403 lines
11 KiB
C
403 lines
11 KiB
C
/* 24.May.2005 v.1.0
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=============================================================================
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U U GGG SSSS TTTTT
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U U G S T
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U U G GG SSSS T
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U U G G S T
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UUU GG SSS T
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========================================
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ITU-T - USER'S GROUP ON SOFTWARE TOOLS
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========================================
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=============================================================
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COPYRIGHT NOTE: This source code, and all of its derivations,
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is subject to the "ITU-T General Public License". Please have
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it read in the distribution disk, or in the ITU-T
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Recommendation G.191 on "SOFTWARE TOOLS FOR SPEECH AND AUDIO
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CODING STANDARDS".
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** This code has (C) Copyright by AT&T Corp. **
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=============================================================
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MODULE: G.711 Appendix I PLC module.
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ORIGINAL BY: AT&T Corp.
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FUNCTIONS:
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g711plc_construct: ...... LowcFE Constructor.
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g711plc_dofe: ........... Generate the synthetic signal.
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At the beginning of an erasure determine the pitch, and extract
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one pitch period from the tail of the signal. Do an OLA for 1/4
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of the pitch to smooth the signal. Then repeat the extracted signal
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for the length of the erasure. If the erasure continues for more than
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10 msec, increase the number of periods in the pitchbuffer. At the end
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of an erasure, do an OLA with the start of the first good frame.
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The gain decays as the erasure gets longer.
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g711plc_addtohistory: ... A good frame was received and decoded.
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If right after an erasure, do an overlap add with the synthetic signal.
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Add the frame to history buffer.
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HISTORY:
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24.May.05 v1.0 Release of 1st G711 PLC module <AT&T>.
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Integration of this module in STL2005 <Cyril Guillaume & Stephane Ragot - stephane.ragot@francetelecom.com>.
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=============================================================================
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*/
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#include <math.h>
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#include <stdio.h>
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#include "lowcfe.h"
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static void g711plc_scalespeech(LowcFE_c*, short *out);
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static void g711plc_getfespeech(LowcFE_c*, short *out, int sz);
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static void g711plc_savespeech(LowcFE_c*, short *s);
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static int g711plc_findpitch(LowcFE_c*);
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static int findpitch_amdf(LowcFE_c *lc);
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static void g711plc_overlapadd(Float *l, Float *r, Float *o, int cnt);
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static void g711plc_overlapadds(short *l, short *r, short *o, int cnt);
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static void g711plc_overlapaddatend(LowcFE_c*, short *s, short *f, int cnt);
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static void g711plc_convertsf(short *f, Float *t, int cnt);
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static void g711plc_convertfs(Float *f, short *t, int cnt);
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static void g711plc_copyf(Float *f, Float *t, int cnt);
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static void g711plc_copys(short *f, short *t, int cnt);
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static void g711plc_zeros(short *s, int cnt);
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void g711plc_construct(LowcFE_c *lc)
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{
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lc->erasecnt = 0;
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lc->pitchbufend = &lc->pitchbuf[HISTORYLEN];
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g711plc_zeros(lc->history, HISTORYLEN);
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}
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/*
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* Get samples from the circular pitch buffer. Update poffset so
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* when subsequent frames are erased the signal continues.
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*/
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static void g711plc_getfespeech(LowcFE_c *lc, short *out, int sz)
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{
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while (sz) {
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int cnt = lc->pitchblen - lc->poffset;
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if (cnt > sz)
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cnt = sz;
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g711plc_copys(&lc->pitchbufstart[lc->poffset], out, cnt);
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lc->poffset += cnt;
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if (lc->poffset == lc->pitchblen)
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lc->poffset = 0;
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out += cnt;
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sz -= cnt;
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}
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}
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static void g711plc_scalespeech(LowcFE_c *lc, short *out)
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{
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int i;
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Float g = (Float)1. - (lc->erasecnt - 1) * ATTENFAC;
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for (i = 0; i < FRAMESZ; i++) {
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out[i] = (short)(out[i] * g);
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g -= ATTENINCR;
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}
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}
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/*
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* Generate the synthetic signal.
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* At the beginning of an erasure determine the pitch, and extract
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* one pitch period from the tail of the signal. Do an OLA for 1/4
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* of the pitch to smooth the signal. Then repeat the extracted signal
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* for the length of the erasure. If the erasure continues for more than
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* 10 msec, increase the number of periods in the pitchbuffer. At the end
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* of an erasure, do an OLA with the start of the first good frame.
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* The gain decays as the erasure gets longer.
