Abstract: A method and apparatus for adapting dual filters is disclosed. In one aspect, a method may include transforming a signal, adapting a first adaptive filter based on the transformed signal, estimating a delay of an impulse response based on the adaptation of the first filter, delaying a signal based on the estimated delay, and adapting a second adaptive filter based on the delayed signal. In one aspect, an echo or other unwanted signal may be reduced or cancelled based on the adaptation of the second filter.

Abstract: The present invention is an echo canceller for sparse channels in an echo channel. The echo channel receives a far-end input and a near-end input. An enable generator asserts a sparse update enable in response to detecting at least one of the double talk condition and an impulse response change. A main weight updater transfers shadow weights of the shadow filter to N sets of sparse weights in N sparse filters of the main filter according to the sparse update enable. A sparse main filter filters the far-end input non-adaptively to generate a main output. A long shadow filter filters the far-end input adaptively to generate a shadow output and to estimate delays of peaks of the sparse weights in the main filter.

Abstract: In visual display devices such as LCD devices with backlight illumination, the backlight typically consumes most of device battery power. In the interest of displaying a given pixel pattern at a minimized backlight level, the pattern can be transformed while maintaining image quality, with a transform determined from pixel luminance statistics. Aside from, or in addition to such minimizing, a transform also can be used for image enhancement, for a displayed image better to meet a visual perception quality. In either case, the transform preferably is constrained for enforcing one or several display attributes.

Abstract: In visual display devices such as LCD devices with backlight illumination, the backlight typically consumes most of device battery power. In the interest of displaying a given pixel pattern at a minimized backlight level, the pattern can be transformed while maintaining image quality, with a transform determined from pixel luminance statistics. Aside from, or in addition to being used for such minimizing, a transform also can be used for image enhancement, for a displayed image better to meet a visual perception quality. In either case, the transform preferably is constrained for enforcing one or several display attributes. In a network setting, the technique can be implemented in distributed fashion, so that subtasks of the technique are performed by different, interconnected processors such as server, client and proxy processors.

Abstract: Disclosed is an integrated tone detection processor for discriminating between tone and voice signals and determining the tones. The tone detection processor performs Automatic Gain Control (AGC) to normalize the power of the tone or voice signal. Further, the energy of the tone or voice signals are determined at specific frequencies utilizing a Goertzel Filter process. The tone detection processor determines whether or not a tone is present, and if a tone exists, determines the type of tone. Based upon determining the two maximum energy levels of the Goertzel filtered tone, whether the tone is a single tone, dual tone, silence, or other (e.g. speech) can be discriminated. The tone can then be identified by a user-defined dictionary of tones. Based upon various ON and OFF cadence checks in combination with the use of TONE ON and TONE OFF counters, tones can be declared.

Abstract: One aspect of the invention relates to a messaging communication scheme for controlling, configuring, monitoring and communicating with a signal processor within a Voice Over Packet (VoP) subsystem without knowledge of the specific architecture of the signal processor. The messaging communication scheme may feature the transmission of control messages between a signal processor and a host processor. Each control message comprises a message header portion and a control header portion. The control header portion includes at least a catalog parameter that indicates a selected grouping of control messages and a code parameter that indicates a selected operation of the selected grouping.

Abstract: A method and apparatus for adapting dual filters is disclosed. In one aspect, a method may include transforming a signal, adapting a first adaptive filter based on the transformed signal, estimating a delay of an impulse response based on the adaptation of the first filter, delaying a signal based on the estimated delay, and adapting a second adaptive filter based on the delayed signal. In one aspect, an echo or other unwanted signal may be reduced or cancelled based on the adaptation of the second filter.

Abstract: A first adaptive filter having a first filter length estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The echo channel has a plurality of sparse multi-path channels. A delay estimator determines a plurality of delays in the echo channel using the estimated channel weight vector. A second adaptive filter estimates a plurality of short weight vectors using the AP update and the plurality of delays. The short weight vectors correspond to the sparse multi-path channels. Each of the short weight vectors has a short filter length.

Abstract: An embodiment of the present invention includes an adaptive predictor, a system white noise generator, and a background noise estimator. The adaptive predictor estimates adaptive weights of autoregressive (AR) model of background noise as background samples in an echo canceler. The adaptive predictor generates adaptive error. The system white noise generator generates a white noise using the adaptive error. The noise background estimator estimates the background noise using the white noise and the estimated adaptive weights.

Abstract: The present invention is an echo canceller for sparse channels in an echo channel. The echo channel receives a far-end input and a near-end input. An enable generator asserts a sparse update enable in response to detecting at least one of the double talk condition and an impulse response change. A main weight updater transfers shadow weights of the shadow filter to N sets of sparse weights in N sparse filters of the main filter according to the sparse update enable. A sparse main filter filters the far-end input non-adaptively to generate a main output. A long shadow filter filters the far-end input adaptively to generate a shadow output and to estimate delays of peaks of the sparse weights in the main filter.

