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Diffstat (limited to '')
-rw-r--r-- | src/pcm_dither.c | 93 |
1 files changed, 0 insertions, 93 deletions
diff --git a/src/pcm_dither.c b/src/pcm_dither.c deleted file mode 100644 index 4811946c8..000000000 --- a/src/pcm_dither.c +++ /dev/null @@ -1,93 +0,0 @@ -/* - * Copyright (C) 2003-2011 The Music Player Daemon Project - * http://www.musicpd.org - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program 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 General Public License for more details. - * - * You should have received a copy of the GNU General Public License along - * with this program; if not, write to the Free Software Foundation, Inc., - * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. - */ - -#include "config.h" -#include "pcm_dither.h" -#include "pcm_prng.h" - -static int16_t -pcm_dither_sample_24_to_16(int32_t sample, struct pcm_dither *dither) -{ - int32_t output, rnd; - - enum { - from_bits = 24, - to_bits = 16, - scale_bits = from_bits - to_bits, - round = 1 << (scale_bits - 1), - mask = (1 << scale_bits) - 1, - ONE = 1 << (from_bits - 1), - MIN = -ONE, - MAX = ONE - 1 - }; - - sample += dither->error[0] - dither->error[1] + dither->error[2]; - - dither->error[2] = dither->error[1]; - dither->error[1] = dither->error[0] / 2; - - /* round */ - output = sample + round; - - rnd = pcm_prng(dither->random); - output += (rnd & mask) - (dither->random & mask); - - dither->random = rnd; - - /* clip */ - if (output > MAX) { - output = MAX; - - if (sample > MAX) - sample = MAX; - } else if (output < MIN) { - output = MIN; - - if (sample < MIN) - sample = MIN; - } - - output &= ~mask; - - dither->error[0] = sample - output; - - return (int16_t)(output >> scale_bits); -} - -void -pcm_dither_24_to_16(struct pcm_dither *dither, - int16_t *dest, const int32_t *src, const int32_t *src_end) -{ - while (src < src_end) - *dest++ = pcm_dither_sample_24_to_16(*src++, dither); -} - -static int16_t -pcm_dither_sample_32_to_16(int32_t sample, struct pcm_dither *dither) -{ - return pcm_dither_sample_24_to_16(sample >> 8, dither); -} - -void -pcm_dither_32_to_16(struct pcm_dither *dither, - int16_t *dest, const int32_t *src, const int32_t *src_end) -{ - while (src < src_end) - *dest++ = pcm_dither_sample_32_to_16(*src++, dither); -} |