JP2005284903A - Document encoding system, document decoding system, method for encoding document, and method for decoding document - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable receiving side to accumulate distribution data more efficiently while improving a compression rate of document data and reducing load of distribution system concerning distribution of document data. <P>SOLUTION: An interpretation part 201 interprets metadata of XML format generated by a metadata control part 102, and generates an analysis table so that it can be used in a difference calculation part 202 and a pattern detection part 204 thereafter. The pattern detection part 204 detects the same elements on XML syntax in metadata referring to the analysis table, and performs marking using the element which appears first as template. The difference calculation part 202 calculates the difference between detected template and each element which continues thereafter, and records attribute and value in each pattern. A compression encoding part 203 encodes by element unit based on the source, the template and the difference information, and generates XML binary data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a document encoding and decoding technique, a document encoding apparatus suitable for improving a compression rate in encoding of a tag-based document such as XML (Extensible Markup Language) or HTML (Hyper Text Markup Language), The present invention relates to a document decoding apparatus, a document encoding method, and a document decoding method.

  In recent years, XML has attracted attention as a means for expressing metadata used for searching content such as broadcast programs. XML is an extensible meta language, and a user can uniquely define a document structure. Details of XML are described in Non-Patent Document 1.

  XML data is described in a text format that can be read by humans. On the other hand, redundancy is high and the amount of information (number of characters) of the entire XML data tends to increase. If the number of characters increases, for example, when stored in storage or transferred over a network, the recording capacity or transfer amount increases, and physical and time costs increase. For this reason, it is necessary to encode (or compress) the XML data into a short code.

  Various data compression methods are known. For example, a run length code, a Huffman code, an arithmetic code, and the like. Details of these encoding methods are described in Non-Patent Document 2, Non-Patent Document 3, and Non-Patent Document 4, for example. However, since these encoding methods are not specialized for XML, high compression efficiency is not always obtained.

  Examples of compression methods specialized in XML data include XMill described in Non-Patent Document 5, or XComp described in Non-Patent Document 6. XMill extracts a content (text) portion for each element from the XML data. This extracted part is called a container. The structure portion is encoded with a number, and the text portion is compressed for each container by a method such as LZ77. Basically, information such as parameters is not required, and compression is possible only by an application. If necessary, it is possible to specify the compression method for each container and specify the compression method for each container, thereby increasing the compression efficiency. Also, since it is implemented in C, it has a feature that the compression speed is fast.

XComp does not encode the part uniquely determined from DTD (Document Type Definition) in the structure part of the XML data, and compresses only the structure part of the part that cannot be uniquely determined. The text part is compressed in the same way as XMill. That is, compression is performed according to the following procedure. (1) Separate structure and content. (2) Generate a push-down automaton (PDA) from the DTD. (3) Generate an encoding transducer that encodes the structural portion using the generated PDA. (4) The number assigned to each node of the encoding transducer is output by chain transition of the automaton, and the structure is encoded. (5) The obtained structure code and content for each element are compressed with LZ77 or the like, and a compressed XML document is output. Among the compression methods specialized for the XML document, XComp does not encode a part of the structural portion, and thus achieves a considerably good compression efficiency.
W3C.Extensible Markup Language (XML) 1.0, 1998.http: //www.w3.org/TR/REC-xml Huffman, DA “A method for the construction of minimum-redundancy codes” Proc. Of the IRE September, 1952 Mark Nelsonand Jean Loup Gailly “The Data Compression Book”, Second Edition. M & TBooks 1996 Jacob Ziv and Abraham Lempel. “A universal algorithm for sequential data compression” IEEE Transactions on Information TheoryMay, 1977 D. Suciu and H. Liefke. XMill: an Efficient Compressor for XML Data, 1999. http://www.research.att.com./sw/tools/xmill/ Igawa Kosaku, Tokyo Institute of Technology, Department of Information Engineering, Graduation thesis “Study on XML Document Compression Algorithm Using DTD”, February 2000

  The conventional XComp has a problem that an automaton for interpreting the structure of XML data is mounted on the receiving side, which places a burden on the receiving device and makes it difficult to increase the efficiency of the process of storing received data. The automaton is necessary when the receiver verifies. In many cases, the receiver is not basically verified by verifying at the time of transmission, and the automaton is not essential.

