306 lines
8.8 KiB
C
306 lines
8.8 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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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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// 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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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "common/bt_target.h"
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#include "sbc_plc.h"
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#if (PLC_INCLUDED == TRUE)
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/* msbc */
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static const uint8_t indices0[] = { 0xad, 0x00, 0x00, 0xc5, 0x00, 0x00, 0x00, 0x00, 0x77, 0x6d,
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0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6d, 0xdd, 0xb6, 0xdb, 0x77, 0x6d,
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0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6d, 0xdd, 0xb6, 0xdb, 0x77, 0x6d,
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0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6d, 0xdd, 0xb6, 0xdb, 0x77, 0x6d,
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0xb6, 0xdd, 0xdb, 0x6d, 0xb7, 0x76, 0xdb, 0x6c};
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/* 8 kHZ */
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static const int16_t indices0_pcm[] = {
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
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/* Raised COSine table for OLA */
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/* 16 kHZ */
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static float rcos[SBC_OLAL] = {
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0.99148655f,0.96623611f,0.92510857f,0.86950446f,
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0.80131732f,0.72286918f,0.63683150f,0.54613418f,
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0.45386582f,0.36316850f,0.27713082f,0.19868268f,
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0.13049554f,0.07489143f,0.03376389f,0.00851345f};
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// /* 8 kHZ */
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// static float rcos[SBC_OLAL] = {
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// 0.96984631f,0.88302222f, 0.75f,0.58682409f,
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// 0.41317591f, 0.25f,0.11697778f,0.09015369f};
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static float SqrtByCarmack(const float x){
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union {
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int i;
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float y;
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} float_int;
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float x2;
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const float threehalfs = 1.5f;
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x2 = x * 0.5f;
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float_int.y = x;
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float_int.i = 0x5f375a86 - (float_int.i >> 1);
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float_int.y = float_int.y * (threehalfs - (x2 * float_int.y * float_int.y));
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// float_int.y = float_int.y * (threehalfs - (x2 * float_int.y * float_int.y));
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// float_int.y = float_int.y * (threehalfs - (x2 * float_int.y * float_int.y));
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return (x * float_int.y);
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}
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static float absolute(float x){
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if (x < 0) {
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x = -x;
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}
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return x;
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}
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/**
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* Compute the cross correlation according to Eq. (4) of Goodman
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* paper, except that the true correlation is used. His formula
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* seems to be incorrect.
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*
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* @param x pointer to x input vector
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* @param y pointer to y input vector
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*
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* @return value containing the cross-correlation of x and y
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*/
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static float CrossCorrelation(int16_t *x, int16_t *y){
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int m;
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float num = 0;
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float den = 0;
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float x2 = 0;
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float y2 = 0;
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for (m = 0; m < SBC_M; m++) {
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num += ((float)x[m]) * y[m];
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x2 += ((float)x[m]) * x[m];
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y2 += ((float)y[m]) * y[m];
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}
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den = (float)SqrtByCarmack(x2 * y2);
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return num / den;
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}
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/**
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* Perform pattern matching to find the match of template with the
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* history buffer according to Section B of Goodman paper.
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*
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* @param y pointer to history buffer
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*
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* @return the lag corresponding to the best match. The lag is
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* with respect to the beginning of the history buffer.
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*
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*/
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static int PatternMatch(int16_t *y){
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int n;
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float maxCn = -999999.0; // large negative number
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float Cn;
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int bestmatch = 0;
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for (n = 0; n < SBC_N; n++){
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Cn = CrossCorrelation(&y[SBC_LHIST-SBC_M], &y[n]);
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if (Cn > maxCn){
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bestmatch = n;
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maxCn = Cn;
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}
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}
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return bestmatch;
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}
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/**
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* Perform amplitude matching using mean-absolute-value according
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* to Goodman paper.
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*
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* @param y pointer to history buffer
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* @param bestmatch value of the lag to the best match
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*
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* @return scale factor
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*/
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static float AmplitudeMatch(int16_t *y, int16_t bestmatch) {
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int i;
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float sumx = 0;
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float sumy = 0.000001f;
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float sf;
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for (i = 0; i < SBC_FS; i++){
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sumx += absolute(y[SBC_LHIST - SBC_FS + i]);
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sumy += absolute(y[bestmatch + i]);
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}
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sf = sumx / sumy;
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// This is not in the paper, but limit the scaling factor to something reasonable to avoid creating artifacts
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if (sf < 0.75f) {
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sf = 0.75f;
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}
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if (sf > 1.2f) {
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sf = 1.2f;
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}
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return sf;
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}
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static int16_t crop_sample(float val){
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float croped_val = val;
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if (croped_val > 32767.0) croped_val= 32767.0;
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if (croped_val < -32768.0) croped_val=-32768.0;
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return (int16_t) croped_val;
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}
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/**
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* Get a zero signal eSCO frame
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* @return pointer to data buffer
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*/
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uint8_t * sbc_plc_zero_signal_frame(void){
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return (uint8_t *)&indices0;
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}
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/**
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* Get a zero signal eSCO pcm frame
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* @return pointer to data buffer
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*/
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int16_t * sbc_plc_zero_signal_frame_pcm(void){
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return (int16_t *)&indices0_pcm;
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}
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/**
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* Perform PLC initialization of memory vectors.
