OSClisten
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## OSClisten

OSClisten — Listen for OSC messages to a particular path.

## Description

On each k-cycle looks to see if an OSC message has been send to a given path of a given type.

## Syntax

    kans OSClisten ihandle, idest, itype [, xdata1, xdata2, ...]

## Initialization

ihandle -- a handle returned by an earlier call to OSCinit, to associate OSClisten with a particular port number.

idest -- a string that is the destination address. This takes the form of a file name with directories. Csound uses this address to decide if messages are meant for csound.

itype -- a string that indicates the types of the optional arguments that are to be read. The string can contain the characters "cdfhis" which stand for character, double, float, 64-bit integer, 32-bit integer, and string. All types other than 's' require a k-rate variable, while 's' requires a string variable.

A handler is inserted into the listener (see OSCinit) to intercept messages of this pattern.

## Performance

kans -- set to 1 if a new message was received, or zero if not. If multiple messages are received in a single control period, the messages are buffered, and OSClisten can be called again until zero is returned.

If there was a message the xdata variables are set to the incoming values, as interpretted by the itype parameter. Note that although the xdata variables are on the right of an operation they are actually outputs, and so must be variables of type k, gk, S, or gS, and may need to be declared with init, or = in the case of string variables, before calling OSClisten.

## Example

The example shows a pair of floating point numbers being received on port 7770.

      sr = 44100
      ksmps = 100
      nchnls = 2

      gihandle OSCinit 7770

      instr   1
        kf1 init 0
        kf2 init 0
    nxtmsg:
        kk  OSClisten gihandle, "/foo/bar", "ff", kf1, kf2
    if (kk == 0) goto ex
        printk 0,kf1
        printk 0,kf2
        kgoto nxtmsg
    ex:
      endin

Below are two .csd files which demonstrate the usage of the OSC opcodes. They use the files OSCmidisend.csd and OSCmidircv.csd.

Example 571. Example of the OSC opcodes.

The following two .csd files demonstrate the usage of the OSC opcodes in csound. The first file, OSCmidisend.csd, transforms received real-time MIDI messages into OSC data. The second file, OSCmidircv.csd, can take these OSC messages, and intrepret them to generate sound from note messages, and store controller values. It will use controller number 7 to control volume. Note that these files are designed to be on the same machine, but if a different host address (in the IPADDRESS macro) is used, they can be separate machines on a network, or connected through the internet.

CSD file to send OSC messages:

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    ; Audio out   Audio in
    -odac           -iadc    ;;;RT audio I/O
    </CsOptions>
    <CsInstruments>

      sr	    =  44100
      ksmps	    =  128
      nchnls    =  1

    ; Example by David Akbari 2007
    ; Modified by Jonathan Murphy
    ; Use this file to generate OSC events for OSCmidircv.csd

    #define IPADDRESS	# "localhost" #
    #define PORT 		# 47120 #

    turnon 1000

        instr	1000

      kst, kch, kd1, kd2  midiin

      OSCsend   kst+kch+kd1+kd2, $IPADDRESS, $PORT, "/midi", "iiii", kst, kch, kd1, kd2

        endin

    </CsInstruments>
    <CsScore>
    f 0 3600  ;Dummy f-table
    e
    </CsScore>
    </CsoundSynthesizer>

CSD file to receive OSC messages:

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    ; Audio out   Audio in
    -odac           -iadc    ;;;RT audio I/O
    </CsOptions>
    <CsInstruments>

      sr	    =  44100
      ksmps	    =  128
      nchnls    =  1

    ; Example by Jonathan Murphy and Andres Cabrera 2007
    ; Use file OSCmidisend.csd to generate OSC events for this file

      0dbfs	    =  1

      gilisten  OSCinit   47120

      gisin	    ftgen     1, 0, 16384, 10, 1
      givel	    ftgen     2, 0, 128, -2, 0
      gicc	    ftgen     3, 0, 128, -7, 100, 128, 100  ;Default all controllers to 100

    ;Define scale tuning
      giji_12   ftgen     202, 0, 32, -2, 12, 2, 256, 60, 1, 16/15, 9/8, 6/5, 5/4, 4/3, 7/5, \
                                   3/2, 8/5, 5/3, 9/5, 15/8, 2

    #define DEST #"/midi"#
    ; Use controller number 7 for volume
    #define VOL #7#

    turnon 1000

        instr   1000

      kst	    init      0
      kch	    init      0
      kd1	    init      0
      kd2	    init      0

    next:

      kk	    OSClisten	gilisten, $DEST, "iiii", kst, kch, kd1, kd2

    if (kk == 0) goto done

    printks "kst = %i, kch = %i, kd1 = %i, kd2 = %i\\n", \
             0, kst, kch, kd1, kd2

    if (kst == 176) then
    ;Store controller information in a table
    	    tablew    kd2, kd1, gicc
    endif

    if (kst == 144) then
    ;Process noteon and noteoff messages.
      kkey	    =  kd1
      kvel	    =  kd2
      kcps	    cpstun    kvel, kkey, giji_12
      kamp	    =  kvel/127

    if (kvel == 0) then
    	    turnoff2  1001, 4, 1
    elseif (kvel > 0) then
    	    event     "i", 1001, 0, -1, kcps, kamp
    endif
    endif

    	kgoto	next  ;Process all events in queue

    done:
        endin

        instr 1001   ;Simple instrument

      icps	    init      p4
      kvol	    table     $VOL, gicc  ;Read MIDI volume from controller table
      kvol	    =  kvol/127

      aenv     linsegr    0, .003, p5, 0.03, p5 * 0.5, 0.3, 0
      aosc	    oscil     aenv, icps, gisin

    	    out	      aosc * kvol
        endin

    </CsInstruments>
    <CsScore>
    f 0 3600  ;Dummy f-table
    e
    </CsScore>
    </CsoundSynthesizer>

## See Also

OSCsend, OSCinit

More information on this opcode: http://www.youtube.com/watch?v=JX1C3TqP_9Y , made by Andrés Cabrera

## Credits

Author: John ffitch
2005
Examples by: David Akbari, Andrés Cabrera and Jonathan Murphy 2007

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