1,720,952 research outputs found
Modeling Audio Fingerprints: Structure, Distortion, Capacity
No full textAn audio fingerprint is a compact low-level representation of a multimedia signal. An audio fingerprint can be used to identify audio files or fragments in a reliable way. The use of audio fingerprints for identification consists of two phases. In the enrollment phase known content is fingerprinted, and ingested into a database, together with all relevant metadata. In the identification phase, unknown audio content is fingerprinted, and the fingerprints form the query to the database. The query fingerprint is compared to the fingerprints in the database. If a similar fingerprint is found in the database, the relevant metadata corresponding to the fingerprint is returned. In this thesis we develop models for audio fingerprints. The emphasis here is on fingerprint extraction and the properties of the fingerprint, not on matching the query fingerprint to the fingerprints in the database, and the actual identification. We also do not develop new practical fingerprinting algorithms. There is a wide variety of applications for audio fingerprinting, including broadcast monitoring, audience measurement, forensic applications, blacklisting of unauthorized content, 'name that tune' services and linking of special offers to television or radio commercials. Content which uses the same recorded source material, but which is in different representation, or distorted in different ways, will generate similar audio fingerprints. This distinguishes audio fingerprints from hashes and content-based retrieval. The hash of an audio file changes when one sample changes. Two perceptually equal audio items can have completely different hash values, but will generate similar fingerprints. Content-based retrieval looks for audio items which apply to a similar concept, like the same genre, artist or style, while fingerprinting looks for the reuse of the recorded content. Of course, the exact requirements for a fingerprinting system strongly depend on the application. Relevant aspects for the topics discussed in this thesis are the robustness, uniqueness, accuracy (notably the False Acceptance Rate and False Rejection Rate), granularity and the size of the fingerprints. In this thesis we make three contributions in the form of models. First, we model the structure of a particular type of audio fingerprint, the Philips Robust Hash (PRH). The PRH fingerprint extracts a series of spectral energy related features from the audio signal, which are represented efficiently but coarsely as a binary time-series. The time-series captures the temporal and spectral dynamics of the audio signal, and has a very particular structure mainly depending on a limited number of parameters in the fingerprint extraction. The model describes the structure of the PRH as a function of a number of parameters. It can be used for better understanding and potentially optimization of the fingerprinting system. We experimentally verify the model on synthetic Gaussian iid data, and conclude that the model capture the structure of the PRH fingerprint well. This analysis was reformulated and extended by Balado, Hurley, McCarthy and Silvestre. Second, we observe that distortions in the audio are reflected in changes in the corresponding fingerprint. This kind of distortion affects the quality of the audio signal and changes the resulting fingerprint. The idea is to estimate the amount of distortion on the audio signal by comparing the corresponding fingerprint to a reference fingerprint extracted from a high quality copy of the same audio. In this way one could extend the functionality of a fingerprinting system. We implement and compare the behaviour of a number of algorithms from literature, and observe similar behaviour of the distance between corresponding fingerprints due to compression. We model the effect of particular distortions in the audio due to compression or additive white noise on the difference introduced in the PRH fingerprints. The main result of our modeling effort is a closed form relation between Signal-to-Noise Ratio (SNR) and average fingerprint distance for PRH audio fingerprints of independent identically distributed (iid) signals. We also experimentally verify the developed models. The model fits perfectly for synthetic signals, and captures the behavior observed in a wider variety of fingerprinting algorithms on actual music. Third, we consider an information theoretical framework developed by Westover and O'Sullivan (WOS). The main question is `how many signals can be identified by a fingerprinting system, under certain conditions'. The conditions relate to characteristics of the fingerprint (size of the fingerprint, and representation of the fingerprint), and characteristics of the environment in which the system operates (representation and statistical characteristics of the signals that need to be identified, how much distortion is allowed). We use the results of the model developed for the PRH fingerprint to compare to estimate up to how many signals can be identified with a binary fingerprint like the PRH. Finally, we check whether the changes in the fingerprints we observe in practice due to distortions in the audio signals, and which have been modeled in this thesis, fit in the information theoretical framework of the WOS model. We outline the differences in the WOS-model compared to practical implementations. We finish with a list of recommendations on extending the models to take jointly consider distortion and uniqueness characteristics; to take more distortion types into account, and to extend to images and video; to develop an evaluation framework for audio fingerprinting; to integrate psycho-acoustics; and to develop a theoretical framework for comparing specific algorithms to the capacity bound.MediamaticsElectrical Engineering, Mathematics and Computer Scienc
Distortion Estimation in Compressed Music Using Only Audio Fingerprints
No full textAn audio fingerprint is a compact yet very robust representation of the perceptually relevant parts of an audio signal. It can be used for content-based audio identification, even when the audio is severely distorted. Audio compression changes the fingerprint slightly. We show that these small fingerprint differences due to compression can be used to estimate the signal-to-noise ratio (SNR) of the compressed audio file compared to the original. This is a useful content-based distortion estimate, when the original, uncompressed audio file is unavailable. The method uses the audio fingerprints only. For stochastic signals distorted by additive noise, an analytical expression is obtained for the average fingerprint difference as function of the SNR level. This model is based on an analysis of the Philips robust hash (PRH) algorithm. We show that for uncorrelated signals, the bit error rate (BER) is approximately inversely proportional to the square root of the SNR of the signal. This model is extended to correlated signals and music. For an experimental verification of our proposed model, we divide the field of audio fingerprinting algorithms into three categories. From each category, we select an algorithm that is representative for that category. Experiments show that the behavior predicted by the stochastic model for the PRH also holds for the two other algorithms.MediamaticsElectrical Engineering, Mathematics and Computer Scienc
On the comparison of audio fingerprints for extracting quality parameters of compressed audio
No full textAudio fingerprints can be seen as hashes of the perceptual content of an audio excerpt. Applications include linking metadata to unlabeled audio, watermark support, and broadcast monitoring. Existing systems identify a song by comparing its fingerprint to pre-computed fingerprints in a database. Small changes of the audio induce small differences in the fingerprint. The song is identified if these fingerprint differences are small enough. In addition, we found that distances between fingerprints of the original and a compressed version can be used to estimate the quality (bitrate) of the compressed version. In this paper, we study the relationship between compression bit-rate and fingerprint differences. We present a comparative study of the response to compression using three fingerprint algorithms (each representative for a larger set of algorithms), developed at Philips, Polytechnic University of Milan, and Microsoft, respectively. We have conducted experiments both using the original algorithms and using versions modified to achieve similar operation conditions, i.e., the fingerprints use the same number of bits per second. Our study shows similar behavior for these three algorithms.Information and Communication Theory GroupElectrical Engineering, Mathematics and Computer Scienc
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
