Abstract: A sampling-rate conversion method receives N input channels which have been digitized at an input sampling rate, and converts the sampling rate of each input channel to produce N output channels at an output sampling rate. The method comprises computing a common FIR interpolating function which depends upon the input and output sample clocks and the instantaneous output time, and applying the common FIR interpolating function to all N input channels to compute all N output channels.

Abstract: A vehicle engine sound simulator includes a crossfade sample playback engine which produces an output waveform comprising at least two constituent waveforms which are transposed up and down in frequency with RPM. The playback engine's output waveform is provided to at least one digital signal processing (DSP) circuit, which processes the output with a function that varies with the rate of change of RPM, an external load value, and/or a combination of both to produce the simulator's output. The crossfade sample playback engine is arranged to crossfade between at least 2 wave samples as RPM changes. Wave samples from additional wave banks associated with different load states can also be mixed into the playback engine's output waveform. The DSP circuit can include both nonlinear and linear processing sections in various combinations.

Abstract: Complex sound events are created by generating multiple different kinds of simpler sounds with randomly varying repetition rates. The average repetition rate can also be variable. The values of sound parameters such as wave selection, pitch distribution, pan distribution and amplitude distribution can have random distributions, as determined by various control inputs, some of which have their own random distributions.

Abstract: Computer-implemented techniques are provided for synthesizing sounds of an internal combustion engine vehicle using a physical model of the vehicle. In general terms, the method includes independently generating and/or synthesizing separate components of the vehicle sound, then combining these components to produce a final sound. Using a physical model of the vehicle, the separate components of the vehicle sound are independently generated from vehicle control parameters characterizing the operating conditions of the vehicle. The components are then combined using mixers and equalizers to produce a realistic vehicle sound. The present technique allows independent control of the separate components of the vehicle sound, is not limited to specific vehicles, and does not require recorded sounds taking large amounts of storage space.

Abstract: A sampled data, non-integer delay line interpolation structure includes a sampled data delay line, two allpass filters, each having an associated read pointer for reading data at a corresponding integer position of the delay line, an alternating crossfader that alternatingly crossfades between the outputs of the two allpass filters, plus a controller that controls when the read position of each allpass filter is updated and also controls when the filter coefficient of each allpass filter is updated. A specified delay length value is sampled by the controller each time the crossfade orientation of the alternating crossfader is changed, and from that value the controller generates a new read pointer and filter coefficient for allpass filter to which the structure will next crossfade. The new read pointer is an integer that corresponds to an integer portion of the specified delay length, and the filter coefficient corresponds to a fractional portion of the specified delay length.

Abstract: A sound synthesis system employs a variable-length delay line whose length is modulated at a frequency that is close to the fundamental frequency of the delay line. By modulating the length of the delay line at a frequency close to the fundamental frequency of the delay line, a new class of sounds is generated. A delay line length modulator produces a periodic modulation signal whose frequency is close to the fundamental frequency of the delay line. The length of the delay line is modulated in accordance with the modulation signal, thereby causing a variable pitch shifting effect in the waveform produced by the delay line structure. Since the length of the delay line is modulated at a frequency close to the average loop frequency, part of the waveform stored by the delay line is time-compressed and the other part is expanded. The waveform's shape changes smoothly so that the compressed part of the waveform is pitched-shifted upwards, and the expanded part is pitch-lowered.