› Audio Latency

How Audio Latency Can Affect 
Your Recording and Mixing


Audio latency is an issue that can cause problems when recording audio through a computer system. But despite these issues, it can be minimized so the problem is no longer noticeable.


I used to get this problem quite often when I was using an old and slow computer in the studio, but it's an area that in general has become easier to handle as computers have become quicker and more powerful.




What is Latency?

Audio latency can become a problem in the studio, but the effect is easily minimized


When recording a vocal or an instrument, latency refers to the time delay that you hear between:


  • the live performance of the musician or vocalist being recorded,
  • this recording then playing back from the hard drive and through monitors or headphones.


The delay between what is played and what is heard back happens because the signal that enters the audio sound card doesn't exit the sound card at the same time. It can cause major problems for musicians, engineers, and producers in the studio when recording a performance or take, as the time difference can make it impossible for anything to be played in time with the rest of the track.


There's no way to completely get rid of this latency, but there are things you can do to minimize it. A latency time of around 10ms or less usually means that it won't affect the recording process. Above 10 ms, the effect starts to become noticeable.




Audio Interface Latency


So why does audio latency happen? There are several reasons why it's introduced into a computer audio system:


  • Audio interface latency, where during recording the audio is converted from analog to digital, and during playback it's converted from digital back to analog so it can be played through studio monitors or headphones.
  • Digital signal processing (DSP).
  • The path through cables, mixers, hard drives etc.


All of these factors can introduce timing delays. Although each delay is very small (sometimes just fractions of a millisecond), they can quickly add up into quite a sizable delay.




How to Reduce Audio Latency


Whenever I notice an issue with latency during recording or mixing, I always run through a few points that usually solves the issue with no further problems:


  • Close all other programs running on the computer, apart from those you have open for your audio work. You could even try restarting your computer.
  • Reduce the buffer size inside the sound card's software and/or your DAW. If the buffer is too low it can cause glitches, and if it's too high this can cause audible latency, so you'll have to try different settings that work well with your computer system. The more powerful the system and the better the sound card, the less trouble you'll potentially have with this buffer size issue.
  • Look at the CPU usage of your system. See if you can increase or decrease the amount of processing power that's assigned to your DAW.
  • Use zero-latency monitoring. This is a feature of the sound card which bypasses the effects of computer-based latency. You can listen to the input that's being recorded through the monitors or headphones, before the signal enters the analog-to-digital/digital-to-analog conversion process.
  • Check that your drivers are up-to-date for your sound card.
  • Delete or make inactive some tracks and plugins, or try to make your use of tracks and plugins more efficient. An example would be to try using one or two reverb plugins instead of four or five.




Pro Tools Latency


Pro Tools contains a feature called the Playback Engine, where you can adjust some internal settings to help reduce Pro Tools audio latency. Some of the settings are:


  • H/W Buffer Size - if you're having latency issues during recording, try lowering the buffer size to as low as possible. But if you have lots of active plugins and tracks, which you'll usually have during the mixing stage, then a low buffer can cause system issues, so you'll have to raise the buffer size again. If you have recording issues and you have lots of plugins on lots of other tracks, try disabling some tracks or plugins, which will free up resources for your recording to take place.
  • CPU Usage Limit - set this to as high a value as you can. If you're having issues, try lowering this number, especially if you haven't got that many plugins being used. If you've set it too low, you should get an error message.
  • RTAS Processors - select as high a number as you can.
  • DAE Buffer - it's best to leave these at their default settings, Size Level 2 and Normal Cache Size.




Final Thoughts


The issue of audio latency can easily be solved once you know where to look inside your computer. You'll probably have to try a few different settings to see what works as one computer is always slightly different to the next. But the good news is that many computers these days are powerful enough and quick enough to prevent the problems linked with latency before they even start.



 

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