Windowing method for decoding of MPEG audio data

• US 5,890,124 A
• Filed: 10/26/1995
• Issued: 03/30/1999
• Est. Priority Date: 03/15/1991
• Status: Expired due to Term

• Current Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Original Assignee: C-Cube Corporation (Broadcom, Inc.)
• Inventors: Galbi, David E.
• Primary Examiner(s): Dorvil, Richemond
• Application Number:
  US08/548,889
• Time in Patent Office: 1,251 Days
• Field of Search: 395/2.09, 395/2.94, 395/2.91, 395/2.12, 382/232, 382/233, 382/234, 382/250, 704/500, 704/501, 704/502, 704/503, 704/504
• US Class Current: 704/501
• CPC Class Codes: G09G 2340/02 Handling of images in compressed format, e.g. JPEG, MPEG
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: H03M 7/425 for the decoding process only
• CPC Class Codes: H04N 19/00 Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/43 Hardware specially adapted for motion estimation or compensation
• CPC Class Codes: H04N 19/433 characterised by techniques for memory access
• CPC Class Codes: H04N 19/436 using parallelised computational arrangements
• CPC Class Codes: H04N 19/439 using cascaded computational arrangements for performing a single operation, e.g. filtering
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/90 using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
• CPC Class Codes: H04N 19/91 : Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
• CPC Class Codes: H04N 21/426 : Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4341 : Demultiplexing of audio and video streams
• CPC Class Codes: H04N 5/21 : Circuitry for suppressing or minimising disturbance, e.g. moiré or halo
• CPC Class Codes: H04N 5/602 : for digital sound signals

Abstract

An MPEG audio/video decoder has memories, a signal processing unit (SPU) including a multiplier and a butterfly unit, a main CPU, and a memory controller which are time division multiplexed between decoding video and audio data. For audio decoding, the butterfly unit determines combinations of components of a frequency-domain vector to reduce the number of multiplies required to transform to the time domain (matrixing). Matrixing is interwoven with MPEG filtering to increase throughput of the decoder by increasing parallel use of the multiplier, the butterfly unit, and a memory controller. A widowing process for the MPEG standard uses only independent components of the audio vectors. This reduces the required number of components to be stored, thereby reducing the size of required memory, the time to write the components after matrixing, and the time to retrieve the components for windowing.

Claims

1. A method for generating sound from data following an MPEG encoding standard comprising:

transferring a block consisting of independent components of time-domain vectors to a first memory, wherein transferring the block comprises transferring a total of 17 components from a first time-domain vector and 16 components from a second time-domain vector;

determining products of the independent components in the block with corresponding windowing coefficients;

accumulating the products in a plurality of sums, each sum corresponding to a different sound amplitude value; and

generating a sound from the sound amplitude values.

2. The method of claim 1, wherein:

the step of determining products comprises performing 64 multiplications, each multiplication involving one of the components from the block and a windowing coefficient; and

the step of accumulating comprises adding a pair of the products to each of 32 sums.

3. The method of claim 2, further comprising:

multiplying each of a series of matrixing coefficients by a corresponding combination of components of a frequency-domain vector;

accumulating the products to generate four components of a time-domain vector; and

writing the four components of the time-domain vector to a second memory, wherein transferring the block is from the second memory to the first memory.

4. The method of claim 3, further comprising repeating the steps of claims 1, 2, and 3 eight times wherein no two steps of transferring a block transfers components from the same pair of time-domain vectors.