  In addition, when an automaton is used, it is necessary to update the automaton to add or update metadata, and the load is high. Further, in the conventional method using the automaton, the compression is performed for each element, and therefore the compression rate does not generally increase when the same element repeatedly appears. In many cases, the number of elements is not increased (there are not many elements), but the same element is generally increased (the number of programs increases = the same element called a program increases) .

  The present invention has been made in view of the above problems, and improves the compression rate of document data, reduces the load on the distribution apparatus related to the distribution of document data, and more efficiently distributes distribution data on the receiving side. An object of the present invention is to provide a document encoding device, a document decoding device, a document encoding method, and a document decoding method that can be stored.

  The document encoding apparatus of the present invention is the same when the interpretation means for interpreting the document, the detection means for detecting whether or not the same element exists in the interpreted document, and the same element exists according to the detection result. It adopts a configuration comprising difference calculating means for calculating a difference between elements and compression encoding means for compressing and encoding each element based on the calculated difference information.

  According to this configuration, the compression rate of the document data can be improved, and the load on the distribution apparatus related to the distribution of the document data can be reduced.

  The document encoding apparatus according to the present invention is the document encoding apparatus according to claim 1, wherein when the same element exists and continues according to the detection result, the compression encoding means converts each continuous element into one element. As a combination,

  According to this configuration, when the same elements included in the document data are continuous, the compression rate of the document data can be improved.

  The document encoding apparatus according to the present invention is the document encoding apparatus according to claim 1 or 2, wherein the element includes attribute information including a plurality of pairs of attribute names and attribute values that can be omitted, and the difference calculating unit includes: The difference between the attribute values is calculated as a difference, and when the entire attribute information is omitted, the difference is calculated assuming that only the attribute value is omitted.

  According to this configuration, the compression rate of the document data can be improved based on the attribute information and attribute values of the elements included in the document data.

  The document encoding apparatus according to the present invention is the document encoding apparatus according to claim 3, wherein the document to be encoded includes a schema document that defines the structure of the document and an instance document derived from the schema document. In the case of a document, the detection means detects an omission of the attribute information by analyzing a schema document.

  According to this configuration, the compression rate can be improved in accordance with the document structure of the XML format document data.

  The document encoding apparatus according to the present invention includes a difference between an interpretation unit that interprets a document, a structure detection unit that detects a structure of an element in the interpreted document, and a similar structure that appears in the document based on the detection result. It adopts a configuration comprising difference calculating means for calculating and compression encoding means for compressing and encoding each structure based on the calculated difference information.

  According to this configuration, individual structures can be compressed based on differences between similar structures included in the document data, and the compression ratio of the entire document data can be improved.

  The document encoding apparatus according to the present invention is the document encoding apparatus according to claim 5, wherein the structure detection unit outputs the structure information of the detected structure in the encoded document.

  According to this configuration, the decoding process on the receiving device side can be facilitated by the structure information included in the encoded document.

  The document encoding apparatus according to the present invention is the document encoding apparatus according to claim 5 or 6, wherein the document to be encoded includes a schema document that defines the structure of the document and an instance document derived from the schema document. In the case of a structured document, the structure detecting means adopts a configuration for detecting the structure by analyzing the schema document.

  According to this configuration, it is possible to easily detect the document structure of XML-format document data.

  The document encoding apparatus according to the present invention is the document encoding apparatus according to claim 7, wherein the document to be encoded includes a schema document that defines the structure of the document and an instance document derived from the schema document. In the case of a document, the structure detection unit analyzes the schema document and switches the structure detection from the analysis of the schema document to the analysis of the instance document based on the information on the appearance possibility of the elements constituting the structure. .

  According to this configuration, the structure analysis process can be efficiently executed in accordance with the document structure of the XML format document data.

  The document decoding apparatus according to the present invention is a document decoding apparatus that decodes an encoded document in which the same elements are individually compressed and encoded based on difference information between elements, and the elements are differentially compressed. It adopts a configuration comprising compression detection means for detecting the fact that it is being performed, and decoding means for decoding the element compressed based on the difference information.

