EE2F2 - Music Technology

1. 6. Sequencers EE2F2 - Music Technology

2. Introduction • Last time: • MIDI – How electronic instruments talk to each other • MIDI Messages – How to play a synthesiser by remote control • Today: • Sequencing – Automatically playing a tune or drum pattern • MIDI and computers – Sequencing using MIDI • The Virtual Studio

3. Early Analogue Sequencers Inputs are transmitted sequentially Three separate channels (e.g. drums)

4. A Virtual Analogue Sequencer • Functionally, this simple sequencer is very similar to an old analogue drum machine • Drum beats are selected/removed using the mouse • Drum kits of increasing complexity can be selected • You will, hopefully, discover the pros and cons of this style of sequencer

5. Modern Computerised Sequencing • The modern day equivalent of a control voltage or trigger signal is a MIDI message • A computer can be set-up to transmit pre-programmed MIDI messages at set times • The sequence can be either pre-programmed or recorded live from a MIDI controller (e.g. a keyboard) • Using the MIDI channels, up to 16 instruments can be independently controlled in this way by a single computer with a single MIDI output

6. Advantages Over Tape Recording • MIDI messages are digitally stored, perfect reproduction/duplication is implicit • Much lower bandwidth; file sizes can be around 1000 times smaller • Virtually unlimited number of tracks (although only 16 instruments per MIDI Out can be controlled independently) • Editing facilities • Tracks can be copied, looped etc. • Mistakes can be corrected • Dud notes can be erased • Timing can be made consistent (quantised) • Completely new sequences can be programmed

7. A Primitive MIDI Sequencer • MIDI events (i.e. a MIDI message plus a time-stamp) are inputted directly • Useful for investigating how MIDI works and what different messages do. • Not very good for actually making music!

8. Examples

9. Standard MIDI Files • To begin with, every sequencing package used its own file format • Swapping files was difficult if not impossible • Standard MIDI files (.MID files) are simply an agreed format that all sequencers are capable of exporting and importing files in • They are the musical equivalent of an ASCII text file – the information’s all there but some of the formatting niceties may be lost.

10. Digital Audio Features • Computers with audio outputs can transmit MIDI information and play back samples (e.g. .WAV files) at the same time • In early sequencers, samples had to be loaded into memory if you wanted to include them in a song • Now, hard disks are fast enough to play samples directly from the disk • In fact several samples of arbitrary length can be played and mixed simultaneously… • … turning the computer into a multi-track hard disk recorder and mixer

11. Virtual Studio Technology • Simple example – the computer transmits two types of data at once: • MIDI sequence to the digital piano • Digital audio sample direct from hard disk Computer Mixer Audio In Audio Out Digital Audio Track Microphone Audio Out MIDI In MIDI Sequence MIDI Out MIDI In Audio Out MIDI Out

12. Virtual Instruments • Actually, the digital piano is just a DSP running some software • If the computer can cope, why not run the same software on the computer instead • Advantages • Much cheaper – save the cost of a digital piano • Easier to program – electronic instruments often have a tiny LCD window, computer has a nice colour monitor and a mouse etc. • Less noise – digital output is implicit • Can be digitally mixed (added) to the audio track so we don’t need a mixer anymore

13. Virtual Mixing & Effects • If all the instruments are virtual and all the audio tracks are on the hard disk, you don’t need a mixer – the computer can do it • Also, the computer can easily simulate: • EQ – just like a real desk • Panning, fading etc. • Effects – many effects like reverberation are usually done digitally anyway • In fact, the only real (non-virtual) piece of studio equipment needed is the microphone (and the singer!)

14. Examples

15. Summary • Most modern recording studios are becoming computer-based • Even a modestly specified computer can: • Digitally record and play multiple tracks • Handle MIDI sequencing • Simulate multiple virtual instruments in real time • Digitally mix and apply virtual effects • Master the whole thing into an MP3 and e-mail it straight to the record company!