You will appreciate BP2's ability to produce intricate polyrhythmic patterns by playing item produced by "-gr.Djinns" with percussive sounds (e.g. Roland's "C-54 percussion set 1"). The piece was created to synchronise the recitation of Victor Hugo's poem " Les Djinns " with the opening section of " La Création du Monde " by Darius Milhaud (EMI CDC-7 47845 2) in Andréine Bel's choreographic work for Collège des Prêcheurs and Conservatoire Darius Milhaud (Aix-en-Provence, 1992). We found that the meaning of the poem would coincide with particular events in the musical piece. Then we calculated a time-base value fitting the two tracks together: setting 1000 beats in exactly 1578 seconds was possible since BP2 does not round integer ratios.

Poem " Les Djinns " is built on verses with variable meters: 2/2/2/2/3/3/3/3/4/4/4/4 ...up to 10/10/10/10 --except 9/9/9/9-- and then decreasing (see appendix).

We decided that every verse should have the same duration marked by 16 beats with a stronger first beat. The result is a polyrhythmic piece with one instrument showing beats at a fixed speed and another one playing ticks at variable speeds. Listening to variable parts made it possible for children to recite the poem at the expected tempi.

The grammar below shows how the piece was produced. It has 15 sections labelled "A2", "A3", etc. Each section puts together a fixed motive "M" and a variable motive "T16", "T24", etc. Here, "T16" stands for 16 ticks played as note "do4". Fixed motive "M" is a string of alternated "do2" and "do3" with a stronger beat in the beginning, where "sib5" is played together with "do2".

-se.Djinns

ORD

S --> A2 A3 A4 A5 A6 A7 A8 A10 A8 A7 A6 A5 A4 A3 A2

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SUB1

A2 --> {M,T16}

A3 --> {M,T24}

A4 --> {M,T32}

A5 --> {M,T40}

A6 --> {M,T48}

A7 --> {M,T56}

A8 --> {M,T64}

A10 --> {M,T80}

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ORD

T16 --> T8 T8

T24 --> T16 T8

T32 --> T16 T16

T40 --> T32 T8

T48 --> T32 T16

T56 --> T48 T8

T64 --> T32 T32

T80 --> T40 T40

T8 --> Tik Tik Tik Tik Tik Tik Tik Tik

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SUB1

M --> {1,do2,sib5} do3 do2 do3 do2 do3 do2 do3 do2 do3 do2 do3 do2 do3 do2 do3

Tik --> do4

Below is a graphic example of the output of "A6 A7".

If only variable parts must be heard then regular beats "do2" and "do3" may be replaced with silences.

It is easy to figure out that the full piece would require an excessively large phase diagram (more than 200,000 columns) because it is based on the lowest common multiple of 2, 3, 4, ... 10. Therefore it can played only if quantization is set to a reasonable value (see §6 of reference manual). We found that musicians were be satisfied with a 50 millisecond quantization even though deviations of ±50ms were still noticeable in the "A7" part. With this setting, computation requires a 2 Mbyte memory partition for BP2 and it takes a couple of minutes on a Mac IIci, so be patient if you can't borrow your rich neighbour's PowerMac...

You may use almost the same grammar with syllabi of the poem stored on a sampler and triggered by appropriate keys. I prefer live children's voices...