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/* $Id: isdn_audio.h,v 1.7 1999/04/12 12:33:11 fritz Exp $
* Linux ISDN subsystem, audio conversion and compression (linklevel).
*
* Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Log: isdn_audio.h,v $
* Revision 1.7 1999/04/12 12:33:11 fritz
* Changes from 2.0 tree.
*
* Revision 1.6 1998/07/26 18:48:44 armin
* Added silence detection in voice receive mode.
*
* Revision 1.5 1997/02/03 22:45:21 fritz
* Reformatted according CodingStyle
*
* Revision 1.4 1996/06/06 14:43:32 fritz
* Changed to support DTMF decoding on audio playback also.
*
* Revision 1.3 1996/06/05 02:24:09 fritz
* Added DTMF decoder for audio mode.
*
* Revision 1.2 1996/05/10 08:48:32 fritz
* Corrected adpcm bugs.
*
* Revision 1.1 1996/04/30 09:29:06 fritz
* Taken under CVS control.
*
*/
#define DTMF_NPOINTS 205 /* Number of samples for DTMF recognition */
typedef struct adpcm_state {
int a;
int d;
int word;
int nleft;
int nbits;
} adpcm_state;
typedef struct dtmf_state {
char last;
int idx;
int buf[DTMF_NPOINTS];
} dtmf_state;
typedef struct silence_state {
int state;
unsigned int idx;
} silence_state;
extern void isdn_audio_ulaw2alaw(unsigned char *, unsigned long);
extern void isdn_audio_alaw2ulaw(unsigned char *, unsigned long);
extern adpcm_state *isdn_audio_adpcm_init(adpcm_state *, int);
extern int isdn_audio_adpcm2xlaw(adpcm_state *, int, unsigned char *, unsigned char *, int);
extern int isdn_audio_xlaw2adpcm(adpcm_state *, int, unsigned char *, unsigned char *, int);
extern int isdn_audio_2adpcm_flush(adpcm_state * s, unsigned char *out);
extern void isdn_audio_calc_dtmf(modem_info *, unsigned char *, int, int);
extern void isdn_audio_eval_dtmf(modem_info *);
dtmf_state *isdn_audio_dtmf_init(dtmf_state *);
extern void isdn_audio_calc_silence(modem_info *, unsigned char *, int, int);
extern void isdn_audio_eval_silence(modem_info *);
silence_state *isdn_audio_silence_init(silence_state *);
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