The Echo Nest API, a suite of web services for music search and recommendations, officially launched at DEMOfall08. As they say: " Input any song and get an XML description of its content." It's a very intriguing API that's increasingly attracting the notice of the developer community. Paul Lamere exemplifies the excitement Echo Nest is eliciting in his recent Sun blogs post "The Echo Nest Developer's API:
This set of webservices solves a whole bunch of problems that typically chew up a researcher's time. With the webservices you can get all sorts of artist data such as links to MP3s for the artist(!), news, blogs, similar artists, links to videos.
Using the APIs you can tap into the Echo Nest capabilities related to music search, music information, music recommendations, and remix tools. Also, use machine listening features including beat and pitch as well as get feeds for any artist, analytics, or remix. The API lets you get "song analytics" that include fade in, fade out, beats, bars, duration, key, loudness, tatums, tempo, metadata, mode, and sections.
Mark Hendrickson wrote about Echo Nest and an early version of its API on TechCrunch calling Echo Nest the "first machine listening API":
"Machine Listening" is the idea that computers can be programmed to interpret audio signals the same way humans do. This means that they can tell when a song belongs to the blues genre rather than techno. And they can detect musical characteristics like tempos, transition types, and harmonies.
Echo Nest is a RESTful API that returns its music results in XML. Authentication is via an API key. See our Echo Nest API profile for more details.
The API is well-documented, including an overview and detailed descriptions of each API method. Forums are available for discussion of API issues and feature requests. A Python SDK is available for the Remix component of the API. The Echo Nest blog frequently discusses the API and related topics.
A recently popular mashup listing here on PW is the our mashup profile for the MoreCowbell.DJ mashup. This fun app uses the Nest Analyze API to analyze audio files, and applies a cowbell based on beats and sections of the music (and lets you add a little bit of Christopher Walken for good measure).
Given the capabilities of the Echo Nest API we'll likely see a variety of interesting and useful applications built with it soon.