From b70566d6ca7b7ae60ec1db01b50d461672c8b03f Mon Sep 17 00:00:00 2001 From: James Almer Date: Sun, 4 Oct 2015 14:09:05 -0300 Subject: avcodec/alacdec: split off decorrelate_stereo and append_extra_bits as alacdsp Reviewed-by: Michael Niedermayer Signed-off-by: James Almer --- libavcodec/alacdsp.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) create mode 100644 libavcodec/alacdsp.c (limited to 'libavcodec/alacdsp.c') diff --git a/libavcodec/alacdsp.c b/libavcodec/alacdsp.c new file mode 100644 index 0000000000..608c0d8915 --- /dev/null +++ b/libavcodec/alacdsp.c @@ -0,0 +1,60 @@ +/* + * 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; +} -- cgit v1.2.3