Topic: Latency
Er wordt veel gesproken over Latency, de tijdvertraging die optreedt bij alle digitale systemen door A/D conversie, signal processing, transport, D/A conversie etc. Vertraging kan voor timing problemen zorgen bij muzikanten, in het luidspreker-systeem, voor fase problemen als er verschillende vertragingen in een systeem (kunnen) onstaan etc. Ieder digitaal systeem kent latency, de vraag is echter in welke mate.
Digidesign VENUE
De systeem latency van een VENUE console, van analoog in naar analoog uit is minder dan 2.8ms. Dit is typisch voor een digitale mengtafel.
Plugins: door de unieke fundementele integratie van plugins bij een VENUE systeem voegen deze vervolgens nauwelijks vertraging toe (tijd-gebaseerde effecten als delays, reverbs e.d. vanzelfsprekend daargelaten), namelijk 3 (routing delay) + 2 samples per plugin. Anders gezegd, 1 plugin in een kanaal geinserteert introduceert 0,104 milliseconden @48kHz, met 4 plugins in serie (!) is het nog steeds maar 0,22 milliseconden.
Ter illustratie: de allersnelste "concurrerende" oplossing, Waves SoundGrid met een direct processor link, introduceert tenminste rond een volle 1 ms (link), oftewel een factor 4 à 5.
Using software plug-ins live also raises the problem of latency. How has VENUE’s design addressed this issue?
Latency is important in live applications, but doesn’t always arise in the places we fear.VENUE has a through-latency of less than 2.8ms.The majority of typical EQ or dynamics plug-ins add only two to five samples of additional latency (around another 0.1ms).The types of plug-ins that add more latency tend to be time-based effects such as reverbs, delays and choruses, where the latency is lost in the much greater delay you actually want to get from the plug-in’s effect or sound.There are a couple of exceptions such as mastering limiters, pitch-processors, feed-forward dynamics — and it remains to be seen if people will want to use these for live sound. VENUE provides input delays on every channel and on most outputs, to make this easy.
It’s also worth noting that an external digital effect unit introduces much more latency than a plug-in — especially when used with an analog console — due to its analog/digital conversion stages. If you combine this advantage with the headroom advantage of a 48-bit internal processor like VENUE’s built-in graphic EQs, there are more than enough reasons to want to keep things inside the board.
The other area where latency is important is when sending a signal to several different busses, particularly where those busses re-combine with each other (as happens when groups are submixed to mains, or in an output matrix). VENUE predicts and automatically deals with most of the common latency problems encountered in these scenarios, so the user doesn’t have anything extra to think about compared with doing those things on an analog console.
