From 7844424d412e894c586f41a8bc0318172509eb0e Mon Sep 17 00:00:00 2001 From: Josh Coalson Date: Fri, 30 Mar 2001 00:43:46 +0000 Subject: [PATCH] add 64-bit versions of some functions --- src/libFLAC/fixed.c | 54 +++++++++++++++++++++++++++++++++---- src/libFLAC/include/private/fixed.h | 5 +++- 2 files changed, 53 insertions(+), 6 deletions(-) diff --git a/src/libFLAC/fixed.c b/src/libFLAC/fixed.c index fbf03f4..a01a14a 100644 --- a/src/libFLAC/fixed.c +++ b/src/libFLAC/fixed.c @@ -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; diff --git a/src/libFLAC/include/private/fixed.h b/src/libFLAC/include/private/fixed.h index 9b87e99..cd63c19 100644 --- a/src/libFLAC/include/private/fixed.h +++ b/src/libFLAC/include/private/fixed.h @@ -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() -- 2.7.4