fix bug where LP was tried even if autoc[0]==0.0
diff --git a/src/libFLAC/encoder.c b/src/libFLAC/encoder.c
index 27bfc32..6208934 100644
--- a/src/libFLAC/encoder.c
+++ b/src/libFLAC/encoder.c
@@ -871,35 +871,38 @@
max_lpc_order = encoder->max_lpc_order;
if(max_lpc_order > 0) {
FLAC__lpc_compute_autocorrelation(real_signal, frame_header->blocksize, max_lpc_order+1, autoc);
- FLAC__lpc_compute_lp_coefficients(autoc, max_lpc_order, lp_coeff, lpc_error);
- if(encoder->do_exhaustive_model_search) {
- min_lpc_order = 1;
- }
- else {
- unsigned guess_lpc_order = FLAC__lpc_compute_best_order(lpc_error, max_lpc_order, frame_header->blocksize, bits_per_sample);
- min_lpc_order = max_lpc_order = guess_lpc_order;
- }
- if(encoder->do_qlp_coeff_prec_search) {
- min_qlp_coeff_precision = FLAC__MIN_QLP_COEFF_PRECISION;
- max_qlp_coeff_precision = min(32 - bits_per_sample - 1, (1u<<FLAC__SUBFRAME_LPC_QLP_COEFF_PRECISION_LEN)-1);
- }
- else {
- min_qlp_coeff_precision = max_qlp_coeff_precision = encoder->qlp_coeff_precision;
- }
- for(lpc_order = min_lpc_order; lpc_order <= max_lpc_order; lpc_order++) {
- lpc_residual_bits_per_sample = FLAC__lpc_compute_expected_bits_per_residual_sample(lpc_error[lpc_order-1], frame_header->blocksize-lpc_order);
- if(lpc_residual_bits_per_sample >= (real)bits_per_sample)
- continue; /* don't even try */
- rice_parameter = (lpc_residual_bits_per_sample > 0.0)? (unsigned)(lpc_residual_bits_per_sample+0.5) : 0; /* 0.5 is for rounding */
- rice_parameter++; /* to account for the signed->unsigned conversion during rice coding */
- if(rice_parameter >= (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN))
- rice_parameter = (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN) - 1;
- for(qlp_coeff_precision = min_qlp_coeff_precision; qlp_coeff_precision <= max_qlp_coeff_precision; qlp_coeff_precision++) {
- _candidate_bits = encoder_evaluate_lpc_subframe_(integer_signal, residual[!_best_subframe], encoder->guts->abs_residual, lp_coeff[lpc_order-1], frame_header->blocksize, bits_per_sample, lpc_order, qlp_coeff_precision, rice_parameter, max_partition_order, subframe[!_best_subframe]);
- if(_candidate_bits > 0) { /* if == 0, there was a problem quantizing the lpcoeffs */
- if(_candidate_bits < _best_bits) {
- _best_subframe = !_best_subframe;
- _best_bits = _candidate_bits;
+ /* if autoc[0] == 0.0, the signal is constant and we usually won't get here, but it can happen */
+ if(autoc[0] != 0.0) {
+ FLAC__lpc_compute_lp_coefficients(autoc, max_lpc_order, lp_coeff, lpc_error);
+ if(encoder->do_exhaustive_model_search) {
+ min_lpc_order = 1;
+ }
+ else {
+ unsigned guess_lpc_order = FLAC__lpc_compute_best_order(lpc_error, max_lpc_order, frame_header->blocksize, bits_per_sample);
+ min_lpc_order = max_lpc_order = guess_lpc_order;
+ }
+ if(encoder->do_qlp_coeff_prec_search) {
+ min_qlp_coeff_precision = FLAC__MIN_QLP_COEFF_PRECISION;
+ max_qlp_coeff_precision = min(32 - bits_per_sample - 1, (1u<<FLAC__SUBFRAME_LPC_QLP_COEFF_PRECISION_LEN)-1);
+ }
+ else {
+ min_qlp_coeff_precision = max_qlp_coeff_precision = encoder->qlp_coeff_precision;
+ }
+ for(lpc_order = min_lpc_order; lpc_order <= max_lpc_order; lpc_order++) {
+ lpc_residual_bits_per_sample = FLAC__lpc_compute_expected_bits_per_residual_sample(lpc_error[lpc_order-1], frame_header->blocksize-lpc_order);
+ if(lpc_residual_bits_per_sample >= (real)bits_per_sample)
+ continue; /* don't even try */
+ rice_parameter = (lpc_residual_bits_per_sample > 0.0)? (unsigned)(lpc_residual_bits_per_sample+0.5) : 0; /* 0.5 is for rounding */
+ rice_parameter++; /* to account for the signed->unsigned conversion during rice coding */
+ if(rice_parameter >= (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN))
+ rice_parameter = (1u << FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN) - 1;
+ for(qlp_coeff_precision = min_qlp_coeff_precision; qlp_coeff_precision <= max_qlp_coeff_precision; qlp_coeff_precision++) {
+ _candidate_bits = encoder_evaluate_lpc_subframe_(integer_signal, residual[!_best_subframe], encoder->guts->abs_residual, lp_coeff[lpc_order-1], frame_header->blocksize, bits_per_sample, lpc_order, qlp_coeff_precision, rice_parameter, max_partition_order, subframe[!_best_subframe]);
+ if(_candidate_bits > 0) { /* if == 0, there was a problem quantizing the lpcoeffs */
+ if(_candidate_bits < _best_bits) {
+ _best_subframe = !_best_subframe;
+ _best_bits = _candidate_bits;
+ }
}
}
}