Texas Instruments Corporation

Stephen (Hsiao Li

Jonathan L Rowlands

Frank L Laczko, Sr

Paul M Look

Fuk Ho Ng

Dong-Seok Youm

James (Sang-Won) Song

David (Shiu Kam

Maria Bh Gill

A data processing device is programmed to decode and transform a stream of data representing a plurality of subband encoded channels of audio data into one or more channels of PCM encoded data for reproduction by a speaker subsystem. An improved method for decoding and transforming utilizes downmix matrices (1021 and 1022) to form downmixed frequency domain channels in buffers (1031-1034). Only two long DCT transform operations (1041 and 1042) and two short DCT transform operations (1043 and 1044) are needed to transform the downmixed frequency domain channels into a left PCM output (1071) and a right PCM output (1072).

Method and apparatus for downmixing decoded data streams in the

A data processing device 100 uses a portion of a random access memory 111 as an input buffer for holding a portion of a stream of data which is received by an input interface 130. Likewise, a portion of a memory 121 is used as an output buffer for holding a portion of processed data which is output by an output interface 140. A processing unit 110 within the processing device manages the flow of input and output data. The input interface asserts an I/O request 860 when it receives a data word, and the output interface asserts an I/O request 870 when it needs a data word. In response to an I/O request, fast interrupt circuitry inserts a ghost instruction which is formed by doppelganger circuitry into an instruction sequence which is being accessed from a ROM 112. The ghost instruction performs the requested data transfer.

Method and apparatus for providing fast interrupt response using a ghost

A data processing device uses a portion of random access memory 121 as an output buffer 124 for holding a portion of a stream of PCM data which is to be output to a digital to analog converter 530. D/A 530 forms a left analog channel and a right analog channel for speaker subsystems 814 and 815. The PCM data stream is stored in the output buffer so that PCM data samples which pertain to the left channel are stored at even address and PCM data samples which pertain to the right channel are stored at odd address. Control circuitry 145 monitors direct memory access (DMA) transfers which transfer PCM data samples to PCM serializer 142. By comparing the address of each DMA transfer to a left/right channel signal from the D/A, the control circuitry can verify that channel synchronization is correct. If a synchronization error is detected, an channel synchronization error correction procedure is invoked.

Method for left/right channel self-alignment

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Garland, TX, United States of America

Stephen (Hsiao Li