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| author | Martijn van Beurden <mvanb1@gmail.com> | 2024-05-16 16:00:19 +0200 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-05-16 16:00:19 +0200 |
| commit | cfe3afca9b3f27f0877203570705e072f0981b2e (patch) | |
| tree | 028d14b8f7804c88b37aeea7b597d3dd41d49dbd | |
| parent | 1ab3c8e748e5f7ff78a0674499cd7291478a7cd8 (diff) | |
| download | flac-upstream-master.tar.gz | |
Further improve calculation of when to use wide residual computation (#702)upstream-master
| -rw-r--r-- | src/libFLAC/include/private/lpc.h | 1 | ||||
| -rw-r--r-- | src/libFLAC/lpc.c | 25 |
2 files changed, 16 insertions, 10 deletions
diff --git a/src/libFLAC/include/private/lpc.h b/src/libFLAC/include/private/lpc.h index 766f0560..3b13e35a 100644 --- a/src/libFLAC/include/private/lpc.h +++ b/src/libFLAC/include/private/lpc.h @@ -181,6 +181,7 @@ void FLAC__lpc_compute_residual_from_qlp_coefficients_wide_intrin_avx2(const FLA #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */ +FLAC__uint64 FLAC__lpc_max_prediction_value_before_shift(uint32_t subframe_bps, const FLAC__int32 qlp_coeff[], uint32_t order); uint32_t FLAC__lpc_max_prediction_before_shift_bps(uint32_t subframe_bps, const FLAC__int32 qlp_coeff[], uint32_t order); uint32_t FLAC__lpc_max_residual_bps(uint32_t subframe_bps, const FLAC__int32 qlp_coeff[], uint32_t order, int lp_quantization); diff --git a/src/libFLAC/lpc.c b/src/libFLAC/lpc.c index 4148b207..34f8301c 100644 --- a/src/libFLAC/lpc.c +++ b/src/libFLAC/lpc.c @@ -939,27 +939,32 @@ FLAC__bool FLAC__lpc_compute_residual_from_qlp_coefficients_limit_residual_33bit #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */ +FLAC__uint64 FLAC__lpc_max_prediction_value_before_shift(uint32_t subframe_bps, const FLAC__int32 * flac_restrict qlp_coeff, uint32_t order) +{ + FLAC__uint64 max_abs_sample_value = (FLAC__uint64)(1) << (subframe_bps - 1); + FLAC__uint32 abs_sum_of_qlp_coeff = 0; + uint32_t i; + for(i = 0; i < order; i++) + abs_sum_of_qlp_coeff += abs(qlp_coeff[i]); + return max_abs_sample_value * abs_sum_of_qlp_coeff; +} + uint32_t FLAC__lpc_max_prediction_before_shift_bps(uint32_t subframe_bps, const FLAC__int32 * flac_restrict qlp_coeff, uint32_t order) { /* This used to be subframe_bps + qlp_coeff_precision + FLAC__bitmath_ilog2(order) * but that treats both the samples as well as the predictor as unknown. The * predictor is known however, so taking the log2 of the sum of the absolute values * of all coefficients is a more accurate representation of the predictor */ - FLAC__uint32 abs_sum_of_qlp_coeff = 0; - uint32_t i; - for(i = 0; i < order; i++) - abs_sum_of_qlp_coeff += abs(qlp_coeff[i]); - return subframe_bps + FLAC__bitmath_extra_mulbits_unsigned(abs_sum_of_qlp_coeff); + return FLAC__bitmath_silog2(FLAC__lpc_max_prediction_value_before_shift(subframe_bps, qlp_coeff, order)); } uint32_t FLAC__lpc_max_residual_bps(uint32_t subframe_bps, const FLAC__int32 * flac_restrict qlp_coeff, uint32_t order, int lp_quantization) { - FLAC__int32 predictor_sum_bps = FLAC__lpc_max_prediction_before_shift_bps(subframe_bps, qlp_coeff, order) - lp_quantization; - if((int)subframe_bps > predictor_sum_bps) - return subframe_bps + 1; - else - return predictor_sum_bps + 1; + FLAC__uint64 max_abs_sample_value = (FLAC__uint64)(1) << (subframe_bps - 1); + FLAC__uint64 max_prediction_value_after_shift = -1 * ((-1 * (FLAC__int64)FLAC__lpc_max_prediction_value_before_shift(subframe_bps, qlp_coeff, order)) >> lp_quantization); + FLAC__uint64 max_residual_value = max_abs_sample_value + max_prediction_value_after_shift; + return FLAC__bitmath_silog2(max_residual_value); } #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && !defined(FUZZING_BUILD_MODE_FLAC_SANITIZE_SIGNED_INTEGER_OVERFLOW) |