Diogo Cocharro | Universidade do Porto (original) (raw)
Papers by Diogo Cocharro
Applying Rhythmic Transformations on Real-Time Audio, Sep 4, 2014
In this paper we present a system that analyses and manipulates the syncopation in rhythmic audio... more In this paper we present a system that analyses and manipulates the syncopation in rhythmic audio loops in real-time. In the core of the system is a model of syncopation that allows for the direct manipulation of syncopation in rhythmic patterns by displacing the musical events from their original positions. The task is performed in three stages. First, the onsets of musical events are detected in the audio signals. Second, the detected onsets are displaced according to their metrical positions in order to generate syncopation or remove the syncopation that is already present. Finally, in the third stage, the audio is reconstructed with the musical events in their new positions. The system is implemented as a MaxForLive device that allows musicians and producers to explore a multitude of rhythmic variations in audio loops inside the Ableton Live environment.
Music Perception
Music often evokes a regular beat and a pleasurable sensation of wanting to move to that beat cal... more Music often evokes a regular beat and a pleasurable sensation of wanting to move to that beat called groove. Recent studies show that a rhythmic pattern’s ability to evoke groove increases at moderate levels of syncopation, essentially, when some notes occur earlier than expected. We present two studies that investigate that effect of syncopation in more realistic polyphonic music examples. First, listeners rated their urge to move to music excerpts transcribed from funk and rock songs, and to algorithmically transformed versions of these excerpts: 1) with the original syncopation removed, and 2) with various levels of pseudorandom syncopation introduced. While the original excerpts were rated higher than the de-syncopated, the algorithmic syncopation was not as successful in evoking groove. Consequently, a moderate level of syncopation increases groove, but only for certain syncopation patterns. The second study provides detailed comparisons of the original and transformed rhythmic...
Encyclopedia of Computer Graphics and Games, 2019
Audio Mostly 2021, 2021
Rhythmic similarity, a fundamental task within Music Information Retrieval, has recently been app... more Rhythmic similarity, a fundamental task within Music Information Retrieval, has recently been applied in creative music contexts to retrieve musical audio or guide audio-content transformations. However, there is still very little knowledge of the typical rhythmic similarity values between overlapping musical structures per instrument, genre, and time scales, which we denote as rhythmic compatibility. This research provides the first steps towards the understanding of rhythmic compatibility from the systematic analysis of MedleyDB, a large multi-track musical database composed and performed by artists. We apply computational methods to compare database stems using representative rhythmic similarity metrics – Rhythmic Histogram (RH) and Beat Spectrum (BS) – per genre and instrumental families and to understand whether RH and BS are prone to discriminate genres at different time scales. Our results suggest that 1) rhythmic compatibility values lie between [.002,.354] (RH) and [.1,.881...
We present HarT, a software tool for assisting users recreating existing music content by harmoni... more We present HarT, a software tool for assisting users recreating existing music content by harmonic transformations while retaining rhythmic and harmonic function structure. Our main contribution is the exploration of the perceptually-motivated Tonal Interval Space to analyze the harmonic content of user-input MIDI files according to the function each vertical music aggregate plays within the structure, as well as providing a ranking order of harmonic related chords to a given function. These strategies are then applied to guide harmonic transformations of the music content in an intuitive user-navigable map.
ArXiv, 2018
We address the task of advertisement detection in broadcast television content. While typically a... more We address the task of advertisement detection in broadcast television content. While typically approached from a video-only or audio-visual perspective, we present an audio-only method. Our approach centres on the detection of short silences which exist at the boundaries between programming and advertising, as well as between the advertisements themselves. To identify advertising regions we first locate all points within the broadcast content with very low signal energy. Next, we use a multiple linear regression model to reject non-boundary silences based on features extracted from the local context immediately surrounding the silence. Finally, we determine the advertising regions based on the long-term grouping of detected boundary silences. When evaluated over a 26 hour annotated database covering national and commercial Portuguese television channels we obtain a Matthews correlation coefficient in excess of 0.87 and outperform a freely available audio-visual approach.