  According to this configuration, when the encoded document is decoded, it can be decoded based on the difference information of the same element, and the processing load can be reduced.

  The document decryption apparatus according to the present invention is the document decryption apparatus according to claim 9, wherein the compression detection is performed when an encoded document in which consecutive identical elements are combined as one element and is encoded is decoded. The means detects the compression of the elements and detects the combination of the elements, and the decoding means separates the combined elements and decodes the compressed elements based on the difference information. take.

  According to this configuration, when the encoded document is decoded, it can be decoded element by element, and the processing load can be reduced.

  The document decoding apparatus of the present invention is a document decoding apparatus that decodes an encoded document in which a similar structure is individually compressed and encoded based on difference information between structures, and the structure is a difference. It adopts a configuration comprising compression detection means for detecting the compression, and structure decoding means for decoding the structure compressed based on the difference information.

  According to this configuration, when the encoded document is decoded, it can be decoded based on the difference information between the structures, and the processing load can be reduced.

  The document decoding apparatus according to the present invention is the document decoding apparatus according to claim 11, wherein the structure decoding unit analyzes the first encoded structure output in the encoded document, thereby compressing the document decoding apparatus. A configuration that recognizes the previous structure is adopted.

  According to this configuration, the decoding process can be executed after the structure before compression of the encoded document is recognized, and the processing load of the decoding process can be reduced.

  The document decoding apparatus according to the present invention is the document decoding apparatus according to claim 11, wherein the structure decoding unit analyzes the structure information output in the encoded document at the time of encoding, thereby A structure that recognizes the structure is adopted.

  According to this configuration, the decoding process can be executed after the structure before compression of the encoded document is recognized, and the processing load of the decoding process can be reduced.

  The document decryption apparatus according to the present invention is the document decryption apparatus according to claim 11, wherein the structure decryption unit recognizes the structure before compression by analyzing the schema document of the encoded instance document. Take.

  According to this configuration, the decoding process can be executed after the structure before compression of the encoded document is recognized, and the processing load of the decoding process can be reduced.

  The document encoding method of the present invention is the same when an interpretation process for interpreting a document, a detection process for detecting whether or not the same element exists in the interpreted document, and the same element exists according to the detection result. A difference calculating step for calculating a difference between elements, and a compression encoding step for compressing and encoding each element based on the calculated difference information are provided.

  According to this method, it is possible to provide a document encoding method that can improve the compression rate based on the same element included in the document data and reduce the load on the distribution apparatus related to the distribution of the document data.

  The document encoding method according to the present invention includes a difference between an interpretation step of interpreting a document, a structure detection step of detecting a structure of an element in the interpreted document, and a similar structure appearing in the document according to the detection result. A difference calculation step for calculating and a compression encoding step for compressing and encoding each structure based on the calculated difference information are provided.

  According to this method, it is possible to provide a document encoding method that can improve the compression rate based on the difference information of the structure included in the document data and reduce the load on the distribution apparatus related to the distribution of the document data. .

  The document decoding method of the present invention is a document decoding method for decoding an encoded document in which the same element is individually compressed and encoded based on difference information between elements, and the element is a difference. A compression detection step for detecting that the compression is performed, and a decoding step for decoding the element compressed based on the difference information are provided.

  According to this method, it is possible to provide a document decoding method capable of decoding based on difference information of the same element when decoding an encoded document, and reducing the processing load.

  The document decoding method of the present invention is an encoded document decoding method for decoding an encoded document in which a similar structure is individually compressed and encoded based on difference information between the structures. A compression detection step for detecting that the structure is differentially compressed and a structure decoding step for decoding the structure compressed based on the difference information are provided.

  According to this method, it is possible to provide a document decoding method capable of decoding based on the difference information of the document structure when decoding the encoded document and reducing the processing load.

  The document encoding program of the present invention is a document encoding program for encoding a document, and includes an interpretation step for interpreting the document and detection for detecting whether or not the same element exists in the interpreted document. A difference calculating step for calculating a difference between the same elements when the same element exists according to the detection result, and a compression encoding step for compressing and encoding each element based on the calculated difference information; , To have.

