pmy@vivaldi.acc.virginia.edu (Pete Yadlowsky) (02/09/90)
Archive-name: lpc-next/08-Feb-90 Original-posting-by: pmy@vivaldi.acc.virginia.edu (Pete Yadlowsky) Original-subject: Announcing... Archive-site: uvaarpa.acc.virginia.edu [128.143.2.7] Archive-directory: /pub/next/source/LPC-source.tar.Z Reposted-by: emv@math.lsa.umich.edu (Edward Vielmetti) ...the release of LPC, a NeXT adaptation of Paul Lansky's linear predictive analysis and pitch tracking programs. LPC reads a NeXT or CSound-NeXT format soundfile and produces a data file which codes the sound in terms of its time-varying formant characteristics and the RMS levels of a residual excitation signal. To resynthesize the audio signal, this LPC-derived dynamic filter is excited with a spectrally rich driver, such as white noise or a pulse train, though many interesting effects can be produced with other types of signals. Also, there is a pitch tracking utility which produces data that may be merged with the LP analysis data. This pitch information may then be used to control the pitch of the driving signal during resynthesis. CSound (Barry Vercoe's software synthesis system) provides signal modification units which read LPC analysis files and resonate specified signals through the LP-encoded filters. CSound has also been ported to the NeXT. The next release of CSound-NeXT (sigh) will have hooks for launching and communicating with LPC-NeXT, thus adding another application to the CSound-NeXT integrated tool set. Due out shortly. CSound-NeXT and LPC-NeXT are both NeXTStep applications, meaning that their front ends are built on the NeXT graphic user interface for clear, intuitive interaction. For a detailed explanation of the workings of linear predictive analysis, try "Computer Music" by Dodge and Jerse. Hal Chamberlin's "Musical Applications of Microprocessors" also has a few paragraphs on this. ftp: uvaarpa.acc.virginia.edu:/pub/next/Apps/LPC.tar.Z uvaarpa.acc.virginia.edu:/pub/next/source/LPC-source.tar.Z Piece-wise uuencoded mailings can be arranged for those who do not have ftp access. Pete Yadlowsky Academic Computing Center University of Virginia pmy@Virginia.EDU -- Peter M. Yadlowsky | "Pay no attention to that man Academic Computing Center | behind the curtain!" University of Virginia | pmy@Virginia.EDU |