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stream_encoder : Improve selection of residual accumulator width

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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>
This commit is contained in:
Miroslav Lichvar
2014-06-19 13:04:33 +02:00
committed by Erik de Castro Lopo
parent 71246dcc81
commit f081524c19
4 changed files with 16 additions and 10 deletions
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6
src/libFLAC/include/private/stream_encoder.h
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@@ -37,6 +37,12 @@
#include <config.h>
#endif
/*
* This is used to avoid overflow with unusual signals in 32-bit
* accumulator in the *precompute_partition_info_sums_* functions.
*/
#define FLAC__MAX_EXTRA_RESIDUAL_BPS 4
#if (defined FLAC__CPU_IA32 || defined FLAC__CPU_X86_64) && defined FLAC__HAS_X86INTRIN
#include "private/cpu.h"
#include "FLAC/format.h"