  According to this program, it is possible to provide a document encoding program that can improve the compression rate based on the same element included in the document data and reduce the load on the distribution apparatus related to the distribution of the document data.

  A document encoding program according to the present invention is a document encoding program for encoding a document, the interpretation step for interpreting the document, the structure detection step for detecting the structure of the element in the interpreted document, A difference calculating step for calculating a difference between similar structures appearing in the document according to a detection result, and a compression encoding step for compressing and encoding each structure based on the calculated difference information I made it.

  According to this program, it is possible to provide a document encoding program that can decode the encoded document based on the difference information of the document structure when decoding the encoded document, and reduce the processing load.

  The document decoding program of the present invention is a document decoding program for decoding an encoded document in which the same elements are individually compressed and encoded based on difference information between the elements. A compression detecting step for detecting that the difference is compressed, and a decoding step for decoding the element compressed based on the difference information.

  According to this program, it is possible to provide a document decoding program that can decode an encoded document based on difference information of the same element when decoding the encoded document and reduce the processing load.

  The document decoding program of the present invention is a document decoding program for decoding an encoded document in which the same element is individually compressed and encoded based on difference information between elements, A compression detection step for detecting that the data is differentially compressed, and a structure decoding step for decoding the structure compressed based on the difference information.

  According to this program, it is possible to provide a document decoding program that can decode the encoded document based on the difference information of the document structure when decoding the encoded document, and reduce the processing load.

  ADVANTAGE OF THE INVENTION According to this invention, the compression rate of document data can be improved, the load of the delivery apparatus which concerns on delivery of document data can be reduced, and delivery data can be more efficiently accumulate | stored on the receiving side.

  The essence of the present invention is to improve the compression ratio of document data, reduce the load on the receiving device related to the distribution of document data, and enable the receiving side to accumulate the distribution data more efficiently. is there.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a content distribution system according to the present embodiment. In this figure, in the content distribution system, a distribution device 100 and a reception device 110 are connected via a network 109. The content distributed by the content distribution system is multimedia-coded in advance and managed by the content management unit 101 of the distribution apparatus 100 in a distributable format.

  The distribution device 100 is a device that distributes content, and includes a content management unit 101, a metadata control unit 102, a metadata encoding unit 103, a distribution control unit 104, and a transmission unit 105.

  The content management unit 101 manages distribution data in which a distribution content is encoded in advance in a multimedia-ready format. The metadata control unit 102 generates XML format metadata by inputting content attribute information such as a title of a content to be distributed and a performer name.

  The metadata encoding unit 103 encodes the XML format metadata generated by the metadata control unit 102 into a binary format, and registers it in the content management unit 101 that manages the distribution content. The distribution control unit 104 instructs the transmission unit 105 to transmit the content and metadata based on the content and metadata distribution schedule information set in advance. The sending unit 105 sends the content and metadata to the receiving device 110 via the network 109 based on the sending instruction from the distribution control unit 104.

  The reception device 110 is a device that receives content, and includes a reception unit 111, a metadata processing unit 112, a metadata decoding unit 113, an ECG processing unit 114, an accumulation control unit 115, an accumulation unit 116, and a reproduction unit 117. .

  The receiving unit 111 receives content and metadata from the distribution apparatus 100 via the network 109. The metadata processing unit 112 decodes the metadata in the binary format received by the receiving unit 111 into the metadata in the XML format via the metadata decoding unit 113 and manages the decoded metadata.

  An ECG (Electric Contents Guide) unit 114 generates an ECG from the metadata managed by the metadata processing unit 112 based on an instruction from the user, presents it to the user, and accumulates content from the user. Accept reservations. When the ECG unit 114 receives a content reservation from the user, the ECG unit 114 instructs the storage control unit 115 to reserve the content. The accumulation control unit 115 accumulates the content in the accumulation unit 116 via the reception unit 111 when the content reserved for accumulation can be received.

  The ECG unit 114 presents a list of stored content via the storage control unit 115 and instructs the playback unit 117 to play back the stored content based on an instruction from the user. The playback unit 117 plays back the content stored in the storage unit 116 via the storage unit control unit 115 based on an instruction from the ECG unit 114.

