An audio codec suitable for robust wireless transmission of high quality audio with low latency, still at a moderate bit rate. The encoding and decoding methods are based on ADPCM and in addition to the encoded output bits APM, additional data QB are included in output data blocks, namely data QB representing an internal value of the adaptive quantization ADQ of the ADPCM encoding algorithm, especially a scaling factor encoded and truncated to such as 8 bits. Further, output data blocks preferably include data CFB representing an internal value of the predictor PR of the ADPCM encoding algorithm, especially data CFB representing coefficients of a lattice prediction FIR filter which, truncated to such as 8 bits, can be sequentially included in output data blocks. These additional data QB, CFB regarding internal values of the ADPCM encoding algorithm can be utilized at the encoder side to increase robustness against loss of data blocks in wireless transmission. Especially, the decoding algorithm may comprise comparing its current internal ADPCM decoding values corresponding to the received internal values QB, CFB from the encoder, and in case there is a difference, the decoder can adapt or overwrite its internal values to the ones received QB, CFB. This helps to ensure fast recovery after lost data blocks, thereby ensuring robustness against artefacts in the reconstructed signal, e.g. clicks in case of audio.

A decoder generates decoded signals based on quantized signals. The decoder includes an inverse quantizer and a predictor circuit. The quantized signals are generated in an encoder by low-pass filtering an input signal and encoding the filtered signal using adaptive differential pulse code modulation. The predictor circuit has filter coefficients based on a frequency response of the low-pass filter used to filter the input signal.

An encoder generates quantized signal words based on a difference signal. The encoder includes an adaptive quantizer. A step size applied by the adaptive quantizer is generated in a feedback loop and based on a loading factor and quantized signal words generated by the adaptive quantizer. The encoder includes coding circuitry which generates code words based on quantized signal words generated by the adaptive quantizer. The coding circuitry generates an escape code in response to a quantized signal word not being associated with a corresponding coding code word.

An adaptive noise shaping filter flattens signal components below a threshold frequency range in a filtered signal to be encoded. An encoder generates quantized signals based on a difference signal and includes an adaptive quantizer and a decoder. The decoder generates feedback signals and has an inverse quantizer and a predictor. The predictor has determined control parameters based on the threshold frequency range.

An encoder includes a low-pass filter to filter input audio signals. The low-pass filter has fixed filter coefficients. The encoder generates quantized signals based on a difference signal. The encoder includes an adaptive quantizer and a decoder to generate feedback signals. The decoder has an inverse quantizer and a predictor. The predictor has fixed control parameters which are based on a frequency response of the low-pass filter. The predictor may include a finite impulse response filter having fixed filter coefficients. The decoder may include an adaptive noise shaping filter coupled between the low-pass filter and the encoder. The adaptive noise shaping filter flattens signals within a frequency spectrum corresponding to a frequency spectrum of the low-pass filter.

A method for providing a digital sensor signal (DS) from an ultrasonic sensor (16) for signal transmission to a signal receiver (28) is disclosed, in which a digital output signal (OS) from the ultrasonic sensor (16) is processed to form the digital sensor signal for signal transmission. Provision is made for the processing to comprise the following steps: (i) determining a signal change (SC) of successive values of the output signal (OS), (ii) scaling this signal change (SC) by means of a variable scaling factor (SF) which is specified by a scaling scheme known to the ultrasonic sensor (16) and the signal receiver (28), and (iii) outputting the scaled signal change (SC) as the digital sensor signal (DS). A corresponding apparatus (32) is disclosed for creating a digital sensor signal (DS) from an ultrasonic sensor (16) for signal transmission to a signal receiver (28), to a corresponding ultrasonic sensor device with an ultrasonic sensor (16) and such an apparatus (32), and to a corresponding ultrasonic sensor system (14).

A data encoding system includes a non-transitory memory, a processor, a digital-to-analog converter (DAC) and a transmitter. The non-transitory memory stores a predetermined file size threshold. The processor is in operable communication with the memory, and is configured to receive data. The processor detects a file size associated with the data. When the file size is below the predetermined file size threshold, the processor compresses the data using a variable length codeword (VLC) encoder. When the file size is not below the predetermined file size threshold, the processor compresses the data, using a hash table algorithm. The DAC is configured to receive a digital representation of the compressed data from the processor and convert the digital representation of the compressed data into an analog representation of the compressed data. The transmitter is coupled to the DAC and configured to transmit the analog representation of the compressed data.

A decoder generates decoded signals based on quantized signals. The decoder includes an inverse quantizer and a predictor circuit. The quantized signals are generated in an encoder by low-pass filtering an input signal and encoding the filtered signal using adaptive differential pulse code modulation. The predictor circuit has filter coefficients based on a frequency response of the low-pass filter used to filter the input signal.

An encoder generates quantized signal words based on a difference signal. The encoder includes an adaptive quantizer. A step size applied by the adaptive quantizer is generated in a feedback loop and based on a loading factor and quantized signal words generated by the adaptive quantizer. The encoder includes coding circuitry which generates code words based on quantized signal words generated by the adaptive quantizer. The coding circuitry generates an escape code in response to a quantized signal word not being associated with a corresponding coding code word.

A source device comprising a memory and a processor may be configured to perform techniques described in this disclosure. The memory may store at least a portion of the audio data. The processor may obtain, from a compressed version of the audio data, a symbol, and obtain a plurality of intervals, each having a same bit length. The processor may obtain a portion of the symbol within the bit length and an excess portion of the symbol over the bit length, and specify, in a first interval, the portion of the symbol. The processor may also specify, in a second interval, the excess portion of the symbol, and apply, to the first interval and the second interval, error resiliency. The processor may specify, in a bitstream representative of the compressed version of the audio data, the first error resilient interval and the second error resilient interval.