Abstract: A multi-channel switchmode audio amplifier is configured by a programmed processor such that each channel drives separate loads, is connected in parallel or is configured in a bridge-tied mode as well as combinations thereof. In one embodiment, amplifier channels that are connected in parallel have power amplifiers that are driven with signals from a single modulator. A feedback circuit and error amplifier from one channel controls the modulated signal that is applied to each parallely connected amplifier channel. Current feedback circuits for parallely connected amplifier channels are eliminated by tightly controlling the timing of switching in the power amplifier output stages.

Abstract: A multi-channel switchmode audio amplifier is configured by a programmed processor such that each channel drives separate loads, is connected in parallel or is configured in a bridge-tied mode as well as combinations thereof. In one embodiment, amplifier channels that are connected in parallel have power amplifiers that are driven with signals from a single modulator. A feedback circuit and error amplifier from one channel controls the modulated signal that is applied to each parallely connected amplifier channel. Current feedback circuits for parallely connected amplifier channels are eliminated by tightly controlling the timing of switching in the power amplifier output stages.

Abstract: A multi-channel switchmode audio amplifier is configured by a programmed processor such that each channel drives separate loads, is connected in parallel or is configured in a bridge-tied mode as well as combinations thereof. In one embodiment, amplifier channels that are connected in parallel have power amplifiers that are driven with signals from a single modulator. A feedback circuit and error amplifier from one channel controls the modulated signal that is applied to each parallely connected amplifier channel. Current feedback circuits for parallely connected amplifier channels are eliminated by tightly controlling the timing of switching in the power amplifier output stages.

Abstract: A method and apparatus for buffer management for digital audio recording/playback wherein a digital signal processor, memory and appropriate interfacing facilitate storage and retrieval of digital audio data samples continuously across non-contiguous areas of memory to achieve substantially seamless flow of audio, as well as precise fade-in, fade-out and cross-fading between channel events, all as required in such critical synchronizing applications as film dubbing. A GUI interface and recorder controller communication with the processor, memory and a recording media may also be included.

Abstract: A decoder capable of decoding audio signals encoded using analog noise reduction techniques, particularly Dolby A, is implemented by means of digital signal processing. The encoded signal passes through one or more digital filters, producing the decoded signal. The decoded signal is fed back to drive control blocks, which determine the parameters of the digital filters. The determination of these parameters may be arranged so as to emulate closely a given analog noise reduction decoder, such as a Dolby A decoder. The one or more digital filters are relocated to the feed-forward portion of the decoder—they are located in the feedback portion of the encoder when performed using analog techniques—to overcome the problems caused by delay introduced by the digital implementation which prevent a direct conversion of the analog decoder to a digital one.

Abstract: The system and method of the present invention provides enhanced surround sound effects. In one embodiment, 90.degree. phase shift and copy of the modified head related transfer functions (HRTF) are applied to each rear sound signal. The modified HRTF for each rear signal is generated by removing the head related transfer function corresponding to the front center signal from the HRTF corresponding to the rear sound signal. This provides the audible effect of distinguishing more clearly sounds originating in front of the listener or to the rear of the listener while not limiting the perceived bandwidth of the signal. The rear signals corresponding to the first channel are inverted. The front and rear signals for each corresponding channel are then combined. The two channels, generated can be stored on media, such as film, and subsequently read and input to a surround sound decoder to generate enhanced surround sound output.

Abstract: The system and method of the present invention provides enhanced surround sound effects. In one embodiment, 90.degree. phase shift and copy of the modified head related transfer functions (HRTF) are applied to each rear sound signal. The modified HRTF for each rear signal is generated by removing the head related transfer function corresponding to the front center signal from the HRTF corresponding to the rear sound signal. This provides the audible effect of distinguishing more clearly sounds originating in front of the listener or to the rear of the listener while not limiting the perceived bandwidth of the signal. The rear signals corresponding to the first channel are inverted. The front and rear signals for each corresponding channel are then combined. The two channels, generated can be stored on media, such as film, and subsequently read and input to a surround sound decoder to generate enhanced surround sound output.

