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"[Programmers] are attached to their programs. Indeed, their programs become extensions of themselves - a fact which is verified in the abominable practice of attaching one's name to the program itself..." --Gerald M. Weinberg, The Psychology of Computer Programming
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Audio Processing

Thursday, 19 January 2006 00:03
Audacity - Free audio editor and recorder
Continuous Media Markup Language CMML

Open Source Libraries

PortAudio - portable cross-platform Audio API
libaudiofile - (LGPL) a library for reading and writing many diff. audio formats.
libsndfile - (LGPL) a library for reading and writing many diff. audio formats.
SoundTouch - (LGPL) library for changing the Tempo, Pitch and Playback Rates of audio streams or files.
libsamplerate - (LGPL) library for changing the sample rate of audio.
aubio - (GPL) library for audio labeling.
AGTK - (Common Public) Annotation Graph Toolkit
MUSTAJUURI - AUDIO APPLICATION AND TOOLKIT
PortAudio - portable cross-platform Audio API
NAudio - NAudio is an open source .NET audio and MIDI library, containing dozens of useful audio related classes intended to speed development of audio related utilities in .NET.
Evolving Software - OpenSebJ - OpenSebJ is a free real time audio sample mixer that runs on Microsoft Windows. The source code for OpenSebJ is released under the GNU General Public License.
OpenSebJ - contains info on naudio and OpenSebJ.


Tools and things of interest

WaveSurfer is an Open Source tool for sound visualization and manipulation.
Signal Analysis/Processing Software - a list of good resources about DSP and audio processing.
Praat: doing Phonetics by Computer
How-to: Autotune/ Pitch Correction Effect with Praat | Debian/Ubuntu Tips & Tricks


Interesting papers and pages on the web

BBC Annotatable Audio - a blog article on BBC's audio tools.
Experiments in computer-assisted annotation of audio
SPEECH SEGMENTATION WITHOUT SPEECH RECOGNITION
Spoken Language Processing for Audio Archives of Lectures and Panel Discussions

Speech Recognition

In many ways speech reconition has been somewhat of a holy grail for the ultimate humain computer interface. Lately I've been getting the feeling that we are getting really close to something that is actually useable. If you haven't used a speech recognition system for a while... try one... you'll be surprised.

Currently I'm looking for ways to integrate a speech SDK into my applications. The features I'm looking for is simple sentence or word segmentation and text with confidence levels.

I heard IBM ViaVoice could be used on the linux platform, but when I called IBM I was sent to an outside company which told me that they don't support or even have such an SDK. So I don't know what the state of development for IBM's ViaVoice is..... but we aren't dead yet.

The next thing that I've been hearing some good things about... is the Sphinx project from CMU. Man, I'm impressed with the people at CMU! I've been following many of their projects since I was a young kid in high school trying to wrap my head around facial recognition and neural networks. Anyways, I'm currently researching this platform... and it looks promising with support for most all OSs.
Here are some links:

Someone built a Robosapien Dance Voice control with Sphinx, here is a video of it in use.

Networked Sound / Loopback Audio Devices

Lately I've been thinking hard about ways to make sound work wirelessly around my home. There really isn't a solution yet for whole home intercom that can be done using simple PCs. Yes, I can setup a sip phone on each computer and have all the systems auto answer.... but this doesn't provide a way for me to say play high quality mp3 audio on the bedroom and kitchen speakers.

Another program is recording and mixing the audio of incoming and outgoing sources. I'd really like to have the ability to mux together any number of channels and distribute that across the entire home. Possibly even have a way to set mixing properties of incoming sources.

A few audio loopback devices I've found so far are:
vsound - (LGPL) an virtual audio loopback for linux/mac machines.
Virtual Audio Cables - (comm) a virtual loopback device for windows.
Using Virtual Audio Cables, there is a way to actually record Skype calls directly on your PC. This pdf talks about it.


Soundflower - Free Inter-application Audio Routing Utility for Mac OS.

Monitor stereo-example
Plantronics Development SDK Blog
Voice Activity Detection for VoIP—An Information Theoretic Approach

csound

codeproject.com: C# Synth Toolkit - Part I


FMOD music & soundeffects system
Ambiera: irrKlang - an audio library for C++, C# and .NET and high level 3D and 2D sound engine
impromptu - very cool OSX programming environment for composers, sound artists, VJ's and graphic artists with an interest in live or interactive programming. Impromptu is a Scheme language environment utilizing MacOSX AudioUnit chains.
SonicBirth - SonicBirth is an AudioUnit designing application. The first in its category, it allows users to build their own AudioUnit plugins, either by working with existing circuits or by creating circuits completely from scratch. SonicBirth is also a free AudioUnits package, as it comes bundled with a set of plugins designed for standalone use as plugins as well as pre-constructed circuits to modify or build upon for creating new plugins. Whether you're looking for traditional eqs, compressors, and reverbs, or softsynths, distortion, and filters, etc., SonicBirth allows you unprecedented freedom and creativity over your sound.
ACID - Oscillating Rhythms - a new approach to rhythm generation - this app is actually based on impromptu. (OSX only)

SuperCollider - real-time audio synthesis and algorithmic composition
SuperColliderAU is an AudioUnit wrapper that allows using SuperCollider servers inside AudioUnits Hosts. The embedded server may be controlled over OSC as usual. In addition, it may be packed with on synth definition and a configuration file that defines its parameters. (this means you could use it from impromptu)
Create Digital Music » Wii Remote Scratching Proof-of-Concept on Open-Source SuperCollider

reactable - collaborative electronic music instrument with a tabletop tangible multi-touch interface.


Ableton Live packs

Ableton Livepack - Downloads
Create Digital Music » Free Ableton Live Pack by Composer Dennis DeSantis

Sounds and effects

Sound samples - OLPC - Over 10GB of FREE Samples – for The Children of the World
Steve Harris' LADSPA Plugin - GPL code for effects that work in Audacity and can be used by others.
Last Updated on Tuesday, 16 February 2010 09:02