14 3 2 Playing MIDI With the Computer Keyboard

pcbuck April 22, 2021 0 Comments

14.1 Monitoring

“Monitoring,“ in the context of Live, means passing a track’s input signal onto the track’s output. Suppose you have set up an audio track to receive itsinput signal from a guitar. Monitoring then means that the signal from yourlive guitar playing actually reaches the track’s output, via the track’sdevice chain. If the track’s output is set to “Master,“ you can hear theguitar signal, processed by whatever effects are used (and delayed by whateverlatency the audio hardware interface incurs), over your speakers.The In/Out section offers, for every audio track and MIDI track, a Monitorradio button with the following three options: * The default Auto-monitoring setting does the right thing for most straightforward recording applications: Monitoring is on when the track is armed (record-enabled) (see Chapter 16), but monitoring is inhibited as long as the track is playing clips.Audio and MIDI Track Arm Buttons. * To permanently monitor the track’s input, regardless of whether the track is armed or clips are playing, choose In. This setting effectively turns the track into what is called an “Aux“ on some systems: the track is not used for recording but for bringing in a signal from elsewhere (for instance, a ReWire device program). With this setting, output from the clips is suppressed. An “In“ monitoring setting can be easily recognized even when the In/Out section is hidden by the blue color of the track’s Activator switch. * Monitoring can be turned off altogether by choosing the Off option. This is useful when recording acoustic instruments which are monitored “through the air,“ when using an external mixing console for monitoring or when using an audio hardware interface with a “direct monitoring“ option that bypasses the computer so as to avoid latency. Generally, it is preferable to work with an audio interface that allows for negligible latencies (a few milliseconds). If you are recording into Live with monitoring set to “Off,“ you may want to make the Audio Preferences’ Overall Latency adjustment, which is described in the built-in program tutorial on setting up the Audio Preferences.If multiple tracks are selected, pressing one of the Monitor buttons appliesthis selection to all of the selected tracks.

14.2 External Audio In/Out

An audio interface’s inputs are selected by choosing “Ext. In“ from the InputType chooser of an audio track. The Input Channel chooser then offers theindividual input channels. Entries in this chooser each have meters next totheir names to help you identify signal presence and overload (when the meterflashes red). Setting up the audio interface’s outputs works the same way viathe output chooser pair. If multiple tracks are selected, any changes you maketo these choosers will be applied to all selected tracks.The list of available inputs and outputs depends on the Audio Preferences,which can be reached via the Input and Output Channel choosers’ “Configure…“option. Note that the Audio Preferences also provide access to the ChannelConfiguration dialogs, which determine which inputs and outputs are used, andwhether they are available to Live as mono or stereo pairs. Essentially, theChannel Configuration dialog tells Live what it needs to know about how thecomputer is connected to the other audio components in your studio.You can rename any input and output channels that appear in the ChannelConfiguration dialogs. If changed, the new name(s) will be displayed in thecorresponding Input / Output Channel chooser drop-down. You can renamechannels more quickly by using the `Tab` key to move between them. Note thatchanged names are always associated with their respective audio device.

14.3 External MIDI In/Out

MIDI from the outside world is routed into Live just like audio. From theInput Type chooser of a MIDI track, you can either select a specific MIDIinput port or “All Ins,“ which is the merged input of all external MIDI ports.The Input Channel chooser offers the individual input channels of the selectedMIDI port and the merged signal of all channels, “All Channels.“ As is thecase with audio inputs, the Input Channel chooser also has meters next toevery entry to represent activity on the respective input channel. If multipleMIDI tracks are selected, any changes you make to these choosers will beapplied to all selected tracks.

14.3.1 The MIDI Ports List in the Preferences

The MIDI Ports List in the Preferences.You can configure which MIDI ports are made available to Live using the MIDIPorts section of the Link/MIDI Preferences. All available input and outputports are listed here. For Live’s tracks to receive/send MIDI from/to aspecific MIDI port, the corresponding switch in the Track column must be setto On. You can use any number of MIDI ports for track input and output; themixer’s In/Out choosers allow them to be addressed individually.

