GEN49

Transfers data from an MP3 soundfile into a function table.

Syntax

f#  time  size  49  filcod  skiptime  format

Performance

size -- number of points in the table. Ordinarily a power of 2 or a power-of-2 plus 1 (see f statement); the maximum tablesize is 16777216 (2²⁴) points. The allocation of table memory can be deferred by setting this parameter to 0; the size allocated is then the number of points in the file (probably not a power-of-2), and the table is not usable by normal oscillators, but it is usable by a loscil unit. The soundfile can also be mono or stereo.

filcod -- integer or character-string denoting the source soundfile name. An integer denotes the file soundin.filcod ; a character-string (in double quotes, spaces permitted) gives the filename itself, optionally a full pathname. If not a full path, the file is sought first in the current directory, then in that given by the environment variable SSDIR (if defined) then by SFDIR. See also soundin.

skiptime -- begin reading at skiptime seconds into the file.

format -- specifies the audio data-file format required:

1 - Mono file                 3 - First channel (left)
2 - Stereo file               4 - Second channel (right)

If format = 0 the sample format is taken from the soundfile header.

Note

• Reading stops at end-of-file or when the table is full. Table locations not filled will contain zeros.
• If p4 is positive, the table will be post-normalized (rescaled to a maximum absolute value of 1 after generation). A negative p4 will cause rescaling to be skipped.

Examples

Here is an example of the GEN49 routine. It uses the files gen49.csd.

<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 gen49.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

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

instr 1

kcps = sr/ftlen(1)
asig oscil .8, kcps, 1
   outs asig, asig

endin
</CsInstruments>
<CsScore>
f 1 0 131072 49 "beats.mp3" 0 1 ;read an audio file (using GEN49).

i 1 0 2
e
</CsScore>
</CsoundSynthesizer>

This is the diagram of the waveforms of the GEN49 routine, as used in the example:

f 1 0 131072 49 "beats.mp3" 0 1

Credits

Written by John ffitch

February 2009.