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monoscope: code cleanup

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Use constants more often. Cleanup comments and add more to explain how things
work.
This commit is contained in:
Stefan Sauer 2016-01-28 08:53:35 +01:00
parent 3738ce8ba1
commit daea0540fd
2 changed files with 54 additions and 53 deletions
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71
gst/monoscope/convolve.c
View File

@ -248,18 +248,25 @@ convolve_run (stack_entry * top, unsigned size, double *scratch)
} while (top->b.main != NULL);
}
int
convolve_match (const int *lastchoice,
const short *input, convolve_state * state)
/* lastchoice is a 256 sized array. input is a 512 array. We find the
* contiguous length 256 sub-array of input that best matches lastchoice.
* A measure of how good a sub-array is compared with the lastchoice is
* given by the sum of the products of each pair of entries. We maximise
/*
* convolve_match:
* @lastchoice: an array of size SMALL.
* @input: an array of siue BIG (2*SMALL)
* @state: a (non-NULL) pointer returned by convolve_init.
*
* We find the contiguous SMALL-size sub-array of input that best matches
* lastchoice. A measure of how good a sub-array is compared with the lastchoice
* is given by the sum of the products of each pair of entries. We maximise
* that, by taking an appropriate convolution, and then finding the maximum
* entry in the convolutions. state is a (non-NULL) pointer returned by
* convolve_init. */
* entry in the convolutions.
*
* Return: the position of the best match
*/
int
convolve_match (const int *lastchoice, const short *input,
convolve_state * state)
{
double avg;
double avg = 0;
double best;
int p = 0;
int i;
@ -268,47 +275,45 @@ convolve_match (const int *lastchoice,
double *scratch = state->scratch;
stack_entry *top = state->stack + (STACK_SIZE - 1);
#if 1
for (i = 0; i < 512; i++)
for (i = 0; i < CONVOLVE_BIG; i++)
left[i] = input[i];
avg = 0;
for (i = 0; i < 256; i++) {
double a = lastchoice[255 - i];
for (i = 0; i < CONVOLVE_SMALL; i++) {
double a = lastchoice[(CONVOLVE_SMALL - 1) - i];
right[i] = a;
avg += a;
}
#endif
/* We adjust the smaller of the two input arrays to have average
* value 0. This makes the eventual result insensitive to both
* constant offsets and positive multipliers of the inputs. */
avg /= 256;
for (i = 0; i < 256; i++)
avg /= CONVOLVE_SMALL;
for (i = 0; i < CONVOLVE_SMALL; i++)
right[i] -= avg;
/* End-of-stack marker. */
top[1].b.null = scratch;
top[1].b.main = NULL;
/* The low 256x256, of which we want the high 256 outputs. */
/* The low SMALLxSMALL, of which we want the high outputs. */
top->v.left = left;
top->v.right = right;
top->v.out = right + 256;
convolve_run (top, 256, scratch);
top->v.out = right + CONVOLVE_SMALL;
convolve_run (top, CONVOLVE_SMALL, scratch);
/* The high 256x256, of which we want the low 256 outputs. */
top->v.left = left + 256;
/* The high SMALLxSMALL, of which we want the low outputs. */
top->v.left = left + CONVOLVE_SMALL;
top->v.right = right;
top->v.out = right;
convolve_run (top, 256, scratch);
convolve_run (top, CONVOLVE_SMALL, scratch);
/* Now find the best position amoungs this. Apart from the first
* and last, the required convolution outputs are formed by adding
* outputs from the two convolutions above. */
best = right[511];
right[767] = 0;
best = right[CONVOLVE_BIG - 1];
right[CONVOLVE_BIG + CONVOLVE_SMALL + 1] = 0;
p = -1;
for (i = 0; i < 256; i++) {
double a = right[i] + right[i + 512];
for (i = 0; i < CONVOLVE_SMALL; i++) {
double a = right[i] + right[i + CONVOLVE_BIG];
if (a > best) {
best = a;
@ -320,21 +325,19 @@ convolve_match (const int *lastchoice,
#if 0
{
/* This is some debugging code... */
int bad = 0;
best = 0;
for (i = 0; i < 256; i++)
for (i = 0; i < CONVOLVE_SMALL; i++)
best += ((double) input[i + p]) * ((double) lastchoice[i] - avg);
for (i = 0; i < 257; i++) {
for (i = 0; i <= CONVOLVE_SMALL; i++) {
double tot = 0;
unsigned int j;
for (j = 0; j < 256; j++)
for (j = 0; j < CONVOLVE_SMALL; j++)
tot += ((double) input[i + j]) * ((double) lastchoice[j] - avg);
if (tot > best)
printf ("(%i)", i);
if (tot != left[i + 255])
if (tot != left[i + (CONVOLVE_SMALL - 1)])
printf ("!");
}

8
gst/monoscope/monoscope.c
View File

@ -95,14 +95,12 @@ monoscope_update (struct monoscope_state *stateptr, gint16 data[512])
int factor;
int val;
int max = 1;
short *thisEq;
short *thisEq = stateptr->copyEq;
memcpy (stateptr->copyEq, data, sizeof (short) * CONVOLVE_BIG);
thisEq = stateptr->copyEq;
#if 1
memcpy (thisEq, data, sizeof (short) * CONVOLVE_BIG);
val = convolve_match (stateptr->avgEq, stateptr->copyEq, stateptr->cstate);
thisEq += val;
#endif
memset (stateptr->display, 0, 256 * 128 * sizeof (guint32));
for (i = 0; i < 256; i++) {
foo = thisEq[i] + (stateptr->avgEq[i] >> 1);