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/* $Id: isdn_audio.h,v 1.1.2.2 2004/01/12 22:37:18 keil Exp $
*
* Linux ISDN subsystem, audio conversion and compression (linklevel).
*
* Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*
*/
#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;
char llast;
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 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 *);
extern void isdn_audio_put_dle_code(modem_info *, u_char);
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