Abstract: A network echo canceller for integrated telecommunications processing. The network echo canceller processes echoes in multiple communication channels over a packet network. The network echo canceller adapts a least means squared finite impulse response filter to each communication channel in order to estimate an echo therein. The echo estimation is subtracted from signals that are being sent over each communication channel. The echo canceller includes a residual error suppressor to suppress non-linear sources of echo when desired. The echo canceller includes a double talk detector to inhibit filter adaptation during double talk. The network echo canceller is programmable into a digital signal processor and can be flexibly controlled through messaging.

Abstract: Apparatus and methods are provided for encoding video data in a manner which significantly reduces the computation performed by the video encoder and the video decoder without suffering any degradation in the perceived quality of the compressed video data. In particular, apparatus and methods are provided for determining which blocks might be zeroed out after quantization. This determination is performed after motion estimation, the classification of the frame as either an I frame, P frame, or a B frame, and the determination of a quantization step size (QP) for the block, but before DCT. If a given block is determined to be a “zero” quantized block, then the DCT, quantization, zig-zag scan and variable length coding steps are omitted, and a variable length code output is provided indicating that the block B is a “zero” quantized block.

Abstract: An adaptive filter estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The channel weight vector has first and second lengths when the adaptive filter operates in a first adaptation mode and a second adaptation mode, respectively. A delay estimator determines a delay in the echo channel using the adaptive filter in the first adaptation mode.

Abstract: The invention provides a novel scheme for performing echo cancellation in the presence of double-talk and near-end channel impulse response changes. In one embodiment of the invention, a non-adaptive main filter is updated with the filtering weights of an adaptive shadow filter if the shadow filter cancels near-end echo in a first signal to a greater extent than the main filter. However, if double-talk is present in the first signal, then the non-adaptive filter is not updated. According to one embodiment of the invention, distinguishing between double-talk and channel impulse response changes is accomplished by maintaining extra taps for the main and shadow filters, in addition to taps employed by the main and shadow filters for echo canceling. The corresponding filtering algorithm weights for the additional taps of the main and shadow filters are compared to detect the onset of double-talk and/or channel impulse response changes.

Abstract: A compression system and process employs a group of quantizers (or set of predefined quantized values) and involves the selection of the quantizers for each video frame or frame portion. For each frame portion, a selection of the most appropriate quantizer is made. The selection of which quantizer from the selection group is most appropriate for coding of a video frame or frame portion is based on a formula which takes account both the distortion (accuracy) and bit rate characteristics of each quantizer. The quantizer that exhibits the best combined distortion and bit rate characteristics is selected for coding the frame or frame portion. A similar formula, based on both distortion and bit rate characteristics, is used to select the particular quantization value within the quantizer set for each video signal value being coded.

Abstract: Disclosed is an integrated voice activation detector for detecting whether voice is present. In one embodiment, the integrated voice activation detector includes a semiconductor integrated circuit having at least one signal processing unit to perform voice detection and a storage device to store signal processing instructions for execution by the at least one signal processing unit to: detect whether noise is present to determine whether a noise flag should be set, detect a predetermined number of zero crossings to determine whether a zero crossing flag should be set, detect whether a threshold amount of energy is present to determine whether an energy flag should be set, and detect whether instantaneous energy is present to determine whether an instantaneous energy flag should be set. Utilizing a combination of the noise, zero crossing, energy, and instantaneous energy flags the integrated voice activation detector determines whether voice is present.

Abstract: A first adaptive filter having a first filter length estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The echo channel has a plurality of sparse multi-path channels. A delay estimator determines a plurality of delays in the echo channel using the estimated channel weight vector. A second adaptive filter estimates a plurality of short weight vectors using the AP update and the plurality of delays. The short weight vectors correspond to the sparse multi-path channels. Each of the short weight vectors has a short filter length.

Abstract: Disclosed is an integrated tone detection processor for discriminating between tone and voice signals and determining the tones. The tone detection processor performs Automatic Gain Control (AGC) to normalize the power of the tone or voice signal. Further, the energy of the tone or voice signals are determined at specific frequencies utilizing a Goertzel Filter process. The tone detection processor determines whether or not a tone is present, and if a tone exists, determines the type of tone. Based upon determining the two maximum energy levels of the Goertzel filtered tone, whether the tone is a single tone, dual tone, silence, or other (e.g. speech) can be discriminated. The tone can then be identified by a user-defined dictionary of tones. Based upon various ON and OFF cadence checks in combination with the use of TONE ON and TONE OFF counters, tones can be declared.

Abstract: An adaptive filter estimates a channel weight vector of an echo channel using an affine projection (AP) update. The echo channel receives a send input sequence and a receive input sequence. The channel weight vector has first and second lengths when the adaptive filter operates in a first adaptation mode and a second adaptation mode, respectively. A delay estimator determines a delay in the echo channel using the adaptive filter in the first adaptation mode.

Abstract: A network echo canceller for integrated telecommunications processing. The network echo canceller processes echoes in multiple communication channels over a packet network. The network echo canceller adapts a least means squared finite impulse response filter to each communication channel in order to estimate an echo therein. The echo estimation is subtracted from signals that are being sent over each communication channel. The echo canceller includes a residual error suppressor to suppress non-linear sources of echo when desired. The echo canceller includes a double talk detector to inhibit filter adaptation during double talk. The network echo canceller is programmable into a digital signal processor and can be flexibly controlled through messaging.