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# sfinstr

sfinstr -- Plays a SoundFont2 (SF2) sample instrument, generating a stereo sound.

## Description

Plays a SoundFont2 (SF2) sample instrument, generating a stereo sound. These opcodes allow management the sample-structure of SF2 files. In order to understand the usage of these opcodes, the user must have some knowledge of the SF2 format, so a brief description of this format can be found in the SoundFont2 File Format Appendix.

## Syntax

ar1, ar2 sfinstr ivel, inotenum, xamp, xfreq, instrnum, ifilhandle [, iflag] [, ioffset]

## Initialization

ivel -- velocity value

inotenum -- MIDI note number value

instrnum -- number of an instrument of a SF2 file.

ifilhandle -- unique number generated by sfload opcode to be used as an identifier for a SF2 file. Several SF2 files can be loaded and activated at the same time.

iflag (optional) -- flag regarding the behavior of xfreq and inotenum

ioffset (optional) -- start playing at offset, in samples.

## Performance

xamp -- amplitude correction factor

xfreq -- frequency value or frequency multiplier, depending by iflag. When iflag = 0, xfreq is a multiplier of a the default frequency, assigned by SF2 preset to the inotenum value. When iflag = 1, xfreq is the absolute frequency of the output sound, in Hz. Default is 0.

When iflag = 0, inotenum sets the frequency of the output according to the MIDI note number used, and xfreq is used as a multiplier. When iflag = 1, the frequency of the output, is set directly by xfreq. This allows the user to use any kind of micro-tuning based scales. However, this method is designed to work correctly only with presets tuned to the default equal temperament. Attempts to use this method with a preset already having non-standard tunings, or with drum-kit-based presets, could give unexpected results.

Adjustment of the amplitude can be done by varying the xamp argument, which acts as a multiplier.

The ioffset parameter allows the sound to start from a sample different than the first one. The user should make sure that its value is within the length of the specific sound. Otherwise, Csound will probably crash.

sfinstr plays an SF2 instrument instead of a preset (an SF2 instrument is the base of a preset layer). instrnum specifies the instrument number, and the user must be sure that the specified number belongs to an existing instrument of a determinate soundfont bank. Notice that both xamp and xfreq can operate at k-rate as well as a-rate, but both arguments must work at the same rate.

These opcodes only support the sample structure of SF2 files. The modulator structure of the SoundFont2 format is not supported in Csound. Any modulation or processing to the sample data is left to the Csound user, bypassing all restrictions forced by the SF2 standard.

## See Also

sfilist, sfinstrm, sfload, sfpassign, sfplay, sfplaym, sfplist, sfpreset

## Credits

Author: Gabriel Maldonado
Italy
May 2000

New in Csound Version 4.07

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