Encyclopedia of Computer Graphics and Games. Springer, Cham., 2019
Technologies which adhere to nonlinear, as opposed to fixed, storytelling are becoming pervasive ... more Technologies which adhere to nonlinear, as opposed to fixed, storytelling are becoming pervasive in the digital media landscape (Lister et al. 2003). In this context, methods for dynamically generating music have been prominently and increasingly adopted in games, virtual and augmented reality, interactive installations, and 360 video. Their adoption is motivated by a wide range of factors from computational constraints (e.g., limited memory) to enhanced interaction with external actuators and artistic endeavor. Dynamic music generation systems are typically driven by formalized or algorithmic methods whose history is interleaved with modern computing (Nierhaus 2009). This article reviews a subset of these systems which adopt musical audio as a source to formalize musical structure algorithmically, which is then used to guide the generation of new musical streams by synthesizing sub-audio clips from the musical audio source – an approach addressed as musical audio analysis-synthesis...
We present Conchord, a system for real-time automatic generation of musical harmony through navig... more We present Conchord, a system for real-time automatic generation of musical harmony through navigation in a novel 12-dimensional Tonal Interval Space. In this tonal space, Euclidean distances among multi-level pitch configurations equate with their perceptual proximity, and Euclidean distances of pitch configurations from the center of the space acts as an indicator of consonance. Building upon these attributes, users can intuitively and dynamically define a collection of chords based on their relation to a tonal center (or key) and their consonance level. Furthermore, two algorithmic strategies grounded in principles from function and root-motion harmonic theories generate chord progressions characteristic of Western tonal music.
Computers in Entertainment, 2016
We present D'accord, a generative music system for creating harmonically compatible accompani... more We present D'accord, a generative music system for creating harmonically compatible accompaniments of symbolic and musical audio inputs with any number of voices, instrumentation, and complexity. The main novelty of our approach centers on offering multiple ranked solutions between a database of pitch configurations and a given musical input based on tonal pitch relatedness and consonance indicators computed in a perceptually motivated Tonal Interval Space. Furthermore, we detail a method to estimate the key of symbolic and musical audio inputs based on attributes of the space, which underpins the generation of key-related pitch configurations. The system is controlled via an adaptive interface implemented for Ableton Live, MAX, and Pure Data, which facilitates music creation for users regardless of music expertise and simultaneously serves as a performance, entertainment, and learning tool. We perform a threefold evaluation of D'accord, which assesses the level of accuracy ...
ABSTRACT This study addresses the relationship between syncopation and groove in simple piano mel... more ABSTRACT This study addresses the relationship between syncopation and groove in simple piano melodies. The principal motivation is to test whether creating syncopations in simple melodies increases the perception of groove in listeners. The basic stimuli comprised 10 simple piano melodies (around 20 s in duration), synthesized using MIDI at a fixed tempo of 100 BPM. Each melody was accompanied by a simple rhythmic pattern to provide a metric reference. These basic melodies were selected on the basis that they contained no syncopating events, and no note events at metrical levels below the quarter note. Each melody was transformed to create four different conditions: (1) "anticipation-syncopation" in which events at weak metrical positions were made one 8th note early, (2) "delay-syncopation" in which events at weak metrical positions were made delayed by one 8th note; iii) "max-syncopation", in which all events were one 8th note early, and (4) "density-transform", in which each event was halved in duration and the number of events doubled. The stimuli were presented to participants in a random order and ratings were collected for the following scales: movement inducing (i.e., groove), swinging, naturalness, preference and familiarity. Ratings were collected anonymously through a web-based experimental setup. Analysis of the data collected revealed a highly significant increase (Cohen’s d’ = 0.4) in the groove ratings for the syncopated melodies compared to the original quantized condition. A smaller effect size was observed (Cohen’s d’ = 0.25) when comparing groove ratings for the density and max-syncopation transformations to the quantized condition.
In this paper we present a novel method that can effectively manipulate the syncopation in rhythm... more In this paper we present a novel method that can effectively manipulate the syncopation in rhythmic performances. The core of the method consists of a set of formalized transformations that can effectively remove and create new syncopations in a binary pattern. One can obtain a multitude of rhythmic patterns with different degrees of syncopation by successively applying the transformations to a single input pattern. The� "Syncopalooza"� software application implements the method as two Max4Live devices: an audio device that can transcribe drum performances in real time and a MIDI device that manipulates the syncopation of the transcribed patterns. In addition, we evaluate the syncopation transformations and show that they perform as they are intended.
Journal of New Music Research, 2016
In this paper we present a 12-dimensional tonal space in the context of the Tonnetz, Chew's Spira... more In this paper we present a 12-dimensional tonal space in the context of the Tonnetz, Chew's Spiral Array, and Harte's 6-dimensional Tonal Centroid Space. The proposed Tonal Interval Space is calculated as the weighted Discrete Fourier Transform of normalized 12-element chroma vectors, which we represent as six circles covering the set of all possible pitch intervals in the chroma space. By weighting the contribution of each circle (and hence pitch interval) independently, we can create a space in which angular and Euclidean distances among pitches, chords, and regions concur with music theory principles. Furthermore, the Euclidean distance of pitch configurations from the centre of the space acts as an indicator of consonance.
