diff options
| -rw-r--r-- | libs/ardour/session_ltc.cc | 87 |
1 files changed, 54 insertions, 33 deletions
diff --git a/libs/ardour/session_ltc.cc b/libs/ardour/session_ltc.cc index 317d6af7c1..c10e62659c 100644 --- a/libs/ardour/session_ltc.cc +++ b/libs/ardour/session_ltc.cc @@ -22,6 +22,7 @@ #include "ardour/session.h" #include "ardour/audioengine.h" #include "ardour/audio_port.h" +#include "ardour/slave.h" #include "i18n.h" @@ -113,13 +114,18 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end out = (jack_default_audio_sample_t*) jack_port_get_buffer (ltcport->jack_port(), nframes); if (!out) return 0; - if (engine().freewheeling()|| !Config->get_send_ltc() + SyncSource sync_src = Config->get_sync_source(); + if (engine().freewheeling() + || !Config->get_send_ltc() /* TODO - * we can relax this a bit, JACK or sample-synced slaves should be fine. - * test before allowing it, do the same for MTC generator in - * libs/ardour/session_midi.cc - * */ - // || config.get_external_sync() // XXX XXX + * decide which time-sources we can generated LTC from. + * Internal, JACK or sample-synced slaves should be fine. + * + * + || (config.get_external_sync() && sync_src == LTC) + || (config.get_external_sync() && sync_src == MTC) + */ + || (config.get_external_sync() && sync_src == MIDIClock) ) { memset(out, 0, nframes * sizeof(jack_default_audio_sample_t)); return nframes; @@ -135,7 +141,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end /* all systems go. Now here's the plan: * * 1) check if fps has changed - * 2) check direction of encoding, calc speed, resample existing buffer + * 2) check direction of encoding, calc speed, re-sample existing buffer * 3) calculate frame and byte to send aligned to jack-period size * 4) check if it's the frame/byte that is already in the queue * 5) if (4) mismatch, re-calculate offset of LTC frame relative to period size @@ -169,11 +175,20 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end #define SIGNUM(a) ( (a) < 0 ? -1 : 1) bool speed_changed = false; - // XXX - //framepos_t cycle_start_frame = (current_speed < 0) ? (start_frame - ltc_latency.max) : (start_frame + ltc_latency.max); + /* use port latency compensation */ +#if 1 + /* The generated timecode is offset by the port-latency, + * therefore the offset depends on the direction of transport. + */ + framepos_t cycle_start_frame = (current_speed < 0) ? (start_frame + ltc_latency.max) : (start_frame - ltc_latency.max); +#else + /* This comes in handy when testing sync - record output on an A3 track + * see also http://tracker.ardour.org/view.php?id=5073 + */ framepos_t cycle_start_frame = start_frame; +#endif - /* cycle-start may become negative due to latency comensation */ + /* 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); @@ -187,9 +202,9 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end /* check ./libs/ardour/interpolation.cc CubicInterpolation::interpolate * if target_speed != current_speed we should interpolate, too. * - * However, currenly in A3 target_speed == current_speed for each process cycle + * However, currency in A3 target_speed == current_speed for each process cycle * (except for the sign and if target_speed > 8.0). - * Besides, above speed calulation uses the difference (end_frame - start_frame). + * Besides, above speed calculation uses the difference (end_frame - start_frame). * end_frame is calculated from 'frames_moved' which includes the interpolation. * so we're good. */ @@ -227,8 +242,9 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end ltc_tx_reset(); } - /* the timecode duration corresponding to the samples still in the buffer - * here we use prev. speed to match the begining of this cycle for aligment. + /* the timecode duration corresponding to the samples that are still + * in the buffer. Here, the speed of previous cycle is used to calculate + * the alignment at the beginning of this cycle later. */ double poff = (ltc_buf_len - ltc_buf_off) * ltc_speed; @@ -236,8 +252,8 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end /* we need to re-sample the existing buffer. * "make space for the en-coder to catch up to the new speed" * - * since the LTC signal is a rect waveform we can simply squeeze it - * by removing samples or duplicating /here and there/. + * since the LTC signal is a rectangular waveform we can simply squeeze it + * by removing samples or duplicating samples /here and there/. * * There may be a more elegant way to do this, in fact one could * simply re-render the buffer using ltc_encoder_encode_byte() @@ -300,7 +316,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: transport speed %1.\n", ltc_speed)); - // (3) bit/sample aligment + // (3) bit/sample alignment Timecode::Time tc_start; framepos_t tc_sample_start; @@ -320,17 +336,23 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end cycle_start_frame, tc_sample_start, soff)); - // (4) check if aligment matches + // (4) check if alignment matches const double fptcf = frames_per_timecode_frame(); // convenient, used a lot below. - double maxdiff; - /* due to rounding error and variations in LTC-bit duration depending - * on the speed, we can be off by +- speed samples. - * during speed-changes we can acually ready += 2*speed audio-samples - * in the cycle after the speed change. The average delta however is 0. + /* maximum difference of bit alignment in audio-samples. + * + * if transport and LTC generator differs more than this, the LTC + * generator will be re-initialized + * + * due to rounding error and variations in LTC-bit duration depending + * on the speed, it can be off by +- ltc_speed audio-samples. + * When the playback speed changes, it can actually reach +- 2 * ltc_speed + * in the cycle _after_ the speed changed. The average delta however is 0. */ - if (config.get_external_sync()) { - maxdiff = fptcf; // TODO get slave max delta + double maxdiff; + + if (config.get_external_sync() && slave()) { + maxdiff = slave()->resolution(); } else { maxdiff = ceil(fabs(ltc_speed))*2.0; } @@ -357,8 +379,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end ltc_encoder_set_timecode(ltc_encoder, &tc); /* workaround for libltc recognizing 29.97 and 30000/1001 as drop-frame TC. - * in A3 only 30000/1001 is drop-frame and there are also other questionable - * DF timecodes such as 24k/1001 and 25k/1001. + * In A3 30000/1001 or 30 fps can be drop-frame. */ LTCFrame ltcframe; ltc_encoder_get_frame(ltc_encoder, <cframe); @@ -393,16 +414,16 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end } } + assert (cyc_off >= 0); + DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX5 restart encoder: soff %1 byte %2 cycoff %3\n", soff, ltc_enc_byte, cyc_off)); - if (ltc_speed == 0) { - /* don't bother to align non-moving loops */ - } else if (cyc_off > 0 && cyc_off <= nframes) { + if (cyc_off > 0 && cyc_off <= nframes) { /* offset in this cycle */ txf= rint(cyc_off / fabs(ltc_speed)); memset(out, 0, cyc_off * sizeof(jack_default_audio_sample_t)); - } else if (cyc_off > 0) { + } else { /* resync next cycle */ memset(out, 0, cyc_off * sizeof(jack_default_audio_sample_t)); return nframes; @@ -471,9 +492,9 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end ltc_buf_len += enc_frames; if (ltc_speed < 0) - ltc_enc_cnt -= fptcf/10.0; //enc_frames * ltc_speed; + ltc_enc_cnt -= fptcf/10.0; else - ltc_enc_cnt += fptcf/10.0; //enc_frames * ltc_speed; + ltc_enc_cnt += fptcf/10.0; if (ltc_speed >= 0) { ltc_enc_byte = (ltc_enc_byte + 1)%10; |