Updated VariSpeed refs for v8.1
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@ -1,5 +1,3 @@
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<p>
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Ardour supports three common timecode formats:
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<abbr title="Linear/Longitudinal Time Code"><dfn>LTC</dfn></abbr>,
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@ -16,7 +14,6 @@
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<dfn>translate</dfn> timecode. e.g create LTC timecode from incoming MTC.
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</p>
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<h2>Ardour Timecode Configuration</h2>
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<p>
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@ -83,6 +80,7 @@
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</p>
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<h3>MTC Generator</h3>
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<p>
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The <dfn>MTC generator</dfn> has no options. Ardour sends full MTC
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frames whenever the transport is relocated or changes state (start/stop).
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@ -91,17 +89,20 @@
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</p>
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<h3>LTC Generator</h3>
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<p>
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The level of the <dfn>LTC generator</dfn> output signal can be configured
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in the <kbd class="menu">Preferences > Transport</kbd> dialog. By
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default it is set to -18 dBFS, which corresponds to 0dBu in an EBU
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calibrated system.
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</p>
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<p>
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The LTC generator has an additional option to keep sending timecode even
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when the transport is stopped. This mode is intended to drive analog tape
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machines which unspool the tape if no LTC timecode is received.
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</p>
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<p>
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LTC is sent regardless of Ardour's transport speed. It is accurately
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generated even for very slow speeds (<5%) and only limited by the
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@ -111,8 +112,8 @@
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for high speeds.
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</p>
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<h2>Ardour Slave Configuration</h2>
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<p>
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The timecode source can be switched with the button just right of
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Ardour's main clock. By default it is set to <kbd
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@ -121,24 +122,30 @@
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timecode source which is chosen in <kbd class="menu">Edit > Preferences
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> Transport</kbd>.
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</p>
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<p>
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When Ardour is <dfn>chasing</dfn> (synchronizing to) an external timecode
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source, the following cases need to be distinguished:
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</p>
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<ol>
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<li>the timecode source shares the clock</li>
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<li>the timecode source is independent (no wordclock sync)</li>
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</ol>
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<p>and</p>
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<ol>
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<li>the timecode source uses the same FPS setting as Ardour</li>
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<li>the timecode source runs at different frames-per-second</li>
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</ol>
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<p>
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In both cases the first option is preferred: clock sync + same FPS setting.
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</p>
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<h3>Frames-per-second</h3>
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<p>
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If the frames-per-second do not match, Ardour can either re-calculate
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and map the frames, or the configured FPS (<kbd class="menu">Session >
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@ -147,6 +154,7 @@
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> Preferences > Transport > Match session video frame rate to
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external timecode</kbd>.
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</p>
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<p>
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When enabled, the session video frame rate will be changed to match that
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of the selected external timecode source. When disabled, the session video
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@ -155,6 +163,7 @@
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flash red, and Ardour will convert between the external timecode standard
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and the session standard.
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</p>
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<p class="warning">
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29.97 drop-frame timecode is another corner case. While the SMPTE 12M-1999
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specifies 29.97df as 30000/1001 frames per second, not all hardware devices
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@ -173,6 +182,7 @@
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</p>
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<h3>Clock Sync Lock</h3>
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<p>
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As described in the
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<a href="@@on-clock-and-time">On Clock and Time</a>
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@ -180,30 +190,29 @@
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source is not in sample-sync with the audio hardware (and JACK), Ardour
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needs to run at varispeed to adjust for the discrepancy.
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</p>
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<p>
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The checkbox <kbd class="option">External timecode is sync locked</kbd>
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allows to select the behavior according to the setup. When enabled, it
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indicates that the selected external timecode source shares sync (Black
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& Burst, Wordclock, etc) with the audio interface.
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</p>
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<p>
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In other words: if enabled, Ardour will only perform initial
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synchronization and keep playing at speed 1.0 instead of vari-speed
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adjusting to compensate for drift.
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</p>
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<p class="note">
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Note that vari-speed is unavailable when recording in Ardour, and all
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tracking happens at speed 1.0. So in order to record in sync with
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external timecode it must be sample-locked or it will drift over time.
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</p>
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<h3>MIDI Clock</h3>
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<p>
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<dfn>MIDI Clock</dfn> is not a timecode format but tempo-based time. The
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absolute reference point is expressed as beats-per-minute and Bar, Beat
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and Tick. There is no concept of sample-locking for MIDI clock signals.
