the CPU meter lights up, our percentage jumps higher than jordan, clicks, pops, gaps, & distortions penetrate our audio. we've all gotten to the end of a mix & had our computers struggling to handle all the processors that have built up.
what's going on & how to stop it? what the CPU meter displays is somewhat confusing, but the easiest way to think about it is as capability at a given speed. in order to process audio in apparent real-time, live must make tons of calculations & the CPU meter determines how much of that allotted time (determined by a variety of factors, namely sample rate & buffer size) is being used. in other words, if your CPU is hitting 99%, live is finishing its requested calculations just barely in time to deliver them when requested. conversely, if the CPU hits 10%, live is only using a portion of its available buffer time & then waiting (albeit fractions of a second). you can learn more about this in the live manual.
CPU isn't always a problem, but when it is, it is prohibitive. let's look at some of the ways we can ease live's load & alleviate problems.
this one is perhaps the most obvious, but it's worth mentioning - a low buffer size is great for tracking & performance when low latency is essential, but it's one of the biggest factor determining the CPU meter's capacity. when doing heavy mixing, it's worth bumping this up to 1024 or 2048 to maximize processing time. keep in mind this is literally determining the amount of time the program has to perform its calculations before you require the audio's "delivery".
sample rate is a critical factor of digital audio - it's basically what's carrying all those 1's & 0's that recreate sound. 44.1 kHz is cd quality & is standard because it's twice the range of human hearing plus a little bit extra for safety. higher sample rates transmit information on frequencies outside the audible spectrum & thus are wholly unnecessary (not to mention take up tons of extra processing power). there's an argument to be made for 48 kHz, & special applications that benefit from higher sample rates (mostly video & fringe audio), but for the average music producer 44.1 kHz (or 48 kHz, if you must) is perfectly sufficient.
freeze/flatten has to be one of the best features of live. right-click any track (midi or audio) & select the freeze option. this will render out your audio so the processors don't have to run on it, thus saving CPU. you won't be able to change settings, but you can unfreeze at any time to make adjustments as needed. keep in mind you can render out multiple tracks at once to save time!
flatten simply replaces the existing track with the frozen, rendered one. when you want to commit to a processed track or quickly switch a midi instrument to an audio clip, this can be extremely handy (& CPU saving - though no more than if just frozen. the only difference between the two is a flattened track is then editable).
if you're putting the same effect on every track, better to just use a return track & process them all at once. otherwise, every instance of a plugin or processor is pulling CPU power.
another no-brainer, enabling this option gives live permission to distribute its processing loads across multiple cores of your computers processor, granting it access to more computing resources. definitely worth ensuring this is checked.
plug in to power if you're using a laptop. when your battery gets low, your computer conserves its resources & live can't pull as much power. this will be extremely noticeable when you get into the 5% range, so make sure this isn't what's preventing you from completing your mix!
turning off what's not needed
this has a very slight effect, but in a very large live set it can make a difference. basically, the idea is ableton is monitoring every stop button & if it doesn't need to be, you can reallocate those (very small) resources elsewhere.
RAM is useful if your disk drive is slow, as it stores the clip into memory rather than reading it from storage, but this literally commits a portion of your CPU to temporarily storing audio, so only use this if you have plenty of processing leftover.
the "HiQ" uses better interpolation for higher quality pitch-shifting at the expense of CPU. worth using if you can, worth turning off if you aren't transposing clips & need the extra processing (you can always render out the transposed audio & turn off HiQ if you want the best of both worlds).
like the rest of these, don't make live work for stuff you're not using! this can be extra oscillators, filters, or lfo's on your synth or high-quality modes on unimportant processors.
there's no reason for live to listen of input if you aren't pulling in audio from them. especially if you have an unused optical expansion on your interface, these should be disabled. this has the added benefit of making your ext. inputs & outputs less cluttered.
live uses the same resources as the rest of your system, so closing down other application can free up processing power for your audio. the same logic applies to turning off wi-fi & bluetooth, so if you're having serious trouble it might be worth trying to nix them.
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