Texas Instruments Corporation

Yoshihide Iwata

Atsuhiro Sakurai

Steven David Trautmann

Ryo Tsutsui

Fred Jay Reuter

Basavaraj I Pawate

Matthew A Woolsey

Judd E Heape

Douglas L Mahlum

Hironori Kakemizu

Ivan Setiawan

This invention involves time-scale modification of audio signals. The invention describes overlap and add time scale modification with variable input and output buffer sizes. Seamless speed change is achieved by keeping track of previously processed data to avoid discontinuities during playback speed transitions.

Seamless audio speed change based on time scale modification

This invention locally controls the pitch of speech and audio signals. The invention is based on a seamless time scale modification (S-TSM) scheme connected to a synchronized sampling rate converter that switches between different time scale factors in a seamless manner and controls pitch during playback in a nearly continuous way.

Local pitch control based on seamless time scale modification and synchronized sampling rate conversion

A method for creating a stereophonic sound image out of a monaural signal combines two sub-methods. Comb filters decorrelate the left and right channel signals. Intra-aural difference cues, such as an Intra-Aural Time Difference (ITD) and an Intra-aural Intensity Difference (IID) separated channels. Strict complementary (SC) linear phase FIR filters divide the incoming monaural signal into three frequency band separation. The comb filters and ITD/IID applied to the low and high frequency bands create a simulated stereo sound image for the instruments other than human voice. Listening tests indicate that this invention provides a wider stereo sound image than previous methods, while retaining human voice centralization. Since the comb filter solution and ITD/IID solution can share the same filter bank, the computational cost of this method is almost the same as the previous method.

Stereo synthesizer using comb filters and intra-aural differences

Audio loudspeaker and headphone virtualizers and cross-talk cancellers and methods use separate virtual speaker locations for different Bark frequency bands and a single reverberation filter for multi-channel virtualizer inputs.

Virtualizer with cross-talk cancellation and reverb

A new method is proposed that produces stereophonic sound image out of monaural signal within a selected frequency regions. The system employs a strictly complementary (SC) linear phase FIR filter pair that separates input signal into different frequency regions. A pair of comb filters is applied to one of the filter's output. This implementation allows a certain frequency range to be relatively localized at center while the other sounds are perceived in a wider space.

Band-selectable stereo synthesizer using strictly complementary filter pair

Bandwidth expansion for audio signals by frequency band translations plus adaptive gains to create higher frequencies; use of a common channel for both stereo channels limits computational complexity. Adaptive cut-off frequency determination by power spectrum curve analysis, and bass expansion by both fundamental frequency illusion and equalization.

Audio bandwidth expansion

A time-domain time-scale modification method based on the synchronous overlap-and-add method consists of a generalization of the envelope-matching time-scale modification method. The cross-correlation function employs a fixed-size cross-correlation buffer to eliminate the need for normalization inside the search loop. This fixed-size cross-correlation buffer is the center of the overlap region corresponding to the case where the fine overlap adjustment value is set to zero. The computational cost of this invention is lower than any other method with a comparable quality.

Fixed-size cross-correlation computation method for audio time scale modification

A time-domain time-scale modification method based on the synchronous overlap-and-add method consists of a generalization of the envelope-matching time-scale modification method. The cross-correlation function employs n most significant bits rather than merely the sign bit of the prior envelope matching method. This provides higher accuracy for n&#x3e;1. A fixed-size cross-correlation buffer is employed to eliminate the need for normalization inside the search loop. This invention makes full use of fast/parallel shift and multiply-and-accumulate (MAC) instructions of current digital signal processors to become at the same time faster and more precise than envelope-matching time-domain time-scale modification.

Generalized envelope matching technique for fast time-scale modification

A computer system includes a main processing unit ( ) coupled to a DSP/memory module ( ). The DSP/memory module ( ) includes semiconductor memory ( ) and digital signal processor circuitry ( ) including one or more digital signal processors ( ). The DSP/memory module ( ) may be placed in standard main memory sockets, such as a SIMM or DIMM sockets, and used as conventional main memory. The memory module can also be used in a smart mode, wherein the digital signal processor ( ) performs operations on data for retrieval by the main processing unit ( ).

System signalling schemes for processor & memory module

A computer system includes a main processing unit (,) coupled to a DSP/memory module (,). The DSP/memory module (,) includes semiconductor memory (,) and digital signal processor circuitry (,) including one or more digital signal processors (,). The DSP/memory module (,) may be placed in standard main memory sockets, such as a SIMM or DIMM sockets, and used as conventional main memory. The memory module can also be used in a smart mode, wherein the digital signal processor (,) performs operations on data for retrieval by the main processing unit (,).

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Ibaraki, Japan

Yoshihide Iwata