Lsi Logic Corporation

Sophia Kao

Arvind Bhaskar Patwardhan

Wen Huang

Kosala Abeywickrema

An audio decoder architecture makes use of various component sharing techniques to conserve hardware and reduce implementation cost. In one embodiment, the audio decoder comprises a bitstreamer, a synchronization controller, a first and second decode controllers, a memory module, a data path, and an output buffer. The bitstreamer retrieves compressed data and provides token-aligned data to the synchronization controller and decode controllers. The synchronization controller initially controls the bitstreamer to locate and parse audio frame headers to extract decoding parameters. The synchronization controller initiates the decode controller which corresponds to an identified compression format, and turns control of the bitstreamer and data path over to the selected decode controller. The selected decode controller then controls the bitstreamer to parse the variable length code compressed transform coefficients. The coefficients are passed to the memory module and data path which operate under the control of the selected decode controller to inverse transform the coefficients and produce digital output audio data. If the inverse transform is successfully completed, the selected decode controller asserts a decode done signal, and control returns uneventfully to the synchronization controller.

DVD audio decoder having a central sync-controller architecture

A multimedia decoder is provided with an audio decoder bypass module for forwarding undecoded audio bitstreams directly to external system components. In one embodiment, the multimedia decoder includes an audio decoder, and a bypass module. The audio decoder operates on the data in an audio bitstream buffer to convert at least a portion of the audio bitstream into a set of digital audio signals. The bypass module is configured to provide the full information content of the audio bitstream to an external system component which may be able to convert a greater portion of the audio bitstream into a second set of digital audio signals. As the audio decoder and bypass module each retrieve data from the audio bitstream buffer, they each use a pointer to track which location of the buffer to access next. The bypass module maintains a loose synchronization with the audio decoder by calculating the difference between the pointers and transmitting the current audio packet only if the magnitude of the difference doesn't exceed a predetermined threshold. If the bypass module is lagging behind the audio decoder by more than the threshold amount, then it skips ahead to the next audio packet. On the other hand, if the decoder is lagging behind the bypass module by more than the threshold amount, the bypass module waits for the audio decoder to catch up. This technique advantageously prevents detectable discrepancies in reproduced audio signals while allowing for system upgradability without significant increase in implementation cost.

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Cupertino, CA, United States of America

Sophia Kao