Recording - April 2011 - 43

WHEN THEY’RE NOT WORRIED ABOUT HOW THEY SOUND, AND THAT WILL TRUMP TECHNOLOGY EVERY TIME.

VOCALISTS GIVE BETTER PERFORMANCES

FIG. 3

A cool tool for navigating the busy-driver maze is the DPC Latency Checker (free download, shown in Figure 3). While it won’t point directly to a guilty driver, by watching its display as you disable various devices, you can locate those which are the worst offenders, many of which you can live without. Troublemakers are wired and wireless networking, virus scanners, screen savers, CD auto-play, Windows Zero Configuration Wireless, and, in laptops, APIC battery monitoring. The red bars in this screenshot show something getting attention for 4 milliseconds every 2 seconds, causing a lot of audio stuttering even with very large buffers. Disabling the network driver solved the latency problem with this computer. Once you’ve cleaned up your computer, fire up the DAW and start reducing the ASIO buffer size as you add more tracks and plug-ins. Your goal is to find the smallest buffer that will let your DAW work as hard as it needs to without skipping. It’s a cut-and-try process. It’s also iterative—if you can’t achieve sufficiently low latency with the smallest buffer that works, hunt for more things to disable. A 128-sample buffer is a good goal, but depending on the drivers and hardware, you may not be able to achieve it. Work smarter, work faster Adjust the buffer size to suit the current job. Use the smallest workable buffers when tracking, use larger buffers when latency is irrelevant. Don’t insert plug-ins that have substantial latency until mixdown. Use an amplifier or effect pedal instead of an amplifier simulator plug-in while tracking. For tracks that really need some help (a direct guitar, for example) in order to play against them, plug in the simulator, get a working sound, then “freeze” the track with that sound. Remove the plug-in, mute the original track in the mix, and monitor the frozen track. At mixdown, return to the original track, pile on the effects, and increase the buffer size as needed. With virtual instruments the DAW becomes the instrument, so you have no choice but to monitor the DAW output. Since the input is MIDI, the A/D converter is idle. Your DAW may allow you to disable the audio input, which may reduce
RECORDING APRIL 2011

latency. Once you’ve recorded a MIDI track, you can “freeze” the virtual instrument, freeing up some processing time. Dedicating a computer to audio work is still valid advice. If you insist on being able to check your email or watch YouTube videos while you’re in session,

you’ll never achieve really low latency. Doubling the sample rate nearly halves the A/D and D/A conversion time. Although the computer works harder at 2x sample rate which may require a larger buffer, by doubling the sample rate, you may end up with less total latency.

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Recording - April 2011

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