blob: ecbaedb06701b906a74e1e6c2a4f6124550a43d5
| 1 | /* |
| 2 | * ALAC (Apple Lossless Audio Codec) decoder |
| 3 | * Copyright (c) 2005 David Hammerton |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | #include "libavutil/attributes.h" |
| 23 | #include "alacdsp.h" |
| 24 | #include "config.h" |
| 25 | |
| 26 | static void decorrelate_stereo(int32_t *buffer[2], int nb_samples, |
| 27 | int decorr_shift, int decorr_left_weight) |
| 28 | { |
| 29 | int i; |
| 30 | |
| 31 | for (i = 0; i < nb_samples; i++) { |
| 32 | int32_t a, b; |
| 33 | |
| 34 | a = buffer[0][i]; |
| 35 | b = buffer[1][i]; |
| 36 | |
| 37 | a -= (b * decorr_left_weight) >> decorr_shift; |
| 38 | b += a; |
| 39 | |
| 40 | buffer[0][i] = b; |
| 41 | buffer[1][i] = a; |
| 42 | } |
| 43 | } |
| 44 | |
| 45 | static void append_extra_bits(int32_t *buffer[2], int32_t *extra_bits_buffer[2], |
| 46 | int extra_bits, int channels, int nb_samples) |
| 47 | { |
| 48 | int i, ch; |
| 49 | |
| 50 | for (ch = 0; ch < channels; ch++) |
| 51 | for (i = 0; i < nb_samples; i++) |
| 52 | buffer[ch][i] = (buffer[ch][i] << extra_bits) | extra_bits_buffer[ch][i]; |
| 53 | } |
| 54 | |
| 55 | av_cold void ff_alacdsp_init(ALACDSPContext *c) |
| 56 | { |
| 57 | c->decorrelate_stereo = decorrelate_stereo; |
| 58 | c->append_extra_bits[0] = |
| 59 | c->append_extra_bits[1] = append_extra_bits; |
| 60 | |
| 61 | if (ARCH_X86) |
| 62 | ff_alacdsp_init_x86(c); |
| 63 | } |
| 64 |