stream_encoder : Improve selection of residual accumulator width
In the precompute_partition_info_sums_ function, instead of selecting
64-bit accumulator when the signal bps is larger than 16, revert to the
original approach based on partition size, but make room for few extra
bits to not overflow with unusual signals where the average residual
magnitude may be larger than bps.
It slightly improves the performance with standard encoding levels and
16-bit files as the 17-bit side channel can still be processed with the
32-bit accumulator and correctly selects the 64-bit accumulator with
very large 16-bit partitions.
This is related to commits 6f7ec60c and 187e596e.
Signed-off-by: Erik de Castro Lopo <erikd@mega-nerd.com>
diff --git a/src/libFLAC/stream_encoder_intrin_sse2.c b/src/libFLAC/stream_encoder_intrin_sse2.c
index bef5545..4e9d5db 100644
--- a/src/libFLAC/stream_encoder_intrin_sse2.c
+++ b/src/libFLAC/stream_encoder_intrin_sse2.c
@@ -37,6 +37,7 @@
#ifndef FLAC__NO_ASM
#if (defined FLAC__CPU_IA32 || defined FLAC__CPU_X86_64) && defined FLAC__HAS_X86INTRIN
#include "private/stream_encoder.h"
+#include "private/bitmath.h"
#ifdef FLAC__SSE2_SUPPORTED
#include <stdlib.h> /* for abs() */
@@ -58,7 +59,7 @@
unsigned e1, e3;
__m128i mm_res, mm_sum, mm_mask;
- if(bps <= 16) {
+ if(FLAC__bitmath_ilog2(default_partition_samples) + bps + FLAC__MAX_EXTRA_RESIDUAL_BPS < 32) {
for(partition = residual_sample = 0; partition < partitions; partition++) {
end += default_partition_samples;
mm_sum = _mm_setzero_si128();