Audio fading is performed in order to smoothly modify over time the level of an audio signal. In particular, the fade-in audio effect designates a gradually increase in the audio volume, starting from silence. In practice, audio fading is mostly carried out within audio editors i.e. in off-line mode by employing various transcendental functions to enforce the fade profile. Taking into account the increasing demand for interactive media services requiring real-time audio processing, the present approach advances an effective method of constructing the audio fade-in shape with a view to real-time computing. The paper encompasses plain and straightforward implementations in pure JavaScript, prepared precisely to validate the method of audio volume processing proposed here.
To a large extent, an audio fade is distinctly acknowledged as a strict increase (fade-up) or decrease (fade-down) of the volume of an audio content. In this broad context, the widely used fade-in and fade-out sound effects, applied to receive smooth transitions from and down to silence, respectively, appear to be restrictive. Taking into account the increasing demand for multimedia techniques adapted for real-time computing, the present investigation advances straightforward procedures intended for customizing the audio fade-up and fade-down profiles, having at hand well-proven techniques of shaping the fade-in and fade-out audio effects, suitable for fast computing.
The fade-out sound effect designates a strict decreasing of the volume of an audio signal, starting from the detected initial level down to silence. Audio fade-outs are usually processed in off-line mode that is within audio editors, by employing different transcendental functions to set the time-related evolution of the audio level. However, the proliferation of mobile devices as well as the increasing popularity of web applications, implemented in HTML5/JavaScript, press for computing techniques suitable for real-time processing. In this context, having in view that the computation of the outputs of transcendental functions is very time-consuming, in order to construct the audio fade-out profile, a technique suitable for real-time computing is developed in the present investigation. The suggested techni-que is validated by means of an implementation in pure JavaScript, put forward with the purpose of immediate testing.
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