5 An audio time-stretching and pitch-shifting library and utility program.
7 Copyright 2007 Chris Cannam, cannam@all-day-breakfast.com.
9 Distributed under the GNU General Public License.
11 Rubber Band is a library and utility program that permits you to
12 change the tempo and pitch of an audio recording independently of one
19 * High quality results suitable for musical use
21 Rubber Band is a phase-vocoder-based frequency domain time
22 stretcher with partial phase locking to peak frequencies and phase
23 resynchronisation at noisy transients. It is suitable for most
24 musical uses with its default settings, and has a range of options
29 In addition to the offline mode (for use in situations where all
30 audio data is available beforehand), Rubber Band supports a true
31 real-time, lock-free streaming mode, in which the time and pitch
32 scaling ratios may be dynamically adjusted during use.
34 * Sample-accurate duration adjustment
36 In offline mode, Rubber Band ensures that the output has exactly
37 the right number of samples for the given stretch ratio. (In
38 real-time mode Rubber Band aims to keep as closely as possible to
39 the exact ratio, although this depends on the audio material
42 * Multiprocessor/multi-core support
44 Rubber Band's offline mode can take advantage of more than one
45 processor core if available, when processing data with two or more
48 * No job too big, or too small
50 Rubber Band is tuned so as to work well with the default settings
51 for any stretch ratio, from tiny deviations from the original
52 speed to very extreme stretches.
54 * Handy utilities included
56 The Rubber Band code includes a useful command-line time-stretch
57 and pitch shift utility (called simply rubberband), two LADSPA
58 pitch shifter plugins (Rubber Band Mono Pitch Shifter and Rubber
59 Band Stereo Pitch Shifter), and a Vamp audio analysis plugin which
60 may be used to inspect the stretch profile decisions Rubber Band
65 Rubber Band is Free Software published under the GNU General
74 The algorithm used by Rubber Band is very processor intensive, and
75 Rubber Band is not the fastest implementation on earth.
77 * Not especially state of the art
79 Rubber Band employs well known algorithms which work well in many
80 situations, but it isn't "cutting edge" in any interesting sense.
84 While the fundamental algorithms in Rubber Band are not especially
85 complex, the implementation is complicated by the support for
86 multiple processing modes, exact sample precision, threading, and
87 other features that add to the flexibility of the API.
93 Rubber Band is supplied with build scripts that have been tested on
94 Linux platforms. It is also possible to build Rubber Band on other
95 platforms, including both POSIX platforms such as OS/X and non-POSIX
96 platforms such as Win32. There are some example Makefiles in the misc
97 directory, but if you're using a proprietary platform and you get
98 stuck I'm afraid you're on your own, unless you want to pay us...
100 To build Rubber Band you will also need libsndfile, libsamplerate,
101 FFTW3, the Vamp plugin SDK, the LADSPA plugin header, the pthread
102 library (except on Win32), and a C++ compiler. The code has been
103 tested with GCC 4.x and with the Intel C++ compiler.
105 Rubber Band comes with a simple autoconf script. Run
110 to compile, and optionally
117 Using the Rubber Band utility
118 -----------------------------
120 The Rubber Band command-line utility builds as bin/rubberband. The
123 $ rubberband -t <timeratio> -p <pitchratio> <infile.wav> <outfile.wav>
127 $ rubberband -t 1.5 -p 2.0 test.wav output.wav
129 stretches the file test.wav to 50% longer than its original duration,
130 shifts it up in pitch by one octave, and writes the output to output.wav.
132 Several further options are available: run "rubberband -h" for help.
133 In particular, different types of music may benefit from different
134 "crispness" options (-c <n> where <n> is from 0 to 5).
137 Using the Rubber Band library
138 -----------------------------
140 The Rubber Band library has a public API that consists of one C++
141 class, called RubberBandStretcher in the RubberBand namespace. You
142 should #include <rubberband/RubberBandStretcher.h> to use this class.
143 There is extensive documentation in the class header.
145 The source code for the command-line utility (src/main.cpp) provides a
146 good example of how to use Rubber Band in offline mode; the LADSPA
147 pitch shifter plugin (src/ladspa/RubberBandPitchShifter.cpp) may be
148 used as an example of Rubber Band in real-time mode.
150 IMPORTANT: Please ensure you have read and understood the licensing
151 terms for Rubber Band before using it in another application. This
152 library is provided under the GNU General Public License, which means
153 that any application that uses it must also be published under the GPL
154 or a compatible license (i.e. with its full source code also available
155 for modification and redistribution). See the file COPYING for more
156 details. Alternative commercial and proprietary licensing terms are
157 available; please contact the author if you are interested.