Current Research in Systematic Musicology
Lecture Notes in Computer Science, 2016
We present Conchord, a system for real-time automatic generation of musical harmony through navig... more We present Conchord, a system for real-time automatic generation of musical harmony through navigation in a novel 12-dimensional Tonal Interval Space. In this tonal space, angular and Euclidean distances among vectors representing multi-level pitch configurations equate with music theory principles, and vector norms acts as an indicator of consonance. Building upon these attributes, users can intuitively and dynamically define a collection of chords based on their relation to a tonal center (or key) and their consonance level. Furthermore, two algorithmic strategies grounded in principles from function and root-motion harmonic theories allow the generation of chord progressions characteristic of Western tonal music.
In this work we present a system that estimates and manipulates rhythmic structures from audio lo... more In this work we present a system that estimates and manipulates rhythmic structures from audio loops in realtime to perform syncopation transformations. The core of our system is a technique for the manipulation of syncopation in symbolic representations of rhythm. In order to apply this technique to audio signals we must first segment the audio loop into musical events using onset detection. Then, we use the symbolic syncopation transformation method to determine how to modify the rhythmic structure in order to change the syncopation. Finally we present two alternative methods to reconstruct the audio loop, one based on time scaling and the other on resampling. Our system, Loopalooza, is implemented as a freely available MaxForLive device to allow musicians and DJs to manipulate syncopation in audio loops in realtime.
In this paper we present a novel method that can effectively manipulate the syncopation in rhythm... more In this paper we present a novel method that can effectively manipulate the syncopation in rhythmic performances. The core of the method consists of a set of formalized transformations that can effectively remove and create new syncopations in a binary pattern. One can obtain a multitude of rhythmic patterns with different degrees of syncopation by successively applying the transformations to a single input pattern. The "Syncopalooza" software application implements the method as two Max4Live devices: an audio device that can transcribe drum performances in real time and a MIDI device that manipulates the syncopation of the transcribed patterns. In addition, we evaluate the syncopation transformations and show that they perform as they are intended.
Applying Rhythmic Transformations on Real-Time Audio, Sep 4, 2014
In this paper we present a system that analyses and manipulates the syncopation in rhythmic audio... more In this paper we present a system that analyses and manipulates the syncopation in rhythmic audio loops in real-time. In the core of the system is a model of syncopation that allows for the direct manipulation of syncopation in rhythmic patterns by displacing the musical events from their original positions. The task is performed in three stages. First, the onsets of musical events are detected in the audio signals. Second, the detected onsets are displaced according to their metrical positions in order to generate syncopation or remove the syncopation that is already present. Finally, in the third stage, the audio is reconstructed with the musical events in their new positions. The system is implemented as a MaxForLive device that allows musicians and producers to explore a multitude of rhythmic variations in audio loops inside the Ableton Live environment.
Music Perception
Music often evokes a regular beat and a pleasurable sensation of wanting to move to that beat cal... more Music often evokes a regular beat and a pleasurable sensation of wanting to move to that beat called groove. Recent studies show that a rhythmic pattern’s ability to evoke groove increases at moderate levels of syncopation, essentially, when some notes occur earlier than expected. We present two studies that investigate that effect of syncopation in more realistic polyphonic music examples. First, listeners rated their urge to move to music excerpts transcribed from funk and rock songs, and to algorithmically transformed versions of these excerpts: 1) with the original syncopation removed, and 2) with various levels of pseudorandom syncopation introduced. While the original excerpts were rated higher than the de-syncopated, the algorithmic syncopation was not as successful in evoking groove. Consequently, a moderate level of syncopation increases groove, but only for certain syncopation patterns. The second study provides detailed comparisons of the original and transformed rhythmic...
Encyclopedia of Computer Graphics and Games, 2019
Audio Mostly 2021, 2021
Rhythmic similarity, a fundamental task within Music Information Retrieval, has recently been app... more Rhythmic similarity, a fundamental task within Music Information Retrieval, has recently been applied in creative music contexts to retrieve musical audio or guide audio-content transformations. However, there is still very little knowledge of the typical rhythmic similarity values between overlapping musical structures per instrument, genre, and time scales, which we denote as rhythmic compatibility. This research provides the first steps towards the understanding of rhythmic compatibility from the systematic analysis of MedleyDB, a large multi-track musical database composed and performed by artists. We apply computational methods to compare database stems using representative rhythmic similarity metrics – Rhythmic Histogram (RH) and Beat Spectrum (BS) – per genre and instrumental families and to understand whether RH and BS are prone to discriminate genres at different time scales. Our results suggest that 1) rhythmic compatibility values lie between [.002,.354] (RH) and [.1,.881...
