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https://github.com/FFmpeg/FFmpeg.git
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87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
/*
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* Direct Stream Digital (DSD) decoder
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* based on BSD licensed dsd2pcm by Sebastian Gesemann
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* Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved.
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* Copyright (c) 2014 Peter Ross
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavcodec/internal.h"
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#include "libavcodec/mathops.h"
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#include "avcodec.h"
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#include "dsd_tablegen.h"
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#include "dsd.h"
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static av_cold void dsd_ctables_tableinit(void)
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{
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int t, e, m, sign;
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double acc[CTABLES];
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for (e = 0; e < 256; ++e) {
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memset(acc, 0, sizeof(acc));
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for (m = 0; m < 8; ++m) {
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sign = (((e >> (7 - m)) & 1) * 2 - 1);
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for (t = 0; t < CTABLES; ++t)
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acc[t] += sign * htaps[t * 8 + m];
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}
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for (t = 0; t < CTABLES; ++t)
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ctables[CTABLES - 1 - t][e] = acc[t];
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}
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}
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av_cold void ff_init_dsd_data(void)
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{
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static int done = 0;
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if (done)
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return;
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dsd_ctables_tableinit();
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done = 1;
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}
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void ff_dsd2pcm_translate(DSDContext* s, size_t samples, int lsbf,
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const unsigned char *src, ptrdiff_t src_stride,
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float *dst, ptrdiff_t dst_stride)
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{
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unsigned pos, i;
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unsigned char* p;
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double sum;
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pos = s->pos;
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while (samples-- > 0) {
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s->buf[pos] = lsbf ? ff_reverse[*src] : *src;
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src += src_stride;
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p = s->buf + ((pos - CTABLES) & FIFOMASK);
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*p = ff_reverse[*p];
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sum = 0.0;
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for (i = 0; i < CTABLES; i++) {
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unsigned char a = s->buf[(pos - i) & FIFOMASK];
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unsigned char b = s->buf[(pos - (CTABLES*2 - 1) + i) & FIFOMASK];
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sum += ctables[i][a] + ctables[i][b];
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}
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*dst = (float)sum;
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dst += dst_stride;
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pos = (pos + 1) & FIFOMASK;
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}
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s->pos = pos;
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}
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