$Page Setting up Audio I/O $TargetName Setting up Audio I/O $Comment Mac Version In this lesson, we'll set up and optimize Live's *audio I/O* (its audio *input* and *output* capabilities). It will take us about ten minutes to configure everything, but this process only needs to be done once for each audio interface you use. When we're finished, we'll have accomplished the following things: -> Selecting a driver type -> Choosing input and output devices -> Configuring ins and outs -> Selecting the sampling rate -> Adjusting the audio I/O buffer size Please press the *Next Page* button below to proceed. $Comment -------------------------------------------------------------------------------- $Page Opening the Audio Preferences $TargetName Opening the Audio Preferences The audio I/O settings are found in Live's *Audio Preferences.* You can reach them by selecting the *Preferences...* entry from the *Live* menu, or by using the keyboard shortcut *$CommandMod + ,* ($CommandMod + comma). PrefsMenuMac.png When the Preferences window opens, select the *Audio* tab: AudioTabFull_Mac.png Divider.tif *Tip:* You might want to drag the Preferences window to another location on your screen so that it doesn't get hidden behind Live's main window as we follow the lesson. If it does get lost, simply press the *$CommandMod + ,* shortcut again to bring it back. $Page Selecting the Audio Device $TargetName Selecting the Audio Device The *Audio Device* settings refer to physical audio interfaces which are either built-in to your computer or connected to it externally. Live communicates with audio devices through a piece of software known as a *driver.* In our first step, we'll use the *Driver Type* chooser to tell Live which driver to use. On macOS, audio I/O is usually handled by a *Core Audio* driver. Please select this from the Driver Type chooser, unless another entry appears which better matches your configuration: DriverChooser_Mac.png Once you've selected a driver type, you'll be able to specify inputs and outputs using the *Audio Input Device* and *Audio Output Device* choosers: IODevicesChoosers_Mac.png The choices available to you here will depend upon your specific hardware and software setup. If you don't see your audio interface listed in these choosers, it probably requires a driver install before it can be recognized; check the manufacturer's documentation for details. There is also a *Use System Device* option, which sets the input/output device in Live to match what is set in the macOS Sound System Preferences. UseSystemDefault_Mac.png Divider.tif *Note:* Although Core Audio allows two different devices to be used for input and output, we recommend selecting the same device for both in order to avoid potential problems. $Page Configuring Ins and Outs $TargetName Configuring Ins and Outs The *Input Config* and *Output Config* buttons determine which of the interface's inputs and outputs can be used by Live, and whether they can be accessed individually (mono), as stereo pairs, or both: ChannelConfigButtons_Mac.png $If Product 03 Divider.tif *Please note that there is a limit of four mono inputs and four mono outputs in Live Intro.* Divider.tif $Endif $If Product 04 Divider.tif *Please note that there is a limit of four mono inputs and four mono outputs in Live Lite.* Divider.tif $Endif The buttons open a window with a pair of On/Off switches for each pair of input or output channels available: InputConfigWindow.png The right column of switches enables pairs of channels for stereo use, while the left column enables them for use as two independent mono channels. If inputs 1 and 2 are always connected to a turntable, for instance, you'll only need to access channels 1 and 2 in stereo. On the other hand, if inputs 1 and 2 are always connected to microphones, you'll only need the mono switch enabled. You can also enable both switches so that you're free to choose the most appropriate configuration for any moment. This is useful for connections that change frequently. When working with the computer's built-in stereo hardware interface, for instance, you might record from a microphone in mono, then reconnect a few minutes later to record in stereo from a turntable. Deactivate *both* switches for any inputs or outputs which you don't use: Disabling unused channels optimizes CPU performance. You can set names for mono or stereo input and output channels using the text fields to the right of the On/Off switches: InputConfigWindowNames.png These names appear in all Input/Output Channel chooser dropdowns within the mixer's In/Out section: InputChannelChooserNames.png Note that the names you set for each channel are always associated with their respective audio device. Click the *OK* button once you've configured your I/O channels to return to the Audio Preferences. $Page Selecting the Sample Rate $TargetName Selecting the Sample Rate The *In/Out Sample Rate* setting determines the sampling rate at which Live and your audio interface operate. On some audio devices, this rate may be fixed (usually at 44,100 Hz). SampleRate.png Audio clips with different sample rates can be used together in Live, because Live performs real-time sample-rate conversion. However, Live will record all new audio clips at the sample rate chosen here. Divider.tif *Background Information:* The term "sample rate" refers to the number of samples per second that are used to represent a sound digitally. A digital representation of a sound is always more accurate at a higher sample rate. Unfortunately, high sample rates are CPU-intensive, since they require more calculations (there are more samples to process) per second of audio. The sample rate for CD-quality audio is 44,100 samples per second; this is usually a suitable Sample Rate setting. $Page Using the Test Tone $TargetName Using the Test Tone All audio passing through your computer is stored momentarily in *buffers* - little sound reservoirs which keep the audio stream flowing when your CPU needs to pay attention to other tasks. Large buffers ensure an uninterrupted flow of audio at the expense of a "sluggish" response in the software. Small buffers provide a snappier response, but are more likely to "run dry," interrupting or mangling your sound. The *Buffer Size* setting lets you define the optimal balance between responsiveness and stability. To find the correct value for your system, we'll have Live simulate the kind of CPU-intensive situation that arises when many tracks, virtual instruments and effects are in use. Locate the *Tone Volume* parameter in the *Test* section of Live's Audio Preferences, and lower it all the way to *-48 dB:* ToneVolumeMin.png Set the *CPU Usage Simulator* to the maximum value of *80%:* CPUUsageSim.png $Page Adjusting the Buffer Size $TargetName Adjusting the Buffer Size Activate the *Test Tone* by clicking on its switch: TestTone.png At this point, things might start to slow down, because the Test Tone also activates CPU Usage Simulator. Raise Tone Volume slowly until you can hear the test tone clearly. Then, in the *Latency* section, set the *Buffer Size* control to its lowest value: BufferSize.png You'll probably hear clicks or dropouts in the Test Tone's output. Slowly increase the buffer size until the clicks or dropouts stop. Find a value just high enough that the signal passes through undisturbed. Note that you can also use your keyboard's arrow keys to adjust the slider after selecting it with the mouse. Once you've found a stable setting, you can turn the Test Tone switch off again. Divider.tif *Note:* Hard drive activity can impose additional constraints on the minimum buffer size. If the sound breaks up while playing or recording multiple tracks of audio, you should probably choose a slightly higher buffer size. $Page Related Factors $TargetName Related Factors There's still one factor remaining to be tuned: *Driver Error Compensation.* Latency.png This setting is only relevant for those of you who record audio into Live. We recommend that you first learn the basics by following the lesson $Link Recording Audio ; then, if necessary, you can follow the $Link Driver Error Compensation lesson to set this accurately. $Comment Status: Translate