#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;
//#define LTC_GEN_FRAMEDBUG
//#define LTC_GEN_TXDBUG
+#ifndef MAX
+#define MAX(a,b) ( (a) > (b) ? (a) : (b) )
+#endif
+#ifndef MIN
+#define MIN(a,b) ( (a) < (b) ? (a) : (b) )
+#endif
+
+/* 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 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(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(1.0));
/* buffersize for 1 LTC frame: (1 + sample-rate / fps) bytes
* usually returned by ltc_encoder_get_buffersize(encoder)
* 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;
}
+void
+Session::ltc_tx_resync_latency()
+{
+ DEBUG_TRACE (DEBUG::LTC, "LTC TX resync latency\n");
+ if (!deletion_in_progress()) {
+ boost::shared_ptr<Port> ltcport = ltc_output_port();
+ if (ltcport) {
+ ltcport->get_connected_latency_range(ltc_out_latency, true);
+ }
+ }
+}
+
void
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
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
boost::shared_ptr<Port> ltcport = ltc_output_port();
Buffer& buf (ltcport->get_buffer (nframes));
-
+
if (!ltc_encoder || !ltc_enc_buf) {
return;
}
/* range from libltc (38..218) || - 128.0 -> (-90..90) */
const float ltcvol = Config->get_ltc_output_volume()/(90.0); // pow(10, db/20.0)/(90.0);
- jack_latency_range_t ltc_latency;
- ltcport->get_connected_latency_range(ltc_latency, true);
- DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX %1 to %2 / %3 | lat: %4\n", start_frame, end_frame, nframes, ltc_latency.max));
+ DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX %1 to %2 / %3 | lat: %4\n", start_frame, end_frame, nframes, ltc_out_latency.max));
/* all systems go. Now here's the plan:
*
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;
}
+ ltc_encoder_set_filter(ltc_encoder, LTC_RISE_TIME(ltc_speed));
ltc_enc_tcformat = cur_timecode;
+ ltc_tx_parse_offset();
ltc_tx_reset();
}
}
// (2) speed & direction
+
+ /* speed 0 aka transport stopped is interpreted as rolling forward.
+ * keep repeating current frame
+ */
#define SIGNUM(a) ( (a) < 0 ? -1 : 1)
bool speed_changed = false;
- /* use port latency compensation */
-#if 1
- /* The generated timecode is offset by the port-latency,
+ /* 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_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
+ 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.
*
* 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 ) {
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) {
* 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
}
}
+ ltc_prev_cycle = start_frame;
ltc_speed = new_ltc_speed;
DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX2: transport speed %1.\n", ltc_speed));
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));
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",
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();
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();
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);
} 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;
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));
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
}
}
- 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
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
DEBUG_TRACE (DEBUG::LTC, string_compose("LTC TX6.4 enc-pos: %1 + %2 [ %4 / %5 ] spd %6\n", ltc_enc_pos, ltc_enc_cnt, ltc_buf_off, ltc_buf_len, ltc_speed));
#endif
}
-
+
dynamic_cast<AudioBuffer*>(&buf)->set_written (true);
return;
}
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