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*
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* @param plc_state pointer to PLC state memory
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*/
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void sbc_plc_init(sbc_plc_state_t *plc_state){
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plc_state->nbf=0;
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plc_state->bestlag=0;
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memset(plc_state->hist, 0, sizeof(plc_state->hist));
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}
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/**
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* Perform PLC deinitialization of memory vectors.
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*
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* @param plc_state pointer to PLC state memory
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*/
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void sbc_plc_deinit(sbc_plc_state_t *plc_state){
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plc_state->nbf=0;
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plc_state->bestlag=0;
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memset(plc_state->hist, 0, sizeof(plc_state->hist));
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}
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/**
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* Perform bad frame processing.
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*
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* @param plc_state pointer to PLC state memory
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* @param ZIRbuf pointer to the ZIR response of the SBC decoder
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* @param out pointer to the output samples
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*/
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void sbc_plc_bad_frame(sbc_plc_state_t *plc_state, int16_t *ZIRbuf, int16_t *out){
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int i = 0;
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float val;
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float sf = 1;
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plc_state->nbf++;
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if (plc_state->nbf == 1){
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// Perform pattern matching to find where to replicate
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plc_state->bestlag = PatternMatch(plc_state->hist);
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// the replication begins after the template match
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plc_state->bestlag += SBC_M;
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// Compute Scale Factor to Match Amplitude of Substitution Packet to that of Preceding Packet
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sf = AmplitudeMatch(plc_state->hist, plc_state->bestlag);
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for (i = 0; i < SBC_OLAL; i++){
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val = ZIRbuf[i] * rcos[i]
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+ sf * plc_state->hist[plc_state->bestlag + i] * rcos[SBC_OLAL - i - 1];
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plc_state->hist[SBC_LHIST + i] = crop_sample(val);
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}
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for (; i < SBC_FS; i++){
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val = sf*plc_state->hist[plc_state->bestlag + i];
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plc_state->hist[SBC_LHIST + i] = crop_sample(val);
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}
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for (; i < SBC_FS + SBC_OLAL; i++){
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val = sf * plc_state->hist[plc_state->bestlag + i] * rcos[i-SBC_FS]
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+ plc_state->hist[plc_state->bestlag + i] * rcos[SBC_OLAL - 1 - i + SBC_FS];
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plc_state->hist[SBC_LHIST + i] = crop_sample(val);
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}
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for (; i < SBC_FS + SBC_RT + SBC_OLAL; i++){
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plc_state->hist[SBC_LHIST + i] = plc_state->hist[plc_state->bestlag + i];
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}
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} else {
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for ( ;i < SBC_FS + SBC_RT + SBC_OLAL; i++){
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plc_state->hist[SBC_LHIST + i] = plc_state->hist[plc_state->bestlag + i];
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}
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}
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for (i = 0; i < SBC_FS; i++){
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out[i] = plc_state->hist[SBC_LHIST + i];
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}
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// shift the history buffer
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for (i = 0; i < SBC_LHIST + SBC_RT + SBC_OLAL; i++){
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plc_state->hist[i] = plc_state->hist[i + SBC_FS];
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}
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}
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/**
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* Perform good frame processing. Most of the time, this function
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* just updates history buffers and passes the input to the output,
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* but in the first good frame after frame loss, it must conceal the
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* received signal as it reconverges with the true output.
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*
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* @param plc_state pointer to PLC state memory
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* @param in pointer to the input vector
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* @param out pointer to the output samples
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*/
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void sbc_plc_good_frame(sbc_plc_state_t *plc_state, int16_t *in, int16_t *out){
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int i = 0;
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if (plc_state->nbf > 0){
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for (i = 0; i < SBC_RT; i++){
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out[i] = plc_state->hist[SBC_LHIST + i];
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}
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for (i = SBC_RT; i < SBC_RT + SBC_OLAL; i++){
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out[i] = (int16_t)(plc_state->hist[SBC_LHIST + i] * rcos[i - SBC_RT] + in[i] * rcos[SBC_OLAL - 1 - i + SBC_RT]);
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}
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}
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for (; i < SBC_FS; i++){
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out[i] = in[i];
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}
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// Copy the output to the history buffer
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for (i = 0; i < SBC_FS; i++){
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plc_state->hist[SBC_LHIST + i] = out[i];
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}
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// shift the history buffer
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for (i = 0; i < SBC_LHIST; i++){
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plc_state->hist[i] = plc_state->hist[i + SBC_FS];
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}
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plc_state->nbf = 0;
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}
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#endif ///(PLC_INCLUDED == TRUE)
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