AuroraMiddleware/flac
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

streamline FLAC__fixed_compute_best_predictor()

Browse Source
This commit is contained in:
Josh Coalson 2001-05-18 18:47:55 +00:00
parent 675effa90e
commit d80c18e4ac
1 changed files with 6 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
src/libFLAC/fixed.c
View File

@ -42,21 +42,16 @@ unsigned FLAC__fixed_compute_best_predictor(const int32 data[], unsigned data_le
int32 last_error_1 = data[-1] - data[-2]; int32 last_error_1 = data[-1] - data[-2];
int32 last_error_2 = last_error_1 - (data[-2] - data[-3]); 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 last_error_3 = last_error_2 - (data[-2] - 2*data[-3] + data[-4]);
int32 error_0, error_1, error_2, error_3, error_4; int32 error, save;
uint32 total_error_0 = 0, total_error_1 = 0, total_error_2 = 0, total_error_3 = 0, total_error_4 = 0; uint32 total_error_0 = 0, total_error_1 = 0, total_error_2 = 0, total_error_3 = 0, total_error_4 = 0;
unsigned i, order; unsigned i, order;
for(i = 0; i < data_len; i++) { for(i = 0; i < data_len; i++) {
error_0 = data[i] ; total_error_0 += local_abs(error_0); error = data[i] ; total_error_0 += local_abs(error); save = error;
error_1 = error_0 - last_error_0; total_error_1 += local_abs(error_1); error -= last_error_0; total_error_1 += local_abs(error); last_error_0 = save; save = error;
error_2 = error_1 - last_error_1; total_error_2 += local_abs(error_2); error -= last_error_1; total_error_2 += local_abs(error); last_error_1 = save; save = error;
error_3 = error_2 - last_error_2; total_error_3 += local_abs(error_3); error -= last_error_2; total_error_3 += local_abs(error); last_error_2 = save; save = error;
error_4 = error_3 - last_error_3; total_error_4 += local_abs(error_4); error -= last_error_3; total_error_4 += local_abs(error); last_error_3 = save;
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)) if(total_error_0 < min(min(min(total_error_1, total_error_2), total_error_3), total_error_4))
@ -70,23 +65,11 @@ unsigned FLAC__fixed_compute_best_predictor(const int32 data[], unsigned data_le
else else
order = 4; 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|) */
#ifdef _MSC_VER
/* with VC++ you have to spoon feed it the casting */
residual_bits_per_sample[0] = (real)((data_len > 0) ? log(M_LN2 * (real)(int64)total_error_0 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[1] = (real)((data_len > 0) ? log(M_LN2 * (real)(int64)total_error_1 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[2] = (real)((data_len > 0) ? log(M_LN2 * (real)(int64)total_error_2 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[3] = (real)((data_len > 0) ? log(M_LN2 * (real)(int64)total_error_3 / (real) data_len) / M_LN2 : 0.0);
residual_bits_per_sample[4] = (real)((data_len > 0) ? log(M_LN2 * (real)(int64)total_error_4 / (real) data_len) / M_LN2 : 0.0);
#else
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[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[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[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[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); residual_bits_per_sample[4] = (real)((data_len > 0) ? log(M_LN2 * (real)total_error_4 / (real) data_len) / M_LN2 : 0.0);
#endif
return order; return order;
} }