diff options
| -rw-r--r-- | util/spkmodem_decode/spkmodem-decode.c | 158 |
1 files changed, 72 insertions, 86 deletions
diff --git a/util/spkmodem_decode/spkmodem-decode.c b/util/spkmodem_decode/spkmodem-decode.c index 8c57ff9a..0a22c6d5 100644 --- a/util/spkmodem_decode/spkmodem-decode.c +++ b/util/spkmodem_decode/spkmodem-decode.c @@ -157,15 +157,10 @@ /* * These determine how long the program will wait during * tone auto-detection, before shifting to defaults. - * - * For tone auto-detection (time waiting for detection) - * NOTE: you could multiply SAMPLE_PER_FRAME instead - * of SAMPLE_RATE in LEARN_SAMPLES, for more granularity. - * Here, 1 * SAMPLE_RATE represents 1 second, which seems - * like a reasonable, conservative default wait time. + * It is done every LEARN_FRAMES number of frames. */ #define LEARN_SECONDS 1 -#define LEARN_SAMPLES ((LEARN_SECONDS) * (SAMPLE_RATE)) +#define LEARN_FRAMES ((LEARN_SECONDS) * (FRAME_RATE)) /* * Sample amplitude threshold used to convert the waveform @@ -209,20 +204,20 @@ struct decoder_state { int freq_min; int freq_max; int freq_threshold; - int learn_samples; + int learn_frames; }; static const char *argv0; static int host_is_big_endian(void); static void handle_audio(struct decoder_state *st); +static void auto_detect_tone(struct decoder_state *st); +static int silent_signal(struct decoder_state *st); +static void select_low_tone(struct decoder_state *st); static void collect_separator_tone(struct decoder_state *st); static int valid_signal(struct decoder_state *st); static void decode_pulse(struct decoder_state *st); -static void auto_detect_tone(struct decoder_state *st); -static int silent_signal(struct decoder_state *st); static signed short read_sample(struct decoder_state *st); -static void select_low_tone(struct decoder_state *st); static int set_ascii_bit(struct decoder_state *st); static void print_char(struct decoder_state *st); static void print_stats(struct decoder_state *st); @@ -317,6 +312,72 @@ handle_audio(struct decoder_state *st) st->sample_count = 0; for (sample = 0; sample < SAMPLES_PER_FRAME; sample++) decode_pulse(st); + + /* Detect tone per each frame */ + auto_detect_tone(st); +} + +/* + * Automatically detect spkmodem tone + */ +static void +auto_detect_tone(struct decoder_state *st) +{ + if (st->learn_frames >= LEARN_FRAMES) + return; + + st->learn_frames++; + + if (silent_signal(st)) + return; + + select_low_tone(st); + + if (st->learn_frames == LEARN_FRAMES) { + st->freq_threshold = + (st->freq_min + st->freq_max) / 2; + + if (st->debug) + printf("auto threshold: %dHz\n", + st->freq_threshold * FRAME_RATE); + } +} + +/* + * Ignore silence / near silence. + * Both FIR windows will be near zero when no signal exists. + */ +static int +silent_signal(struct decoder_state *st) +{ + return (st->freq_data <= 2 && + st->freq_separator <= 2); +} + +/* + * Choose the lowest active tone. + * Separator frames carry tone in the separator window, + * data frames carry tone in the data window. + */ +static void +select_low_tone(struct decoder_state *st) +{ + int f; + + f = st->freq_data; + + if (f <= 0 || (st->freq_separator > 0 && + st->freq_separator < f)) + f = st->freq_separator; + + if (f <= 0) + return; + + if (f < st->freq_min) + st->freq_min = f; + + if (f > st->freq_max) + st->freq_max = f; } /* @@ -439,84 +500,9 @@ decode_pulse(struct decoder_state *st) st->ringpos = ringpos; st->sep_pos = sep_pos; - /* - * Attempt to auto-detect spkmodem tone - */ - auto_detect_tone(st); - st->sample_count++; } -/* - * Observe signal for LEARN_SAMPLES samples (e.g. 1 second). - * The exact amount of time is determined by LEARN_SAMPLES - * divided by SAMPLE_RATE, logically. For example, if - * LEARN_SAMPLES were half of the SAMPLE_RATE, this - * corresponds to roughly 500ms before timeout. - * - * to guess the correct timing. If it fails, - * fall back to known good values. - */ -static void -auto_detect_tone(struct decoder_state *st) -{ - if (st->learn_samples >= LEARN_SAMPLES) - return; - - st->learn_samples++; - - if (silent_signal(st)) - return; - - select_low_tone(st); - - if (st->learn_samples == LEARN_SAMPLES) { - st->freq_threshold = - (st->freq_min + st->freq_max) / 2; - - if (st->debug) - printf("auto threshold: %dHz\n", - st->freq_threshold * FRAME_RATE); - } -} - -/* - * Ignore silence / near silence. - * Both FIR windows will be near zero when no signal exists. - */ -static int -silent_signal(struct decoder_state *st) -{ - return (st->freq_data <= 2 && - st->freq_separator <= 2); -} - -/* - * Choose the lowest active tone. - * Separator frames carry tone in the separator window, - * data frames carry tone in the data window. - */ -static void -select_low_tone(struct decoder_state *st) -{ - int f; - - f = st->freq_data; - - if (f <= 0 || (st->freq_separator > 0 && - st->freq_separator < f)) - f = st->freq_separator; - - if (f <= 0) - return; - - if (f < st->freq_min) - st->freq_min = f; - - if (f > st->freq_max) - st->freq_max = f; -} - static signed short read_sample(struct decoder_state *st) { |