  Next, details of the metadata encoding unit 103 will be described. The metadata generated by the metadata control unit 102 is generated as XML format metadata. The XML format metadata has a metadata structure defined by an XML grammar description language (DTD, XML Schema, etc.), a metadata encoding unit 103 that binary-encodes the XML format metadata, It is shared by the metadata decoding unit 113 that decodes the converted binary XML-format metadata.

  Next, the internal configuration of the metadata encoding unit 103 will be described with reference to FIG.

  The interpretation unit 201 interprets the XML format metadata generated by the metadata control unit 102 and generates an analysis table so that it can be used by the difference calculation unit 202 and the pattern detection unit 204 thereafter. The pattern detection unit 204 refers to the analysis table, detects the same element in the XML grammar in the metadata, and marks the first appearing pattern as a template.

  The difference calculation unit 202 calculates the difference between the template detected by the pattern detection unit 204 and each subsequent pattern and records the attribute and value in each pattern together with the appearance location. The compression encoding unit 203 generates XML binary data by encoding on an element basis based on the source, the template, and the difference information.

  Next, XML format metadata encoding processing in the metadata encoding unit 103 in FIG. 2 will be described with reference to an example of XML format metadata shown in FIG.

  FIG. 3 is a diagram illustrating an example of encoding in a case where the same element is continuous. In FIG. 3A, “<AAA a =“ W ”b =“ X ”d =“ Y ”> DATA1 </ AAA>” ”is described as XML text data (1) (line 1), 2) It is shown that “<AAA a =“ W ”c =“ X ”d =“ Z ”> DATA2 </ AAA>” ”is described in the (second line). FIG. 4B shows an example in which the metadata of FIG. 4A is encoded, and FIG. 4C shows the attribute map and value map of FIG.

  The analysis unit 201 interprets the metadata in FIG. 3A and generates an analysis table. Next, the pattern detection unit 204 refers to the analysis table generated by the analysis unit 201 and detects the same element in the XML grammar in the metadata. In the case of the metadata in FIG. 3A, the element “AAA” is first described in the first line indicated by (1) and the second line indicated by (2). AAA "is detected. And the pattern detection part 204 marks the element which appeared first as a template.

  Next, the difference calculation unit 202 calculates the difference between the element “AAA” detected by the pattern detection unit 204 and each subsequent element, and sets the attribute and value in each element as an attribute map and a value map. Record. In the case of the metadata shown in FIG. 3A, “a =“ W ”b =“ X ”d =“ Y ”> DATA1” ”is described as the element that continues after the element“ AAA ”in the first line. In the line, “a =“ W ”c =“ X ”d =“ Z ”> DATA2” ”is described as a continuous element after the element“ AAA ”, and the difference between these elements is calculated.

  FIG. 3 shows the presence / absence of each occurrence of the attribute “a, b, c, d” and its value “W, X, Y, X, Z” described in FIG. The attribute map and value map shown in (c) are recorded. In the attribute map, the presence or absence of each occurrence of the attribute “a, b, d” from the description of the attribute on the first line and the presence or absence of each occurrence of the attribute name “a, c, d” from the description of the attribute on the second line , Mapped in association with the attribute name “a, b, c, d”. In this case, “1” is set if the attribute exists, and “0” is set if the attribute does not exist.

  In addition, this value map represents a correspondence between an attribute value that is an element of the attribute value list and an attribute name. In the value map, “W”, “X”, “Y” ”from the value description on the first line and“ W ”,“ X ”,“ Z ”from the value description on the second line, Mapping is performed in association with the attribute name “a, b, c, d”. In this case, if a value exists with the same attribute name on the first line, “1” is set. On the second line, if the same value exists with the same attribute name as the first line, If “0” is set and a different value exists with the same attribute name as the first line, “1” is set.

  Next, the compression encoding unit 203 performs encoding in element units based on the source, template, and difference information, and generates XML binary data shown in FIG. In FIG. 3B, the mark “1” indicating that the metadata of FIG. 3A is continuously encoded is described at the head part, and the number of consecutive elements “AAA” whose pattern is detected in the next part. “2” indicating the element “AAA” is described in the next part, “2” indicating the id of the element “AAA”, and “4” indicating the number of the attributes “a, b, c, d” in the next part. It is described.

