Abstract: A video transcoder for converting an encoded input video bit-stream having one spatial resolution into an encoded output video bit-stream having a lower spatial resolution, wherein learned statistics of intra-mode transcoding are used to constrain the search of intra modes for the output video bit-stream. The statistics of intra-mode transcoding can be gathered, e.g., by applying brute-force downsizing to a training set of video frames and then analyzing the observed intra-mode transcoding patterns to determine a transition-probability matrix for use during normal operation of the transcoder. The transition-probability matrix enables the transcoder to select appropriate intra modes for the output video bit-stream without performing a corresponding exhaustive full search, which advantageously reduces the computational complexity and processor load compared to those of a comparably performing prior-art video transcoder.

Abstract: Superresolution image processing that can be applied when two image frames of the same scene are available so that image information from one frame can be used to enhance the image from the other frame. The superresolution image processing uses a sparse matrix generated based on a Markov random field defined over these two image frames. The sparse matrix is inverted and applied to the image data from the image frame that is being enhanced to generate a corresponding enhanced image.

Abstract: In one embodiment, a DSP having four arithmetic logic units (ALUs) and able to have two read/write operations per clock cycle performs silence detection and tone detection for data frames containing samples of an audio signal. The ALUs are used together in parallel to process the samples in the data frames received by the DSP. A received data frame is filtered by the silence detection so that substantially silent frames are dropped and non-silent frames are further processed. In the tone detection, a filtered data frame is processed, four samples at a time, to determine the power of the signal at a given frequency, where the power determination is used to determine whether a given tone (i.e., a signal at a given frequency) is present in the data frame.

Abstract: A video transcoder for converting a compressed input video bit-stream having one spatial resolution into a compressed output video bit-stream having a different spatial resolution in a manner that enables the transcoder to dynamically change the amount of computational resources allocated to the conversion process. In one embodiment, the video transcoder has a plurality of configurable processing paths whose configuration determines the amount of allocated computational resources. Exemplary processing-path configuration changes may include, but are not limited to engaging or disengaging a processing path, redirecting a data flow from flowing through one processing path to flowing through another processing path, and attaching or detaching one or more processing modules to an engaged processing path.

Abstract: A video transcoder for converting an encoded input video bit-stream having one spatial resolution into an encoded output video bit-stream having a lower spatial resolution, wherein motion-vector dispersion observed at the higher spatial resolution is quantified and used to configure the motion-vector search at the lower spatial resolution. For example, for video-frame areas characterized by relatively low motion-vector dispersion values, the motion-vector search may be performed over a relatively small vector space and with the use of fewer search patterns and/or hierarchical search levels. These constraints enable the transcoder to find appropriate motion vectors for inter-prediction coding without having to perform an exhaustive motion-vector search for these video-frame areas, which advantageously reduces the computational complexity and processor load compared to those of a comparably performing prior-art video transcoder.

Abstract: A method for ordering trapping sets to find one or more dominant trapping sets includes analyzing a trapping set and a random set of codewords to generate a distance value for each trapping set, and ordering the trapping sets by the distance value. Distance values may be determined for each trapping set by tracking a vote count wherein a correct decode at a certain noise level produces a “right” vote and an incorrect decode at a certain noise level produces a “left” vote. A certain threshold number of “left” votes terminates processing at that noise level.

Abstract: A computer-aided design method for developing, simulating, and testing a read-channel architecture to be implemented in a VLSI circuit. The method uses codeword/waveform classification to accelerate simulation of the read-channel's error-rate characteristics, with said classification being generated using a first read-channel simulator having a limited functionality. A second read-channel simulator having an extended functionality is then run only for some of the codewords, with the latter having been identified based on said codeword/waveform classification. The acceleration is achieved, at least in part, because the relatively highly time-consuming processing steps implemented in the second read-channel simulator are applied to fewer codewords than otherwise required by conventional simulation methods.