We present HarT, a software tool for assisting users recreating existing music content by harmoni... more We present HarT, a software tool for assisting users recreating existing music content by harmonic transformations while retaining rhythmic and harmonic function structure. Our main contribution is the exploration of the perceptually-motivated Tonal Interval Space to analyze the harmonic content of user-input MIDI files according to the function each vertical music aggregate plays within the structure, as well as providing a ranking order of harmonic related chords to a given function. These strategies are then applied to guide harmonic transformations of the music content in an intuitive user-navigable map.
ArXiv, 2018
We address the task of advertisement detection in broadcast television content. While typically a... more We address the task of advertisement detection in broadcast television content. While typically approached from a video-only or audio-visual perspective, we present an audio-only method. Our approach centres on the detection of short silences which exist at the boundaries between programming and advertising, as well as between the advertisements themselves. To identify advertising regions we first locate all points within the broadcast content with very low signal energy. Next, we use a multiple linear regression model to reject non-boundary silences based on features extracted from the local context immediately surrounding the silence. Finally, we determine the advertising regions based on the long-term grouping of detected boundary silences. When evaluated over a 26 hour annotated database covering national and commercial Portuguese television channels we obtain a Matthews correlation coefficient in excess of 0.87 and outperform a freely available audio-visual approach.
Encyclopedia of Computer Graphics and Games. Springer, Cham., 2019
Technologies which adhere to nonlinear, as opposed to fixed, storytelling are becoming pervasive ... more Technologies which adhere to nonlinear, as opposed to fixed, storytelling are becoming pervasive in the digital media landscape (Lister et al. 2003). In this context, methods for dynamically generating music have been prominently and increasingly adopted in games, virtual and augmented reality, interactive installations, and 360 video. Their adoption is motivated by a wide range of factors from computational constraints (e.g., limited memory) to enhanced interaction with external actuators and artistic endeavor. Dynamic music generation systems are typically driven by formalized or algorithmic methods whose history is interleaved with modern computing (Nierhaus 2009). This article reviews a subset of these systems which adopt musical audio as a source to formalize musical structure algorithmically, which is then used to guide the generation of new musical streams by synthesizing sub-audio clips from the musical audio source – an approach addressed as musical audio analysis-synthesis...
We present Conchord, a system for real-time automatic generation of musical harmony through navig... more We present Conchord, a system for real-time automatic generation of musical harmony through navigation in a novel 12-dimensional Tonal Interval Space. In this tonal space, Euclidean distances among multi-level pitch configurations equate with their perceptual proximity, and Euclidean distances of pitch configurations from the center of the space acts as an indicator of consonance. Building upon these attributes, users can intuitively and dynamically define a collection of chords based on their relation to a tonal center (or key) and their consonance level. Furthermore, two algorithmic strategies grounded in principles from function and root-motion harmonic theories generate chord progressions characteristic of Western tonal music.
Computers in Entertainment, 2016
We present D'accord, a generative music system for creating harmonically compatible accompani... more We present D'accord, a generative music system for creating harmonically compatible accompaniments of symbolic and musical audio inputs with any number of voices, instrumentation, and complexity. The main novelty of our approach centers on offering multiple ranked solutions between a database of pitch configurations and a given musical input based on tonal pitch relatedness and consonance indicators computed in a perceptually motivated Tonal Interval Space. Furthermore, we detail a method to estimate the key of symbolic and musical audio inputs based on attributes of the space, which underpins the generation of key-related pitch configurations. The system is controlled via an adaptive interface implemented for Ableton Live, MAX, and Pure Data, which facilitates music creation for users regardless of music expertise and simultaneously serves as a performance, entertainment, and learning tool. We perform a threefold evaluation of D'accord, which assesses the level of accuracy ...
