FFmpeg
dsd_tablegen.h
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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 */
#define CTABLES
Definition: dsd_tablegen.h:31
static const double htaps[HTAPS]
The 2nd half (48 coeffs) of a 96-tap symmetric lowpass filter.
Definition: dsd_tablegen.h:55
Macro definitions for various function/variable attributes.
static float ctables[CTABLES][256]
Definition: dsd_tablegen.h:74
#define HTAPS
Definition: dsd_tablegen.h:30
common internal and external API header