  Next, in FIG. 3B, the contents shown in FIG. 3C are described as attribute maps “a-map (attribute map)” and “v-map (value map)” in the next part of the number of attributes. Next, set the attribute name list “a, b, c, d” and attribute value list “W, X, Y, X, Z” corresponding to the attribute map, and finally set the data “DATA1, DATA2” doing.

  The XML binary data shown in FIG. 3B is transmitted from the content management unit 101 to the receiving device 110 via the network 109 from the content management unit 101 in the data format shown in FIG. In the data format of FIG. 4, in the “element name list” portion, the continuous encoding mark, the number of consecutive elements, the element id, and the number of attributes shown in FIG. In the “attribute name list” part, the attribute name list of FIG. 3B is set. The “string pool” portion includes “data string pool” and “element name / attribute name string pool”, and the attribute map and value map of FIG. 3B are set. In the “element data” portion, data shown in FIG. 3B is set.

  Next, the case where the XML binary data in FIG. 3B is decoded by the metadata decoding unit 113 in the receiving apparatus 110 will be described.

  Details of the metadata decoding unit 113 will be described with reference to a block diagram shown in FIG. The compression detection unit 301 detects the encoding format of the XML binary data based on the setting contents of the encoding mark of the XML binary data (see FIG. 3B) input from the metadata processing unit 112, and detects the detection. The result and XML binary data are output to the structure decoding unit 302. In the case of the XML binary data in FIG. 3B, since the continuous encoding mark “1” is set as the encoding mark, the compression detection unit 301 detects that it is in the “continuous encoding” format. Is output to the structure decoding unit 302.

  The structure decoding unit 302 identifies the encoding format of the XML binary data based on the detection result input from the compression detection unit 301 and the XML binary data, and also identifies the encoding structure of the XML binary data, and the identification. The result and XML binary data are output to the decoding unit 303. In the case of the XML binary data in FIG. 3B, since the number of consecutive elements “2”, the element id “2 =“ AAA ”, the number of attributes“ 4 ”, and the attribute map are set, the structure decoding unit In 302, the coding structure in FIG. 3A is identified, and the identification result is output to the decoding unit 303.

  The decryption unit 303 decrypts the XML binary data based on the document structure identification result and the XML binary data input from the structure decryption unit 302. Decoding processing of attributes and attribute values in the XML binary data will be described with reference to FIG. 6 (a) shows the same XML text data as FIG. 3 (a), FIG. 6 (b) shows the same XML binary data as FIG. 3 (b), and FIG. 6 (c) shows the XML binary data. The decoding process of the attribute and attribute value is shown.

  The process of decoding the attributes and attribute values shown in FIG. First, it is identified that the attribute “a, b, d” is described based on the setting content “1101” on the first line among the setting content of the attribute map. Next, the description contents of the attribute value are identified based on the setting contents of the first line among the setting contents of the attribute value map.

  However, in this case, it is indicated that the setting corresponding to the attribute value map has been set to the initial state “1011” as shown in the figure by the decoding process of the attribute value of the previous XML binary data. This initial state “1101” is changed by the setting content “1101” in the first line of the setting contents of the attribute value map, and the description contents of the attribute value are identified. Through the above decoding process, the identification contents of each attribute and each attribute value on the first line are identified, and the attribute values “W, X, Y” shown in the figure are the attributes “a, b, It is identified in association with “d”.

  The contents of the attribute value map (1) identified in the first line are reflected as information for identifying the setting contents of the attribute value map in the next second line. In the figure, the state in which the setting contents of the attribute value map are reflected is indicated by arrows.

  Next, it is identified that the attribute “a, c, d” is described based on the setting content “1011” on the second line of the attribute map. Next, the attribute value map (1) “1101” inherited from the identification result of the first row is changed according to the setting content “0011” of the attribute value map of the second row. In this case, since the attribute value of the attribute “a” is the same as the attribute value corresponding to the attribute “a” in the first row, the attribute value “0” is set and decoded with the previous attribute value “W”. The Through the above decryption processing, identification of the description contents of each attribute and each attribute value on the first line is completed, and the attribute values “W, X, Z” shown in the figure are the attributes “a, c, It is identified in association with “d”.

