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https://github.com/google/liblc3.git
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daa580235e
Duplicate interfaces for HR mode spec: Remove intermediate quantized table fix: legacy lc3_frame_bytes() and lc3_resolve_bitrate() Cosmetic: rename fast_xxx math function to lc3_xxx
93 lines
2.9 KiB
C
93 lines
2.9 KiB
C
/******************************************************************************
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*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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******************************************************************************/
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#include "attdet.h"
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/**
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* Time domain attack detector
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*/
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bool lc3_attdet_run(enum lc3_dt dt, enum lc3_srate sr,
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int nbytes, struct lc3_attdet_analysis *attdet, const int16_t *x)
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{
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/* --- Check enabling --- */
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const int nbytes_ranges[][LC3_NUM_SRATE - LC3_SRATE_32K][2] = {
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[LC3_DT_7M5 - LC3_DT_7M5] = { { 61, 149 }, { 75, 149 } },
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[LC3_DT_10M - LC3_DT_7M5] = { { 81, INT_MAX }, { 100, INT_MAX } },
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};
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if (dt < LC3_DT_7M5 || sr < LC3_SRATE_32K || lc3_hr(sr) ||
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nbytes < nbytes_ranges[dt - LC3_DT_7M5][sr - LC3_SRATE_32K][0] ||
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nbytes > nbytes_ranges[dt - LC3_DT_7M5][sr - LC3_SRATE_32K][1] )
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return 0;
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/* --- Filtering & Energy calculation --- */
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int nblk = 4 - (dt == LC3_DT_7M5);
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int32_t e[4];
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for (int i = 0; i < nblk; i++) {
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e[i] = 0;
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if (sr == LC3_SRATE_32K) {
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int16_t xn2 = (x[-4] + x[-3]) >> 1;
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int16_t xn1 = (x[-2] + x[-1]) >> 1;
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int16_t xn, xf;
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for (int j = 0; j < 40; j++, x += 2, xn2 = xn1, xn1 = xn) {
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xn = (x[0] + x[1]) >> 1;
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xf = (3 * xn - 4 * xn1 + 1 * xn2) >> 3;
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e[i] += (xf * xf) >> 5;
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}
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}
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else {
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int16_t xn2 = (x[-6] + x[-5] + x[-4]) >> 2;
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int16_t xn1 = (x[-3] + x[-2] + x[-1]) >> 2;
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int16_t xn, xf;
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for (int j = 0; j < 40; j++, x += 3, xn2 = xn1, xn1 = xn) {
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xn = (x[0] + x[1] + x[2]) >> 2;
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xf = (3 * xn - 4 * xn1 + 1 * xn2) >> 3;
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e[i] += (xf * xf) >> 5;
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}
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}
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}
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/* --- Attack detection ---
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* The attack block `p_att` is defined as the normative value + 1,
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* in such way, it will be initialized to 0 */
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int p_att = 0;
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int32_t a[4];
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for (int i = 0; i < nblk; i++) {
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a[i] = LC3_MAX(attdet->an1 >> 2, attdet->en1);
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attdet->en1 = e[i], attdet->an1 = a[i];
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if ((e[i] >> 3) > a[i] + (a[i] >> 4))
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p_att = i + 1;
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}
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int att = attdet->p_att >= 1 + (nblk >> 1) || p_att > 0;
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attdet->p_att = p_att;
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return att;
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}
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