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authorRobin Gareus <robin@gareus.org>2012-11-09 07:48:04 +0000
committerRobin Gareus <robin@gareus.org>2012-11-09 07:48:04 +0000
commit838a8a01371a95bf7efa4dd94d96055c6dde344c (patch)
tree9f29aca045c20032ad858a17388acbdd0bd9ec1c /libs/ardour/session_ltc.cc
parent9d4974ede943a89fe9e30c80b54d29b3e39a55b6 (diff)
LTC encoder: fix signal polarity
git-svn-id: svn://localhost/ardour2/branches/3.0@13403 d708f5d6-7413-0410-9779-e7cbd77b26cf
Diffstat (limited to 'libs/ardour/session_ltc.cc')
-rw-r--r--libs/ardour/session_ltc.cc34
1 files changed, 26 insertions, 8 deletions
diff --git a/libs/ardour/session_ltc.cc b/libs/ardour/session_ltc.cc
index 089a8f7d56..d7ff89366e 100644
--- a/libs/ardour/session_ltc.cc
+++ b/libs/ardour/session_ltc.cc
@@ -81,6 +81,7 @@ Session::ltc_tx_initialize()
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
@@ -136,6 +137,7 @@ Session::ltc_tx_recalculate_position()
config.get_subframes_per_frame(),
config.get_timecode_offset_negative(), config.get_timecode_offset()
);
+ restarting = false;
}
void
@@ -466,6 +468,10 @@ 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 ( (ltc_speed < 0 && ltc_enc_byte !=9 ) || (ltc_speed >= 0 && ltc_enc_byte !=0 ) ) {
+ restarting = true;
+ }
+
if (cyc_off > 0 && cyc_off <= nframes) {
/* offset in this cycle */
txf= rint(cyc_off / fabs(ltc_speed));
@@ -485,11 +491,11 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
/* 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 the slave]
+ * 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 drift
+ * 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
@@ -538,13 +544,24 @@ 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(&ltc_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
@@ -575,6 +592,7 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
ltc_enc_cnt = 0;
} else if (ltc_enc_byte == 0) {
ltc_enc_cnt = 0;
+ restarting=false;
}
}
#ifdef LTC_GEN_FRAMEDBUG