14.3.2 Playing MIDI With the Computer Keyboard

The computer keyboard can be used for generating MIDI notes from computerkeyboard strokes. To turn the computer MIDI keyboard on, use the Control Bar’sComputer MIDI Keyboard button, or the `M` shortcut to the Options menu entry.Activating the Computer MIDI Keyboard.The center row of letter keys on the keyboard will play notes corresponding tothe white keys on a piano, beginning on the left with the note C3. The blackkeys on a piano correspond to the upper row of computer keys. The fourleftmost letters on the lower row of the keyboard (Z,X,C, and V on aU.S.-English keyboard) are used to transpose the note range and to setvelocity, as follows: * The leftmost keys (Z and X) adjust the keyboard’s octave range. * The next two keys (C and V) adjust incoming note velocity by intervals of twenty (20, 40, 60, and so on).As it happens, when the computer keyboard is set to send notes between C3 andC4, the keys are mapped to MIDI notes such that the center row of the keyboard(ASDF…) addresses the Impulse percussion sampler’s sample slots (see 24.5).This means that you can play and record drum patterns right off the computerkeyboard.Note that when the computer MIDI keyboard is activated, it will “steal“ keysthat may have otherwise been assigned to remote-control (see 27.2.5) elementsof the Live interface. To prevent this, you can turn the computer MIDIkeyboard off when it is not needed.

14.3.4 MIDI In/Out Indicators

Live’s Control Bar contains three pairs of indicator LEDs that tell you aboutincoming and outgoing MIDI. These indicators tell you not only about thepresence of signals, but also about their use. In every pair, the upperindicator flashes when a MIDI message is received, and the lower indicatorflashes when a MIDI message is sent.The Control Bar’s MIDI Indicators.The three indicator pairs represent, from left to right: 1. MIDI Clock and Timecode signals that are used for synchronizing Live with other sequencers (see Chapter 30). Note that this set of indicators is only visible when an external sync source has been enabled in the MIDI Ports List in the Preferences; 2. MIDI messages that are used for remote-controlling Live’s user-interface elements (see Chapter 27); 3. MIDI messages coming from and going to Live’s MIDI tracks.MIDI messages that are mapped to remote-control Live’s user-interface elementsare “eaten up“ by the remote control assignment and will not be passed on tothe MIDI tracks. This is a common cause of confusion that can be easilyresolved by looking at the indicators.

Post-Effects Recording

Let’s say that you are feeding a guitar into Live, building up a song track bytrack, overlaying take onto take. It is certainly powerful to have a separateeffects chain per track for applying different effects to different takes —after the fact. You might, however, want to run the guitar signal througheffects (a noise gate or an amp model, for instance) before the recordingstage, and record the post-effects signal.An Example Setup for Post-Effects Recording.This is easily accomplished by devoting a special audio track for processingand monitoring the incoming guitar signal. We call this track “Guitar“ anddrag the desired effects into its device chain. We do not record directly intothe Guitar track; instead we create a couple more tracks to use for recording.Those tracks are all set up to receive their input Post FX from the Guitartrack. Note that we could also tap the Guitar track Post Mixer if we wished torecord any level or panning from it.As for monitoring, we set the Guitar track’s Monitor radio button to In,because we always want to listen to our guitar through this track, no matterwhat else is going on in Live. The other tracks’ Monitor radio buttons are setto Off.

Recording MIDI as Audio

When working with MIDI and complex software instruments, it is sometimes moreuseful to record the resulting audio than the incoming MIDI. A single MIDInote can prompt, for example, Native Instruments’ Absynth to produce somethingthat sounds more like a piece of music than a single tone. This output lendsitself more to representation as an audio waveform than a single note in aMIDI clip, particularly when comparing the editing options.Recording the Output of a Complex Instrument in Audio Tracks.A setup similar to the one described above (see “Post-Effects Recording”)accomplishes the task. We have one MIDI track hosting the virtual instrument,and we use additional audio tracks to record the audio result of playing theinstrument.

Several MIDI Tracks Playing the Same Instrument

Consider a MIDI track containing a virtual instrument — a Simpler playing apad sound, for example. We have already recorded MIDI clips into this trackwhen we realize that we would like to add an independent, parallel take forthe same instrument. So we add another MIDI track. We could now drag anotherSimpler into the new track, but we would really like to reuse the Simpler fromthe pad track, so that changing the pad’s sound affects the notes from bothtracks.Feeding an Additional MIDI Track Into an Existing MIDI Track to Reuse itsInstrument.This is accomplished by setting the new MIDI track’s Output Type chooser to“Pad.“ Note that the Output Channel chooser now offers a selection ofdestinations: We can either feed the new track’s output into the input of thepad track, or we can directly address the Simpler. The “Track In“ option inthe Output Channel represents the pad track’s input signal (the signal to berecorded), which is not what we want. We instead select “Simpler Ch. 1“ tosend the new track’s MIDI directly to the Simpler, bypassing the recording andmonitoring stage. With this setup, we can choose to record new takes on eithertrack and they will all play the same pad sound.The Instrument Has Been Isolated in a Dedicated Track.We might be bothered by the fact that muting the pad track (by turning off itsActivator switch) also mutes the other MIDI track. To be precise, the othertrack keeps playing, but its MIDI is played by an instrument that is out ofthe mix. This can be easily remedied by cutting the clips from the pad trackand pasting them into a third track that can be independently muted (and thatcan hold its own MIDI effects). The original pad track now acts as a mereinstrument container. As we are not recording new clips into this track, wecan set its Input Type chooser to “No Input,“ which makes its Arm buttondisappear and helps to avoid confusion when the mixer’s In/Out section ishidden.

