Drummer ITP is designed to automatically compensate for audio latency, but for some devices it may be necessary to activate the manual ‘Learn Latency’ feature, accessed in the App Settings section of Drummer ITP. It is only necessary to use this feature if the app doesn’t measure its own click sound to 100% accuracy.
But what is latency? Latency is the amount of time an audio device takes between playing a sound and recording that same sound back into the system. The sound leaves the device at the loudspeaker, travels through the air and then sound comes back in from the microphone ideally at exactly the same time. This is important in recording studio scenarios, because if you are recording some Tamborine over a previously recorded drumbeat, then the audio that you record needs to be perfectly in time with the audio that you hear and play along too. Latency also occurs when sending sound out to audio devices and other equipment, it even takes a few milliseconds for sound to travel through air (approximately 3 feet travelling Ellen per millisecond) so latency is just something we can’t avoid in audio systems.
Luckily, advanced audio systems are able to work out what the latency is and then compensate for this very small time delay. An easy way to implement this is to play a sharp quick sound and then record that same sound back, and compare the timing of the two. All DAW workstations incorporate a latency buffer to allow for this time delay and to allow the software to perform all of its functions which all take some time to process. Drummer ITP works join these exact same principles – you listen to the click and then play along, and if you play perfectly fun time then there should be no time difference between the two sounds. So we need a latency value to tell the ITP algorithm how much delay is purely from the electronics of the iPhone and then it can work out how close your playing is, to a very precise accuracy. Drummer ITP knows the latency of the iPhone already, but some iPads and other setups have slightly different electronics inside, so it might be necessary to recalibrate the apps ;latency with the Learn Latency routine.
Before using Learn Latency in the App Settings page, go back to the main Drummer ITP display and turn up the volume of the click so that the app measures its own sound output. The accuracy indicator light should position itself in the middle of the display, and sound should be recorded to 100% accuracy and 100% consistency. If 100% self-accuracy is not measured, then use the Learn Latency feature to calculate the necessary latency offset. Ensure that the click sound is audible before running Learn Latency. You’ll be guided through the process and the app should be able to record its own clicks to 100% accuracy after the latency has been setup.
From the App Settings page you can also adjust the microphone sensitivity, to ensure that all of your practice pad stick hits are measured correctly.
Additionally, in manual mode, it’s possible to switch off the ‘Interval Analysis’, which means that only the accuracy of your hits on the beat are used in the calculation. So with Interval Analysis switched off, you can play a swing style or experiment with pushing and pulling your hits on the intervals, and you’ll only be penalised if you are out of time on the 1, 2, 3 or 4 beat counts. It is also possible to set a pronounced or accented ‘beat one’ sound to the metronome, and then use this setting to designate how many beats are in a bar.
Download Drummer ITP in the iPhone App Store