Soundware Guides: Latency

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In this guide we'll explain possible causes of latency, and give some tips to help you reduce it...

What is Latency?

A common problem experienced by people using a home computer to record is a delay - when they press a key on a keyboard or speak into a microphone, there's a gap before they hear it through their speakers or headphones.

This delay is called latency, and it's caused by the time the computer takes to process the incoming sound before it can send it back to the outside world again. Processing audio is an intensive job and can use a lot of a computer's resources, so it takes time for the system to be able to deal with it.

Long latency times can be offputting when recording, especially if you're overdubbing onto a backing track. It can also make different types of sound tracks played at the same time (eg., a MIDI file and an audio recording) sound like they're out of sync with each other.

Unfortunately, there's no way to remove latency completely - but it can almost always be reduced to a manageable level, and often to the point where it's not really noticeable any more. Latency can be caused by many areas of your computer's setup, so it's important to be sure that everything is configured to be as efficient as possible.

These recommendations are kept very general to make them apply to as many different platforms and operating systems as possible. Any examples given are for PC systems running Windows XP SP2. If you have specific questions about different operating systems or software applications, please contact us and we'll do out best to help.

Causes of Latency

Sound Cards

Your computer's sound card is the first port of call for an audio or MIDI signal being sent into your computer. If you're using onboard sound or a standard sound card supplied with your computer, it's possible that it's just not up to the job and you might need to upgrade.

A professional sound card for recording will be specially designed to provide the lowest latency possible, so it might be worth considering a new card.

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Drivers

Even if you do have a pro-audio quality sound card, it can cause problems if you're not using the driver software supplied with it, or if these aren't installed properly.

Many sound cards designed for recording use ASIO drivers - these are specially designed to provide very low latency and should be used wherever possible.

If your sound card comes with a driver CD, install the correct driver for your operating system, following the manufacturer's instructions. If it doesn't come with a CD, check the manufacturer's website for a driver you can download. Avoid using your operating system's default drivers wherever possible - the manufacturer's own drivers are virtually always better.

Ninety-nine per cent of all "faults" with sound cards or other audio interfaces are in fact driver problems, so if in doubt, reinstall. If you're installing a new card, consider backing up important files, formatting your hard drive and reinstalling your operating system first - working with a clean system is a lot easier than trying to install new hardware on a machine clogged with old drivers, and can save a lot of time and trouble in the long run.

Software

Once your sound card's drivers are correctly installed, it's important to make sure that they're being used by whatever software you're using to record.

Most software like Cubase, Logic, Ableton or Reason will have a "Device Settings" section somewhere that will allow you to check the driver setup for your audio or MIDI devices. Ensure that this is configured to use your sound card's ASIO drivers - these will contain a reference to either the model or manufacturer somewhere in their name. If in doubt, consult your software's help file for harware configuration instructions.

System

The way your computer system is set up can also have an effect on the latency within your recording software. Latency happens because your computer can't process the audio or MIDI signal you are sending it quickly enough. The more system resources you are able to devote to the task, the faster your machine will be able to process the signal. So, it makes sense to make it easy for your computer to devote as many resources as it can to the job at hand when you're recording.

Background Applications

Make sure that you're running the absolute minimum number of other programs or background services when you're recording. Everything present in your system tray or running in the background is sapping your system's memory and processing power, even if you're not actually using it for anything. This includes your virus scanner and firewall (only exit these when you're not connected to the internet), as well as applications that run by default on startup like MSN messenger or extra toolbars.

A free startup manager program (a variety are available at www.download.com) can show you which applications are running every time you start your computer and help you to disable anything unnecessary.

Not everything that runs on startup can be safely disabled, though. Most startup manager programs can help you to distinguish between unnecessary applications and essential services. As a rule, if you don't know what it is, don't disable it!

System Maintenence

Even if your computer is correctly set up and you rarely install new software or hardware, it will still need maintaining. Every time you use your computer, new files are being created and deleted again, and in some cases these can build up as junk files. Not only do they take up hard disk space, but they can cause your computer to crash or run slower than it would without them.

A system maintainence program can be useful for finding and deleting unnecessary files and registry entries, and can speed your computer up. If you don't want to use one of these.

It's also important to regularly defragment your hard drive. Defragmenting reorganises your hard drive, so that related information is put physically close together on the surface of the disk. This allows your hard drive to access it faster, and can speed up your system.

System Tweaks

A clean, well configured system will generally give you minimum latency. However, there are other ways of tweaking your system to make it run faster.

Prioritising Background Services over Programs (in Control Panel - System - Advanced - Performance - Settings - Advanced) will cause the system to devote more resources to audio processing. Reducing the number of visual effects (Control Panel - System - Advanced - Performance - Settings - Visual Effects) will also free up more system resources.

Many websites give details of other tweaks, many of which can provide small improvements in performance. As always, back up or create a system restore point before making any changes to your Registry or making any other drastic changes.

Upgrading

If you've tried all of the above and are still having problems with latency, it may be that your computer is simply too slow to run your recording software. This may be the case if your system only just matches the minimm system requirements for a piece of software. Always try to make sure that your system matches or if possible exceeds the recommended system requirements for whatever software you're using.

If you find you need an upgrade, extra RAM will probably give you the most noticeable difference in performance for the least money. After that, upgrading your CPU chip will also make a big difference, but could work out more expensive as you may also need to buy a new motherboard.

Further Reading

Many sites on the internet provide resources for dealing with latency problems.

www.download.com provides free downloads of utility software for computer maintainence.

www.musicxp.net has information on setting up Windows XP for optimal audio performance.

www.tweakxp.com gives many tweaks to improve Windows XP performance.

If you're unsure about any of the above, or if you're not sure which products would be best for you, please contact us and we'll be happy to offer friendly, impartial advice and recommendations.

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