Abstract: In one embodiment, a programmable vector processor performs preamble detection in a wireless communication network. Implementation of preamble detection in the vector processor is made possible by a set of vector instructions that include (i) a circular load instruction for loading vectors of received data, (ii) a correlation instruction for correlating the vectors of received data with vectors of the scrambling code to concurrently generate a plurality of complex correlations, (iii) a partial-transpose instruction for arranging vectors of the complex correlations for use by a Fast Hadamard Transform (FHT) processor, and (iv) an FHT instruction for performing FHT processing on a vector of complex correlations. Implementing preamble detection in the vector processor allows more of the received data to be processed concurrently. As a result, preamble detectors of the disclosure may detect preambles using fewer clock cycles than that of comparable preamble detectors implemented using hardware accelerators.

Abstract: A method for estimating error probability of LDPC codes includes ordering LDPC codes according to features in each code with known error characteristics. The method includes identifying features in each LDPC code having known error characteristics; adding each code to one or more categories based on the existence of such features; and ranking the LDPC codes according to the level of error risk.

Abstract: An iterative decoder dynamically controls the number of local iterations of error-correction decoding performed for each global iteration of channel detection. In so doing, the iterative decoder (i) limits the number of local iterations that are performed after error-correction decoding has likely encountered a trapping set and (ii) permits decoding to continue when error-correction decoding is on the path to converging on a valid codeword. To predict whether error-correction decoding is on the path to encountering a trapping set or converging on a valid codeword, a model is generated based on observed numbers of unsatisfied check nodes for a specified number of local iterations. For local iterations following the specified number of local iterations, the observed numbers of unsatisfied check nodes are then compared to the model to determine whether to continue or terminate local iterations of error-correction decoding.

Abstract: An adaptive filter configured to use multiple algorithm species that differ in the quality of echo suppression and respective burdens imposed on the computational resources of the host communication device. Depending on the available computational budget, the adaptive filter selects an algorithm species that, while supporting a relatively high quality of echo suppression, involves a relatively low risk of overwhelming the computational resources. The adaptive filter monitors changes in the available computational budget and, if appropriate or necessary, can change the algorithm species to maintain a quality of echo suppression that is optimal for the current computational budget. If a change of the algorithm species is initiated, then at least a portion of internal algorithm data from the previously running algorithm species might be transferred for use in the subsequent algorithm species.

Abstract: In one embodiment, the present invention is a method for performing incremental preamble detection in a wireless communication network. The method processes non-overlapping chunks of incoming antenna data, where each chunk is smaller than the preamble length, to detect the signature of the transmitted preamble. For each chunk processed, chips of the chunk are correlated with possible signatures employed by the wireless network to update a set of correlation profiles, each profile comprising a plurality of profile values. Further, an intermediate detection is performed by comparing the updated profile values to an intermediate threshold that is also updated for each chunk. Upon receiving the final chunk, the correlation profiles are updated, and a final preamble detection is made by comparing the updated profile values to a final threshold. Detections are performed on an incremental basis to meet latency requirements of the wireless network.

Abstract: A search method for identifying an intra mode that can produce acceptable video-encoding quality for a pixel block while striking a proper balance between the quality and processor load. In a representative embodiment, the search method relies on a set of mode-selection rules for iteratively identifying candidate intra modes. Each identified candidate is evaluated based on a comparison of its sum of absolute differences (SAD) with the smallest SAD in the set of the previously identified candidates. The mode-selection rules use the comparison results as conditions that efficiently guide the search method toward an intra mode that is suitable for encoding the pixel block with acceptable video quality. On average, a representative embodiment of the search method disclosed herein is advantageously capable of finding a suitable intra mode in fewer iterations than a comparable prior-art search method.

Abstract: In one embodiment, a high-level compensation (HLC) module receives samples of an input signal and determines whether a magnitude of each sample, represented in a linear domain, is relatively low or relatively high by comparing the magnitude to a threshold. If a sample is less than or equal to the threshold, then it is considered to have a relatively low magnitude and the sample is not attenuated. If a sample is greater than the threshold, then it is considered to have a relatively high magnitude and the HLC module attenuates the sample according to a “soft” non-linear function. The “soft” non-linear function is characterized by at least two of the following characteristics: the non-linear function (i) increases monotonically, (ii) forms a convex upwards curve, (iii) has a first derivative at the threshold equal to one, and (iv) has a first derivative at a maximum possible magnitude value equal to zero.

