C-Netz: Improved RX speech quality and decoder debugging
This commit is contained in:
Andreas Eversberg
parent
059d4f25b1
commit
89e3b89758
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@ -127,8 +127,8 @@ struct cnetz {
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double frame_last_phase; /* master's bit phase of last frame sync */
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/* audio offset removal */
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double offset_factor; /* filer alpha of high-pass filter */
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double offset_y_last; /* last stored sample */
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double offset_last; /* last sample value of last frame */
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int offset_range; /* range of samples to ramp the offset */
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/* measurements */
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int measure_speed; /* measure clock speed */
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@ -46,7 +46,6 @@
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#define MAX_DISPLAY 1.4 /* something above speech level, no emphasis */
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#define BITRATE 5280.0 /* bits per second */
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#define BLOCK_BITS 198 /* duration of one time slot including pause at beginning and end */
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#define CUT_OFF_OFFSET 300.0 /* cut off frequency for offset filter (level correction between subsequent audio chunks) */
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#ifdef TEST_SCRAMBLE
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jitter_t scrambler_test_jb;
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@ -103,7 +102,6 @@ int dsp_init_sender(cnetz_t *cnetz, int measure_speed, double clock_speed[2], en
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{
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int rc = 0;
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double size;
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double RC, dt;
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PDEBUG_CHAN(DDSP, DEBUG_DEBUG, "Init FSK for 'Sender'.\n");
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@ -150,7 +148,7 @@ int dsp_init_sender(cnetz_t *cnetz, int measure_speed, double clock_speed[2], en
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}
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/* reinit the sample rate to shrink/expand audio */
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init_samplerate(&cnetz->sender.srstate, 8000.0, (double)cnetz->sender.samplerate / 1.1, 3300.0); /* 66 <-> 60 */
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init_samplerate(&cnetz->sender.srstate, 8000.0, (double)cnetz->sender.samplerate / (1.1 / (1.0 + clock_speed[0] / 1000000.0)), 3300.0); /* 66 <-> 60 */
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rc = fsk_fm_init(&cnetz->fsk_demod, cnetz, cnetz->sender.samplerate, (double)BITRATE / (1.0 + clock_speed[0] / 1000000.0), demod);
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if (rc < 0)
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@ -170,10 +168,8 @@ int dsp_init_sender(cnetz_t *cnetz, int measure_speed, double clock_speed[2], en
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* shall not exceed according to ITU G.162 */
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init_compandor(&cnetz->cstate, 8000, 5.0, 22.5);
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/* use this filter to compensate level changes between two subsequent audio chunks */
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RC = 1.0 / (CUT_OFF_OFFSET * 2.0 *3.14);
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dt = 1.0 / cnetz->sender.samplerate;
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cnetz->offset_factor = RC / (RC + dt);
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/* use duration of one bit to ramp level of last frame to current frame */
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cnetz->offset_range = ceil(cnetz->fsk_bitduration);
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#ifdef TEST_SCRAMBLE
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rc = jitter_create(&scrambler_test_jb, cnetz->sender.samplerate / 5);
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@ -821,7 +817,8 @@ void unshrink_speech(cnetz_t *cnetz, sample_t *speech_buffer, int count)
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{
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sample_t *spl;
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int pos, i;
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double x, y, x_last, y_last, factor;
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int range;
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double offset;
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/* check if we still have a transaction
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* this might not be true, if we just released transaction, but still
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@ -830,21 +827,13 @@ void unshrink_speech(cnetz_t *cnetz, sample_t *speech_buffer, int count)
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if (!cnetz->trans_list)
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return;
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/* fix offset between speech blocks by using high pass filter */
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/* use first sample as previous sample, so we don't have a level jump between two subsequent audio chunks */
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x_last = speech_buffer[0];
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y_last = cnetz->offset_y_last;
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factor = cnetz->offset_factor;
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for (i = 0; i < count; i++) {
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/* change level */
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x = speech_buffer[i];
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/* high-pass to remove low level frequencies, caused by level jump between audio chunks */
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y = factor * (y_last + x - x_last);
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x_last = x;
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y_last = y;
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speech_buffer[i] = y;
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/* ramp from level of last frame to level of current frame */
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range = cnetz->offset_range;
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offset = speech_buffer[0] - cnetz->offset_last;
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for (i = 0; i < range; i++) {
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speech_buffer[i] -= offset * (1.0 - (double)i / (double)range);
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}
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cnetz->offset_y_last = y_last;
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cnetz->offset_last = speech_buffer[count - 1];
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/* 4. de-emphasis is done by cnetz code, not by common code */
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/* de-emphasis is only used when scrambler is off, see FTZ 171 TR 60 Clause 4 */
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@ -121,7 +121,10 @@
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* if debug is set to 1, debugging will start at program start
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*/
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//#define DEBUG_DECODER
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//static int debug = 0;
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#ifdef DEBUG_DECODER
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static int debug = 0;
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#endif
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#include <stdio.h>
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#include <stdint.h>
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@ -182,7 +185,7 @@ int fsk_fm_init(fsk_fm_demod_t *fsk, cnetz_t *cnetz, int samplerate, double bitr
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#ifdef DEBUG_DECODER
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char debug_filename[256];
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sprintf(debug_filename, "/tmp/debug_decoder_channel_%d.txt", cnetz->sender.kanal);
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sprintf(debug_filename, "/tmp/debug_decoder_channel_%s.txt", cnetz->sender.kanal);
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fsk->debug_fp = fopen(debug_filename, "w");
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if (!fsk->debug_fp) {
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fprintf(stderr, "Failed to open decoder debug file '%s'!\n", debug_filename);
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@ -414,17 +417,6 @@ static inline void find_change_slope(fsk_fm_demod_t *fsk)
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sample_t threshold;
