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add 64-bit versions of some functions

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This commit is contained in:
Josh Coalson 2001-03-30 00:43:46 +00:00
parent f24a98c426
commit 7844424d41
2 changed files with 53 additions and 6 deletions
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54
src/libFLAC/fixed.c
View File

@ -53,11 +53,55 @@ unsigned FLAC__fixed_compute_best_predictor(const int32 data[], unsigned data_le
error_3 = error_2 - last_error_2; total_error_3 += local_abs(error_3);
error_4 = error_3 - last_error_3; total_error_4 += local_abs(error_4);
/* WATCHOUT - total_error_* has been know to overflow when encoding
* erratic signals when the bits-per-sample is large. We avoid the
* speed penalty of watching for overflow, and instead rely on the
* encoder's evaluation of the subframe to catch these cases.
*/
last_error_0 = error_0;
last_error_1 = error_1;
last_error_2 = error_2;
last_error_3 = error_3;
}
if(total_error_0 < min(min(min(total_error_1, total_error_2), total_error_3), total_error_4))
order = 0;
else if(total_error_1 < min(min(total_error_2, total_error_3), total_error_4))
order = 1;
else if(total_error_2 < min(total_error_3, total_error_4))
order = 2;
else if(total_error_3 < total_error_4)
order = 3;
else
order = 4;
/* Estimate the expected number of bits per residual signal sample. */
/* 'total_error*' is linearly related to the variance of the residual */
/* signal, so we use it directly to compute E(|x|) */
residual_bits_per_sample[0] = (real)((data_len > 0) ? log(M_LN2 * (real)total_error_0 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[1] = (real)((data_len > 0) ? log(M_LN2 * (real)total_error_1 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[2] = (real)((data_len > 0) ? log(M_LN2 * (real)total_error_2 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[3] = (real)((data_len > 0) ? log(M_LN2 * (real)total_error_3 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[4] = (real)((data_len > 0) ? log(M_LN2 * (real)total_error_4 / (real) data_len) / M_LN2 : 0.0);
return order;
}
unsigned FLAC__fixed_compute_best_predictor_slow(const int32 data[], unsigned data_len, real residual_bits_per_sample[FLAC__MAX_FIXED_ORDER+1])
{
int32 last_error_0 = data[-1];
int32 last_error_1 = data[-1] - data[-2];
int32 last_error_2 = last_error_1 - (data[-2] - data[-3]);
int32 last_error_3 = last_error_2 - (data[-2] - 2*data[-3] + data[-4]);
int32 error_0, error_1, error_2, error_3, error_4;
/* total_error_* are 64-bits to avoid overflow when encoding
* erratic signals when the bits-per-sample and blocksize are
* large.
*/
uint64 total_error_0 = 0, total_error_1 = 0, total_error_2 = 0, total_error_3 = 0, total_error_4 = 0;
unsigned i, order;
for(i = 0; i < data_len; i++) {
error_0 = data[i] ; total_error_0 += local_abs(error_0);
error_1 = error_0 - last_error_0; total_error_1 += local_abs(error_1);
error_2 = error_1 - last_error_1; total_error_2 += local_abs(error_2);
error_3 = error_2 - last_error_2; total_error_3 += local_abs(error_3);
error_4 = error_3 - last_error_3; total_error_4 += local_abs(error_4);
last_error_0 = error_0;
last_error_1 = error_1;

5
src/libFLAC/include/private/fixed.h
View File

@ -26,13 +26,16 @@
* FLAC__fixed_compute_best_predictor()
* --------------------------------------------------------------------
* Compute the best fixed predictor and the expected bits-per-sample
* of the residual signal for each order.
* of the residual signal for each order. The _slow() version uses
* 64-bit integers which is statistically necessary when bits-per-
* sample + log2(blocksize) > 30
*
* IN data[0,data_len-1]
* IN data_len
* OUT residual_bits_per_sample[0,FLAC__MAX_FIXED_ORDER]
*/
unsigned FLAC__fixed_compute_best_predictor(const int32 data[], unsigned data_len, real residual_bits_per_sample[FLAC__MAX_FIXED_ORDER+1]);
unsigned FLAC__fixed_compute_best_predictor_slow(const int32 data[], unsigned data_len, real residual_bits_per_sample[FLAC__MAX_FIXED_ORDER+1]);
/*
* FLAC__fixed_compute_residual()