X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fardour%2Fsession_ltc.cc;h=945f96519e3f60a8c7ed1c7483eacf9b8d0c4e47;hb=7cc2e8c969e7b778af90f3b45a4c3fa3cbc90ef6;hp=e24a233b7b632976fb3768eb33520a987205acc2;hpb=fb630f622df6f65f253800bdd979e89f26123c3b;p=ardour.git diff --git a/libs/ardour/session_ltc.cc b/libs/ardour/session_ltc.cc index e24a233b7b..945f96519e 100644 --- a/libs/ardour/session_ltc.cc +++ b/libs/ardour/session_ltc.cc @@ -27,11 +27,10 @@ #include "ardour/session.h" #include "ardour/slave.h" -#include "i18n.h" +#include "pbd/i18n.h" using namespace std; using namespace ARDOUR; -using namespace MIDI; using namespace PBD; using namespace Timecode; @@ -48,24 +47,33 @@ using namespace Timecode; /* LTC signal should have a rise time of 25 us +/- 5 us. * yet with most sound-cards a square-wave of 1-2 sample - * introduces rather some ringing and small oscillations. - * so we low-pass filter the signal a bit, depending - * on the sample-rate + * introduces ringing and small oscillations. + * https://en.wikipedia.org/wiki/Gibbs_phenomenon + * A low-pass filter in libltc can reduce this at + * the cost of being slightly out of spec WRT to rise-time. + * + * This filter is adaptive so that fast vari-speed signals + * will not be affected by it. */ -#define LTC_RISE_TIME MIN (150, MAX(25, (4000000 / engine().frame_rate()))) +#define LTC_RISE_TIME(speed) MIN (100, MAX(40, (4000000 / ((speed==0)?1:speed) / engine().sample_rate()))) + +#define TV_STANDARD(tcf) \ + (timecode_to_frames_per_second(tcf)==25.0 ? LTC_TV_625_50 : \ + timecode_has_drop_frames(tcf)? LTC_TV_525_60 : LTC_TV_FILM_24) void Session::ltc_tx_initialize() { ltc_enc_tcformat = config.get_timecode_format(); + ltc_tx_parse_offset(); DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX init sr: %1 fps: %2\n", nominal_frame_rate(), timecode_to_frames_per_second(ltc_enc_tcformat))); ltc_encoder = ltc_encoder_create(nominal_frame_rate(), timecode_to_frames_per_second(ltc_enc_tcformat), - 0); + TV_STANDARD(ltc_enc_tcformat), 0); ltc_encoder_set_bufsize(ltc_encoder, nominal_frame_rate(), 23.0); - ltc_encoder_set_filter(ltc_encoder, LTC_RISE_TIME); + ltc_encoder_set_filter(ltc_encoder, LTC_RISE_TIME(1.0)); /* buffersize for 1 LTC frame: (1 + sample-rate / fps) bytes * usually returned by ltc_encoder_get_buffersize(encoder) @@ -73,17 +81,20 @@ Session::ltc_tx_initialize() * since the fps can change and A3's min fps: 24000/1001 */ ltc_enc_buf = (ltcsnd_sample_t*) calloc((nominal_frame_rate() / 23), sizeof(ltcsnd_sample_t)); ltc_speed = 0; + ltc_prev_cycle = -1; ltc_tx_reset(); ltc_tx_resync_latency(); Xrun.connect_same_thread (*this, boost::bind (&Session::ltc_tx_reset, this)); engine().GraphReordered.connect_same_thread (*this, boost::bind (&Session::ltc_tx_resync_latency, this)); + restarting = false; } void Session::ltc_tx_cleanup() { DEBUG_TRACE (DEBUG::LTC, "LTC TX cleanup\n"); - if (ltc_enc_buf) free(ltc_enc_buf); + free(ltc_enc_buf); + ltc_enc_buf = NULL; ltc_encoder_free(ltc_encoder); ltc_encoder = NULL; } @@ -109,6 +120,19 @@ Session::ltc_tx_reset() ltc_buf_off = 0; ltc_enc_byte = 0; ltc_enc_cnt = 0; + + ltc_encoder_reset(ltc_encoder); +} + +void +Session::ltc_tx_parse_offset() { + Timecode::Time offset_tc; + Timecode::parse_timecode_format(config.get_timecode_generator_offset(), offset_tc); + offset_tc.rate = timecode_frames_per_second(); + offset_tc.drop = timecode_drop_frames(); + timecode_to_sample(offset_tc, ltc_timecode_offset, false, false); + ltc_timecode_negative_offset = !offset_tc.negative; + ltc_prev_cycle = -1; } void @@ -126,10 +150,11 @@ Session::ltc_tx_recalculate_position() a3tc.drop = timecode_has_drop_frames(ltc_enc_tcformat); Timecode::timecode_to_sample (a3tc, ltc_enc_pos, true, false, - double(frame_rate()), + (double)frame_rate(), config.get_subframes_per_frame(), - config.get_timecode_offset_negative(), config.get_timecode_offset() + ltc_timecode_negative_offset, ltc_timecode_offset ); + restarting = false; } void @@ -189,15 +214,17 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end TimecodeFormat cur_timecode = config.get_timecode_format(); if (cur_timecode != ltc_enc_tcformat) { DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX1: TC format mismatch - reinit sr: %1 fps: %2\n", nominal_frame_rate(), timecode_to_frames_per_second(cur_timecode))); - if (ltc_encoder_reinit(ltc_encoder, nominal_frame_rate(), timecode_to_frames_per_second(cur_timecode), 0)) { + if (ltc_encoder_reinit(ltc_encoder, nominal_frame_rate(), + timecode_to_frames_per_second(cur_timecode), + TV_STANDARD(cur_timecode), 0 + )) { PBD::error << _("LTC encoder: invalid framerate - LTC encoding is disabled for the remainder of this session.") << endmsg; ltc_tx_cleanup(); return; } - if (nominal_frame_rate() <= 48000) { - ltc_encoder_set_filter(ltc_encoder, LTC_RISE_TIME); - } + ltc_encoder_set_filter(ltc_encoder, LTC_RISE_TIME(ltc_speed)); ltc_enc_tcformat = cur_timecode; + ltc_tx_parse_offset(); ltc_tx_reset(); } @@ -217,20 +244,60 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end /* port latency compensation: * The _generated timecode_ is offset by the port-latency, * therefore the offset depends on the direction of transport. + * + * latency is compensated by adding it to the timecode to + * be generated. e.g. if the signal will reach the output in + * N samples time from now, generate the timecode for (now + N). + * + * sample-sync is achieved by further calculating the difference + * between the timecode and the session-transport and offsetting the + * buffer. + * + * The timecode is generated directly in the Session process callback + * using _transport_frame. It requires that the session has set the + * port's playback latency to worst_playback_latency() prior to + * calling ltc_tx_send_time_code_for_cycle(). */ - framepos_t cycle_start_frame = (current_speed < 0) ? (start_frame - ltc_out_latency.max) : (start_frame + ltc_out_latency.max); + framepos_t cycle_start_frame; + + if (current_speed < 0) { + cycle_start_frame = (start_frame - ltc_out_latency.max + worst_playback_latency()); + } else if (current_speed > 0) { + cycle_start_frame = (start_frame + ltc_out_latency.max - worst_playback_latency()); + } else { + /* There is no need to compensate for latency when not rolling + * rather send the accurate NOW timecode + * (LTC encoder compenates latency by sending earlier timecode) + */ + cycle_start_frame = start_frame; + } + + /* LTC TV standard offset */ + if (current_speed != 0) { + /* ditto - send "NOW" if not rolling */ + cycle_start_frame -= ltc_frame_alignment(frames_per_timecode_frame(), TV_STANDARD(cur_timecode)); + } /* cycle-start may become negative due to latency compensation */ if (cycle_start_frame < 0) { cycle_start_frame = 0; } - double new_ltc_speed = double(labs(end_frame - start_frame) * SIGNUM(current_speed)) / double(nframes); + double new_ltc_speed = (double)(labs(end_frame - start_frame) * SIGNUM(current_speed)) / (double)nframes; + if (nominal_frame_rate() != frame_rate()) { + new_ltc_speed *= (double)nominal_frame_rate() / (double)frame_rate(); + } if (SIGNUM(new_ltc_speed) != SIGNUM (ltc_speed)) { DEBUG_TRACE (DEBUG::LTC, "LTC TX2: transport changed direction\n"); ltc_tx_reset(); } - if (ltc_speed != new_ltc_speed) { + if (ltc_speed != new_ltc_speed + /* but only once if, current_speed changes to 0. In that case + * new_ltc_speed is > 0 because (end_frame - start_frame) == jack-period for no-roll + * but ltc_speed will still be 0 + */ + && (current_speed != 0 || ltc_speed != current_speed) + ) { /* check ./libs/ardour/interpolation.cc CubicInterpolation::interpolate * if target_speed != current_speed we should interpolate, too. * @@ -240,8 +307,9 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end * end_frame is calculated from 'frames_moved' which includes the interpolation. * so we're good. */ - DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: speed change