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45 lines
1.5 KiB
C
45 lines
1.5 KiB
C
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/* $Id: isdn_audio.h,v 1.1.2.2 2004/01/12 22:37:18 keil Exp $
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*
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* Linux ISDN subsystem, audio conversion and compression (linklevel).
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*
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* Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*
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*/
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#define DTMF_NPOINTS 205 /* Number of samples for DTMF recognition */
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typedef struct adpcm_state {
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int a;
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int d;
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int word;
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int nleft;
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int nbits;
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} adpcm_state;
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typedef struct dtmf_state {
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char last;
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char llast;
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int idx;
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int buf[DTMF_NPOINTS];
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} dtmf_state;
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typedef struct silence_state {
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int state;
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unsigned int idx;
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} silence_state;
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extern void isdn_audio_ulaw2alaw(unsigned char *, unsigned long);
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extern void isdn_audio_alaw2ulaw(unsigned char *, unsigned long);
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extern adpcm_state *isdn_audio_adpcm_init(adpcm_state *, int);
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extern int isdn_audio_adpcm2xlaw(adpcm_state *, int, unsigned char *, unsigned char *, int);
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extern int isdn_audio_xlaw2adpcm(adpcm_state *, int, unsigned char *, unsigned char *, int);
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extern void isdn_audio_calc_dtmf(modem_info *, unsigned char *, int, int);
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extern void isdn_audio_eval_dtmf(modem_info *);
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dtmf_state *isdn_audio_dtmf_init(dtmf_state *);
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extern void isdn_audio_calc_silence(modem_info *, unsigned char *, int, int);
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extern void isdn_audio_eval_silence(modem_info *);
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silence_state *isdn_audio_silence_init(silence_state *);
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extern void isdn_audio_put_dle_code(modem_info *, u_char);
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