- </ul>
- </li>
-</ul>
-
-<h2 id="preferences-sync">Sync</h2>
-
-<ul>
- <li>
- <dfn>External Synchronization</dfn>
- <ul>
- <li>
- <dfn>External timecode source</dfn> determines which external source to
- use when Ardour is using an external
- <a href="@@working-with-synchronization">synchronization</a> source.
- Depending on the timecode source chosen, the additional preference options
- below are available.
- </li>
- <li>
- <dfn>Match session video frame rate to external timecode</dfn>
- controls the value of the video frame rate <em>while chasing</em>
- an external timecode source. When enabled, the session video frame rate will be
- changed to match that of the selected external timecode source. When disabled,
- the session video frame rate will not be changed to match that of the selected
- external timecode source. Instead, the frame rate indication in the main clock
- will flash red and Ardour will convert between the external timecode standard
- and the session standard.
- </li>
- <li>
- <dfn>Sync-lock timecode to clock (disable drift compensation)</dfn>
- When enabled, Ardour will never varispeed when slaved to external
- timecode. Sync Lock indicates that the selected external timecode
- source shares clock-sync (Black & Burst, Wordclock, etc) with
- the audio interface. This options disables drift compensation.
- The transport speed is fixed at 1.0. Vari-speed LTC will be ignored
- and cause drift. When disabled, Ardour will compensate for potential
- drift regardless if the timecode sources shares clock sync.
- </li>
- <li>
- <dfn>Lock to 29.9700 fps instead of 30000/1001</dfn>, when
- enabled, will force Ardour to assume the external timecode source
- uses 29.97 fps instead of 30000/1001.
- SMPTE 12M-1999 specifies 29.97 df as 30000/1001. The spec
- further mentions that drop-frame timecode has an accumulated error
- of -86 ms over a 24 hour period. Drop-frame timecode would
- compensate exactly for an NTSC color frame rate of 30 × 0.9990 (i.e.
- 29.970000). That is not the actual rate. However, some vendors use
- that rate—despite it being against the specs—because the
- variant of using exactly 29.97 fps has zero timecode drift.
- </li>
- </ul>
- </li>
-</ul>
-
-<h3 id="ltc">LTC</h3>
-
-<ul>
- <li>
- <dfn>Linear Timecode (LTC) Reader</dfn>
- <ul>