Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1999-03-29
2001-09-25
Kelley, Chris (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C348S462000, C369S060010
Reexamination Certificate
active
06295319
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a decoding device for decoding a bit stream defined by MPEG2 Multichannel, Layer II, for example, or decoding both a bit stream defined by MPEG2 Multichannel and a bit stream defined by MPEG1.
2. Description of the Related Art
Conventionally, in a decoding device for decoding a bit stream defined by MPEG2 Multichannel stipulated in ISO-IEC 13818-3.2, decoding of an MPEG2 multichannel extended area of a bit stream defined by MPEG2 Multichannel is begun only after decoding of an MPEG1 compatible area thereof is completed. Such a conventional MPEG2 multichannel decoding device is therefore required to secure a memory of at least [2×1152×(number of bytes given to one sample after reverse quantization)] bytes.
On the other hand, in a conventional decoding device for decoding both a bit stream defined by MPEG2 Multichannel and a bit stream defined by MPEG1, whether or not a bit stream is a bit stream defined by MPEG2 Multichannel is determined in the following manner. An MPEG2 multichannel determination method stipulated in ISO-IEC 13818-3, for example, uses cyclic redundancy check (CRC). According to this method, even if the bit stream is a bit stream defined by MPEG1 which does not include an MPEG2 multichannel extended area, decoding for multichannel streams is performed if the bit stream passes the CRC (error check). This causes erroneous operation.
Another problem is that, in a decoding method stipulated in ISO-IEC 13818-3, for example, decoding is continued even when a length of bit stream exceeding one frame length has been decoded. This also causes erroneous operation.
As described above, the conventional MPEG2 multichannel decoding device has a problem of requiring a buffer memory with large capacity, thereby increasing the size of the device.
The conventional decoding device which decodes both bit streams defined by MPEG2 Multichannel and MPEG1 also has a problem that decoding for MPEG2 multichannel streams is performed for an MPEG1 bit stream if the bit stream passes the CRC for MPEG2 multichannel streams, causing erroneous operation.
The object of the present invention is to provide a decoding device capable of decoding an MPEG2 multichannel bit stream using a buffer memory with a small capacity and determining correctly whether or not an MPEG2 multichannel extended area exists in a bit stream in the case where the decoding device decodes both bit streams defined by MPEG1 and MPEG2 Multichannel.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a decoding device is provided for decoding a bit stream defined by MPEG2 Audio Multichannel, the bit stream including an MPEG1 compatible area and an MPEG2 multichannel extended area, the MPEG1 compatible area including MPEG1 side information. The decoding device includes: MPEG1 decoding means for decoding the MPEG1 compatible area; MC decoding means for decoding the MPEG2 multichannel extended area; and MC header detection means for executing a first processing including locating a position of a header of the MPEG2 multichannel extended area based on the MPEG1 side information and shifting a read position of the bit stream to the position of the header.
In one embodiment of the invention, the MC header detection means executes the first processing on the way to the decoding of the MPEG1 compatible area by the MPEG1 decoding means. The MC decoding means executes a predetermined second processing after the MC header detection means executes the first processing.
In one embodiment of the invention, after the execution of the predetermined second processing by the MC decoding means, the decoding device alternately executes the decoding of the MPEG1 compatible area by the MPEG1 decoding means and the decoding of the MPEG2 multichannel extended area by the MC decoding means.
In one embodiment of the invention, the bit stream includes a bit stream defined by MPEG2 Audio Multichannel, Layer I. The MPEG1 side information includes allocation information. The MC header detection means locates the position of the header of the MPEG2 multichannel extended area based on the allocation information.
In one embodiment of the invention, the bit stream includes a bit stream defined by MPEG2 Audio Multichannel, Layer II. The MPEG1 side information includes allocation information and scale factor selection information. The MC header detection means locates the position of the header of the MPEG2 multichannel extended area based on the allocation information and the scale factor selection information.
In one embodiment of the invention, the predetermined second processing includes a processing of reading MC side information from the position and executing error check for the MC side information.
In one embodiment of the invention, the error check includes at least CRC.
According to another aspect of the present invention, a decoding device is provided for decoding a first bit stream defined by MPEG1 and a second bit stream defined by MPEG2 Audio Multichannel, the first bit stream including an MPEG1 compatible area, the second bit stream including the MPEG1 compatible area and an MPEG2 multichannel extended area, the MPEG1 compatible area including MPEG1 side information. The decoding device includes: MPEG1 decoding means for decoding the MPEG1 compatible area; MC decoding means for decoding the MPEG2 multichannel extended area; and MC header detection means for executing a first processing including locating a position of a header of the MPEG2 multichannel extended area based on the MPEG1 side information and shifting a read position of the bit stream to the position of the header. The MC header detection means executes the first processing on the way to a processing of the MPEG1 decoding means. The MC decoding means reads information from the position after the MC header detection means executes the first processing, and executes CRC for the information, when results of the CRC are normal. The decoding device alternately executes the decoding of the MPEG1 compatible area by the MPEG1 decoding means and the decoding of the MPEG2 multichannel extended area by the MC decoding means. When the results of the CRC are abnormal, the decoding device executes only the decoding of the MPEG1 compatible area by the MPEG1 decoding means.
According to still another aspect of the present invention, a decoding device is provided for decoding a first bit stream defined by MPEG1 and a second bit stream defined by MPEG2 Audio Multichannel, the first bit stream including an MPEG1 compatible area, the second bit stream including the MPEG1 compatible area and an MPEG2 multichannel extended area, the MPEG1 compatible area including MPEG1 side information. The decoding device includes: MPEG1 decoding means for decoding the MPEG1 compatible area; MC decoding means for decoding the MPEG2 multichannel extended area; and MC header detection means for executing a first processing including locating a position of a header of the MPEG2 multichannel extended area based on the MPEG1 side information and shifting a read position of the bit stream to the position of the header. The MC header detection means executes the first processing on the way to a processing of the MPEG1 decoding means. The MC decoding means determines whether or not the number of channels in the MPEG2 multichannel extended area is zero based on information read from a position where MC side information for the MPEG2 multichannel extended area is stored. If the number of channels in the MPEG2 multichannel extended area is zero, the decoding of the MPEG2 multichannel extended area is not performed, but only the MPEG1 compatible area is decoded.
In one embodiment of the invention, the MC decoding means reads information from the position after the MC header detection means executes the first processing, and executes CRC for the information. If the number of channels in the MPEG2 multichannel extended area is zero, the decoding device does not decode the MPEG2 multichannel extended ar
Abe Kazutaka
Fujita Takeshi
Ishito Tsukuru
Katayama Takashi
Kawamura Akihisa
Kelley Chris
Matsushita Electric - Industrial Co., Ltd.
Renner , Otto, Boisselle & Sklar, LLP
Vo Tung
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