GsoC 2008 Application : Mixxx , Key Detection Idea

Abstract

Harmonic Mixing is relatively a new technique used by professional DJs in order to achieve a smooth transmission between songs that are pre-recorded in any known format (Vinyl, CDs, MP3, etc).
In the last few years, many software vendors (mostly proprietary software) have implemented key detection algorithms and other methods on their DJ suites, so as to provide their users the necessary information required in deploying the harmonic mixing technique in their mix.
Our goal is to design a new key detection algorithm or suggest an existing one, and implement it efficiently in Mixxx .

Detailed Description

+ In theory

- In theory

A key detection algorithm mainly requires the use of a pitch detection algorithm (PDA) . Because of the fact that a song/track is a compilation of many audio signals , the required algorithm must be a polyphonic PDA . A PDA in combination with traditional harmonic mixing techniques and theory taken from the Western Music can provide Minx’s user the necessary information to achieve a smooth song transition in a DJ mix.For details check the Reference section.

+ In action

- In action

Given the fact that an appropriate PDA has been chosen via a testing enviroment (thinking about using MATLAB) , the next step is to implement that PDA in Mixxx . Currently Mixxx is using the SoundTouch library (Language used is C++) in order to affect an audio stream's Tempo,Pitch and Playback Rate . Furthermore a light modification in Mixxx UI is needed so as to fully intergrate this idea as a Mixxx feature (Qt4 as a framework).For details check the Reference section.

+ Objectives & Importance

- Objectives & Importance

This proposal is concerned with the following three objectives.

Determine a suitable PDA for key detection in multi-signal tracks.
Implement this PDA in Mixxx's library.
Provide user PDA's results through Mixxx's UI in order to achieve harmonic mixing.

In addition to the above objectives , if project's development progress is satisfactory enough and there is the necessary time , I will try to design (hopefully implement) a key-lock functionality.Key-lock stands for pitch-independent time stretch on a track/song, which simply means that the tempo of a track can be modified without altering track's pitch.This feature along with the results of Key detection can provide to Mixxx users a huge sense of flexibility in their mixes.

The importance of succesfully completing this project is huge . The majority of the modern software DJ tools/suites provide this feature and many Djs (professional and amateur) recognise it's value . Knowning the key of the tracks in mixer channels is very usefull , even to user who is not quite involved in music theory . From there a DJ/user can go beyond the process of beatmatching , avoid sour mixes and please the most demanding ears.

+ Deliverables

- Deliverables

Part 1 : Choosing a suitable PDA (Theoretical part).
1. Implementing and testing PDAs in a testing DSP enviroment (considering MATLAB).
2. Must conclude to one or at most two appropriate PDAs.
Part 2 : PDA implementation in Mixxx (Developing part).
1. Implementing the PDA we decided from the Part 1 , using SoundTouch library.
2. Embodying our Key detection algorithm in Mixxx interfaces (mixer channel buttons , attributes/tags in the playlist).
3. Testing our results and comparing them with results from a commercial key detection tools.
4. Testing , Feedback, Debugging.

+ Proposed Schedule

- Proposed Schedule

This is a proposed time schedule regarding Mixxx's Key Detection functionality. Dates included are not obligatory , they mainly serve as period indicators. Changes may come up in order to support faster development progress.

Time period	Comment
18 April – 5 May	Researching on PDAs. A page regarding project's progress will be added in this wiki in that period.
6 May - 27 May	Starting Part 1 (check Deliverables section). Testing on a suitable DSP environment.
28 May – 10 June	Finishing Part 1 . Taking a brief break from the project to attend some university exams.
11 June – 16 June	Starting Part 2 . Code design week.
17 June – 10 July	Heavy coding . Implementing our Key Detection algorithm . Probably have a full version (maybe tested) of code to submit before mid term evaluation.
10 June – 11 August	Still coding and testing . Hopefully coding at this period revolves more of the UI matter than the Key Detection algorithm itself.
12 August – 1 September	Testing, documenting and releasing

+ Personal information

- Personal information

My name is Dimitris Bousis and i am currently studying to graduate from the Computer Engineering and Informatics Dept of the Univerisity of Patras , Greece . Born on 27/12/1986 at Ioannina , Greece i am now in the fourth year of university studies . My research interests are primarily focused on Distributed Operating Systems , Middleware development and Application development in Embeded Systems .
Moreover , I ve been involved in home studio music production for about two years using a large variety of music production tools and software musical audio workstations (Ableton Live , Native Instruments , Celemony Melodyne, etc) for about four years.My hobbies also include playing the guitar and mixing progressive house, techno, tech house, minimal on Ableton Live and of course Mixxx :) .
As for coding , i should mention that i first started learning programming languages at the age of seventeen . In the last four years , i gained much of my programming experience through course projects assigned to me by my professors at the university department.I mainly code in C++,Java,C and PHP.
I consider myself relatively new to the open source community (exploring open source communities for about a year) , so I think of this project as great opportunity for me to contribute to a open source project I use and enjoy.

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