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more tweaks to the Sync manual

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Robin Gareus 2013-02-16 02:04:11 +01:00
parent 876124925e
commit 6fc429e091
3 changed files with 8 additions and 8 deletions
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12
_manual/19_synchronization/01_on-clock-and-time.html
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@ -9,15 +9,15 @@ Synchronisation in multimedia involves two concepts which are often confused: <s
<p>
A <em>clock</em> is the mechanism by which two systems <em>tick</em> simultaneously.
In the audio world this is generally referred to as <a href="http://en.wikipedia.org/wiki/Word_clock" title="http://en.wikipedia.org/wiki/Word_clock">Word_clock</a>.
In the audio world this is generally referred to as <a href="http://en.wikipedia.org/wiki/Word_clock" title="http://en.wikipedia.org/wiki/Word_clock">Word Clock</a>.
It does not carry any absolute reference to a point in time: A clock is used to keep a systems sample rate constant, regular and accurate.
Word clock is usually at the frequency of the sample-rate - ie at 48KHz, its period is about 20μs. Word Clock is the most common &#039;sample rate&#039; based clock but other clocks do exist such as Black and Burst, Tri-Level and DARS. Sample rates can also be derived from these clocks as well.
Word clock is usually at the frequency of the sample rate - ie at 48KHz, its period is about 20μs. Word Clock is the most common &#039;sample rate&#039; based clock but other clocks do exist such as Black and Burst, Tri-Level and DARS. Sample rates can also be derived from these clocks as well.
</p>
<p>
Time – or <em>timecode</em> – on the other hand specifies an absolute relationship or position on a timeline e.g. <code>01:02:03:04</code> (expressed as Hours:Mins:Secs:Frames). It is actual data and not a clock-signal per se.
The granularity of timecode is <strong>Video Frames</strong> and is an order of magnitude lower than, say, Word Clock which is counted in <strong>samples</strong>. A typical frame-rate is 25 fps with a period of 40ms.
In the case of 48kHz and 25fps, there are 1920 samples per video frame.
Time – or <em>timecode</em> – on the other hand specifies an absolute relationship or position on a timeline e.g. <code>01:02:03:04</code> (expressed as Hours:Mins:Secs:Frames). It is actual <em>data</em> and not a clock <em>signal</em> per se.
The granularity of timecode is <strong>Video Frames</strong> and is an order of magnitude lower than, say, Word Clock which is counted in <strong>samples</strong>. A typical frame rate is 25 fps with a period of 40ms.
In the case of 48KHz and 25fps, there are 1920 audio samples per video frame.
</p>
<p>
@ -25,7 +25,7 @@ The concept of clock and timecode is reflected in JACK and Ardour:
</p>
<p>
JACK provides clock-synchronization and is not concerned with time-code (this is not entirely true, more on jack-transport later).
JACK provides clock synchronization and is not concerned with time code (this is not entirely true, more on jack-transport later).
Within software, jackd provides sample-accurate synchronization between all JACK applications.
On the hardware side JACK uses the clock of the audio-interface. Synchronization of multiple interfaces requires hardware support to sync the clocks.
If two interfaces run at different clocks the only way to align the signals is via re-sampling (SRC - Sample Rate Conversion) - which decreases fidelity.

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_manual/19_synchronization/03_timecode-generators-and-slaves.html
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@ -43,7 +43,7 @@ Note that some timecode formats are limited to a subset of Ardour's available fp
</p>
<p>
The video-pullup modes change the effective samplerate of Ardour to allows for changing a film soundtrack from one frame rate to another. The scope is beyond this manual, but wikipedia's entry on <a href="http://en.wikipedia.org/wiki/Telecine" title="http://en.wikipedia.org/wiki/Telecine">Telecine</a> may get you started.
The video-pullup modes change the effective samplerate of Ardour to allows for changing a film soundtrack from one frame rate to another. The concept is beyond the scope of this manual, but wikipedia's entry on <a href="http://en.wikipedia.org/wiki/Telecine" title="http://en.wikipedia.org/wiki/Telecine">Telecine</a> may get you started.
</p>
<h2>Ardour Timecode Generator Configuration</h2>

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_manual/19_synchronization/04_overview-of-timecode-related-settings.html
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@ -21,7 +21,7 @@ Timecode related settings are accessed from the menu:
<h2>Timecode Settings</h2>
<p>Thes settings are session specific:</p>
<ul>
<li><strong>Timecode frames-per-second</strong> – configure Timecode frames-per-second (23.976, 24, 24.975, 25, 29.97, 29.97 drop, 30, 30 drop, 59.94, 60). Note that all fractional framerates are actually fps*(1000.0/1001.0).</li>
<li><strong>Timecode frames-per-second</strong> – configure timecode frames-per-second (23.976, 24, 24.975, 25, 29.97, 29.97 drop, 30, 30 drop, 59.94, 60). Note that all fractional framerates are actually fps*(1000.0/1001.0).</li>
<li><strong>Pull up/down</strong> – video-pullup modes change the effective samplerate of Ardour to allows for changing a film soundtrack from one frame rate to another. see <a href="http://en.wikipedia.org/wiki/Telecine" title="http://en.wikipedia.org/wiki/Telecine">Telecine</a></li>
<li><strong>Slave Timecode offset</strong> – The specified offset is added to the received timecode (MTC or LTC).</li>
<li><strong>Timecode Generator offset</strong> – Specify an offset which is added to the generated timecode (so far only LTC).</li>