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*/
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void g711plc_dofe(LowcFE_c *lc,short *out)
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{
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if (lc->erasecnt == 0) {
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/* get history */
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g711plc_copys(lc->history, lc->pitchbuf, HISTORYLEN);
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lc->pitch = g711plc_findpitch(lc); /* find pitch */
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lc->poverlap = lc->pitch >> 2; /* OLA 1/4 wavelength */
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/* save original last poverlap samples */
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g711plc_copys(lc->pitchbufend - lc->poverlap, lc->lastq,
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lc->poverlap);
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lc->poffset = 0; /* create pitch buffer with 1 period */
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lc->pitchblen = lc->pitch;
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lc->pitchbufstart = lc->pitchbufend - lc->pitchblen;
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g711plc_overlapadds(lc->lastq, lc->pitchbufstart - lc->poverlap,
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lc->pitchbufend - lc->poverlap, lc->poverlap);
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/* update last 1/4 wavelength in history buffer */
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g711plc_copys(lc->pitchbufend - lc->poverlap,
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&lc->history[HISTORYLEN-lc->poverlap], lc->poverlap);
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/* get synthesized speech */
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g711plc_getfespeech(lc, out, FRAMESZ);
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} else if (lc->erasecnt == 1 || lc->erasecnt == 2) {
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/* tail of previous pitch estimate */
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short tmp[POVERLAPMAX];
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int saveoffset = lc->poffset; /* save offset for OLA */
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/* continue with old pitchbuf */
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g711plc_getfespeech(lc, tmp, lc->poverlap);
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/* add periods to the pitch buffer */
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lc->poffset = saveoffset;
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while (lc->poffset > lc->pitch)
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lc->poffset -= lc->pitch;
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lc->pitchblen += lc->pitch; /* add a period */
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lc->pitchbufstart = lc->pitchbufend - lc->pitchblen;
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g711plc_overlapadds(lc->lastq, lc->pitchbufstart - lc->poverlap,
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lc->pitchbufend - lc->poverlap, lc->poverlap);
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/* overlap add old pitchbuffer with new */
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g711plc_getfespeech(lc, out, FRAMESZ);
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g711plc_overlapadds(tmp, out, out, lc->poverlap);
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g711plc_scalespeech(lc, out);
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} else if (lc->erasecnt > 2) {
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g711plc_zeros(out, FRAMESZ);
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} else {
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g711plc_getfespeech(lc, out, FRAMESZ);
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g711plc_scalespeech(lc, out);
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}
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lc->erasecnt++;
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g711plc_savespeech(lc, out);
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}
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/*
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* Save a frames worth of new speech in the history buffer.
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* Return the output speech delayed by POVERLAPMAX.
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*/
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static void g711plc_savespeech(LowcFE_c *lc, short *s)
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{
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/* make room for new signal */
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g711plc_copys(&lc->history[FRAMESZ], lc->history, HISTORYLEN - FRAMESZ);
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/* copy in the new frame */
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g711plc_copys(s, &lc->history[HISTORYLEN - FRAMESZ], FRAMESZ);
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/* copy out the delayed frame */
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g711plc_copys(&lc->history[HISTORYLEN - FRAMESZ - POVERLAPMAX], s,
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FRAMESZ);
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}
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/*
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* A good frame was received and decoded.
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* If right after an erasure, do an overlap add with the synthetic signal.
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* Add the frame to history buffer.
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*/
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void g711plc_addtohistory(LowcFE_c *lc, short *s)
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{
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if (lc->erasecnt) {
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short overlapbuf[FRAMESZ];
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/*
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* longer erasures require longer overlaps
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* to smooth the transition between the synthetic
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* and real signal.
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*/
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int olen = lc->poverlap + (lc->erasecnt - 1) * EOVERLAPINCR;
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if (olen > FRAMESZ)
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olen = FRAMESZ;
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g711plc_getfespeech(lc, overlapbuf, olen);
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g711plc_overlapaddatend(lc, s, overlapbuf, olen);
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lc->erasecnt = 0;
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}
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g711plc_savespeech(lc, s);
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}
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/*
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* Overlapp add the end of the erasure with the start of the first good frame
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* Scale the synthetic speech by the gain factor before the OLA.
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*/
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static void g711plc_overlapaddatend(LowcFE_c *lc, short *s, short *f, int cnt)
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{
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int i;
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Float incrg;
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Float lw, rw;
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Float t;
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Float incr = (Float)1. / cnt;
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Float gain = (Float)1. - (lc->erasecnt - 1) * ATTENFAC;
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if (gain < 0.)
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gain = (Float)0.;
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incrg = incr * gain;
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lw = ((Float)1. - incr) * gain;
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rw = incr;
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for (i = 0; i < cnt; i++) {
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t = lw * f[i] + rw * s[i];
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if (t > 32767.)
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t = (Float)32767.;
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else if (t < -32768.)
