/* $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);