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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 6147 | serge | 1 | /* |
| 2 | * Header file for hardcoded DSD tables |
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| 3 | * based on BSD licensed dsd2pcm by Sebastian Gesemann |
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| 4 | * Copyright (c) 2009, 2011 Sebastian Gesemann. All rights reserved. |
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| 5 | * |
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| 6 | * This file is part of FFmpeg. |
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| 7 | * |
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| 8 | * FFmpeg is free software; you can redistribute it and/or |
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| 9 | * modify it under the terms of the GNU Lesser General Public |
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| 10 | * License as published by the Free Software Foundation; either |
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| 11 | * version 2.1 of the License, or (at your option) any later version. |
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| 12 | * |
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| 13 | * FFmpeg is distributed in the hope that it will be useful, |
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| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 16 | * Lesser General Public License for more details. |
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| 17 | * |
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| 18 | * You should have received a copy of the GNU Lesser General Public |
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| 19 | * License along with FFmpeg; if not, write to the Free Software |
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| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 21 | */ |
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| 22 | |||
| 23 | #ifndef AVCODEC_DSD_TABLEGEN_H |
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| 24 | #define AVCODEC_DSD_TABLEGEN_H |
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| 25 | |||
| 26 | #include |
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| 27 | #include "libavutil/attributes.h" |
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| 28 | |||
| 29 | #define HTAPS 48 /** number of FIR constants */ |
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| 30 | #define CTABLES ((HTAPS + 7) / 8) /** number of "8 MACs" lookup tables */ |
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| 31 | |||
| 32 | #if CONFIG_HARDCODED_TABLES |
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| 33 | #define dsd_ctables_tableinit() |
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| 34 | #include "libavcodec/dsd_tables.h" |
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| 35 | #else |
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| 36 | #include "libavutil/common.h" |
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| 37 | |||
| 38 | /* |
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| 39 | * Properties of this 96-tap lowpass filter when applied on a signal |
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| 40 | * with sampling rate of 44100*64 Hz: |
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| 41 | * |
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| 42 | * () has a delay of 17 microseconds. |
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| 43 | * |
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| 44 | * () flat response up to 48 kHz |
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| 45 | * |
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| 46 | * () if you downsample afterwards by a factor of 8, the |
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| 47 | * spectrum below 70 kHz is practically alias-free. |
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| 48 | * |
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| 49 | * () stopband rejection is about 160 dB |
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| 50 | * |
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| 51 | * The coefficient tables ("ctables") take only 6 Kibi Bytes and |
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| 52 | * should fit into a modern processor's fast cache. |
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| 53 | */ |
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| 54 | |||
| 55 | /** |
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| 56 | * The 2nd half (48 coeffs) of a 96-tap symmetric lowpass filter |
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| 57 | */ |
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| 58 | static const double htaps[HTAPS] = { |
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| 59 | 0.09950731974056658, 0.09562845727714668, 0.08819647126516944, |
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| 60 | 0.07782552527068175, 0.06534876523171299, 0.05172629311427257, |
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| 61 | 0.0379429484910187, 0.02490921351762261, 0.0133774746265897, |
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| 62 | 0.003883043418804416, -0.003284703416210726, -0.008080250212687497, |
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| 63 | -0.01067241812471033, -0.01139427235000863, -0.0106813877974587, |
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| 64 | -0.009007905078766049, -0.006828859761015335, -0.004535184322001496, |
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| 65 | -0.002425035959059578, -0.0006922187080790708, 0.0005700762133516592, |
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| 66 | 0.001353838005269448, 0.001713709169690937, 0.001742046839472948, |
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| 67 | 0.001545601648013235, 0.001226696225277855, 0.0008704322683580222, |
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| 68 | 0.0005381636200535649, 0.000266446345425276, 7.002968738383528e-05, |
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| 69 | -5.279407053811266e-05, -0.0001140625650874684, -0.0001304796361231895, |
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| 70 | -0.0001189970287491285, -9.396247155265073e-05, -6.577634378272832e-05, |
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| 71 | -4.07492895872535e-05, -2.17407957554587e-05, -9.163058931391722e-06, |
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| 72 | -2.017460145032201e-06, 1.249721855219005e-06, 2.166655190537392e-06, |
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| 73 | 1.930520892991082e-06, 1.319400334374195e-06, 7.410039764949091e-07, |
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| 74 | 3.423230509967409e-07, 1.244182214744588e-07, 3.130441005359396e-08 |
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| 75 | }; |
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| 76 | |||
| 77 | static float ctables[CTABLES][256]; |
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| 78 | |||
| 79 | static av_cold void dsd_ctables_tableinit(void) |
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| 80 | { |
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| 81 | int t, e, m, k; |
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| 82 | double acc; |
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| 83 | for (t = 0; t < CTABLES; ++t) { |
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| 84 | k = FFMIN(HTAPS - t * 8, 8); |
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| 85 | for (e = 0; e < 256; ++e) { |
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| 86 | acc = 0.0; |
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| 87 | for (m = 0; m < k; ++m) |
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| 88 | acc += (((e >> (7 - m)) & 1) * 2 - 1) * htaps[t * 8 + m]; |
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| 89 | ctables[CTABLES - 1 - t][e] = (float)acc; |
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| 90 | } |
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| 91 | } |
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| 92 | } |
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| 93 | #endif /* CONFIG_HARDCODED_TABLES */ |
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| 94 | |||
| 95 | #endif /* AVCODEC_DSD_TABLEGEN_H */ |