The Alternative Csound Reference Manual
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# pvsfread

pvsfread -- Read a selected channel from a PVOC-EX analysis file.

## Description

Create an fsig stream by reading a selected channel from a PVOC-EX analysis file loaded into memory, with frame interpolation. Only format 0 files (amplitude+frequency) are currently supported. The operation of this opcode mirrors that of pvoc, but outputs an fsig instead of a resynthesized signal.

## Syntax

fsig pvsfread ktimpt, ifn [, ichan]

## Initialization

ifn -- Name of the analysis file. This must have the .pvx file extension.

A multi-channel PVOC-EX file can be generated using the extended pvanal utility.

ichan -- (optional) The channel to read (counting from 0). Default is 0.

## Performance

ktimpt -- Time pointer into analysis file, in seconds. See the description of the same parameter of pvoc for usage.

Note that analysis files can be very large, especially if multi-channel. Reading such files into memory will very likely incur breaks in the audio during real-time performance. As the file is read only once, and is then available to all other interested opcodes, it can be expedient to arrange for a dedicated instrument to preload all such analysis files at startup.

## Examples

    idur  filelen   "test.pvx"         ; find dur of (stereo) analysis file
    kpos  line      0,p3,idur          ; to ensure we process whole file
    fsigr pvsfread  kpos,"test.pvx",1  ; create fsig from R channel

(NB: as this example shows, the filelen opcode has been extended to accept both old and new analysis file formats).

## Credits

Author: Richard Dobson
August 2001

New in version 4.13

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