mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-25 08:42:39 +00:00
64ab577954
To avoid data dependencies, this does the following unroll, which
requires one extra but probably free addition:
coeff = (b * left_weight) >> decorr_shift;
b += a;
a -= coeff;
b -= coeff;
swap(a, b);
67 lines
1.9 KiB
C
67 lines
1.9 KiB
C
/*
|
|
* ALAC (Apple Lossless Audio Codec) decoder
|
|
* Copyright (c) 2005 David Hammerton
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include "libavutil/attributes.h"
|
|
#include "alacdsp.h"
|
|
#include "config.h"
|
|
|
|
static void decorrelate_stereo(int32_t *buffer[2], int nb_samples,
|
|
int decorr_shift, int decorr_left_weight)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < nb_samples; i++) {
|
|
uint32_t a, b;
|
|
|
|
a = buffer[0][i];
|
|
b = buffer[1][i];
|
|
|
|
a -= (int)(b * decorr_left_weight) >> decorr_shift;
|
|
b += a;
|
|
|
|
buffer[0][i] = b;
|
|
buffer[1][i] = a;
|
|
}
|
|
}
|
|
|
|
static void append_extra_bits(int32_t *buffer[2], int32_t *extra_bits_buffer[2],
|
|
int extra_bits, int channels, int nb_samples)
|
|
{
|
|
int i, ch;
|
|
|
|
for (ch = 0; ch < channels; ch++)
|
|
for (i = 0; i < nb_samples; i++)
|
|
buffer[ch][i] = ((unsigned)buffer[ch][i] << extra_bits) | extra_bits_buffer[ch][i];
|
|
}
|
|
|
|
av_cold void ff_alacdsp_init(ALACDSPContext *c)
|
|
{
|
|
c->decorrelate_stereo = decorrelate_stereo;
|
|
c->append_extra_bits[0] =
|
|
c->append_extra_bits[1] = append_extra_bits;
|
|
|
|
#if ARCH_RISCV
|
|
ff_alacdsp_init_riscv(c);
|
|
#elif ARCH_X86
|
|
ff_alacdsp_init_x86(c);
|
|
#endif
|
|
}
|