THE DIFFERENCES BETWEEN AUDIO AND MIDI
In a recording studio, the differences between digital audio and its original sound source are an essential part of understanding how digital music is produced. This section will cover the key points and fundamental differences between audio, digital audio, and midi data, as they relate to music production in a recording studio.
AUDIO SIGNALS AND DIGITAL AUDIO
Audio is acoustic vibrations that you can hear. Digital audio, is basically a digital recording of an analog signal. It is stored as a sound file and processed by a digital device. (I.E. your computer) Digital audio is recorded to hard disc, and can be manipulated in a number or ways. In a digital audio workstation, an audio signal is transmitted in one of the two following forms before it can be recorded.
- Sound Waves - Sound Waves are audio in its original form. It is transmitted by vibrations through the air. (What you hear)
- Electrical Signals - Are varying amounts of voltage carrying musical information through the signal path. (I.E. Recording into a microphone converts the audio into an electrical signal, or, an amplifier transmits analog signals.)
AUDIO RECORDING WITH A MICROPHONE
1) Acoustic instruments emit sound waves that are recorded or amplified through a microphone.
2) Microphones transfer the sounds into electric voltage, which is called the signal.
3) The analog signal is sent from the microphone, to an audio interface which converts the audio signal into a digital audio file.
4) The audio waveform is sent through your multi track recorder/sequencer where it is displayed, and stored onto hard disc
for random access editing.
Before being accepted into this new digital realm of flexible existence, analog signals must be converted into a digital audio file. This transformation is processed by an analog to digital converter, which measures electrical signals transmitted by a microphone, and converts them into digital audio samples. Yes, even though your a/d converter is inside of your audio interface and you may not see or use an external converter, you should understand their effect on the signal path.
(Learn more about the analog to digital converter here.)
The analog signal can be sent to an amplifier and external speakers to be monitored in its current format. Further, it can be sent to an analog recorder (i.e. reel-to-reel) for printing the audio onto cassette tape.
Analog recorders, and multi track tape recorders have been the standard for audio recording and music production - only up until recent advances in digital audio over the last several years. Today they are practically unused in the recording industry.
What are the advantages of digital audio?
Digital audio and midi recordings conveniently offer random access editing directly from the hard disc. This allows you to edit
any part of the audio file at anytime seamlessly. This functionality
of the digital recording studio is the new benchmark of audio
recording. It removes many limitations of its predecessor
digital audio tape.
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MIDI PRODUCTION
MIDI (Musical Instrument Digital Interface) is a computer-generated data protocol that triggers tones and tells them when to start and stop, how loud to play these tones, (velocity) and other informational commands. It is important to understand that MIDI is not audio, and cannot be processed or edited the same way.
MIDI has been used since it was introduced in 1983. The last couple of decades have made it a standard computer format that is universally compatible. Midi has become very efficient for composing digital music since it uses much less hard-disc space or processing power than audio file formats.
Midi (Musical Instrument Digital Interface) is a universal format
used for recording musical performance data to hard disc, or other digital medium. It is a protocol that is understood by any computer
- via midi interface.
(Similar to the standard “platform independent” language of html)
Midi data is used to sequence musical notes made by synthesizers and samplers.
In review, audio is a live sound. Audio is the original vibrations made by an acoustic guitar, a vocalist, etc. Audio is received by a microphone and transmitted as a signal. It is sent as an electrical signal to any desired destination, such as a recorder, amplifier, etc. Recording the original audio signal using music software is done by converting the audio signal into a digital audio file. This conversion happens when the signal passes through an analog to digital converter in audio interfaces or soundcards. This is a hardware device needed to translate the analog signal into a digital audio recording.
Midi is computer data that is recorded and read back on command by your computer. This information is used to triggers sounds, then together record both elements using an audio and midi sequencer. The song file and all relative audio file components are stored onto hard disk for the convenience of random access editing.
Benefits of Midi?
MIDI uses significantly less computer resources for track recording and mixing. It is now a standard music composition tool. Midi has advanced over the last couple decades to now being a revolutionary composition and production tool.
