Taming the Flexi-time latency beast

by Daniel Spreadbury on October 11, 2009 · 0 comments

in Tips

The Latency Beast. It's more frightening when not in silhouette. (Courtesy nutmeg66 on Flickr)

The Latency Beast. It's more frightening when not in silhouette. (Courtesy nutmeg66 on Flickr)

If you find that Sibelius always seems to be a sixteenth note (semiquaver) or an eighth note (quaver) behind you when you’re using Flexi-time note input to play notes in from your MIDI keyboard, then chances are you have been struck by the Flexi-time latency monster. Read on to find out how to tame this beast.

Latency refers to the delay between Sibelius telling your sound device to make a sound, and that sound actually coming out of your speakers and reaching your ears. In order for Flexi-time to work effectively, that delay needs to be really short: if it takes a long time for the metronome click to reach your ears, then by the time you hear it, Sibelius is already halfway towards the next beat, and the note you play on your keyboard in response to each click is going to be late.

The most common cause of this problem is when you are using a high-latency playback device, such as the built-in Microsoft GS Wavetable Synth. This is the default playback device in Sibelius 5 for Windows, and it may also be the default in Sibelius 6 if you have not installed the supplied Sibelius Sounds Essentials sample library. Unfortunately, the Microsoft GS Wavetable Synth has really high latency, even if you have the fastest computer in the world: it can take as long as a quarter of a second for it to produce a sound.

You’ll never get great results in Flexi-time if you’re using this device, so the first step to taming the latency monster is to switch to a lower-latency playback device. Choose Play > Playback Devices and choose Sibelius Sounds from the Configuration menu (or Sibelius Essentials (32 sounds) if you’re running Sibelius 5), which will activate the Sibelius Player sample player (or Kontakt Player 2 in Sibelius 5). This should make a tremendous difference already.

If you still discover that you have any problems with notes being entered late after switching to a low-latency playback device, go back to Play > Playback Devices and click Audio Engine Options. Make sure you’ve chosen the best available choice in the Interface menu, preferably the one with ASIO in its name (and if there’s no ASIO choice, you should think about getting an ASIO-compatible soundcard or audio interface, or at least try installing the ASIO4ALL universal ASIO audio driver), or failing that the one with DirectSound in its name. Check that the Buffer size is set to 1024 samples or lower to reduce the latency further. Ideally, latency should be less than 50ms to get optimal results.

Having tamed the latency monster, you should find Flexi-time a lot more usable.

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