mirror of
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
63 lines
1.6 KiB
C
63 lines
1.6 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 "plc.h"
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#include "tables.h"
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/**
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* Reset Packet Loss Concealment state
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*/
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void lc3_plc_reset(struct lc3_plc_state *plc)
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{
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plc->seed = 24607;
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lc3_plc_suspend(plc);
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}
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/**
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* Suspend PLC execution (Good frame received)
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*/
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void lc3_plc_suspend(struct lc3_plc_state *plc)
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{
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plc->count = 1;
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plc->alpha = 1.0f;
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}
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/**
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* Synthesis of a PLC frame
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*/
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void lc3_plc_synthesize(enum lc3_dt dt, enum lc3_srate sr,
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struct lc3_plc_state *plc, const float *x, float *y)
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{
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uint16_t seed = plc->seed;
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float alpha = plc->alpha;
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int ne = lc3_ne(dt, sr);
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alpha *= (plc->count < 4 ? 1.0f :
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plc->count < 8 ? 0.9f : 0.85f);
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for (int i = 0; i < ne; i++) {
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seed = (16831 + seed * 12821) & 0xffff;
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y[i] = alpha * (seed & 0x8000 ? -x[i] : x[i]);
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}
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plc->seed = seed;
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plc->alpha = alpha;
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plc->count++;
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}
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