Coded data generation or conversion – Digital code to digital code converters – With error detection or correction
Reexamination Certificate
1999-11-09
2001-12-18
Wamsley, Patrick (Department: 2819)
Coded data generation or conversion
Digital code to digital code converters
With error detection or correction
C714S776000
Reexamination Certificate
active
06331829
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a decoding device and method for receiving bitstreams including coded, multiplexed video, audio, and so on, and extracting coded data from each bitstream to decode the coded data.
2. Description of the Prior Art
When a prior art decoding device decodes an input bitstream, including coded, multiplexed data, such as video, audio, and so on, the bitstream forming a hierarchy comprised of packs, each of which is high-level information, and packets, each of which is low-level information, it detects a pack header from each pack and then detects a packet header based on pack header information included in the pack header detected. At that time, the prior art decoding device can detect errors in the pack header information, such as a stuffing length or a pack header length, within the pack header, and then detect the packet header only when there is no error in the pack header information. The prior art decoding device then detects packet header information from the packet header, and also tries to detect errors in the packet header information, such as a stuffing length and a packet header length, within the packet header. Only when there is no error in the packet header information, the prior art decoding device separates a coded data region from each packet included in the bitstream, including coded, multiplexed data, such as video, audio and so on, and then extracts coded data from the coded data region.
In addition, when the coded data region separated includes a private data other than the coded data, which is information associated with the coded data, the prior art decoding device tries to detect errors in the private data and then decodes the coded data only when there in no error in the private data.
In an audio information coding system which conforms to a DVD-Video standard, such as Dolby digital, linear PCM, or MPEG audio, the private data other than the coded data, which is information associated with coded data, is a coded data placed and multiplexed as a private stream packet in the coded data region. For example, the private data can be either audio frame information indicating the number of audio frames within each packet or audio data information indicating the number of audio channels.
Japanese Patent Application Publication No. 8-251146 discloses another prior art decoding device that can send an error detection result including a resend requirement, as a response packet, to the sender when it detects an error in a data packet included in another input bitstream, and then replace the data having an error with a data that is resent thereto.
A problem with prior art decoding devices constructed as above is that if the pack header information within each pack header includes an error, the packet header cannot be detected and an error process is carried out even though the packet data hierarchically arranged in each pack does not include any errors and the coded data is correct. Further, an error detection in the packet header information triggers an error process and hence prevents the coded data from being decoded even though the pack header information does not include any errors and the coded data is correct. In addition, an error detection in information associated with the coded data, other than the coded data, which is placed in the coded data region of each packet, prevents the coded data from being decoded even though any one of the coded data, pack header information, and packet header information does not include any errors.
SUMMARY OF THE INVENTION
The present invention is made to overcome the above problem. It is therefore an object of the present invention to provide a decoding device and method, for checking or determining whether either pack or packet header information or information associated with coded data within each pack included in each bitstream has an error, for changing the checked information with valid one without carrying out an error process if it is determined that the checked information has an error, and for separating the coded data from each pack included in each bitstream and decoding the coded data.
In accordance with one aspect of the present invention, there is provided a decoding device for extracting coded data from a sequence of data that forms a hierarchy in which each of a plurality of packs includes at least a packet and each packet includes coded data within a coded data region thereof, the device comprising: a pack header detecting unit for detecting a pack header placed at the head of each of the plurality of packs; a pack header information extracting unit for extracting pack header information contained in the pack header detected by the pack header detecting unit; a pack header information database for storing at least a piece of reference pack header information that conforms to a specific standard; a packet header detecting unit for detecting a packet header placed at the head of each packet contained in each of the plurality of packs based on the pack header information extracted by the pack header information extracting unit; a unit for checking whether an error occurs in the pack header information extracted by the pack header information extracting unit, for retrieving a piece of reference pack header information that mostly conforms to the specific standard from the pack header information database if the extracted pack header information has an error, and for replacing the extracted pack header information having an error with the reference pack header information that mostly conforms to the specific standard to enable the packet header detecting unit to detect the packet header; a packet header information extracting unit for extracting packet header information contained in the packet header; a coded data extracting unit for separating a coded data region from each packet based on the packet header information extracted by the packet header information extracting unit, and for extracting coded data from the coded data region; and a decoding unit for decoding the coded data extracted by the coded data extracting unit.
In accordance with a preferred embodiment of the present invention, the decoding device further comprises: a packet header information database for storing at least a piece of reference packet header information that conforms to the specific standard; and a unit for checking whether an error occurs in the packet header information extracted by the packet header information extracting unit, for retrieving a piece of reference packet header information that mostly conforms to the specific standard from the packet header information database if the extracted packet header information has an error, and for replacing the extracted packet header information having an error with the reference packet header information that mostly conforms to the specific standard to enable the coded data extracting unit to extract the coded data.
As an alternative, the decoding device further comprises: a coded-data-specific information extracting unit for extracting coded-data-specific information other than the coded data, which is associated with the coded data, from the coded data region separated by the coded data extracting unit; a coded-data-specific information database for storing at least a piece of reference coded-data-specific information that conforms to the specific standard; and a unit for checking whether an error occurs in the coded-data-specific information extracted by the coded-data-specific information extracting unit, for retrieving a piece of reference coded-data-specific information that mostly conforms to the specific standard from the coded-data-specific information database if the extracted coded-data-specific information has an error, and for replacing the extracted coded-data-specific information having an error with the reference coded-data-specific information that mostly conforms to the specific standard to enable the decoding unit to decode the coded data.
In accordance with another preferred embod
Burns Doane , Swecker, Mathis LLP
Mitsubishi Denki & Kabushiki Kaisha
Wamsley Patrick
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