diff options
Diffstat (limited to 'main/dsp.c')
| -rw-r--r-- | main/dsp.c | 121 |
1 files changed, 86 insertions, 35 deletions
diff --git a/main/dsp.c b/main/dsp.c index 884f610e7..6ba9abdaa 100644 --- a/main/dsp.c +++ b/main/dsp.c @@ -205,9 +205,9 @@ enum gsamp_thresh { #define DTMF_GSIZE 102 /* How many successive hits needed to consider begin of a digit */ -#define DTMF_HITS_TO_BEGIN 4 +#define DTMF_HITS_TO_BEGIN 2 /* How many successive misses needed to consider end of a digit */ -#define DTMF_MISSES_TO_END 4 +#define DTMF_MISSES_TO_END 3 /*! * \brief The default silence threshold we will use if an alternate @@ -353,7 +353,7 @@ typedef struct { } fragment_t; /* Note on tone suppression (squelching). Individual detectors (DTMF/MF/generic tone) - * report fragmens of the frame in which detected tone resides and which needs + * report fragments of the frame in which detected tone resides and which needs * to be "muted" in order to suppress the tone. To mark fragment for muting, * detectors call mute_fragment passing fragment_t there. Multiple fragments * can be marked and ast_dsp_process later will mute all of them. @@ -438,7 +438,7 @@ static void ast_tone_detect_init(tone_detect_state_t *s, int freq, int duration, s->block_size = periods_in_block * sample_rate / freq; /* tone_detect is currently only used to detect fax tones and we - do not need suqlching the fax tones */ + do not need squelching the fax tones */ s->squelch = 0; /* Account for the first and the last block to be incomplete @@ -550,7 +550,7 @@ static int tone_detect(struct ast_dsp *dsp, tone_detect_state_t *s, int16_t *amp for (i = limit, ptr = amp ; i > 0; i--, ptr++) { samp = *ptr; - /* signed 32 bit int should be enough to suqare any possible signed 16 bit value */ + /* signed 32 bit int should be enough to square any possible signed 16 bit value */ s->energy += (int32_t) samp * (int32_t) samp; goertzel_sample(&s->tone, samp); @@ -727,39 +727,90 @@ static int dtmf_detect(struct ast_dsp *dsp, digit_detect_state_t *s, int16_t amp } } - if (hit == s->td.dtmf.lasthit) { - if (s->td.dtmf.current_hit) { - /* We are in the middle of a digit already */ - if (hit) { - if (hit != s->td.dtmf.current_hit) { - /* Look for a start of a new digit. - This is because hits_to_begin may be smaller than misses_to_end - and we may find the beginning of new digit before we consider last one ended. */ - s->td.dtmf.current_hit = 0; - } else { - /* Current hit was same as last, so increment digit duration (of last digit) */ - s->digitlen[s->current_digits - 1] += DTMF_GSIZE; - } - } else { - /* No Digit */ - s->td.dtmf.misses++; - if (s->td.dtmf.misses == s->td.dtmf.misses_to_end) { - /* There were enough misses to consider digit ended */ - s->td.dtmf.current_hit = 0; - } - } - } else if (hit) { - /* Detecting new digit */ - s->td.dtmf.hits++; - if (s->td.dtmf.hits == s->td.dtmf.hits_to_begin) { - store_digit(s, hit); - s->td.dtmf.current_hit = hit; +/* + * Adapted from ETSI ES 201 235-3 V1.3.1 (2006-03) + * (40ms reference is tunable with hits_to_begin and misses_to_end) + * each hit/miss is 12.75ms with DTMF_GSIZE at 102 + * + * Character recognition: When not DRC *(1) and then + * Shall exist VSC > 40 ms (hits_to_begin) + * May exist 20 ms <= VSC <= 40 ms + * Shall not exist VSC < 20 ms + * + * Character recognition: When DRC and then + * Shall cease Not VSC > 40 ms (misses_to_end) + * May cease 20 ms >= Not VSC >= 40 ms + * Shall not cease Not VSC < 20 ms + * + * *(1) or optionally a different digit recognition condition + * + * Legend: VSC The continuous existence of a valid signal condition. + * Not VSC The continuous non-existence of valid signal condition. + * DRC The existence of digit recognition condition. + * Not DRC The non-existence of digit recognition condition. + */ + +/* + * Example: hits_to_begin=2 misses_to_end=3 + * -------A last_hit=A hits=0&1 + * ------AA hits=2 current_hit=A misses=0 BEGIN A + * -----AA- misses=1 last_hit=' ' hits=0 + * ----AA-- misses=2 + * ---AA--- misses=3 current_hit=' ' END A + * --AA---B last_hit=B hits=0&1 + * -AA---BC last_hit=C hits=0&1 + * AA---BCC hits=2 current_hit=C misses=0 BEGIN C + * A---BCC- misses=1 last_hit=' ' hits=0 + * ---BCC-C misses=0 last_hit=C hits=0&1 + * --BCC-CC misses=0 + * + * Example: hits_to_begin=3 misses_to_end=2 + * -------A last_hit=A hits=0&1 + * ------AA hits=2 + * -----AAA hits=3 current_hit=A misses=0 BEGIN A + * ----AAAB misses=1 last_hit=B hits=0&1 + * ---AAABB misses=2 current_hit=' ' hits=2 END A + * --AAABBB hits=3 current_hit=B misses=0 BEGIN B + * -AAABBBB misses=0 + * + * Example: hits_to_begin=2 misses_to_end=2 + * -------A last_hit=A hits=0&1 + * ------AA hits=2 current_hit=A misses=0 BEGIN A + * -----AAB misses=1 hits=0&1 + * ----AABB misses=2 current_hit=' ' hits=2 current_hit=B misses=0 BEGIN B + * ---AABBB misses=0 + */ + + if (s->td.dtmf.current_hit) { + /* We are in the middle of a digit already */ + if (hit != s->td.dtmf.current_hit) { + s->td.dtmf.misses++; + if (s->td.dtmf.misses == s->td.dtmf.misses_to_end) { + /* There were enough misses to consider digit ended */ + s->td.dtmf.current_hit = 0; } + } else { + s->td.dtmf.misses = 0; + /* Current hit was same as last, so increment digit duration (of last digit) */ + s->digitlen[s->current_digits - 1] += DTMF_GSIZE; } - } else { - s->td.dtmf.hits = 1; - s->td.dtmf.misses = 1; + } + + /* Look for a start of a new digit no matter if we are already in the middle of some + digit or not. This is because hits_to_begin may be smaller than misses_to_end + and we may find begin of new digit before we consider last one ended. */ + + if (hit != s->td.dtmf.lasthit) { s->td.dtmf.lasthit = hit; + s->td.dtmf.hits = 0; + } + if (hit && hit != s->td.dtmf.current_hit) { + s->td.dtmf.hits++; + if (s->td.dtmf.hits == s->td.dtmf.hits_to_begin) { + store_digit(s, hit); + s->td.dtmf.current_hit = hit; + s->td.dtmf.misses = 0; + } } /* If we had a hit in this block, include it into mute fragment */ |