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Ardour will vari-speed if necessary to chase the incoming signal.
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</p>
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<p>
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Note that the MIDI Clock source must be connected to the
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<code>ardour:MIDI clock in</code> port.
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@ -271,23 +280,26 @@
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</p>
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<p>
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When Ardour is chasing MTC, the main transport clock will display the
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received Timecode as well as the delta between the incoming signal and
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received timecode as well as the delta between the incoming signal and
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Ardour's transport position.
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</p>
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<h3>JACK Transport</h3>
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<p>
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When slaved to jack, Ardour's transport will be identical to
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JACK-transport. As opposed to other slaves, Ardour can be used to control
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the JACK transport states (stopped/rolling). No port connections need to
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be made for jack-transport to work.
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When slaved to jack, Ardour's transport will be identical to JACK Transport.
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As opposed to other slaves, Ardour can be used to control the JACK transport
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states (stopped/rolling). No port connections need to be made for
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JACK Transport to work.
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</p>
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<p>
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JACK-transport does not support vari-speed, nor offsets. Ardour does not
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JACK Transport does not support vari-speed, nor offsets. Ardour does not
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chase the timecode but is always in perfect sample-sync with it.
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</p>
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<p>
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JACK-transport also includes temp-based-time information in Bar:Beats:Ticks
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JACK Transport also includes temp-based time information in Bar:Beats:Ticks
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and beats-per-minute. However, only one JACK application can provide this
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information at a given time. The checkbox
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<kbd class="option">Session > Properties > JACK Time Master</kbd>
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@ -61,9 +61,9 @@
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allows to <em>temporarily</em> scrub through the audio quickly. The slider
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decides the playback speed: the further from the center it is set,
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the faster the playback will scrub in both directions. The range of
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this acceleration can be set by <kbd class="mouse">right</kbd>
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clicking the control and setting the multiplier, between 1.5
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(± 150%) and 8 (± 800%).
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this acceleration can be set by <kbd class="mouse">right</kbd>-clicking
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the control and setting the multiplier, either 1.5 (± 150%) or 2
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(± 200%).
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</p>
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<h4 id="transport_varispeed">VariSpeed</h4>
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@ -71,21 +71,22 @@
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The <kbd class="menu">VS</kbd> (for <em>V</em>ari<em>S</em>peed)
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button sets a <em>constant</em> playback/record speed. It can be set
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in semitones (1 semitone = × 2 <sup>1⁄12</sup> ≈
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105,9%), or cents of semitones, and is armed/disarmed by clicking the
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button. The <kbd class="menu">VS</kbd> button will blink when VariSpeed
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is enabled. Whether or not this VariSpeed is persistent when
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stopping/restarting transport depends on the <kbd class="option">Reset
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default speed on stop</kbd> parameter in the <a
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href="@@preferences#preferences-transport">Preferences</a>.
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105,9%), cents of semitones, or percentages, and is armed/disarmed
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by clicking the button. The <kbd class="menu">VS</kbd> button will blink
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when VariSpeed is enabled. Whether or not this VariSpeed is persistent
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when stopping/restarting transport depends on the
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<kbd class="option">Reset default speed on stop</kbd> parameter in the
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<a href="@@preferences#preferences-transport">Preferences</a> dialog.
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</p>
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<h4 id="transport_sync">Transport Sync</h4>
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<p>
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On the left of the slider is the positional sync button (which might show <dfn>Internal</dfn>,
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or <dfn>MTC</dfn> or several other values), than can be used to control whether or not the
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transport position and start is controlled by Ardour, or by an external positional
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synchronization source, such as MIDI Time Code (MTC), Linear Time Code (LTC) or JACK
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(see <a href="@@timecode-generators-and-slaves">Timecode Generators and Slaves</a>).
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On the left of the slider is the positional sync button (which might show
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<dfn>Internal</dfn>, or <dfn>MTC</dfn> or several other values), than can be
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used to control whether or not the transport position and start is controlled
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by Ardour, or by an external positional synchronization source, such as MIDI
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Time Code (MTC), Linear Time Code (LTC) or JACK (see
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<a href="@@timecode-generators-and-slaves">Timecode Generators and Slaves</a>).
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</p>
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<h4 id="transport_status">Transport Status</h4>
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