(int k=0; k<n; k++) {
c[k] = cost_of_distance_one(vq, n, dim, prob, k, st, en, verbose);
}
int A[n];
sort_c(A, n);
// Try switching each vector with A(i)
float best_delta = 0; int best_j = 0;
for(int j=1; j<n; j++) {
float distortion1, distortion2, delta = 0.0;
// we can't switch with ourself
if (j != A[i]) {
if (fast_en) {
// subtract just those contributions to delta that will change
delta -= cost_of_distance_one(vq, n, dim, prob, A[i], st, en, verbose);
delta -= cost_of_distance_one(vq, n, dim, prob, j, st, en, verbose);
for (int b=0; b<log2N; b++) {
unsigned int index_neighbour;
index_neighbour = A[i] ^ (1<<b);
if ((index_neighbour != j) && (index_neighbour != A[i]))
delta -= cost_of_distance_one(vq, n, dim, prob, index_neighbour, st, en, verbose);
index_neighbour = j ^ (1<<b);
if ((index_neighbour != j) && (index_neighbour != A[i]))
delta -= cost_of_distance_one(vq, n, dim, prob, index_neighbour, st, en, verbose);
}
}
else
distortion1 = distortion_of_current_mapping(vq, n, dim, prob, st, en);
// switch vq entries A(i) and j
swap(vq, dim, prob, A[i], j);
if (fast_en) {
// add just those contributions to delta that will change
delta += cost_of_distance_one(vq, n, dim, prob, A[i], st, en, verbose);
delta += cost_of_distance_one(vq, n, dim, prob, j, st, en, verbose);
for (int b=0; b<log2N; b++) {
unsigned int index_neighbour;
index_neighbour = A[i] ^ (1<<b);
if ((index_neighbour != j) && (index_neighbour != A[i]))
delta += cost_of_distance_one(vq, n, dim, prob, index_neighbour, st, en, verbose);
index_neighbour = j ^ (1<<b);
if ((index_neighbour != j) && (index_neighbour != A[i]))
delta += cost_of_distance_one(vq, n, dim, prob, index_neighbour, st, en, verbose);
}
}
else {
distortion2 = distortion_of_current_mapping(vq, n, dim, prob, st, en);
delta = distortion2 - distortion1;
}
if (delta < 0.0) {
if (fabs(delta) > best_delta) {
best_delta = fabs(delta);
best_j = j;
}
}
// unswitch
swap(vq, dim, prob, A[i], j);
}
} //next j
// printf("best_delta: %f best_j: %d\n", best_delta, best_j);
if (best_delta == 0.0) {
// Hmm, no improvement, lets try the next vector in the sorted cost list
if (i == n-1) finished = 1; else i++;
} else {
// OK keep the switch that minimised the distortion
swap(vq, dim, prob, A[i], best_j);
switches++;
// save results
FILE *fq=fopen(argv[dx+1], "wb");
if (fq == NULL) {
fprintf(stderr, "Couldn't open: %s\n", argv[dx+1]);
exit(1);
}
int nwr = fwrite(vq, sizeof(float), n*dim, fq);
assert(nwr == n*dim);
fclose(fq);
// set up for next iteration
iteration++;
float distortion = distortion_of_current_mapping(vq, n, dim, prob, st, en);
fprintf(stderr, "it: %3d dist: %f %3.2f i: %3d sw: %3d\n", iteration, distortion,
distortion/distortion0, i, switches);
if (iteration >= max_iter) finished = 1;
i = 0;
}
}
return 0;
}
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