Jazzperiments Jam Introduction ObjectiveJazzperiments jam is an interactive music application. The main objective is to produce an interesting musical response on musical input, thus creating an environment which is fun to play in. The application: - picks up sound - determines the pitch using Fast Fourier Transform - processes only the notes of the selected scale - transposes notes which selected intervals - delays notes with selected rests - plays notes with selected midi instruments With a good unidirectional (cardioid) microphone you get the best results. When you change the Arrangements (control 51), you can easily explore different sounds. It is also interesting to experiment with (transposed or delayed) feedback. Living with latency This program has to cope with 4 kinds of latency: 1 The frequency of notes produced by instruments or the human voice is not constant during the attack of the note (wind instruments and voice: lower, piano and percussion: higher). The minimum sample to get an accurate measurement has to be about 100 ms long. Experiments with shorter samples and some kind of control mechanism were not accurate enough or even slower. There is no way to avoid the latency caused by this feature of musical instruments. 2 To reduce the net latency the program reads the sample of 100 ms in 4 chunks of about 25 ms and calculates the frequencies each time for the 'shifting' sample. The acquisition of the sample, the calculation for Fast Fourier Transformation and all other processing by the program take about 35 ms. The calculation could be optimized somewhat, but the experience is that this doesn't reduce the processing time by more than a few ms. 3 The input and output latency of the hardware and the OS (infamous under Windows) both affect this system. As this is a free online program there aren't many options to reduce this latency from within the application. 4 The user can select a delay of 1/8 up to 12 bars and in this way cause a kind of voluntary latency. Short delays create arpeggios; long delays can result in something like automatic accompaniment. Details The lowest notes are transposed one octave up in the presentation (not in pitch). The version of the program with the option to record samples doesn't work on older Apple computers. Click here to start a version without samples. Help Help for each key and control Colophon Jazzperiments Jam is a free software under the Creative Commons BY-NC-SA license. 2008, 2009 Teun de Lange Basic implementation of Fast Fourier Transform by Arnault Pachot. Synthesizer: Gervill, distributed under the terms of the GNU General Public License v2 with "Classpath" exception. Contact: info@jazzperiments.com |