Cirrus Logic Inc.

Crystal Semiconductor Corporation

Miroslav V Dokic

Raghunath Krishna Rao

Jeffrey A Niehaus

James S Divine

Zheng Luo

Vladimir Mesarovic

Nariankadu Datatreya Hemkumar

Terry Ritchie

Sachin Deo

John Robert Pacourek

Joel C McKee Cooper

Baker Scott, Iii

Pu Liu

Narsimham Gangishetti

Nariankadu Datareya Hemkumar

Sanjay Joshi

A digital audio decoder for receiving an encoded audio signal and decoding the audio signal. The digital audio decoder uses both real time computations and calculations pre-stored in a look-up table to decode the encoded audio signal. The digital audio decoder uses fixed point arithmetic but a variable word format to represent the intermediate computations and pre-stored look-up table entries.

Fixed point audio decoding system and method

Overlay buffering scheme for multi-channel data in which one memory buffer content is overlayed over another as memory locations of an input buffer are freed when data is output from the input buffer. By overlaying the buffer content, only one input buffer is used, reducing the needed memory by half.

Method and apparatus to provide overlay buffering

A method of processing a stream of encoded units of data samples includes the step of calculating a sample advantage using timing information embedded in selected ones of the encoded units, the sample advantage representing a time difference in number of samples between the presentation of a reference sample and the availability of the reference sample. A number of phantom samples substantially equal to the number of samples represented by the calculated sample advantage are queued and then output from the queue at a selected rate. Substantially simultaneous with the outputting of the phantom samples from the queue, at least some data samples of at least one encoded unit are decoded and queued behind the phantom samples.

Methods and systems for prefilling a buffer in streaming data applications

Digital tone controlsinclude a first pathincluding a digital filterand a scalerfor controlling a level of a low frequency component of a received digital audio signal. A secondincludes a digital filterand a scalerfor controlling a level of a high frequency component of the received digital audio signal. A third pathincludes a scalerfor controlling a level of an unfiltered component of the received audio signal. A summeradds a contribution from each of the paths to generate a composite signal having a selected gain-frequency response.

Digital tone controls and systems using the same

A multi-channel digital audio decoder which receives an encoded audio signal having at least two channels and which decodes the audio signal. The digital audio decoder includes an input, which receives the encoded audio signal and a processor, which receives the encoded audio signal from the input. The processor decodes the encoded audio signal and provides decoded digital audio data. Also included is a buffer, which receives the decoded digital audio data from the processor. The buffer has a first-channel portion and a second-channel portion which have unequal sizes.

Efficient PCM buffer

A method for transferring data bursts via a synchronous data link includes the step of receiving a burst of packets, each packet including a header and a frame of data compressed at a selected sampling rate and transmitted at a selected bit rate. At least one of the packets of the stream of packets is embedded into a carrier frame including a carrier frame header. The carrier frame is then transmitted via the synchronous link. The data frame is extracted from the carrier frame and decompressed at the sample rate.

Systems and methods for transmitting bursty-asnychronous data over a synchronous link

A method of decoding an encoded bitstream. The method includes performing a two-table lookup. A first table is addressed in response to a first plurality of bits from the bitstream. An address into a second table is generated using a value in an entry in said first table accessed in the addressing step. A value (representing the decoded value corresponding to the codeword in the bitstream) in an entry in said second table at the address from the generating step is output.

Systems and methods for decoding compressed data

A method of operating shared memory in a multiple processor system. A token is by default maintained with a first processor, the token enabling access to shared memory. A determination is made that a second processor requires access to shared memory. A determination is also made as to whether the first processor is accessing to the shared memory. The token is transferred the second processor if the first processor is not accessing the shared memory. The second processor accesses the shared memory with the token.

Accessing shared memory using token bit held by default by a single processor

A method for synchronizing stream processing with a locally generated system time clock is disclosed. A program clock reference is recovered from a transport layer and used to vary the frequency of the locally generated system time clock. A presentation time stamp is recovered from a packetized elementary stream derived from the transport layer. The relationship between a reference sample associated with the presentation time stamp from the packetized elementary stream and a current sample being streamed is determined relative to the system time clock. Data samples are added or subtracted from a stream of data samples being streamed in response to the step of determining to establish a relationship between the stream of samples and the presentation time stamp relative to the system time clock.

Methods and circuits for synchronizing streaming data and systems using the same

A method of managing multiple channels of audio data in an audio system having multiple speakers. A first channel signal is selectively passed through a software high-pass filter to selectively drive a first one of the speakers. A plurality of channel signals are selectively summed in software to generate a composite signal and the composite signal passed through a software low-pass filter to selectively drive a second one of the speakers.

Audio bass management methods and circuits and systems using the same

A method of processing a stream of audio information received by a multiple processor audio decoder. Processing operations are performed by a first processor on the stream of audio information to produce at set of results. The first processor writes the set of results into a shared memory and a flag is set indicating that the results are ready. In response to the flag, a second processor reads the results from shared memory. When the results have been read from shared memory, the second processor sends a command to the first processor. The first processor then clears the flag.

Methods for processing audio information in a multiple processor audio decoder

A method of automatically detecting a data format type of a stream of data. A determination is made as to whether a current word and a previously received words comprise a set of identifiers associated with a selected type of data. When a preselected number of detections of the set of identifiers has been reached within a predefined time period, the input stream is declared to be the selected type of data. Simultaneously, when the selected type of data is not detected, other data types are sequentially selected for similar checking. This successive selection of different data types allows the method to classify the input data into one out of multiple data types.

Input data format autodetection systems and methods

A method of exchanging messages between first and second processors. A pending flag in a first register is polled by the first processor and if the flag is in a first selected logic state, a message is written into a second register with the first processor. The pending flag is set to a second selected logic state with the first processor and an interrupt to the second processor is generated. The message is read from the second register with the second processor when the pending flag is in the second logic state. The pending flag set to the first logic state with the second processor.

Interprocessor communication circuitry and methods

A method of operating a multiple processor device. A first word of a sequence of words is received in a register. A target processor is determined from the first word and the target processor is interrupted. An input ready bit is set and first word from in the register is read with the target processor. A number of words in the sequence to follow the first word determined from the first word. A word counter is set and the input ready bit is cleared with the target processor. The target processor is returned to main code execution.

Methods for debugging a multiprocessor system

An audio decoder 100 for operating on a received compressed audio data stream compressed using an algorithm employing transform encoding and a bit allocation routine. A first processor 200 performs a first set of operations on the received compressed audio data stream including parsing the compressed audio data stream, recovering data fields within the compressed audio data stream, calculating a bit allocation, and passing frequency domain coefficients to shared memory. A second digital signal processor 100b performs a second set of operations on data passed from the first digital signal processor to shared memory including performing inverse transform operations on the data passed from the first digital signal processor.

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Austin, TX, United States of America

Miroslav V Dokic