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int i;
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#ifdef DEBUG_DECODER
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/* show deviation of middle sample in windows (in a range of bandwidth) */
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if (debug) {
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fprintf(fsk->debug_fp, "%s",
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debug_amplitude(
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fsk->bit_buffer_spl[(fsk->bit_buffer_pos + fsk->bit_buffer_half) % fsk->bit_buffer_len]
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)
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);
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}
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#endif
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/* get level range (level_min and level_max) and also
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* get maximum slope (change_max) and where it was
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* (change_at) and what direction it went (change_positive)
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@ -492,10 +484,6 @@ static inline void find_change_slope(fsk_fm_demod_t *fsk)
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}
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fsk->next_bit -= fsk->bits_per_sample;
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#ifdef DEBUG_DECODER
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if (debug)
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fprintf(fsk->debug_fp, "\n");
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#endif
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}
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/* find bit change by looking at zero crossing */
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@ -507,12 +495,6 @@ static inline void find_change_level(fsk_fm_demod_t *fsk)
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/* get bit in the middle of the buffer */
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s = fsk->bit_buffer_spl[(fsk->bit_buffer_pos + fsk->bit_buffer_half) % fsk->bit_buffer_len];
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#ifdef DEBUG_DECODER
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/* show deviation */
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if (debug)
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fprintf(fsk->debug_fp, "%s", debug_amplitude(s));
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#endif
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/* just sample first bit in distributed mode */
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if (fsk->cnetz->dsp_mode == DSP_MODE_SPK_V && fsk->bit_count == 0) {
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if (fmod(fsk->bit_time, BITS_PER_SPK_BLOCK) < 1.5)
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@ -569,10 +551,6 @@ static inline void find_change_level(fsk_fm_demod_t *fsk)
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fsk->next_bit -= fsk->bits_per_sample;
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done:
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#ifdef DEBUG_DECODER
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if (debug)
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fprintf(fsk->debug_fp, "\n");
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#endif
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return;
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}
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@ -580,7 +558,7 @@ done:
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void fsk_fm_demod(fsk_fm_demod_t *fsk, sample_t *samples, int length)
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{
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int i;
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double t;
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double t = 0.0;
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/* process signaling block, sample by sample */
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for (i = 0; i < length; i++) {
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@ -590,6 +568,14 @@ void fsk_fm_demod(fsk_fm_demod_t *fsk, sample_t *samples, int length)
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if (fsk->bit_buffer_pos == fsk->bit_buffer_len)
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fsk->bit_buffer_pos = 0;
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#ifdef DEBUG_DECODER
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/* show deviation of center sample in window */
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if (debug)
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fprintf(fsk->debug_fp, "%s", debug_amplitude(fsk->bit_buffer_spl[(fsk->bit_buffer_pos + fsk->bit_buffer_half) % fsk->bit_buffer_len]));
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if (debug && fmod(fsk->bit_time - fsk->bits_per_sample, 1.0) > fmod(fsk->bit_time, 1.0))
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fprintf(fsk->debug_fp, " -bitchange-");
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#endif
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/* for each sample process buffer */
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if (fsk->cnetz->dsp_mode != DSP_MODE_SPK_V) {
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if (fsk->demod_type == FSK_DEMOD_SLOPE)
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@ -611,7 +597,7 @@ void fsk_fm_demod(fsk_fm_demod_t *fsk, sample_t *samples, int length)
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fsk->next_bit = 1.0 - fsk->bits_per_sample;
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#ifdef DEBUG_DECODER
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if (debug && fsk->bit_count)
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fprintf(fsk->debug_fp, "---- SPK(V) BLOCK START ----\n");
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fprintf(fsk->debug_fp, "\n---- SPK(V) BLOCK START ----");
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#endif
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fsk->bit_count = 0;
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} else
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@ -622,13 +608,21 @@ void fsk_fm_demod(fsk_fm_demod_t *fsk, sample_t *samples, int length)
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find_change_level(fsk);
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} else
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if (t >= 5.5 && t < 65.5) {
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#ifdef DEBUG_DECODER
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if (debug && !fsk->speech_count)
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fprintf(fsk->debug_fp, " (start recording speech)");
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#endif
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/* get audio for the duration of 60 bits */
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/* prevent overflow, if speech_size != 0 and SPK_V
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* has been restarted. */
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if (fsk->speech_count < fsk->speech_size)
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fsk->speech_buffer[fsk->speech_count++] = samples[i];
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fsk->speech_buffer[fsk->speech_count++] = fsk->bit_buffer_spl[(fsk->bit_buffer_pos + fsk->bit_buffer_half) % fsk->bit_buffer_len];
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} else
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if (t >= 65.5) {
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#ifdef DEBUG_DECODER
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if (debug && fsk->speech_count)
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fprintf(fsk->debug_fp, " (stop recording speech)");
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#endif
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if (fsk->speech_count) {
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unshrink_speech(fsk->cnetz, fsk->speech_buffer, fsk->speech_count);
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fsk->speech_count = 0;
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@ -641,6 +635,10 @@ void fsk_fm_demod(fsk_fm_demod_t *fsk, sample_t *samples, int length)
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if (fsk->bit_time >= BITS_PER_SUPERFRAME) {
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fsk->bit_time -= BITS_PER_SUPERFRAME;
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}
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#ifdef DEBUG_DECODER
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if (debug && samples)
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fprintf(fsk->debug_fp, "\n");
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#endif
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/* another clock is used to measure actual super frame time */
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fsk->bit_time_uncorrected += fsk->bits_per_sample;
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if (fsk->bit_time_uncorrected >= BITS_PER_SUPERFRAME) {
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