X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fardour%2Fsession_ltc.cc;h=51a39d0677c2f6169320aa84454e3b681baa8aaf;hb=6f7f527e1db300fb532390348db132446a211085;hp=2ce25b5a4808853754f969707b918f1db40f21fc;hpb=0da34e65e3470b1c2298ddf571df6356d0d42bd8;p=ardour.git

diff --git a/libs/ardour/session_ltc.cc b/libs/ardour/session_ltc.cc
index 2ce25b5a48..51a39d0677 100644
--- a/libs/ardour/session_ltc.cc
+++ b/libs/ardour/session_ltc.cc
@@ -27,7 +27,7 @@
 #include "ardour/session.h"
 #include "ardour/slave.h"
 
-#include "i18n.h"
+#include "pbd/i18n.h"
 
 using namespace std;
 using namespace ARDOUR;
@@ -244,13 +244,26 @@ 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;
 
 	if (current_speed < 0) {
-		cycle_start_frame = (start_frame - ltc_out_latency.max);
+		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);
+		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
@@ -262,7 +275,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
 	/* 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_frame -= ltc_frame_alignment(samples_per_timecode_frame(), TV_STANDARD(cur_timecode));
 	}
 
 	/* cycle-start may become negative due to latency compensation */
@@ -435,7 +448,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
 
 
 	// (4) check if alignment matches
-	const double fptcf = frames_per_timecode_frame();
+	const double fptcf = samples_per_timecode_frame();
 
 	/* maximum difference of bit alignment in audio-samples.
 	 *
@@ -469,8 +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
 				));
 
+	const framecnt_t wrap24h = 86400. * frame_rate();
 	if (ltc_enc_pos < 0
-			|| (ltc_speed != 0 && fabs(ceil(ltc_enc_pos + ltc_enc_cnt - poff) - cycle_start_frame) > maxdiff)
+			|| (ltc_speed != 0 && fabs(fmod(ceil(ltc_enc_pos + ltc_enc_cnt - poff), wrap24h) - (cycle_start_frame % wrap24h)) > maxdiff)
 			) {
 
 		// (5) re-align
@@ -478,7 +492,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
 
 		/* set frame to encode */
 		SMPTETimecode tc;
-		tc.hours = tc_start.hours;
+		tc.hours = tc_start.hours % 24;
 		tc.mins = tc_start.minutes;
 		tc.secs = tc_start.seconds;
 		tc.frame = tc_start.frames;
@@ -541,7 +555,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
 			return;
 		}
 
-		ltc_enc_pos = tc_sample_start;
+		ltc_enc_pos = tc_sample_start % wrap24h;
 
 		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));
@@ -564,7 +578,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
 		 * 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();
+		ltc_speed -= fmod(((ltc_enc_pos + ltc_enc_cnt - poff) - cycle_start_frame), wrap24h) / engine().sample_rate();
 	}