239 lines
7.2 KiB
C
239 lines
7.2 KiB
C
/*
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* libteletone
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* Copyright (C) 2005/2006, Anthony Minessale II <anthmct@yahoo.com>
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*
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* Version: MPL 1.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is tone_detect.c - General telephony tone detection, and specific detection of DTMF.
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*
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*
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* The Initial Developer of the Original Code is
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* Stephen Underwood <steveu@coppice.org>
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* Portions created by the Initial Developer are Copyright (C)
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* The the original interface designed by Steve Underwood was preserved to retain
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*the optimizations when considering DTMF tones though the names were changed in the interest
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* of namespace.
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*
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* Much less efficient expansion interface was added to allow for the detection of
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* a single arbitrary tone combination which may also exceed 2 simultaneous tones.
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* (controlled by compile time constant TELETONE_MAX_TONES)
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*
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* Copyright (C) 2006 Anthony Minessale II <anthmct@yahoo.com>
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*
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*
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* libteletone_detect.c Tone Detection Code
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*
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*
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*********************************************************************************
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*
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* Derived from tone_detect.h - General telephony tone detection, and specific
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* detection of DTMF.
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*
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* Copyright (C) 2001 Steve Underwood <steveu@coppice.org>
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*
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* Despite my general liking of the GPL, I place this code in the
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* public domain for the benefit of all mankind - even the slimy
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* ones who might try to proprietize my work and use it to my
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* detriment.
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*/
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#ifndef LIBTELETONE_DETECT_H
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#define LIBTELETONE_DETECT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <libteletone.h>
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/*! \file libteletone_detect.h
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\brief Tone Detection Routines
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This module is responsible for tone detection specifics
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*/
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#define FALSE 0
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#ifndef TRUE
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#define TRUE (!FALSE)
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#endif
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/* Basic DTMF specs:
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*
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* Minimum tone on = 40ms
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* Minimum tone off = 50ms
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* Maximum digit rate = 10 per second
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* Normal twist <= 8dB accepted
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* Reverse twist <= 4dB accepted
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* S/N >= 15dB will detect OK
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* Attenuation <= 26dB will detect OK
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* Frequency tolerance +- 1.5% will detect, +-3.5% will reject
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*/
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#define DTMF_THRESHOLD 8.0e7
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#define DTMF_NORMAL_TWIST 6.3 /* 8dB */
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#define DTMF_REVERSE_TWIST 2.5 /* 4dB */
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#define DTMF_RELATIVE_PEAK_ROW 6.3 /* 8dB */
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#define DTMF_RELATIVE_PEAK_COL 6.3 /* 8dB */
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#define DTMF_2ND_HARMONIC_ROW 2.5 /* 4dB */
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#define DTMF_2ND_HARMONIC_COL 63.1 /* 18dB */
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#define GRID_FACTOR 4
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#define BLOCK_LEN 102
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#define M_TWO_PI 2.0*M_PI
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/*! \brief A continer for the elements of a Goertzel Algorithm (The names are from his formula) */
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typedef struct {
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teletone_process_t v2;
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teletone_process_t v3;
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teletone_process_t fac;
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} teletone_goertzel_state_t;
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/*! \brief A container for a DTMF detection state.*/
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typedef struct {
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int hit1;
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int hit2;
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int hit3;
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int hit4;
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int mhit;
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teletone_goertzel_state_t row_out[GRID_FACTOR];
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teletone_goertzel_state_t col_out[GRID_FACTOR];
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teletone_goertzel_state_t row_out2nd[GRID_FACTOR];
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teletone_goertzel_state_t col_out2nd[GRID_FACTOR];
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teletone_process_t energy;
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int current_sample;
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char digits[TELETONE_MAX_DTMF_DIGITS + 1];
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int current_digits;
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int detected_digits;
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int lost_digits;
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int digit_hits[16];
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} teletone_dtmf_detect_state_t;
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/*! \brief An abstraction to store the coefficient of a tone frequency */
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typedef struct {
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teletone_process_t fac;
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} teletone_detection_descriptor_t;
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/*! \brief A container for a single multi-tone detection
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TELETONE_MAX_TONES dictates the maximum simultaneous tones that can be present
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in a multi-tone representation.
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*/
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typedef struct {
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int sample_rate;
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teletone_detection_descriptor_t tdd[TELETONE_MAX_TONES];
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teletone_goertzel_state_t gs[TELETONE_MAX_TONES];
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teletone_goertzel_state_t gs2[TELETONE_MAX_TONES];
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int tone_count;
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teletone_process_t energy;
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int current_sample;
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int min_samples;
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int total_samples;
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int positives;
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int negatives;
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int hits;
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int positive_factor;
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int negative_factor;
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int hit_factor;
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} teletone_multi_tone_t;
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/*!
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\brief Initilize a multi-frequency tone detector
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\param mt the multi-frequency tone descriptor
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\param map a representation of the multi-frequency tone
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*/
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void teletone_multi_tone_init(teletone_multi_tone_t *mt, teletone_tone_map_t *map);
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/*!
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\brief Check a sample buffer for the presence of the mulit-frequency tone described by mt
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\param mt the multi-frequency tone descriptor
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\param sample_buffer an array aof 16 bit signed linear samples
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\param samples the number of samples present in sample_buffer
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\return true when the tone was detected or false when it is not
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*/
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int teletone_multi_tone_detect (teletone_multi_tone_t *mt,
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int16_t sample_buffer[],
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int samples);
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/*!
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\brief Initilize a DTMF detection state object
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\param dtmf_detect_state the DTMF detection state to initilize
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\param sample_rate the desired sample rate
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*/
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void teletone_dtmf_detect_init (teletone_dtmf_detect_state_t *dtmf_detect_state, int sample_rate);
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/*!
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\brief Check a sample buffer for the presence of DTMF digits
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\param dtmf_detect_state the detection state object to check
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\param sample_buffer an array aof 16 bit signed linear samples
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\param samples the number of samples present in sample_buffer
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\return true when DTMF was detected or false when it is not
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*/
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int teletone_dtmf_detect (teletone_dtmf_detect_state_t *dtmf_detect_state,
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int16_t sample_buffer[],
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int samples);
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/*!
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\brief retrieve any collected digits into a string buffer
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\param dtmf_detect_state the detection state object to check
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\param buf the string buffer to write to
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\param max the maximum length of buf
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\return the number of characters written to buf
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*/
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int teletone_dtmf_get (teletone_dtmf_detect_state_t *dtmf_detect_state,
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char *buf,
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int max);
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/*!
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\brief Step through the Goertzel Algorithm for each sample in a buffer
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\param goertzel_state the goertzel state to step the samples through
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\param sample_buffer an array aof 16 bit signed linear samples
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\param samples the number of samples present in sample_buffer
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*/
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void teletone_goertzel_update(teletone_goertzel_state_t *goertzel_state,
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int16_t sample_buffer[],
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int samples);
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/*!
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\brief Compute the result of the last applied step of the Goertzel Algorithm
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\param goertzel_state the goertzel state to retrieve from
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\return the computed value for consideration in furthur audio tests
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*/
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teletone_process_t teletone_goertzel_result (teletone_goertzel_state_t *goertzel_state);
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#ifdef __cplusplus
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}
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#endif
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#endif
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/* For Emacs:
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* Local Variables:
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* mode:c
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* indent-tabs-mode:nil
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* tab-width:4
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* c-basic-offset:4
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* End:
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* For VIM:
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* vim:set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:
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*/
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