| /* $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); |