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[ardour-manual] / include / on-clock-and-time.html

diff --git a/include/on-clock-and-time.html b/include/on-clock-and-time.html
index 5c7ac1cfe68ebb372a31b49722e45c669383df10..2e221e2f5e4c5e9230ae3ef49ab8f8707634b251 100644 (file)
--- a/include/on-clock-and-time.html
+++ b/include/on-clock-and-time.html
@@ -1,31 +1,32 @@
 
 <p>
-  <dfn>Synchronization</dfn> in multimedia involves two concepts which are 
-  often confused: <dfn>clock</dfn> (or speed) and <dfn>time</dfn> (location 
+  <dfn>Synchronization</dfn> in multimedia involves two concepts which are
+  often confused: <dfn>clock</dfn> (or speed) and <dfn>time</dfn> (location
   in time).
 </p>
 
 <p>
-  A <dfn>clock</dfn> determines the speet at which one or more systems 
-  operate. In the audio world this is generally referred to as 
+  A <dfn>clock</dfn> determines the speed at which one or more systems
+  operate. In the audio world this is generally referred to as
   <a href="https://en.wikipedia.org/wiki/Word_clock" title="https://en.wikipedia.org/wiki/Word_clock">Word Clock</a>.
-  It does not carry any absolute reference to a point in time: A clock is 
+  It does not carry any absolute reference to a point in time: A clock is
   used to keep a system's sample rate regular and accurate.
-  Word clock is usually at the frequency of the sample rate&mdash;at 48&nbsp;kHz, its period is about 20&nbsp;μs. Word Clock is the most 
-  common sample rate based clock but other clocks do exist such as Black and 
+  Word clock is usually at the frequency of the sample rate&mdash;at 48&nbsp;kHz,
+  its period is about 20&nbsp;μs. Word Clock is the most
+  common sample rate based clock but other clocks do exist such as Black and
   Burst, Tri-Level and DARS. Sample rates can be derived from these clocks as well.
 </p>
 
 <p>
-  Time or <dfn>timecode</dfn> specifies an absolute  position on a timeline, 
-  such as <code>01:02:03:04</code> (expressed as Hours:Mins:Secs:Frames). It is 
+  Time or <dfn>timecode</dfn> specifies an absolute  position on a timeline,
+  such as <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 <dfn>Video Frames</dfn> and is an order of 
-  magnitude lower than, say, Word Clock which is counted in 
+  The granularity of timecode is <dfn>Video Frames</dfn> and is an order of
+  magnitude lower than, say, Word Clock which is counted in
   <dfn>samples</dfn>. A typical frame rate is 25&nbsp;<abbr title="frames
   per second">fps</abbr> with a period of
   40&nbsp;ms.
-  In the case of 48&nbsp;kHz and 25&nbsp;fps, there are 1920 audio samples 
+  In the case of 48&nbsp;kHz and 25&nbsp;fps, there are 1920 audio samples
   per video frame.
 </p>
 
@@ -34,35 +35,36 @@
 </p>
 
 <p>
-  JACK provides clock synchronization and is not concerned with time code 
+  JACK (Ardour does this internally if using the ALSA backend) provides
+  clock synchronization and is not concerned with time code
   (this is not entirely true, more on jack-transport later).
-  On the software side, jackd provides sample-accurate synchronization 
+  On the software side, 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 
+  On the hardware side, JACK and Ardour use 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 
+  If two interfaces run at different clocks the only way to align the
   signals is via re-sampling (SRC&mdash;Sample Rate Conversion), which is
-  expensive in terms of CPU usage and may decreases fidelity if done
+  expensive in terms of CPU usage and may decrease fidelity if done
   incorrectly.
 </p>
 
 <p>
-  Timecode is used to align systems already synchronized by a clock to 
-  a common point in time, this is application specific and various 
+  Timecode is used to align systems already synchronized by a clock to
+  a common point in time, this is application specific and various
   standards and methods exist to do this.
 </p>
 
 <p class="note">
-  To make things confusing, there are possibilities to synchronize clocks 
-  using timecode. e.g. using mechanism called <dfn>jam-sync</dfn> and a 
+  To make things confusing, there are possibilities to synchronize clocks
+  using timecode. e.g. using mechanism called <dfn>jam-sync</dfn> and a
   <dfn>phase-locked loop</dfn>.
 </p>
 
 <p>
-  An interesting point to note is that LTC (Linear Time Code) is a 
-  Manchester encoded, frequency modulated signal that carries both 
-  clock and time. It is possible to extract absolute position data 
+  An interesting point to note is that LTC (Linear Time Code) is a
+  Manchester encoded, frequency modulated signal that carries both
+  clock and time. It is possible to extract absolute position data
   and speed from it.
 </p>