drivers/isdn/i4l/isdn_audio.h

   1 /* $Id: isdn_audio.h,v 1.1.2.2 2004/01/12 22:37:18 keil Exp $
   2  *
   3  * Linux ISDN subsystem, audio conversion and compression (linklevel).
   4  *
   5  * Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)
   6  *
   7  * This software may be used and distributed according to the terms
   8  * of the GNU General Public License, incorporated herein by reference.
   9  *
  10  */
  11
  12 #define DTMF_NPOINTS 205        /* Number of samples for DTMF recognition */
  13 typedef struct adpcm_state {
  14         int a;
  15         int d;
  16         int word;
  17         int nleft;
  18         int nbits;
  19 } adpcm_state;
  20
  21 typedef struct dtmf_state {
  22         char last;
  23         char llast;
  24         int idx;
  25         int buf[DTMF_NPOINTS];
  26 } dtmf_state;
  27
  28 typedef struct silence_state {
  29         int state;
  30         unsigned int idx;
  31 } silence_state;
  32
  33 extern void isdn_audio_ulaw2alaw(unsigned char *, unsigned long);
  34 extern void isdn_audio_alaw2ulaw(unsigned char *, unsigned long);
  35 extern adpcm_state *isdn_audio_adpcm_init(adpcm_state *, int);
  36 extern int isdn_audio_adpcm2xlaw(adpcm_state *, int, unsigned char *, unsigned char *, int);
  37 extern int isdn_audio_xlaw2adpcm(adpcm_state *, int, unsigned char *, unsigned char *, int);
  38 extern void isdn_audio_calc_dtmf(modem_info *, unsigned char *, int, int);
  39 extern void isdn_audio_eval_dtmf(modem_info *);
  40 dtmf_state *isdn_audio_dtmf_init(dtmf_state *);
  41 extern void isdn_audio_calc_silence(modem_info *, unsigned char *, int, int);
  42 extern void isdn_audio_eval_silence(modem_info *);
  43 silence_state *isdn_audio_silence_init(silence_state *);
  44 extern void isdn_audio_put_dle_code(modem_info *, u_char);