If your bass player is playing behind the beat is that latency? “I’ve been reading about computer digital audio latency and I know why it’s there, but what is typical in practice with a medium speed computer, 16 – 24 tracks, plug ins running, etc? Also, do hardware disk recording systems (such as the Akai DR series, and the Fostex hard disc recorders) also exhibit throughput latency? How much?”
Latency has become a big buzz word in the industry because most host based computer digital audio systems have enough that it can be a problem. That is the time delay between when you play a note and when you hear it come out of the system is great enough that it can be hard to play, especially against already recorded tracks. The latency in these systems is caused by three major factors: The A/D, D/A converters, the processing buffer delay, which is the processor “handling” the audio, and the drivers that may pass the data from one processing subsystem to another inside the computer. “Typical” delays for most real world sessions on a decently fast properly configured computer are in the range of 12 – 30 ms, but can fall well outside of this range depending upon the exact configuration. Things like Direct I/O, for example, can dramatically reduce latency on some systems. There are really too many potential variables to quantify it easily. The buffer is generally where most of the delay comes from. Some systems allow the user to set the buffer size small enough to eliminate most of the latency, but at the expense of computer overhead. This means that the computer can’t handle as many tracks or plug-ins. It’s all a big compromise. Some software comes with a low latency streamlined version of the program or a special mode in the programs specifically to handle audio I/O in overdub situations. Hardware systems do still have an A/D, D/A converter delay of roughly 1.5 ms, and some additional buffer delay, but the total delay is usually well under 5 ms, which is easy to play along with. Any computer based system with dedicated hardware to do the processing and handling of the audio such as Pro Tools, and the Yamaha DSP Factory (among others) is going to have very minimal latency as well.