Abstract: The present invention provides apparatus and methods which allow music synthesis and audio processing tasks to dynamically scale from a default processor to additional processors in a heterogeneous array of processors in a manner transparent to the user. A router running on one of the processors in the array knows or estimates the load on each processor, and dynamically allocates processing tasks based upon the current load on each processor and its capacity. Processing parameters are shared between all the audio processors to ensure that perceived audio quality is independent of where a task is running.

Abstract: A spatial enhancement system broadens the sound image of a stereo signal. The system emphasizes dissimilarity between the left and right channels by (i) boosting the level of the dissimilar components, (ii) providing spectral equalization to enhance the perception of breadth, and (iii) injecting an equalized, attenuated and inverted version of the dissimilar component into the opposite channel to broaden the components stereo image. The present invention avoids spectral coloration by providing a generally flat transfer function from input to output. Interchannel dissimilarity is estimated by performing a first order comparison of the left and right input signals. The comparison may be implemented by a peak detector on the L-R signal, a cross-correlation procedure, or some other scheme. As a feature, a feedback mechanism alters the equalization characteristics of the signals in a manner that is responsive to the dissimilarity of the output signals.

Abstract: Audio spatial localization is accomplished by utilizing input parameters representing the physical and geometrical aspects of a sound source to modify a monophonic representation of the sound or voice and generate a stereo signal which simulates the acoustical effect of the localized sound. The input parameters include location and velocity, and may also include directivity, reverberation, and other aspects. The input parameters are used to generate control parameters which control voice processing. Thus, each voice is Doppler shifted, separated into left and right channels, equalized, and one channel is delayed, according to the control parameters. In addition, the left and right channels may be separated into front and back channels, which are separately processed to simulate front and back location and motion. The stereo signals may be fed into headphones, or may be fed into a crosstalk cancellation device for use with loudspeakers.

Abstract: Apparatus for simultaneously decompressing and interpolating compressed audio data. The compressed audio data is stored in differential log format, meaning that the difference between each two consecutive data points is taken and the log of the difference calculated to form each compressed data point. To efficiently decompress and interpolate the compressed data, advantage is taken of the fact that addition of logs is equivalent to multiplication of linear values. Thus the log of an interpolation factor is added to each compressed data point prior to taking the inverse log of the sum. An integrator block completes the interpolation and decompression of the data.

Abstract: A parametric signal modeling musical tone synthesizer utilizes a multidimensional filter coefficient space consisting of many sets of filter coefficients to model an instrument. These sets are smoothly interpolated over pitch, intensity, and time. The filter excitation for a particular note is derived from a collection of single period excitations, which form a multidimensional excitation space, which is also smoothly interpolated over pitch, intensity and time. The synthesizer includes effective modeling of attacks of tones, and the noise component of a tone is modelled separately from the pitched component. The input control signals may include initial pitch and intensity, or the intensity may be time-varying. A variety of instruments may be specified.