Open-source library and tools for audio and music analysis, description and synthesis.
- Extensive collection of reusable algorithms
- Cross-platform
- Fast prototyping
- Optimized for computational speed
Category Archives: Analysis
MAnalyzer ~ Spectral Analyzer & Sonogram
MAnalyzer is an advanced spectral analyzer and sonogram containing unique features such as smoothing, normalization, super-resolution, prefiltering and deharmonization. The included meters provide a peak meter and EBU R128 and ITU-R BS 1770-3 compliant loudness meter.

HOLMImpulse ~ Frequency & Impulse-response Measurement
- Measure Impulse-response
- Measure Phase-response
- Measure Frequency-response
- Measure Harmonic Distortion (THD)
- Make bandwidth limited measurements with no phase-errors
- Compare measurements
- Import Frequency-response & Impulse-response
- Export Frequency-responses & Impulse-responses
- Use open formats for saved files (zip, wav/flac, txt)

www.diyaudio.com/community/threads/holmimpulse-measuring-frequency-impulse-response
Resources:
- www.diyaudio.com/community/threads/holmimpulse-measuring-frequency-impulse-response.144984/page-61#post-7549045
- web.archive.org/web/20180707023302/http://holmacoustics.com/holmimpulse.php
- rephase.org/dl/Holm
Note: It appears this software is no longer available from the original source.
Similarity ~ Refines Music Collections
As an active music fan you surely know how difficult it sometimes may be to keep your music collection ordered. The more sound files you have, the more time and effort it takes to clean out duplicates, low-quality files and purify the entire collection of any musical garbage it contains. That’s where Similarity comes in handy!
Similarity rapidly scans your music collection and shows all duplicate music files you may have. The comparison, powered by “acoustic fingerprint” technology, considers the actual contents of files, not just tags or filenames, and thus ensures the extreme accuracy of similarity estimation. Moreover, the comparison isn’t audio file format dependent; the application supports almost every file format in full.
Alongside eliminating musical doubles, Similarity also provides advanced quality control functions. Really, who wants a collection full of low-bitrate music, badly remastered compositions and songs full of noise? Similarity analyzes files and calculates a quality score basing on various technical parameters of that recording, such as: bitrate, frequency, amplitude cut value, amplitude average value, amplitude maximum and many others. The program automatically detects all common problems with audio files and assigns a corresponding quality mark to each file. A quick sort – and you’ve got files with the highest quality at the top and files you can delete without doubts at the bottom.

AnSpec ~ Analog-style Spectrum Analyzer
AnSpec is an analog-style one/third-octave spectrum analyzer AAX, AudioUnit and VST plugin for professional sound and music production applications. It was designed to be a handy visual feedback tool for those who like visual smoothness and easiness of use of analog analyzers. AnSpec also provides peak level indication.
While there are no adjustable parameters available in this plugin, you can still change level meter ballistics and resize plugin’s window.
Features:
- 1/3 octave analog-style spectrum analyzer
- Peak level indication
- User interface window resizing
- Stereo and mono analysis
- All sample rates support
- Zero processing latency
- User interface color schemes
- Resizable user interface
- Retina and High DPI support

www.voxengo.com/product/anspec
References:
Snd ~ Unix Sound Editor
Snd is a sound editor modelled loosely after Emacs. It can be customized and extended using either s7 (included in the Snd sources), Ruby, or Forth. Snd is free; the code is available via anonymous FTP as Snd tarball.

ccrma.stanford.edu/software/snd/
ccrma.stanford.edu/software/snd/snd/snd
sourceforge.net/projects/snd
Lossless Audio Checker ~ Truly Lossless Or Not
Internet music dealers currently sell “CD-Quality” tracks, or even better (“Studio-Master”), thanks to lossless audio coding formats (FLAC, ALAC). However, a lossless format does not guarantee that the audio content is what it seems to be. The audio signal may have been upscaled (increasing the resolution), upsampled (increasing the sampling rate) or even transcoded from a lossy to a lossless format. Lossless Audio Checker analyzes lossless audio tracks and detects upscaling, upsampling and transcoding.
FreqAnalyst ~ Spectrum Analyzer VST
Blue Cat’s FreqAnalyst is a free spectrum analyzer plug-in that lets you monitor the spectral content of your audio signal in real time.
This plug-in has been designed to provide extreme smoothness and high resolution for both time and frequency: unlike most spectrum analyzers, Blue Cat’s FreqAnalyst is able to display continuous variations even with a very high frequency resolution, thanks to its unique smooth interpolation algorithms.
Most aspects of the audio to frequency display conversion can be managed, which lets you total control over the monitoring. A special thresholding system has been developed to help you see the important parts of the spectrum easily. In case you need extra precision in a particular frequency range, you can zoom the display and check the part of the graph you are interested in.

www.bluecataudio.com/Products/Product_FreqAnalyst
References:
DeltaWave ~ Audio Null Comparator
mvMeter2 ~ Freeware Multivariable Meter
mvMeter2 is a multivariable meter including RMS, EBUR128, VU and PPM measurement. mvMeter2 is the successor of mvMeter and adds single/dual meter display, adjustable reference level for all meter modes, adjustable meter delay and preset management.
Features:
- behavior of classic analog VU and PPM meters
- multiple measurement modes: PEAK, RMS, EBU R128, VU and PPM
- multi channel metering: stereo, left, right, mid, side
- single and dual meter display
- adjustable reference level for all meter modes
- adjustable meter delay
- preset management
- adjustable pre-gain including gain matching
- instance label
- large and accurate live meters
- 64-bit internal processing
- 5 different meter themes
- GUI resizing up 400%, ready for 4k displays
- free of charge

The ABC Music Project ~ Plain Text Notation Format
ABC, developed by Chris Walshaw, is a format designed to notate music using plain text. It was originally designed for folk tunes of Western European origin which can be written on one staff, but has since been extended to support the notation of complete, classical music scores.
Since its introduction at the end of 1991, ABC has become very popular. Programs on many operating systems use ABC as an input and/or output format. There are programs which produce printed sheet music or allow for computer performances, search in tune databases, or that analyze tunes in some way.
The aim of this project is to promote the ABC language by maintaining the ABC standard and a set of software and source code that manipulate and present music written in ABC.
abcnotation.com
abc.sourceforge.net
ABC Tune Search
The abc tune search / tune finder gives you access to thousands of folk & traditional tunes from across the web.
Classical music extensions:
abcplus.sourceforge.net
sourceforge.net/projects/abcplus
ABC to HTML ~ sourceforge.net/projects/netabc
User Interfaces ~ sourceforge.net/projects/runabc
Reference: en.wikipedia.org/wiki/ABC_notation
VSLM ~ Virtual Sound Level Meter
This project is the MATLAB development of a virtual sound level meter. The program will read in a calibrated .wav file and allow the user to analyze it as one would analyze a sound field with a sound level meter. The software implements Fast, Slow, Impulse and LEQ; A, C and Flat Weighting; Ln and Noise Dose analysis; Octave and 1/3 Octave band analysis; high resolution FFT analysis and spectrograms. Band analysis can be made using fast FFT methods or slower, but ANSI standard methods.
Source code requires MATLAB + Signal Processing Toolbox.
Developed under MATLAB R2010a (but might work with some earlier versions)Executable version does not require MATLAB and runs under Windows XP, Vista, and Windows 7.
Features
- MATLAB Based Software Sound Analyzer
- Mimics results of an ANSI Standard Integrating Sound Level Meter
- Includes Lp, LEQ, Octave and 1/3 Octave Band, NC, RC and FFT Analysis