old: %1 cur: %2 tgt: %3 ctd: %4\n", ltc_speed, current_speed, target_speed, fabs(current_speed) - target_speed)); + DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: speed change old: %1 cur: %2 tgt: %3 ctd: %4\n", ltc_speed, current_speed, target_speed, fabs(current_speed) - target_speed, new_ltc_speed)); speed_changed = true; + ltc_encoder_set_filter(ltc_encoder, LTC_RISE_TIME(new_ltc_speed)); } if (end_frame == start_frame || fabs(current_speed) < 0.1 ) { @@ -259,6 +327,10 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end ltc_speed = new_ltc_speed; return; } + if (start_frame != ltc_prev_cycle) { + DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: no-roll seek from %1 to %2 (%3)\n", ltc_prev_cycle, start_frame, cycle_start_frame)); + ltc_tx_reset(); + } } if (fabs(new_ltc_speed) > 10.0) { @@ -291,8 +363,8 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end * which is left for later.. */ - double oldbuflen = double(ltc_buf_len - ltc_buf_off); - double newbuflen = double(ltc_buf_len - ltc_buf_off) * fabs(ltc_speed / new_ltc_speed); + double oldbuflen = (double)(ltc_buf_len - ltc_buf_off); + double newbuflen = (double)(ltc_buf_len - ltc_buf_off) * fabs(ltc_speed / new_ltc_speed); DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: bufOld %1 bufNew %2 | diff %3\n", (ltc_buf_len - ltc_buf_off), newbuflen, newbuflen - oldbuflen @@ -342,6 +414,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end } } + ltc_prev_cycle = start_frame; ltc_speed = new_ltc_speed; DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: transport speed %1.\n", ltc_speed)); @@ -350,17 +423,26 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end framepos_t tc_sample_start; /* calc timecode frame from current position - round down to nearest timecode */ - sample_to_timecode(cycle_start_frame, tc_start, true, false); + Timecode::sample_to_timecode(cycle_start_frame, tc_start, true, false, + timecode_frames_per_second(), + timecode_drop_frames(), + (double)frame_rate(), + config.get_subframes_per_frame(), + ltc_timecode_negative_offset, ltc_timecode_offset + ); /* convert timecode back to sample-position */ Timecode::timecode_to_sample (tc_start, tc_sample_start, true, false, - double(frame_rate()), + (double)frame_rate(), config.get_subframes_per_frame(), - config.get_timecode_offset_negative(), config.get_timecode_offset() + ltc_timecode_negative_offset, ltc_timecode_offset ); /* difference between current frame and TC frame in samples */ frameoffset_t soff = cycle_start_frame - tc_sample_start; + if (current_speed == 0) { + soff = 0; + } DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX3: A3cycle: %1 = A3tc: %2 +off: %3\n", cycle_start_frame, tc_sample_start, soff)); @@ -384,6 +466,12 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end maxdiff = slave()->resolution(); } else { maxdiff = ceil(fabs(ltc_speed))*2.0; + if (nominal_frame_rate() != frame_rate()) { + maxdiff *= 3.0; + } + if (ltc_enc_tcformat == Timecode::timecode_23976 || ltc_enc_tcformat == Timecode::timecode_24976) { + maxdiff *= 15.0; + } } DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX4: enc: %1 + %2 - %3 || buf-bytes: %4 enc-byte: %5\n", @@ -394,7 +482,9 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end rint(ltc_enc_pos + ltc_enc_cnt - poff) - cycle_start_frame )); - if (ltc_speed != 0 && fabs(ceil(ltc_enc_pos + ltc_enc_cnt - poff) - cycle_start_frame) > maxdiff) { + if (ltc_enc_pos < 0 + || (ltc_speed != 0 && fabs(ceil(ltc_enc_pos + ltc_enc_cnt - poff) - cycle_start_frame) > maxdiff) + ) { // (5) re-align ltc_tx_reset(); @@ -418,7 +508,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX4: now: %1 trs: %2 toff %3\n", cycle_start_frame, tc_sample_start, soff)); - uint32_t cyc_off; + int32_t cyc_off; if (soff < 0 || soff >= fptcf) { /* session framerate change between (2) and now */ ltc_tx_reset(); @@ -428,7 +518,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end if (ltc_speed < 0 ) { /* calculate