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    Wyświetlanie 1-6 z 6
    Tytuł:
    Entropy Coder for Audio Signals
    Autorzy:
    Ulacha, G.
    Stasinski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/226974.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    lossless audio coding
    entropy coding
    OLS
    Opis:
    In the paper an effective entropy coder designed for coding of prediction errors of audio signals is presented. The coder is implemented inside a greater structure, which signal modeling part is a lossless coding backward adaptation algorithm consisting of cascaded Ordinary Least Squares (OLS), three Normalized Least Mean Square (NLMS), and prediction error bias correction sections. The technique performance is compared to that of four other lossless codecs, including MPEG-4 Audio Lossless (ALS) one, and it is shown that indeed, on the average the new method is the best. The entropy coder is an advanced context adaptive Golomb one followed by two context adaptive arithmetic coders.
    Źródło:
    International Journal of Electronics and Telecommunications; 2015, 61, 2; 219-224
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Novel Ideas for Lossless Audio Coding
    Autorzy:
    Ulacha, G.
    Stasiński, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/227339.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Lossless Audio Coding
    context coding
    LS predictors
    MMSE
    MMAE
    zero-order entropy
    Opis:
    Novel ideas for lossless audio coding analyzed in the paper are linked with forward predictor adaptation, and concern optimization of predictors on the basis of zero-order entropy and MMAE criterions, and context sound coding. Direct use of the former criterion is linked with exponential growth of optimization procedure, hence, a suboptimal algorithm having polynomial complexity is proposed. It is shown that on average the new types of predictors are better than those obtained by MMSE technique, while two- and three context systems are on average better than a single predictor one. It also appears that 7-bit PARCOR coefficients in the MPEG-4 ALS standard have insufficient precision for some predictor length, and that for very long frames coding results improve with the predictor rank practically in unlimited way.
    Źródło:
    International Journal of Electronics and Telecommunications; 2013, 59, 1; 17-23
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    On the Consumption of Multimedia Content Using Mobile Devices : a Year to Year User Case Study
    Autorzy:
    Falkowski-Gilski, Przemysław
    Powiązania:
    https://bibliotekanauki.pl/articles/177009.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    audio coding
    broadcasting
    mobile devices
    multimedia
    signal processing
    streaming services
    Opis:
    In the early days, consumption of multimedia content related with audio signals was only possible in a stationary manner. The music player was located at home, with a necessary physical drive. An alternative way for an individual was to attend a live performance at a concert hall or host a private concert at home. To sum up, audio-visual effects were only reserved for a narrow group of recipients. Today, thanks to portable players, vision and sound is at last available for everyone. Finally, thanks to multimedia streaming platforms, every music piece or video, e.g. from one’s favourite artist or band, can be viewed anytime and everywhere. The background or status of an individual is no longer an issue. Each person who is connected to the global network can have access to the same resources. This paper is focused on the consumption of multimedia content using mobile devices. It describes a year to year user case study carried out between 2015 and 2019, and describes the development of current trends related with the expectations of modern users. The goal of this study is to aid policymakers, as well as providers, when it comes to designing and evaluating systems and services.
    Źródło:
    Archives of Acoustics; 2020, 45, 2; 321-328
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Methods of Time-Frequency Analysis in Authentication of Digital Audio Recordings
    Autorzy:
    Korycki, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/226798.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    tampering detection
    audio authenticity analysis
    media authentication
    electric network frequency
    time-frequency analysis
    digital audio forensics
    inverse decoder
    MP3
    compressed audio
    perceptual audio coding
    Opis:
    This paper describes the problem of tampering detection and discusses the main methods used for authenticity analysis of digital audio recordings. For the first topic, two frequency measurement algorithms based on electric network frequency criterion are applied. Time-frequency analysis is used and improved with reassignment method for purpose of visual inspection of modified recordings. The algorithms are shortly described and exemplary plots are presented with interpretation. The last described method, recently proposed, is based on checking frame offsets in compressed audio files.
    Źródło:
    International Journal of Electronics and Telecommunications; 2010, 56, 3; 257-262
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Detection of Montage in Lossy Compressed Digital Audio Recordings
    Autorzy:
    Korycki, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/177075.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    tampering detection
    digital forgeries
    digital audio authenticity
    lossy compression
    frame offsets
    modified discrete cosine transform
    MDCT
    advanced audio coding
    AAC
    ogg vorbis
    Opis:
    This paper addresses the problem of tampering detection and discusses methods used for authenticity analysis of digital audio recordings. Presented approach is based on frame offset measurement in audio files compressed and decoded by using perceptual audio coding algorithms which employ modified discrete cosine transform. The minimum values of total number of active MDCT coefficients occur for frame shifts equal to multiplications of applied window length. Any modification of audio file, including cutting off or pasting a part of audio recording causes a disturbance within this regularity. In this study the algorithm based on checking frame offset previously described in the literature is expanded by using each of four types of analysis windows commonly applied in the majority of MDCT based encoders. To enhance the robustness of the method additional histogram analysis is performed by detecting the presence of small value spectral components. Moreover, computation of maximum values of nonzero spectral coefficients is employed, which creates a gating function for the results obtained based on previous algorithm. This solution radically minimizes a number of false detections of forgeries. The influence of compression algorithms’ parameters on detection of forgeries is presented by applying AAC and Ogg Vorbis encoders as examples. The effectiveness of tampering detection algorithms proposed in this paper is tested on a predefined music database and compared graphically using ROC-like curves.
    Źródło:
    Archives of Acoustics; 2014, 39, 1; 65-72
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance Evaluation of Audio Coding by Amalgam AAC and FLAC Audio codec using MDCT and INTMDCT Algorithm
    Autorzy:
    Dhas, M. Davidson Kamala
    Priyadharsini, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/226258.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    audio codec
    advanced audio coding (AAC)
    free lossless audio codec (FLAC)
    modified discrete cosine transform (MDCT)
    integer modified discrete cosine transform (IntMDCT)
    mean opinion square (MOS)
    perceptual evaluation audio quality (PEAQ)
    Opis:
    The MDCT and IntMDCT Algorithm is widely utilized is Audio coding. By lifting scheme or rounding operation IntegerMDCT is evolved from Modified Discrete Cosine Transform. This method acquire the properties of MDCT and contribute excelling invertiblity and good spectral mean. In this paper we discuss about the audio codec like AAC and FLAC using MDCT and Integer MDCT algorithm and to find which algorithm shows better Compression Ratio(CR). The confines of this task is to hybriding lossy and lossless audio codec with diminished bit rate but with finer sound quality. Certainly the quality of the audio is figure out by Subjective and Objective testing which is in terms of MOS (Mean opinion square), ABx and some of the hearing aid testing methodology like PEAQ (Perceptual Evaluation Audio Quality) and ODG (Objective Difference Grade)is followed. Execution measure, that is Compression Ratio(CR) and Sound Pressure Level (SPL) is approximated.
    Źródło:
    International Journal of Electronics and Telecommunications; 2019, 65, 3; 533-539
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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