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- /*
- * Header file for hardcoded DSD tables
- * based on BSD licensed dsd2pcm by Sebastian Gesemann
- * Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved.
- *
- * 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
- */
- #ifndef AVCODEC_DSD_TABLEGEN_H
- #define AVCODEC_DSD_TABLEGEN_H
- #include <stdint.h>
- #include "libavutil/attributes.h"
- #include "dsd.h"
- #define HTAPS 48 /** number of FIR constants */
- #define CTABLES ((HTAPS + 7) / 8) /** number of "8 MACs" lookup tables */
- #include "libavutil/common.h"
- /*
- * Properties of this 96-tap lowpass filter when applied on a signal
- * with sampling rate of 44100*64 Hz:
- *
- * () has a delay of 17 microseconds.
- *
- * () flat response up to 48 kHz
- *
- * () if you downsample afterwards by a factor of 8, the
- * spectrum below 70 kHz is practically alias-free.
- *
- * () stopband rejection is about 160 dB
- *
- * The coefficient tables ("ctables") take only 6 Kibi Bytes and
- * should fit into a modern processor's fast cache.
- */
- /**
- * The 2nd half (48 coeffs) of a 96-tap symmetric lowpass filter
- */
- static const double htaps[HTAPS] = {
- 0.09950731974056658, 0.09562845727714668, 0.08819647126516944,
- 0.07782552527068175, 0.06534876523171299, 0.05172629311427257,
- 0.0379429484910187, 0.02490921351762261, 0.0133774746265897,
- 0.003883043418804416, -0.003284703416210726, -0.008080250212687497,
- -0.01067241812471033, -0.01139427235000863, -0.0106813877974587,
- -0.009007905078766049, -0.006828859761015335, -0.004535184322001496,
- -0.002425035959059578, -0.0006922187080790708, 0.0005700762133516592,
- 0.001353838005269448, 0.001713709169690937, 0.001742046839472948,
- 0.001545601648013235, 0.001226696225277855, 0.0008704322683580222,
- 0.0005381636200535649, 0.000266446345425276, 7.002968738383528e-05,
- -5.279407053811266e-05, -0.0001140625650874684, -0.0001304796361231895,
- -0.0001189970287491285, -9.396247155265073e-05, -6.577634378272832e-05,
- -4.07492895872535e-05, -2.17407957554587e-05, -9.163058931391722e-06,
- -2.017460145032201e-06, 1.249721855219005e-06, 2.166655190537392e-06,
- 1.930520892991082e-06, 1.319400334374195e-06, 7.410039764949091e-07,
- 3.423230509967409e-07, 1.244182214744588e-07, 3.130441005359396e-08
- };
- static float ctables[CTABLES][256];
- #endif /* AVCODEC_DSD_TABLEGEN_H */
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