Abstract: In one embodiment, an acoustic echo control (AEC) module receives an outgoing signal and an incoming signal, which, at various times, contains acoustic echo corresponding to the outgoing signal. The AEC module has a delay estimation block that estimates, in the time domain, the echo delay using an adaptive filtering technique. This delay estimation is used to align samples of the incoming signal having acoustic echo with the corresponding samples of the outgoing signal from which the acoustic echo originated. The AEC module determines whether or not samples of the incoming signal contain acoustic echo based on the aligned outgoing signal, and the determinations are applied to a hangover counter. The AEC module then suppresses acoustic echo in the incoming signal and adds comfort noise to the incoming signal. The amount of echo suppression performed is gradually increased or decreased based on comparisons of the counter to a hangover threshold.

Abstract: In one embodiment, a pause-based music detection (MD) module detects music by analyzing pauses in a received audio signal. The energy of each frame of the signal is compared to an energy threshold to determine whether the frame corresponds to background noise only (i.e., a pause) or sound such as speech or music. A window having a number of frames is analyzed to determine whether there is a pause within the window. If no pauses are detected in the window, then the current frame is presumed to correspond to music. If a pause is detected, then the current frame is presumed to correspond to speech. In another embodiment, the pause-based MD module output is applied to Boolean “OR” logic along with a tone-based MD module output to generate a final MD decision. The tone-based MD module detects music by analyzing tones in the signal using any suitable tone-based MD algorithm.

Abstract: In one embodiment, a music detection (MD) module accumulates sets of one or more frames and performs FFT processing on each set to recover a set of coefficients, each corresponding to a different frequency k. For each frame, the module identifies candidate musical tones by searching for peak values in the set of coefficients. If a coefficient corresponds to a peak, then a variable TONE[k] corresponding to the coefficient is set equal to one. Otherwise, the variable is set equal to zero. For each variable TONE[k] having a value of one, a corresponding accumulator A[k] is increased. Candidate musical tones that are short in duration are filtered out by comparing each accumulator A[k] to a minimum duration threshold. A determination is made as to whether or not music is present based on a number of candidate musical tones and a sum of candidate musical tone durations using a state machine.

Abstract: A video transcoder for converting an encoded input video bit-stream having one spatial resolution into an encoded output video bit-stream having a lower spatial resolution, wherein motion-vector dispersion observed at the higher spatial resolution is quantified and used to configure the motion-vector search at the lower spatial resolution. For example, for video-frame areas characterized by relatively low motion-vector dispersion values, the motion-vector search may be performed over a relatively small vector space and with the use of fewer search patterns and/or hierarchical search levels. These constraints enable the transcoder to find appropriate motion vectors for inter-prediction coding without having to perform an exhaustive motion-vector search for these video-frame areas, which advantageously reduces the computational complexity and processor load compared to those of a comparably performing prior-art video transcoder.

Abstract: A video transcoder for converting an encoded input video bit-stream having one spatial resolution into an encoded output video bit-stream having a lower spatial resolution, wherein learned statistics of intra-mode transcoding are used to constrain the search of intra modes for the output video bit-stream. The statistics of intra-mode transcoding can be gathered, e.g., by applying brute-force downsizing to a training set of video frames and then analyzing the observed intra-mode transcoding patterns to determine a transition-probability matrix for use during normal operation of the transcoder. The transition-probability matrix enables the transcoder to select appropriate intra modes for the output video bit-stream without performing a corresponding exhaustive full search, which advantageously reduces the computational complexity and processor load compared to those of a comparably performing prior-art video transcoder.

Abstract: A video transcoder for converting a compressed input video bit-stream having one spatial resolution into a compressed output video bit-stream having a different spatial resolution in a manner that enables the transcoder to dynamically change the amount of computational resources allocated to the conversion process. In one embodiment, the video transcoder has a plurality of configurable processing paths whose configuration determines the amount of allocated computational resources. Exemplary processing-path configuration changes may include, but are not limited to engaging or disengaging a processing path, redirecting a data flow from flowing through one processing path to flowing through another processing path, and attaching or detaching one or more processing modules to an engaged processing path.