the byte that starts at or after the current position */ ltc_enc_byte = floor((10.0 * soff) / (fptcf)); - ltc_enc_cnt = double(ltc_enc_byte * fptcf / 10.0); + ltc_enc_cnt = ltc_enc_byte * fptcf / 10.0; /* calculate difference between the current position and the byte to send */ cyc_off = soff- ceil(ltc_enc_cnt); @@ -436,7 +526,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end } else { /* calculate the byte that starts at or after the current position */ ltc_enc_byte = ceil((10.0 * soff) / fptcf); - ltc_enc_cnt = double(ltc_enc_byte * fptcf / 10.0); + ltc_enc_cnt = ltc_enc_byte * fptcf / 10.0; /* calculate difference between the current position and the byte to send */ cyc_off = ceil(ltc_enc_cnt) - soff; @@ -450,7 +540,11 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX5 restart encoder: soff %1 byte %2 cycoff %3\n", soff, ltc_enc_byte, cyc_off)); - if (cyc_off > 0 && cyc_off <= nframes) { + if ( (ltc_speed < 0 && ltc_enc_byte !=9 ) || (ltc_speed >= 0 && ltc_enc_byte !=0 ) ) { + restarting = true; + } + + if (cyc_off >= 0 && cyc_off <= (int32_t) nframes) { /* offset in this cycle */ txf= rint(cyc_off / fabs(ltc_speed)); memset(out, 0, cyc_off * sizeof(Sample)); @@ -465,6 +559,26 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX5 restart @ %1 + %2 - %3 | byte %4\n", ltc_enc_pos, ltc_enc_cnt, cyc_off, ltc_enc_byte)); } + else if (ltc_speed != 0 && (fptcf / ltc_speed / 80) > 3 ) { + /* reduce (low freq) jitter. + * The granularity of the LTC encoder speed is 1 byte = + * (frames-per-timecode-frame / 10) audio-samples. + * Thus, tiny speed changes [as produced by some slaves] + * may not have any effect in the cycle when they occur, + * but they will add up over time. + * + * This is a linear approx to compensate for this jitter + * and prempt re-sync when the drift builds up. + * + * However, for very fast speeds - when 1 LTC bit is + * <= 3 audio-sample - adjusting speed may lead to + * invalid frames. + * + * To do better than this, resampling (or a rewrite of the + * encoder) is required. + */ + ltc_speed -= ((ltc_enc_pos + ltc_enc_cnt - poff) - cycle_start_frame) / engine().sample_rate(); + } // (6) encode and output @@ -502,13 +616,24 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end } } - if (ltc_encoder_encode_byte(ltc_encoder, ltc_enc_byte, (ltc_speed==0)?1.0:(1.0/ltc_speed))) { - DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.3 encoder error byte %1\n", ltc_enc_byte)); - ltc_encoder_buffer_flush(ltc_encoder); - ltc_tx_reset(); - return; + int enc_frames; + + if (restarting) { + /* write zero bytes -- don't touch encoder until we're at a frame-boundary + * otherwise the biphase polarity may be inverted. + */ + enc_frames = fptcf / 10.0; + memset(<c_enc_buf[ltc_buf_len], 127, enc_frames * sizeof(ltcsnd_sample_t)); + } else { + if (ltc_encoder_encode_byte(ltc_encoder, ltc_enc_byte, (ltc_speed==0)?1.0:(1.0/ltc_speed))) { + DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.3 encoder error byte %1\n", ltc_enc_byte)); + ltc_encoder_buffer_flush(ltc_encoder); + ltc_tx_reset(); + return; + } + enc_frames = ltc_encoder_get_buffer(ltc_encoder, &(ltc_enc_buf[ltc_buf_len])); } - int enc_frames = ltc_encoder_get_buffer(ltc_encoder, &(ltc_enc_buf[ltc_buf_len])); + #ifdef LTC_GEN_FRAMEDBUG DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.3 encoded %1 bytes for LTC-byte %2 at spd %3\n", enc_frames, ltc_enc_byte, ltc_speed)); #endif @@ -529,10 +654,17 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end ltc_enc_byte = (ltc_enc_byte + 1)%10; if (ltc_enc_byte == 0 && ltc_speed != 0) { ltc_encoder_inc_timecode(ltc_encoder); +#if 0 /* force fixed parity -- scope debug */ + LTCFrame f; + ltc_encoder_get_frame(ltc_encoder, &f); + f.biphase_mark_phase_correction=0; + ltc_encoder_set_frame(ltc_encoder, &f); +#endif ltc_tx_recalculate_position(); ltc_enc_cnt = 0; } else if (ltc_enc_byte == 0) { ltc_enc_cnt = 0; + restarting=false; } } #ifdef LTC_GEN_FRAMEDBUG