Abstract:
The invention relates to an audio compression system (100) for compressing an input audio signal, the audio compression system (100) comprising a digital filter (101) for filtering the input audio signal, the digital filter (101) comprising a frequency transfer function having a magnitude over frequency, the magnitude being formed by an equal loudness curve of a human ear to obtain a filtered audio signal, and a compressor (103) being configured to compress the input audio signal upon the basis of the filtered audio signal to obtain a compressed audio signal.
Abstract:
The invention provides a concept for combined dynamic range compression and guided clipping prevention for audio devices. An audio decoder for decoding an audio bitstream and a metadata bitstream related to the audio bitstream according to the concept includes an audio processing chain including a plurality of adjustment stages including a dynamic range control stage for adjusting a dynamic range of the audio output signal and a guided clipping prevention stage for preventing clipping of the audio output signal; and a metadata decoder configured to receive the metadata bitstream and to extract dynamic range control gain sequences and guided clipping prevention gain sequences from the metadata bitstream, at least a part of the dynamic range control gain sequences being supplied to the dynamic range control stage, and at least a part of the guided clipping prevention gain sequences being supplied to the guided clipping prevention stage.
Abstract:
A method for computing the "clippings" of an audio signal in the digital domain to prevent aliasing is disclosed. An offset signal is found (10) by subtracting a threshold from samples of the audio signal (12). These are multiplied by a pulse (14) after the pulse is lined up in time with the crossing of the audio signal at the threshold (16). The pulse is the sum of two step functions (18), both of which are bandwidth-limited.
Abstract:
A digital clipper is highly oversampled to decrease aliasing and increase accuracy. The difference between the clipper's input (50) and output (80) is then downsampled and added to the delayed, unclipped signal at Ix sample rate to achieve clipping. Filters (90) operating at Ix can be placed in series with the downsampled differentially-clipped signal to achieve overshoot compensation, bandlimiting of the clipped signal, and other goals.
Abstract:
A method is described of generating an electrical output signal (CFCS) from an electrical input signal (CS) wherein said input signal (CS) is first clipped (12) and then filtered (13) into said output signal (CFCS). The invention is characterized in that said input signal (CS) is clipped dependant on said succeeding filtering. Thereby, a finite power peak capacity of a succeeding amplifier is not exceeded.
Abstract:
A soft digital limiter (2) for limiting an analog input signal (1) from a maximum expected range (61) to a useful range (60). The number (m) of desired levels of resolution in the limiter (2) is preselected to be any power of two. An analog-to-digital converter (9) converts the input analog signal (1) to a digital representation (20). The converter (9) has its input voltage rating matched to the maximum expected range (61) and its output resolution matched to the preselected degree (m) of resolution. In the preferred two's complement numbering system, the condition for the input signal (1) falling within the useful range (60) is that the most significant p + 1 bits of the digital representation (20) are all identical, where p is the number of bits required by the converter (9) to delineate that portion of the maximum expected range (61) outside of the useful range (60). A network of comparators (e.g., 38. 39) implements this condition.
Abstract:
A method of attenuating an input signal to obtain an output signal is described. The method comprises receiving the input signal, attenuating the input signal with a gain factor to obtain the output signal, applying a filter having a frequency response with a frequency-dependent filter gain to at least one of a copy of the input signal and a copy of the output signal to obtain a filtered signal, the frequency-dependent filter gain being arranged to emphasize frequencies within a number N of predetermined frequency ranges, N>1; wherein the filter comprises a sequence ofN sub-filters, each one of the N sub-filters having a frequency response adapted to emphasize frequencies within a corresponding one of the N predetermined frequency ranges; determining a signal strength of the filtered signal, and determining the gain factor from at least the signal strength.
Abstract:
The present technology relates to a decoding apparatus, a decoding method and a program which make it possible to obtain sound with higher quality. A demultiplexing circuit demultiplexes an input code string into a gain code string and a signal code string. A signal decoding circuit decodes the signal code string to output a time series signal. A gain decoding circuit decodes the gain code string. That is, the gain decoding circuit reads out gain values and gain inclination values at predetermined gain sample positions of the time series signal and interpolation mode information. An interpolation processing unit obtains a gain value at each sample position between two gain sample positions through linear interpolation or non-linear interpolation according to the interpolation mode based on the gain values and the gain inclination values. A gain applying circuit adjusts a gain of the time series signal based on the gain values. The present technology can be applied to a decoding apparatus.