Abstract: The system and method of the present invention provides surround sound effects through a two channel system. In one embodiment, the first channel is connected to one speaker (e.g., the right speaker) of a headset and the second channel is connected to the other speaker (e.g., the left speaker) of the headset. Thus, surround sound effects, including providing effects to distinguish front and rear sound sources, are provided through headsets which isolate the sound provided to right ear and the left ear of the listener. Alternately, the signals are output to a two speaker system, enabling surround sound effects to be output through home stereo systems not necessarily configured specifically for surround sound. Modified head related transfer functions (HRTF) are applied to each rear sound signal. The modified HRTF for each rear signal is generated by removing the head related transfer function corresponding to the front center signal from the HRTF corresponding to the rear sound signal.

Abstract: The system and method of the present invention provides surround sound effects through a two channel system. In one embodiment, the first channel is connected to one speaker (e.g., the right speaker) of a headset and the second channel is connected to the other speaker (e.g., the left speaker) of the headset. Thus, surround sound effects, including providing effects to distinguish front and rear sound sources, are provided through headsets which isolate the sound provided to right ear and the left ear of the listener. Alternately, the signals are output to a two speaker system, enabling surround sound effects to be output through home stereo systems not necessarily configured specifically for surround sound. Modified head related transfer functions (HRTF) are applied to each rear sound signal. The modified HRTF for each rear signal is generated by removing the head related transfer function corresponding to the front center signal from the HRTF corresponding to the rear sound signal.

Abstract: A method and apparatus for sample accurate parameter update management in digital audio recording/playback wherein a digital signal processor, memory, recording controller, and appropriate interfacing facilitate storage and retrieval of digital audio data samples continuously to achieve substantially seamless flow and sample accurate audio state updated at precisely designated times, all as required in such critical synchronizing applications as film dubbing.

Abstract: A decoder capable of decoding audio signals encoded using analog noise reduction techniques, particularly Dolby SR, is implemented by means of digital signal processing. The typical decoding paradigm used by analog Dolby SR decoders is modified to overcome the problems caused by delay which is introduced by the digital implementation. A gain factor is factored out of the feedback transfer function and is placed in the forward signal path of each stage of the digital decoder. A single control circuit can then be used to generate coefficients which define transfer functions of each filter stage of the signal path. Linear interpolation techniques are used to limit the number of coefficient entries necessary to emulate the transfer function of an analog Dolby SR decoder. The digital decoder structure can be inverted to produce a digital encoder which is capable of implementing any noise reduction standard desired, including Dolby SR.

Abstract: A decoder capable of decoding audio signals encoded using analog noise reduction techniques, particularly Dolby A, is implemented by means of digital signal processing. The encoded signal passes through one or more digital filters, producing the decoded signal. The decoded signal is fed back to drive control blocks, which determine the parameters of the digital filters. The determination of these parameters may be arranged so as to emulate closely a given analog noise reduction decoder, such as a Dolby A decoder. The one or more digital filters are relocated to the feed-forward portion of the decoder--they are located in the feedback portion of the encoder when performed using analog techniques--to overcome the problems caused by delay introduced by the digital implementation which prevent a direct conversion of the analog decoder to a digital one.

Abstract: A system for providing audible cues that enable a listener to identify locations of origins of sounds. In one embodiment, a front and rear signal are copies of an input signal. The rear signal is modified by application of a modified head related transfer function which is the difference between the front and rear head related transfer functions. Copies are then made of the front signal and the modified rear signal, one copy of each associated with a first channel and one copy of each associated with a second channel. Front/rear cues are applied by delaying one of the rear signals or inverting the phase of one of the rear signals. Volume levels are then modified according to the location of the sound source. Locations of sound sources, including sources location behind the user are therefore audibly distinguished. Thus, in an interactive environment, such as a video game environment, the sounds generated by moving objects can be readily modified by simply modifying the volume levels.