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/* $Id: isdn_audio.h,v 1.1.1.1 2001-09-10 07:44:18 simons Exp $
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* Linux ISDN subsystem, audio conversion and compression (linklevel).
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*
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* Copyright 1994-1998 by Fritz Elfert (fritz@isdn4linux.de)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Log: not supported by cvs2svn $
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* Revision 1.1.1.1 2001/07/02 17:58:31 simons
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* Initial revision
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*
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* Revision 1.5.2.2 1998/11/05 22:11:39 fritz
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* Changed mail-address.
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*
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* Revision 1.5.2.1 1998/08/22 16:43:06 armin
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* Added silence detection in audio receive mode (AT+VSD).
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*
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* Revision 1.5 1997/02/03 22:45:21 fritz
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* Reformatted according CodingStyle
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*
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* Revision 1.4 1996/06/06 14:43:32 fritz
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* Changed to support DTMF decoding on audio playback also.
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*
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* Revision 1.3 1996/06/05 02:24:09 fritz
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* Added DTMF decoder for audio mode.
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*
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* Revision 1.2 1996/05/10 08:48:32 fritz
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* Corrected adpcm bugs.
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*
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* Revision 1.1 1996/04/30 09:29:06 fritz
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* Taken under CVS control.
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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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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 int isdn_audio_2adpcm_flush(adpcm_state * s, unsigned char *out);
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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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