blob: e5da86a1dc018112c252fd37ad75bef54e313a9f
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 |