The MIDI Sequencer - continued.

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This section walks you through some of the main features and functions of Windows based MIDI sequencer software, with reference to one particular package: Passport Designs Master Track Pro 6.  Other sequencers will obviously vary significantly in appearance and screen layout, but from a functional point-of-view will be broadly equivalent.  It is worth noting here that most MIDI sequencer software is Windows based (whether using PC, MAC, Atari or other platforms), since the windows Graphical User Interface (GUI) lends itself particularly well to the MIDI sequencer.

3.1    The Main Screen Display

The screen captured image below show the main screen display for Master Tracks Pro 6, with a MIDI sequence called "rockin.mid" loaded.

Notice first the main 'Track' window.  All sequencers will have something equivalent to this, allowing the overall structure and organisation of the multi-part sequence to be managed.  The left most column shows the track (or part) number, and in this sequence there are just five tracks, corresponding to 2 lead/rythm Guitar parts, 1 Brass part, 1 Bass guitar part and finally 1 Drum part.  These are named in the 'Name' column, and each is assigned to a different MIDI channel in the 'Chnl' column.  (The reason the MIDI channels are shown above as A1, A2.. etc, is that this sequencer supports multiple MIDI output ports, where each port is designated A, B, C.. etc and each supports, of course, up to 16 MIDI channels).  The column headed 'Program Name' assigns an instrument (or 'patch', using the MIDI 'program change' message) to each particular Track, and in the example above we are using a General MIDI (GM) compatible synthesiser which assigns a 'standard' set of instruments to program change numbers.  (General MIDI has the - dubious - advantage that you can play a MIDI sequence back on different GM compatible synths and hear the same instruments for each part.)  The 'Cntlr' (Controller) and 'Val' (Value) columns show current settings for a given MIDI Controller Number, in this case number 7 'volume', thus allowing the volume level of each track to be adjusted individually (the MIDI equivalent to the faders on a mixing desk).  Finally, at the right hand side of the Track window we have a graphical representation of each 'bar' (in this case 4 beats) of the arrangement, where solid blocks indicate that a bar does have notes in it, and an open block denotes that the bar is empty.

Next look at the 'Transport' window.  This contains a largely self-explanatory set of transport controls, allowing the user to 'play' the sequence, or 'pause', 'stop', 'rewind', etc, as if this were a real audio tape recorder.  Using the P or S columns in the track window certain parts may be muted, or 'soloed' so that when the sequence is played back we can selectively play certain tracks.  Importantly, using the R column to select a track to record into, together with the 'REC' button in the transport window we can start real-time recording to a given track, from a MIDI input device (normally a MIDI keyboard).  During playback or record a vertical bar will move through the graphical section of the track window, to indicate which current bar is being played back (or recorded).  Of course a key feature of the MIDI sequencer is that we can record onto the first track, then when we're happy with it, record onto a second track whilst simultaneously playing back the first - in real time.  Then when we're happy with the second track (repeating the process if not), we can playback tracks 1 and 2 together, whilst recording into track 3, and so on.  In this way we can build up a multi-part MIDI sequence in a fashion directly equivalent to multi-track audio recording, except that we are not limited by the number of tracks on the tape machine, nor do we experience any noise or signal degradation through multiple playback and record.

Finally notice the 'Conductor' window, which allows us to set the number of beats per bar (in this case set to 4:4 or 'common' time), and the overall 'tempo' in beats per minute (bpm).  Here the tempo is set to 134bpm.  Varying this value obviously alters the speed of playback.

3.2    The Piano Roll Editor

Selecting the Piano Roll Editor allows any track, or part, to be viewed and edited on a graphical display analogous to a 'piano roll' (a roll of paper with holes cut into it, as used in automatic 'player' pianos or 'pianolas' popular early this Century), as shown below for track 1.

The piano roll editor allows the user to enter, or edit notes manually as an alternative to 'playing' them in real-time using a MIDI controller keyboard, and has the additional advantage of not requiring knowledge of musical notation (although a separate notation editor is sometimes avaiable, as described below).  The vertical representation of a piano keyboard down the left hand side of the piano roll editor allows the user to click and 'hear' a note, via MIDI, as an additional aid while entering notes.  Notes are drawn graphically onto the 'piano roll' using the mouse to click and drag, and a set of drawing tools accessible at the top of the editor.  (I do not propose to explain these in detail here.)

3.3    The Notation Editor

Like the piano roll editor described above the Notation Editor allows the notes for a selected part to be entered, or edited manually using the mouse and a set of drawing tools, but unlike the piano roll editor, this editor requires familiarity with standard musical notation.  The screen capture below shows the notation editor display for the same bars shown in the notation editor above.  Try to identify the corresponding notes in the two displays.

3.4    The MIDI Event Editor

Occasionally it is useful to be able to examine and edit the MIDI sequence at the lowest level, that of single MIDI events (or commands), and most sequencers provide this facility.  The screen capture below shows the MIDI event editor for the same track and few bars in the piano roll and notation editors above.  A particularly powerful feature of most MIDI event editors is that of being able to insert System Exclusive command sequences, in order to access features of the synthesizer hardware not normally accessible at the level of musical notation.

3.5    The Quantisation Function

When entering music into a sequencer, in real-time, by playing a keyboard connected as the MIDI input device it is quite normal to make timing errors, in other words to play notes either slightly too early or slightly too late.  Of course this may be regarded as part of the performance and therefore perfectly acceptable.  However if it is not then the 'quantisation' function, available in most MIDI sequencers allows such timing errors to be corrected automatically, by pulling notes back or forward slightly so that they start 'on the beat'.   The screen capture below shows the 'quantisation function' setup window in Master Tracks Pro.

Of course the downside of using the quantisation function is that music can sound too 'mechanical' if every note is played exactly on the beat.  Depending on the musical idiom in which you are working this may be exactly appropriate, but for many kinds of music it is not, and with heavy use of quantisation music can lose its 'feel'.  Use the quantisation function, therefore, with care.

3.6    The Humanisation Function

The 'humanise' function provides the logical converse of quantisation, by deliberately allowing timing inaccuracies to be introduced into the sequence.  This can provide 'feel' to an otherwise mechanical sounding sequence, and depending upon whether the timing is pulled slightly before or after the beat, the sequence can be made to sound 'upbeat' or 'laid back'.  Of course if the music has been played in real-time on a keyboard then it is likely to have this human 'feel' in the timing already and the humanise function is probably not necessary.  However, if the sequence has been entered manually using the piano roll or notation editors, then all notes are likely to be exactly on the beat, and so the humanise function is extremely useful in introducing subtle random timing inaccuracies in order to make the sequence sound less mechanical.  The screen capture below shows the setup window for the humanise function in Master Tracks Pro.