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t = (Float)-32768.;
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s[i] = (short)t;
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lw -= incrg;
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rw += incr;
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}
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}
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/*
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* Overlapp add left and right sides
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*/
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static void g711plc_overlapadd(Float *l, Float *r, Float *o, int cnt)
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{
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int i;
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Float incr, lw, rw, t;
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if (cnt == 0)
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return;
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incr = (Float)1. / cnt;
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lw = (Float)1. - incr;
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rw = incr;
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for (i = 0; i < cnt; i++) {
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t = lw * l[i] + rw * r[i];
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if (t > (Float)32767.)
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t = (Float)32767.;
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else if (t < (Float)-32768.)
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t = (Float)-32768.;
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o[i] = t;
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lw -= incr;
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rw += incr;
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}
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}
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/*
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* Overlapp add left and right sides
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*/
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static void g711plc_overlapadds(short *l, short *r, short *o, int cnt)
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{
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int i;
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Float incr, lw, rw, t;
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if (cnt == 0)
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return;
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incr = (Float)1. / cnt;
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lw = (Float)1. - incr;
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rw = incr;
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for (i = 0; i < cnt; i++) {
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t = lw * l[i] + rw * r[i];
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if (t > (Float)32767.)
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t = (Float)32767.;
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else if (t < (Float)-32768.)
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t = (Float)-32768.;
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o[i] = (short)t;
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lw -= incr;
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rw += incr;
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}
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}
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/*
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* Estimate the pitch.
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* l - pointer to first sample in last 20 msec of speech.
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* r - points to the sample PITCH_MAX before l
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*/
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static int g711plc_findpitch(LowcFE_c *lc)
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{
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int i, j, k;
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int bestmatch;
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int bestcorr;
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int corr; /* correlation */
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unsigned int energy; /* running energy */
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unsigned int scale; /* scale correlation by average power */
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short *rp; /* segment to match */
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short *l = lc->pitchbufend - CORRLEN;
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short *r = lc->pitchbufend - CORRBUFLEN;
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/* coarse search */
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rp = r;
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energy = 0;
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corr = 0;
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for (i = 0; i < CORRLEN; i += NDEC) {
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energy += rp[i] * rp[i];
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corr += rp[i] * l[i];
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}
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scale = energy;
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if (scale < CORRMINPOWER)
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scale = CORRMINPOWER;
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corr = corr / sqrt(scale);
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bestcorr = corr;
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bestmatch = 0;
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for (j = NDEC; j <= PITCHDIFF; j += NDEC) {
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energy -= rp[0] * rp[0];
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energy += rp[CORRLEN] * rp[CORRLEN];
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rp += NDEC;
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corr = 0;
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for (i = 0; i < CORRLEN; i += NDEC)
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corr += rp[i] * l[i];
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scale = energy;
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if (scale < CORRMINPOWER)
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scale = CORRMINPOWER;
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corr /= sqrt(scale);
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if (corr >= bestcorr) {
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bestcorr = corr;
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bestmatch = j;
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}
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}
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/* fine search */
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j = bestmatch - (NDEC - 1);
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if (j < 0)
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j = 0;
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k = bestmatch + (NDEC - 1);
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if (k > PITCHDIFF)
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k = PITCHDIFF;
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rp = &r[j];
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energy = 0;
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corr = 0;
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for (i = 0; i < CORRLEN; i++) {
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energy += rp[i] * rp[i];
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corr += rp[i] * l[i];
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}
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scale = energy;
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if (scale < CORRMINPOWER)
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scale = CORRMINPOWER;
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corr = corr / sqrt(scale);
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bestcorr = corr;
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bestmatch = j;
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for (j++; j <= k; j++) {
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energy -= rp[0] * rp[0];
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energy += rp[CORRLEN] * rp[CORRLEN];
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rp++;
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corr = 0;
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for (i = 0; i < CORRLEN; i++)
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corr += rp[i] * l[i];
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scale = energy;
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if (scale < CORRMINPOWER)
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scale = CORRMINPOWER;
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corr = corr / sqrt(scale);
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if (corr > bestcorr) {
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bestcorr = corr;
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bestmatch = j;
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}
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}
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return PITCH_MAX - bestmatch;
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}
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static void g711plc_convertsf(short *f, Float *t, int cnt)
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{
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int i;
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for (i = 0; i < cnt; i++)
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t[i] = (Float)f[i];
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}
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static void g711plc_convertfs(Float *f, short *t, int cnt)
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{
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int i;
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for (i = 0; i < cnt; i++)
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t[i] = (short)f[i];
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}
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static void g711plc_copyf(Float *f, Float *t, int cnt)
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{
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int i;
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for (i = 0; i < cnt; i++)
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t[i] = f[i];
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}
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static void g711plc_copys(short *f, short *t, int cnt)
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{
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int i;
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for (i = 0; i < cnt; i++)
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t[i] = f[i];
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}
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static void g711plc_zeros(short *s, int cnt)
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{
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int i;
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for (i = 0; i < cnt; i++)
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s[i] = 0;
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}
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