ABSTRACT This study addresses the relationship between syncopation and groove in simple piano mel... more ABSTRACT This study addresses the relationship between syncopation and groove in simple piano melodies. The principal motivation is to test whether creating syncopations in simple melodies increases the perception of groove in listeners. The basic stimuli comprised 10 simple piano melodies (around 20 s in duration), synthesized using MIDI at a fixed tempo of 100 BPM. Each melody was accompanied by a simple rhythmic pattern to provide a metric reference. These basic melodies were selected on the basis that they contained no syncopating events, and no note events at metrical levels below the quarter note. Each melody was transformed to create four different conditions: (1) "anticipation-syncopation" in which events at weak metrical positions were made one 8th note early, (2) "delay-syncopation" in which events at weak metrical positions were made delayed by one 8th note; iii) "max-syncopation", in which all events were one 8th note early, and (4) "density-transform", in which each event was halved in duration and the number of events doubled. The stimuli were presented to participants in a random order and ratings were collected for the following scales: movement inducing (i.e., groove), swinging, naturalness, preference and familiarity. Ratings were collected anonymously through a web-based experimental setup. Analysis of the data collected revealed a highly significant increase (Cohen’s d’ = 0.4) in the groove ratings for the syncopated melodies compared to the original quantized condition. A smaller effect size was observed (Cohen’s d’ = 0.25) when comparing groove ratings for the density and max-syncopation transformations to the quantized condition.
In this paper we present a novel method that can effectively manipulate the syncopation in rhythm... more In this paper we present a novel method that can effectively manipulate the syncopation in rhythmic performances. The core of the method consists of a set of formalized transformations that can effectively remove and create new syncopations in a binary pattern. One can obtain a multitude of rhythmic patterns with different degrees of syncopation by successively applying the transformations to a single input pattern. The� "Syncopalooza"� software application implements the method as two Max4Live devices: an audio device that can transcribe drum performances in real time and a MIDI device that manipulates the syncopation of the transcribed patterns. In addition, we evaluate the syncopation transformations and show that they perform as they are intended.
Journal of New Music Research, 2016
In this paper we present a 12-dimensional tonal space in the context of the Tonnetz, Chew's Spira... more In this paper we present a 12-dimensional tonal space in the context of the Tonnetz, Chew's Spiral Array, and Harte's 6-dimensional Tonal Centroid Space. The proposed Tonal Interval Space is calculated as the weighted Discrete Fourier Transform of normalized 12-element chroma vectors, which we represent as six circles covering the set of all possible pitch intervals in the chroma space. By weighting the contribution of each circle (and hence pitch interval) independently, we can create a space in which angular and Euclidean distances among pitches, chords, and regions concur with music theory principles. Furthermore, the Euclidean distance of pitch configurations from the centre of the space acts as an indicator of consonance.
Current Research in Systematic Musicology
Lecture Notes in Computer Science, 2016
We present Conchord, a system for real-time automatic generation of musical harmony through navig... more We present Conchord, a system for real-time automatic generation of musical harmony through navigation in a novel 12-dimensional Tonal Interval Space. In this tonal space, angular and Euclidean distances among vectors representing multi-level pitch configurations equate with music theory principles, and vector norms acts as an indicator of consonance. Building upon these attributes, users can intuitively and dynamically define a collection of chords based on their relation to a tonal center (or key) and their consonance level. Furthermore, two algorithmic strategies grounded in principles from function and root-motion harmonic theories allow the generation of chord progressions characteristic of Western tonal music.
In this work we present a system that estimates and manipulates rhythmic structures from audio lo... more In this work we present a system that estimates and manipulates rhythmic structures from audio loops in realtime to perform syncopation transformations. The core of our system is a technique for the manipulation of syncopation in symbolic representations of rhythm. In order to apply this technique to audio signals we must first segment the audio loop into musical events using onset detection. Then, we use the symbolic syncopation transformation method to determine how to modify the rhythmic structure in order to change the syncopation. Finally we present two alternative methods to reconstruct the audio loop, one based on time scaling and the other on resampling. Our system, Loopalooza, is implemented as a freely available MaxForLive device to allow musicians and DJs to manipulate syncopation in audio loops in realtime.
In this paper we present a novel method that can effectively manipulate the syncopation in rhythm... more In this paper we present a novel method that can effectively manipulate the syncopation in rhythmic performances. The core of the method consists of a set of formalized transformations that can effectively remove and create new syncopations in a binary pattern. One can obtain a multitude of rhythmic patterns with different degrees of syncopation by successively applying the transformations to a single input pattern. The "Syncopalooza" software application implements the method as two Max4Live devices: an audio device that can transcribe drum performances in real time and a MIDI device that manipulates the syncopation of the transcribed patterns. In addition, we evaluate the syncopation transformations and show that they perform as they are intended.