MP3 and MIDI files

What are MP3 and MIDI?

Executive summary:

An MP3 file records the sound of a performance of the music. Almost all computers understand MP3 files, just as they understand JPEG and GIF files for pictures, so the chances are excellent that they will just work, on your computer, tablet or smart phone.

A MIDI file records a performance -- which notes were played, when, how loudly, and so on. To hear the performance, you need either a program [app] such as TiMidity which can act as a synthesiser or a real electronic keyboard which can be connected to your computer/tablet/phone. In the absence of these, you're SOL. Sorry!

In more detail ...:

There are basically two ways of representing music. The first is to take the actual wave forms of the soundwaves that you hear. In the days of vinyl, this was the shape of the groove that was impressed into the plastic, tracked by the needle as the disc rotated and converted back into the corresponding sounds by the record player. In more modern times, a CD equally encodes that shape, but it does so by sampling the "groove" many thousands of times per second, and recording each sample as a number.

The other is to follow a score. In printed music, this gives instructions to the performers to play such-and-such notes at such-and-such times with such-and-such loudness, plus other instructions, such as pedalling. This leaves a certain amount of discretion to the performers; though some composers are more prescriptive than others.

However, neither of these is directly good for computer reproduction. The numbers on a CD are extremely voluminous, amounting to around 10 million bytes per minute; so a gigabyte will hold around 100 minutes of music. Until quite recently, this meant that each CD occupied a significant part of your computer's store, and it would take a long time to download if you were transferring it over the InterWeb thingie. So for practical reasons, it is compressed into so-called MP3 format. Details are beyond the present scope; but we gain typically a factor of ten or so, so we can now store around 15 CDs into a gigabyte. MP3 files are understood by virtually all computers, in the same way that GIF and JPEG formats for pictures are recognised. Your computer will turn them back into music, so that you will hear what you would have heard from a CD of the same music.

Although there is software that deals directly with music scores, this is not the way that most music in MIDI format is produced or processed. Rather, to turn a score into a performance, a performer or sequencer [see later] plays the music into a computer or electronic keyboard which records what notes are played and when, how long the key is held down, and how hard the note is pressed. Playing back that recording will reproduce the performance. If you are a good-enough pianist, that is almost the end of the process. Otherwise, which certainly applies to me, the record needs to be edited, or created in the first place, by a sequencer. This is a program that can be used, like a text editor, to change the details of the performance. I use a now rather old program called Cakewalk, which has lots of useful facilities and can include many aspects of the music not available in other sequencers. When the editing is complete, Cakewalk can convert the music into MP3 and/or MIDI. Whereas MP3 files are almost universally understood, MIDI files are only understood directly by a subset of computers. They are much, much smaller than MP3 files, so even very old and small computers can hold hundreds or even thousands of them. But you need either a soundcard that understands them, or a program that will interpret them, or an electronic keyboard that accepts them as input.

There is still a 'gotcha'. What you hear is not what I hear, but a rendition of the same notes with the same timing and the same loudness. Just as two pianos or violins can sound quite different, so can one same MIDI file played on two different computers, even if the speakers and all other facilities are the same. Your piano may be better or worse than mine, so the performance may equally be better or worse.

But if you want to play around with the music -- make certain bits faster or slower, correct a wrong note, whatever -- then MIDI is the way to go. Another caution; as noted, Cakewalk is richer in facilities than your average sequencer and in particular than MIDI, so there is information in my files that is lost in the MIDI version. In addition, I have a few 'trade secrets' up my sleeve, so you can't expect your copy of my MIDI files to reproduce the MP3 version that you can hear! Sorry.

For information: MP3 is more formally MPEG-1 Audio Layer III, where MPEG is the Moving Picture Experts Group. MIDI is the Musical Instrument Digital Interface, and is a lowest-common denominator standard understood by almost all electronic instrument companies [though many have home-grown extensions], including things like lighting gantries for theatre productions and the like.

Sequencing

Sequencing is the process of converting music to a list of instructions, to play particular notes at time so-and-so with loudness this-or-that and lasting for so long. This is exactly what you need for a Midi file, but actual sequencers, such as Cakewalk, typically use their own formats, though they can turn those formats into Midi [often with some loss of information] and can read and interpret Midi files.

There are several ways to get notes into Cakewalk. The fastest, if you are a good pianist, is simply to play the music on a keyboard with a USB connexion to your computer. Or, for repetitive bits, you can cut and paste the repetitions. Or you can, so to speak, ink in the notes into one of various sorts of window, such as one that looks rather like a music score. Or you can step record, play one chord at a time, and Cakewalk will accumulate these into the piece. Note that there is no implication that the music is for piano; Cakewalk associates an instrument with each track, and it's your choice from a wide range, including a standard set known to all Midi software but also including whatever else your keyboard or sound card provides. So you can sequence up a full orchestra if you choose; though it has to be said that the results are often not entirely satisfactory. See below for some philosophical musings on the process.

Cakewalk can also include audio clips, and can trigger other equipment, such as lighting gantries, that may be attached to your computer. It can include, for example, lyrics, which can be displayed when particular notes are played, for use in karaoke. It comes with what amounts to a sound engineer's console, similar to the ones you see as complex hardware in recording studios but simplified to appear in a window on a PC. You can use this to fade in or fade out tracks. It also comes with a wide range of effects, so you can add echoes, ambient sounds and resonances, transpose up or down, play backwards, etc., etc. You can select individual notes or groups of notes and edit them in all sorts of ways. So, broadly speaking, it is to music what Photoshop or Gimp is to pictures.

There are many other sequencers out there, including quite a few that are free software. There are also conversion programs, and, for example, programs that will take Midi or proprietary format files and display them as printed scores. Cakewalk can do scores, but they are typically not of high quality; for that, you need a program such as Lilypond.

Philosophy

My aim in this collection of pieces has been to supply interested people with an accurate rendition of an assortment of pieces, almost all from my own music collection, and all pieces I like, most of them not very familiar to the general public. Here, accuracy means faithfulness to what the composer wrote, not a metronomic painting by numbers version of the music. However, some composers are much more amenable to my treatment than others; and so are some genres. As noted above on this page, orchestral music in general shows up the limitations of Midi; orchestral sounds are often not all that realistic, and although it is possible to add expression [such as pitch bend or vibrato] to notes, it's a labour-intensive process and works much better in some cases than others.

The quest for faithfulness starts with the notes [including, for example, pedalling and tempi]. But if you play some notes, they are extremely unlikely to correspond exactly to the score. You will very likely make errors perhaps of hundredths of a second in timing and of a few percent in the loudness. It's much easier to edit the music if you can start from a precisely-known point. So my first step is usually to quantise the notes; to round the start and duration of the notes to exactly the quaver [eighth note] or whatever that the composer notated. The next step is to flatten out all the loudnesses to be all exactly the same. Yes, musically this is a disaster, and at this stage the sound is very artificial and robotic, as you might expect. But this is the low point of the process.

The remainder of the editing process is to put back in all the expressiveness that has been flattened out. Cakewalk has some tools to help this, but more importantly allows me to write my own tools for the purpose. So I can put back in the variations in loudness, the subtle emphases, the ornamentation, the phrasing, the variations of tempi and so on, that the composer wrote, or at least intended by the conventions of the period. I can also put in, for example, stereo effects and an ambient resonance.

The final stage before finalising each project is to derive, from the Cakewalk version, the MP3 and Midi versions that you find on the web site.

Enjoy!