1 /* 2 * Header file for hardcoded DSD tables 3 * based on BSD licensed dsd2pcm by Sebastian Gesemann 4 * Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved. 5 * 6 * This file is part of FFmpeg. 7 * 8 * FFmpeg is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; either 11 * version 2.1 of the License, or (at your option) any later version. 12 * 13 * FFmpeg is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with FFmpeg; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23 #ifndef AVCODEC_DSD_TABLEGEN_H 24 #define AVCODEC_DSD_TABLEGEN_H 25 26 #include <stdint.h> 27 #include "libavutil/attributes.h" 28 #include "dsd.h" 29 30 #define HTAPS 48 /** number of FIR constants */ 31 #define CTABLES ((HTAPS + 7) / 8) /** number of "8 MACs" lookup tables */ 32 33 #include "libavutil/common.h" 34 35 /* 36 * Properties of this 96-tap lowpass filter when applied on a signal 37 * with sampling rate of 44100*64 Hz: 38 * 39 * () has a delay of 17 microseconds. 40 * 41 * () flat response up to 48 kHz 42 * 43 * () if you downsample afterwards by a factor of 8, the 44 * spectrum below 70 kHz is practically alias-free. 45 * 46 * () stopband rejection is about 160 dB 47 * 48 * The coefficient tables ("ctables") take only 6 Kibi Bytes and 49 * should fit into a modern processor's fast cache. 50 */ 51 52 /** 53 * The 2nd half (48 coeffs) of a 96-tap symmetric lowpass filter 54 */ 55 static const double htaps[HTAPS] = { 56 0.09950731974056658, 0.09562845727714668, 0.08819647126516944, 57 0.07782552527068175, 0.06534876523171299, 0.05172629311427257, 58 0.0379429484910187, 0.02490921351762261, 0.0133774746265897, 59 0.003883043418804416, -0.003284703416210726, -0.008080250212687497, 60 -0.01067241812471033, -0.01139427235000863, -0.0106813877974587, 61 -0.009007905078766049, -0.006828859761015335, -0.004535184322001496, 62 -0.002425035959059578, -0.0006922187080790708, 0.0005700762133516592, 63 0.001353838005269448, 0.001713709169690937, 0.001742046839472948, 64 0.001545601648013235, 0.001226696225277855, 0.0008704322683580222, 65 0.0005381636200535649, 0.000266446345425276, 7.002968738383528e-05, 66 -5.279407053811266e-05, -0.0001140625650874684, -0.0001304796361231895, 67 -0.0001189970287491285, -9.396247155265073e-05, -6.577634378272832e-05, 68 -4.07492895872535e-05, -2.17407957554587e-05, -9.163058931391722e-06, 69 -2.017460145032201e-06, 1.249721855219005e-06, 2.166655190537392e-06, 70 1.930520892991082e-06, 1.319400334374195e-06, 7.410039764949091e-07, 71 3.423230509967409e-07, 1.244182214744588e-07, 3.130441005359396e-08 72 }; 73 74 static float ctables[CTABLES][256]; 75 #endif /* AVCODEC_DSD_TABLEGEN_H */ 76