zretune(1)

NAME
zretune - resample an audio file in order to change its pitch

SYNOPSIS
zretune [options] input-file output-file

DESCRIPTION
zretune resamples an audio file by a the inverse of a ratio given directly or expressed in cents, without changing the nominal sample rate. The result is to change the musical pitch and length of the file. Input can be any audio file readable by the libsndfile library. The output file type is either WAV, WAVEX, CAF, AIFF or FLAC.

OPTIONS

--help
    Display a short help text.

--ratio pitch ratio
    The accepted range is 0.5 to 2.0. The useful range in practice will be smaller.

--cent pitch change in cents
    The number of cents by which the pitch is changed. The accepted range is +/- 1200 cents, the useful range in practice will be something like +/- 100 cents.

  Output file type

--wav
    Produce a WAV file, or for more than 2 channels, a WAVEX file. This is the default.

--amb
    Produce a WAVEX file with the Ambisonic GUID. Such files should have the .amb filename extension.

--caf
    Produce a Core Audio file.

--aiff
    Produce an AIFF file.

--flac
    Produce a FLAC file.

  Output sample format

--16bit
    Output sample format is signed 16-bit. This option also enables the use of dithering, described below.

--24bit
    Output sample format is 24-bit. This is the default.

--float
    Output sample format is 32-bit floating point.

  Dithering

--rec
    Add white dithering noise with a rectangular distribution. This is the best option if the output data is going to processed again, but in that case it would be advisable to use 24-bit or float.

--tri
    Add filtered noise with a triangular distribution. Compared to the rectangular dither this reduces the noise density in the lower frequency range.

--lips
    This uses the optimal error feedback filter described by Stanley Lipschitz. This is recommended is the output is the final distribution format, e.g. for a CD.

  Timing

--pad
    Insert zero valued input samples at the start and end so that the output includes the full symmetric filter response even for the first and last samples.

EXIT STATUS
Zero in case there are no errors, non-zero otherwise.

AUTHOR
Fons Adriaensen (fons (at) linuxaudio.org)