linux/drivers/isdn/i4l/isdn_audio.h
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00

46 lines
1.5 KiB
C

/* $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 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 *);
extern void isdn_audio_put_dle_code(modem_info *, u_char);