II. Data structure 40g2 bytes except for las block in a file 12 bytes; 341 records/standard block Each tape file is actually a set of many data files. Each data file within a tape file starts with a BEGIN record and ends with an END record. The first 8 records in a logical file (including the BEGIN record) make up the file header. The remaining records (up to the END record) contain the musical daa. Description of Header Record 1: BEGIN record Record 2: BWV number and movement field 1: bytes 1-6 BWV number field 2: bytes 7-10 movement number field 3: byte 11 number of sections in movement (blank if only one) field 4: byte 12 section number( blank if only one) Records 3-5: information on the source of the data Record 6 Musical track nuber (fields in his record are terminated by blanks) field 1: number of tracks in this movement and section field 2: track number for this data Record 7: Musical and data parameters (fields in this record . are terminated by blanks) field 1: length of movement or section of movement in measures field 2: key signature (-7 = seven flats; 7 = seven sharps) field 3: number of divisions per measure field 4: number of divisions per quarter note Note: Note lengths in a data file are expressed in terms of divisions. The size of a division is specified by fields 3 and 4 of record 7. The division size applies only to the data in the specified file. For example, the top track of a piece in 4/4 time might have both 32nd notes and 16th note triplets. In this case there would be at least) 96 divisions per measure and 24 divisions per quarter note. A 32nd note would last 3 divisions, and a 16th triplet would last 4 divisions. The bottom track of this same piece might have 8th notes as the shortest notes. For this track, there would be 8 divisions per measure and 2 divisions per quarter note. Record 8: Other parameters and flags (fields in this record are terminated by blanks) field 1: time signature (numerator) field 2: time signature (denominator) field 3: clef (O= treble, 1= bass) field 4: principal mode (O = major, 1 = minor) field 5: movement type (1 = prelude, 2 = fugue) Note: The time signature is specified by fields 1 and 2 of record 8. At the moment, we do not distinguish between common time and 4/4 time or between alle breve and 2/2 or 4/2, which ever the case may be. Description of Data The musical data begins with record 9 and ends with the END record. There are two types of records: note records (which include rests) and measure number records. Measure number records: field 1: bytes 1-7 containes the word measure field 2: bytes 9-12 contains the measure number for which musical data follows Note: If there is a pickup, this will be designated as measure O and will be a full measure. In cases where the section number is greater than 1, all previous secions will be stored as rests. For example, if section 2 of a movement starts at measure 30, the file storing data for this section will show 29 measures of rest and valid musical data starting in measure 30. This was done to accommodate the printing program for proofreading purposes. Note records are of two types. Type 1: note or rest with duration field 1: bytes 1-4 contains a pitch name or a rest field 2: bytes 5-7 contains a duration expressed in terms of divisions field 3: byte 8 "-" = note tied, blank = no tie Type 2: note with no duration. This note sounds simultaneously with the note just above it and has the same duration, i.e. it is part of a chord. field 1: byte 1 blank field 2: bytes 2-5 contains a pitch name Note: pitch names are given by a letter [A..G], accidentals if appropriate [ff,f,#,##] and an octave number [l..7]. C4 is middle C. III. Representation of Polyphonic Music. Polyphonic music is represented in tracks. Each track is suppose to represent a single voice. For vocal and most instrumental parts, the representation process is straight forward. But for some instrumental music, especially certain lute and keyboard pieces, decomposition of the musical fabric into separate tracks is often arbitrary and problematic. Where extra notes occur simultaneously, we have tried to void adding extra tracks by allowing a single tracks to split into chords. All notes of the same chord must be of the same length, otherwise they will be put onto separate tracks. Arpeggios and other free-style figuration present especially difficult problems for this kind o representation. IV. Data Files on this Tape File l; Well-tempered Clavier Preludes and Fugues Volume I BWV 746--769 File 2: Well-tempered Clavier Preludes and Fugues Volume II BWV 770--793