Using Multi-Timbral Plug-In Instruments

Many plug-in instruments support multi-timbral operation. A multi-timbralinstrument is like several instruments in one, with each component “part“ (orwhatever term the manufacturer uses) receiving MIDI on a separate MIDIchannel. Usually, the multi-timbral instrument offers individual outputs sothat the parts can be separately routed into the mixer. Or, the instrumentmight offer a submixer of its own.Tracks Feeding MIDI to and Tapping Audio From the Parts of a Multi-TimbralInstrument.Sending MIDI from the mixer to a multi-timbral instrument is a variation of acase described above (see “Several MIDI Tracks Playing the Same Instrument”).One MIDI track hosts the multi-timbral instrument, and additional MIDI tracksare used to feed its individual parts. Each additional MIDI track has itsOutput Type chooser pointed to the track that contains the instrument, and itsOutput Channel chooser referencing the target MIDI channel. Additional audiotracks can then be used to tap the instrument’s individual outputs, asdescribed earlier (see “Tapping Individual Outs From an Instrument”).It is also possible to use the External Instrument device to route MIDI to(and audio from) the secondary outputs on multi-timbral plug-ins. Thisscenario eliminates the need to create an additional audio track for eachtapped output: 1. Insert the multi-timbral instrument on a MIDI track. 2. Insert an External Instrument device on another MIDI track. 3. Select the track that contains the instrument in the first MIDI To chooser on the External Instrument device. 4. Select the MIDI channel to route to in the second chooser on the External Instrument device. 5. From the External Instrument’s Audio From chooser, select a secondary output on the instrument to which you are sending MIDI.Repeat steps 2-5 to feed and tap additional components of your multi-timbralinstrument. You could also put the entire system of External Instrumentdevices into a single track, by placing each one in a Rack’s device chain.Note that the main outputs of the multi-timbral instrument will still outputto the track that contains the instrument — only auxiliary outputs areavailable to the External Instrument device.

Inputs and outputs

The inputs to the ALU are the data to be operated on (called operands) and acode from the control unit indicating which operation to perform. Its outputis the result of the computation. One thing designers must keep in mind iswhether the ALU will operate on big-endian or little-endian numbers.In many designs the ALU also takes or generates as inputs or outputs a set ofcondition codes from or to a status register. These codes are used to indicatecases such as carry-in or carry-out, overflow, divide-by-zero, etc.A floating-point unit also performs arithmetic operations between two values,but they do so for numbers in floating-point representation, which is muchmore complicated than the two’s complement representation used in a typicalALU. In order to do these calculations, a FPU has several complex circuitsbuilt-in, including some internal ALUs.In modern practice, engineers typically refer to the ALU as the circuit thatperforms integer arithmetic operations (like two’s complement and BCD).Circuits that calculate more complex formats like floating point, complexnumbers, etc. usually receive a more specific name such as FPU.

Instrument Level, Mic Level, and Line Level Signal

There are 3 different levels of analog signal that you’ll be commonlyworking with. Instrument level signal is produced by guitars and basses andmic level signal is generated by microphones; these types of signals need tobe amplified to line level signal before getting run through outboard deviceslike compressors, EQs, saturators, etc. You can bring an instrument level signal up to line level by either running itthrough a standalone DI box or running it through one of the HI-Z (highimpedance) inputs on your audio interface. To bring a microphone’s signal upto line level, you’ll need to run it through a mic preamp. Your audiointerface likely has at least a couple of built-in mic preamps, so astandalone preamp probably isn’t required. For example, on my Apollo x8, there are 2 Hi-Z inputs, 4 microphone inputsalong with 4 built-in mic preamps, and 8 line level inputs. This means I canconnect 2 guitars, 4 microphones, and 4 line level signals at once. Themicrophone inputs are switchable with the first 4 line inputs, so I canpotentially record 8 line level signals at one if I choose not to connect anymicrophones.

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