Ableton/Live/UG/38 Computer Audio Resources
- How Live uses the CPU and disk, and what to do when the Overload indicator lights.
- Live performs a large number of calculations every second to keep audio flowing. When the processor falls behind, playback and recording get gaps or clicks.
- What affects CPU performance:
- Clock speed — instructions per second, in GHz.
- Architecture — how efficiently the CPU runs instructions and talks to other parts.
- Cache memory — how fast the CPU fetches data.
- System bus bandwidth — how fast data moves between components.
- Temperature — an overheating CPU throttles itself.
- Live needs a multi-core processor and spreads instruments, effects and I/O across the cores.
- The CPU meter in the Ableton/Live/UI/Control Bar compares the time Live takes to compute one audio buffer with the time that buffer takes to play. 50% means computing runs twice as fast as playback; over 100% is possible.
- The operating system schedules threads, so other applications can cause spikes. The meter counts audio processing only, not work such as drawing Live's interface.
- The meter's menu, opened from its triangle button or by right-clicking:
- Average (default) — average load from audio processing.
- Current — total current, or peak, load. With both on, the menu shows both values and the meter shows average in a lighter shade and current in a darker one.
- Meter Text Shows — which of the two values appears as a number.
- Warn on Current CPU Overload — off by default; turns on CPU warnings in the Overload indicator.
- Moving audio between the CPU and the audio hardware is a constant load. Turn off unused inputs and outputs with the Input Config and Output Config buttons in the Audio Settings.
- Live does not turn them off itself, because some drivers glitch audibly whenever the audio configuration changes.
- Tracks and devices cost CPU only while they process audio. Adding devices while stopped adds little load; an effect with no input is essentially idle, and a reverb or delay stays active until its tail finishes.
- That lowers average load but not peak load. To stress-test a Set before a show, play a clip on every track with all devices on; if the CPU meter's Current value stays well under 100%, the Set should hold up.
- The mixer's Performance Impact indicators show each track's share of the load as six rectangles. Turn them on from the Show/Hide Mixer Config menu at the bottom right, or View → Mixer Controls.
- Freeze a heavy track, or turn off some of its devices, to lower its impact.
- Freeze Track renders every Session and Arrangement clip on a track to a sample file, so playback stops recomputing its devices and clip settings. Run it from the Edit menu, a track or clip context menu, or
Cmd+Option+Shift+F (Mac) / Ctrl+Alt+Shift+F (Win). - Only tracks holding clips can be frozen, so Group Tracks, return tracks and the Main track cannot. Tracks using External Audio Effect or External Instrument freeze in real time.
- A frozen track's device and clip settings are locked until Unfreeze Track. Bounce Track in Place commits a track to new audio for good, and also works on Group Tracks.
- Still available on frozen tracks: clip launching, volume, pan and sends, and also:
- cutting, copying, pasting, duplicating and trimming clips
- drawing mixer automation and mixer clip envelopes
- consolidating clips
- recording Session launches into the Arrangement
- creating, moving and duplicating scenes
- dragging frozen MIDI clips onto audio tracks
- Edits to a frozen track with time-based effects can sound different after unfreezing, because those effects are recomputed then.
- Frozen Arrangement tracks keep effect tails as crosshatched temporary clips beside the original clips; select the tail along with its clip when moving it. Frozen Session clips hold only two loop cycles.
- Dragging a frozen clip into a drop area makes a new frozen track with that clip, or only its selected part.
- Freeze files go in the project's
Samples/Processed/Freeze folder, or the Temporary Folder for an unsaved Set. Freezing also lets a slower computer, or one missing a device, play a Set.
- When the disk cannot read or write fast enough, audio drops out and the Overload indicator flashes. Disk traffic grows with the number of audio channels in use; a stereo sample costs more than a mono one.
- Ways to lower it:
- Put layered clips, such as stacked vocals, into a Group Track and bounce the group in place to one file.
- Use RAM Mode on audio clips, so Live reads them from memory instead of disk.
- The Overload indicator in the Ableton/Live/UI/Control Bar shows "Disk" when the disk falls behind and, once CPU warnings are on, "CPU" when the processor is overloaded.
- CPU warnings are off by default. Turn them on with Warn on Current CPU Overload in the CPU meter's menu or CPU Overload Indicator in the indicator's context menu; the two options share one state.
- Both kinds of overload can cause dropouts or crackles while playing or recording.
