aac5773f
 hucm
功能基本完成，接口待打磨
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/*
* 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++) {
int32_t a, b;
a = buffer[0][i];
b = buffer[1][i];
a -= (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] = (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_X86)
ff_alacdsp_init_x86(c);
}
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