super_tone_rx.h

00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * super_tone_rx.h - Flexible telephony supervisory tone detection.
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2003 Steve Underwood
00009  *
00010  * All rights reserved.
00011  *
00012  * This program is free software; you can redistribute it and/or modify
00013  * it under the terms of the GNU Lesser General Public License version 2.1,
00014  * as published by the Free Software Foundation.
00015  *
00016  * This program is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU Lesser General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU Lesser General Public
00022  * License along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00024  *
00025  * $Id: super_tone_rx.h,v 1.21 2009/02/10 13:06:47 steveu Exp $
00026  */
00027 
00028 #if !defined(_SPANDSP_SUPER_TONE_RX_H_)
00029 #define _SPANDSP_SUPER_TONE_RX_H_
00030 
00031 /*! \page super_tone_rx_page Supervisory tone detection
00032 
00033 \section super_tone_rx_page_sec_1 What does it do?
00034 
00035 The supervisory tone detector may be configured to detect most of the world's
00036 telephone supervisory tones - things like ringback, busy, number unobtainable,
00037 and so on.
00038 
00039 \section super_tone_rx_page_sec_2 How does it work?
00040 
00041 The supervisory tone detector is passed a series of data structures describing
00042 the tone patterns - the frequencies and cadencing - of the tones to be searched
00043 for. It constructs one or more Goertzel filters to monitor the required tones.
00044 If tones are close in frequency a single Goertzel set to the centre of the
00045 frequency range will be used. This optimises the efficiency of the detector. The
00046 Goertzel filters are applied without applying any special window functional
00047 (i.e. they use a rectangular window), so they have a sinc like response.
00048 However, for most tone patterns their rejection qualities are adequate. 
00049 
00050 The detector aims to meet the need of the standard call progress tones, to
00051 ITU-T E.180/Q.35 (busy, dial, ringback, reorder). Also, the extended tones,
00052 to ITU-T E.180, Supplement 2 and EIA/TIA-464-A (recall dial tone, special
00053 ringback tone, intercept tone, call waiting tone, busy verification tone,
00054 executive override tone, confirmation tone).
00055 */
00056 
00057 /*! Tone detection indication callback routine */
00058 typedef void (*tone_report_func_t)(void *user_data, int code, int level, int delay);
00059 
00060 typedef struct super_tone_rx_segment_s super_tone_rx_segment_t;
00061 
00062 typedef struct super_tone_rx_descriptor_s super_tone_rx_descriptor_t;
00063 
00064 typedef struct super_tone_rx_state_s super_tone_rx_state_t;
00065 
00066 #if defined(__cplusplus)
00067 extern "C"
00068 {
00069 #endif
00070 
00071 /*! Create a new supervisory tone detector descriptor.
00072     \param desc The supervisory tone set desciptor. If NULL, the routine will allocate space for a
00073                 descriptor.
00074     \return The supervisory tone set descriptor.
00075 */
00076 SPAN_DECLARE(super_tone_rx_descriptor_t *) super_tone_rx_make_descriptor(super_tone_rx_descriptor_t *desc);
00077 
00078 /*! Free a supervisory tone detector descriptor.
00079     \param desc The supervisory tone set desciptor.
00080     \return 0 for OK, -1 for fail.
00081 */
00082 SPAN_DECLARE(int) super_tone_rx_free_descriptor(super_tone_rx_descriptor_t *desc);
00083 
00084 /*! Add a new tone pattern to a supervisory tone detector set.
00085     \param desc The supervisory tone set descriptor.
00086     \return The new tone ID. */
00087 SPAN_DECLARE(int) super_tone_rx_add_tone(super_tone_rx_descriptor_t *desc);
00088 
00089 /*! Add a new tone pattern element to a tone pattern in a supervisory tone detector.
00090     \param desc The supervisory tone set desciptor.
00091     \param tone The tone ID within the descriptor.
00092     \param f1 Frequency 1 (-1 for a silent period).
00093     \param f2 Frequency 2 (-1 for a silent period, or only one frequency).
00094     \param min The minimum duration, in ms.
00095     \param max The maximum duration, in ms.
00096     \return The new number of elements in the tone description.
00097 */
00098 SPAN_DECLARE(int) super_tone_rx_add_element(super_tone_rx_descriptor_t *desc,
00099                                             int tone,
00100                                             int f1,
00101                                             int f2,
00102                                             int min,
00103                                             int max);
00104 
00105 /*! Initialise a supervisory tone detector.
00106     \param s The supervisory tone detector context.
00107     \param desc The tone descriptor.
00108     \param callback The callback routine called to report the valid detection or termination of
00109            one of the monitored tones.
00110     \param user_data An opaque pointer passed when calling the callback routine.
00111     \return The supervisory tone detector context.
00112 */
00113 SPAN_DECLARE(super_tone_rx_state_t *) super_tone_rx_init(super_tone_rx_state_t *s,
00114                                                          super_tone_rx_descriptor_t *desc,
00115                                                          tone_report_func_t callback,
00116                                                          void *user_data);
00117 
00118 /*! Release a supervisory tone detector.
00119     \param s The supervisory tone context.
00120     \return 0 for OK, -1 for fail.
00121 */
00122 SPAN_DECLARE(int) super_tone_rx_release(super_tone_rx_state_t *s);
00123 
00124 /*! Free a supervisory tone detector.
00125     \param s The supervisory tone context.
00126     \return 0 for OK, -1 for fail.
00127 */
00128 SPAN_DECLARE(int) super_tone_rx_free(super_tone_rx_state_t *s);
00129 
00130 /*! Define a callback routine to be called each time a tone pattern element is complete. This is
00131     mostly used when analysing a tone.
00132     \param s The supervisory tone context.
00133     \param callback The callback routine.
00134 */
00135 SPAN_DECLARE(void) super_tone_rx_segment_callback(super_tone_rx_state_t *s,
00136                                                   void (*callback)(void *data, int f1, int f2, int duration));
00137 
00138 /*! Apply supervisory tone detection processing to a block of audio samples.
00139     \brief Apply supervisory tone detection processing to a block of audio samples.
00140     \param super The supervisory tone context.
00141     \param amp The audio sample buffer.
00142     \param samples The number of samples in the buffer.
00143     \return The number of samples processed.
00144 */
00145 SPAN_DECLARE(int) super_tone_rx(super_tone_rx_state_t *super, const int16_t amp[], int samples);
00146 
00147 #if defined(__cplusplus)
00148 }
00149 #endif
00150 
00151 #endif
00152 /*- End of file ------------------------------------------------------------*/

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