isdn_audio.h
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上传日期：2013-04-10
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- /* $Id: isdn_audio.h,v 1.1.4.1 2001/11/20 14:19:34 kai 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;
- 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);
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