X-Git-Url: http://shamusworld.gotdns.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=include%2Fon-clock-and-time.html;h=2e221e2f5e4c5e9230ae3ef49ab8f8707634b251;hb=53168d99209b770d9894692b820f06393a63abb5;hp=ae577f654b25233597ef76bd3cbd4ec20180bc2d;hpb=fc55149168a9d75cf6760d96558d63cbdbbbc5df;p=ardour-manual diff --git a/include/on-clock-and-time.html b/include/on-clock-and-time.html index ae577f6..2e221e2 100644 --- a/include/on-clock-and-time.html +++ b/include/on-clock-and-time.html @@ -11,7 +11,8 @@ Word Clock. 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—at 48 kHz, its period is about 20 Î¼s. Word Clock is the most + Word clock is usually at the frequency of the sample rate—at 48 kHz, + its period is about 20 Î¼s. 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.

@@ -34,16 +35,17 @@

- 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 between all JACK applications. - On the hardware side, JACK uses the clock of the audio-interface. + 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 signals is via re-sampling (SRC—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.