lorisread

lorisread — Imports a set of bandwidth-enhanced partials from a SDIF-format data file, applying control-rate frequency, amplitude, and bandwidth scaling envelopes, and stores the modified partials in memory.

Syntax

lorisread ktimpnt, ifilcod, istoreidx, kfreqenv, kampenv, kbwenv[, ifadetime]

Description

lorisread imports a set of bandwidth-enhanced partials from a SDIF-format data file, applying control-rate frequency, amplitude, and bandwidth scaling envelopes, and stores the modified partials in memory.

Initialization

ifilcod - integer or character-string denoting a control-file derived from reassigned bandwidth-enhanced analysis of an audio signal. An integer denotes the suffix of a file loris.sdif (e.g. loris.sdif.1); a character-string (in double quotes) gives a filename, optionally a full pathname. If not a full pathname, the file is sought first in the current directory, then in the one given by the environment variable SADIR (if defined). The reassigned bandwidth-enhanced data file contains breakpoint frequency, amplitude, noisiness, and phase envelope values organized for bandwidth-enhanced additive resynthesis. The control data must conform to one of the SDIF formats that can be

Loris stores partials in SDIF RBEP frames. Each RBEP frame contains one RBEP matrix, and each row in a RBEP matrix describes one breakpoint in a Loris partial. A RBEL frame containing one RBEL matrix describing the labeling of the partials may precede the first RBEP frame in the SDIF file. The RBEP and RBEL frame and matrix definitions are included in the SDIF file's header. In addition to RBEP frames, Loris can also read and write SDIF 1TRC frames. Since 1TRC frames do not represent bandwidth-enhancement or the exact timing of Loris breakpoints, their use is not recommended. 1TRC capabilities are provided to allow interchange with programs that are unable to handle RBEP frames.

istoreidx, ireadidx, isrcidx, itgtidx are labels that identify a stored set of bandwidth-enhanced partials. lorisread imports partials from a SDIF file and stores them with the integer label istoreidx. lorismorph morphs sets of partials labeled isrcidx and itgtidx, and stores the resulting partials with the integer label istoreidx. lorisplay renders the partials stored with the label ireadidx. The labels are used only at initialization time, and may be reused without any cost or benefit in efficiency, and without introducing any interaction between instruments or instances.

ifadetime (optional) - In general, partials exported from Loris begin and end at non-zero amplitude. In order to prevent artifacts, it is very often necessary to fade the partials in and out, instead of turning them abruptly on and off. Specification of a non-zero ifadetime causes partials to fade in at their onsets and to fade out at their terminations. This is achieved by adding two more breakpoints to each partial: one ifadetime seconds before the start time and another ifadetime seconds after the end time. (However, no breakpoint will be introduced at a time less than zero. If necessary, the onset fade time will be shortened.) The additional breakpoints at the partial onset and termination will have the same frequency and bandwidth as the first and last breakpoints in the partial, respectively, but their amplitudes will be zero. The phase of the new breakpoints will be extrapolated to preserve phase correctness. If no value is specified, ifadetime defaults to zero. Note that the fadetime may not be exact, since the partial parameter envelopes are sampled at the control rate (krate) and indexed by ktimpnt (see below), and not by real time.

Performance

lorisread reads pre-computed Reassigned Bandwidth-Enhanced analysis data from a file stored in SDIF format, as described above. The passage of time through this file is specified by ktimpnt, which represents the time in seconds. ktimpnt must always be positive, but can move forwards or backwards in time, be stationary or discontinuous, as a pointer into the analysis file. kfreqenv is a control-rate transposition factor: a value of 1 incurs no transposition, 1.5 transposes up a perfect fifth, and .5 down an octave. kampenv is a control-rate scale factor that is applied to all partial amplitude envelopes. kbwenv is a control-rate scale factor that is applied to all partial bandwidth or noisiness envelopes. The bandwidth-enhanced partial data is stored in memory with a specified label for future access by another generator.

Examples

Here is an example of the lorisread opcode. It uses the file lorisread.csd.

Example 427. Example of the lorisread opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac      ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o lorisread.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

; Play the partials in clarinet.sdif from 0 to 3 sec with 1 ms fadetime
; and no frequency , amplitude, or bandwidth modification.

instr 1

ktime linseg 0, p3, 3			; linear time function from 0 to 3 seconds
      lorisread	ktime, "clarinet.sdif", 1, 1, 1, 1, .001
asig  lorisplay	1, 1, 1, 1
      outs asig, asig
endin


; Play the partials in clarinet.sdif from 0 to 3 sec with 1 ms fadetime
; adding tuning and vibrato, increasing the "breathiness" (noisiness) and overall
; amplitude, and adding a highpass filter.

instr 2

ktime linseg 0, p3, 3			; linear time function from 0 to 3 seconds
					; compute frequency scale for tuning  
ifscale	= cpspch(p4)/cpspch(8.08)	; (original pitch was G#4)
					; make a vibrato envelope
kvenv  linseg 0, p3/6, 0, p3/6, .02, p3/3, .02, p3/6, 0, p3/6, 0
kvib   oscil  kvenv, 4, 1		; table 1, sinusoid
kbwenv linseg 1, p3/6, 1, p3/6, 2, 2*p3/3, 2	;lots of noise
       lorisread ktime, "clarinet.sdif", 1, 1, 1, 1, .001
a1     lorisplay 1, ifscale+kvib, 2, kbwenv
asig   atone a1, 1000			; highpass filter, cutoff 1000 Hz
       outs  asig, asig
endin

</CsInstruments>
<CsScore>
; a sinus
f 1 0 4096 10 1

i 1    0      3
i 1    +      1
i 1    +      6
s

;                  pitch
i 2      1    3    8.08
i 2      3.5  1    8.04
i 2      4    6    8.00
i 2      4    6    8.07
e
</CsScore>
</CsoundSynthesizer>


Credits

This implementation of the Loris unit generators was written by Kelly Fitz (loris@cerlsoundgroup.org). It is patterned after a prototype implementation of the lorisplay unit generator written by Corbin Champion, and based on the method of Bandwidth-Enhanced Additive Synthesis and on the sound morphing algorithms implemented in the Loris library for sound modeling and manipulation. The opcodes were further adapted as a plugin for Csound 5 by Michael Gogins.