  Then, the decoding unit 303 combines the XML text data based on the description contents of the decoded attribute and attribute value together with the previously identified coding structure. As a result, the original text data shown in FIG. 6A is decoded.

  As described above, the same element in the XML grammar is detected from the XML text data described in a plurality of lines, the attribute and the attribute value are detected for each element in each line, and the attribute map and attribute including the description contents Encoding to XML binary data including value map, encoding type, number of consecutive elements, element id, number of attributes, attribute name list, attribute value list, and data can improve the compression rate of document data Thus, it is possible to reduce the load on the distribution apparatus related to the distribution of the document data. In addition, document data can be more efficiently stored on the receiving device side.

  The document encoding apparatus, document decoding apparatus, document encoding method, and document decoding method of the present invention can improve the compression rate of document data and reduce the load on the receiving apparatus related to the distribution of document data. It is possible to apply to the distribution system.

The block diagram which shows the structure of the content delivery system which concerns on embodiment of this invention The block diagram which shows the internal structure of the metadata encoding part of FIG. (A) is a diagram showing an example of XML format metadata in which the same elements are continuous, (b) is a diagram showing a configuration of XML binary data obtained by encoding the metadata of (a), and (c) is ( The figure which shows each structure of the attribute map and value map of b) The figure which shows the data format at the time of XML binary data delivery The block diagram which shows the internal structure of the metadata decoding part of FIG. (A) is a diagram showing an example of XML format metadata in which the same elements are continuous, (b) is a diagram showing a configuration of XML binary data obtained by encoding the metadata of (a), and (c) is ( The figure which shows the decoding process based on the attribute map and value map of b)

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Distribution apparatus 101 Content management part 102 Metadata control part 103 Metadata encoding part 104 Distribution control part 105 Transmission part 110 Receiving apparatus 111 Reception part 112 Metadata processing part 113 Metadata decoding part 114 ECG processing part 115 Accumulation control part 116 Accumulation unit 117 Playback unit 201 Interpretation unit 202 Difference calculation unit 203 Compression encoding unit 204 Pattern detection unit 301 Compression detection unit 302 Structure decoding unit 303 Decoding unit

Claims (22)

Interpretation means for interpreting the document;
Detecting means for detecting whether or not the same element exists in the interpreted document;
If the same element exists according to the detection result, a difference calculation means for calculating a difference between the same elements;
Compression encoding means for compressing and encoding individual elements based on the calculated difference information;
A document encoding apparatus comprising:   2. The document encoding apparatus according to claim 1, wherein when the same element exists and is continuous according to the detection result, the compression encoding unit combines the continuous individual elements as one element. The element includes attribute information including a plurality of optional attribute name and attribute value pairs,
The difference calculation means calculates the difference between the attribute values as a difference, and calculates the difference assuming that only the attribute value is omitted when the entire attribute information is omitted. Or the document encoding apparatus of 2 description.   When the document to be encoded is a structured document including a schema document that defines the structure of the document and an instance document derived from the schema document, the detecting means omits the attribute information from the schema document. The document encoding apparatus according to claim 3, wherein the detection is performed by analysis. Interpretation means for interpreting the document;
Structure detection means for detecting the structure of the element in the interpreted document;
A difference calculating means for calculating a difference between similar structures appearing in the document according to the detection result;
Compression encoding means for compressing and encoding individual structures based on the calculated difference information;
A document encoding apparatus comprising:   6. The document encoding apparatus according to claim 5, wherein the structure detection unit outputs structure information of the detected structure in an encoded document.   When the document to be encoded is a structured document consisting of a schema document that defines the structure of the document and an instance document derived from the schema document, the structure detection unit analyzes the schema document to analyze the structure. The document encoding apparatus according to claim 5 or 6, wherein the document encoding apparatus is detected.   When the document to be encoded is a structured document consisting of a schema document that defines the structure of the document and an instance document derived from the schema document, the structure detection means analyzes the schema document to construct the structure. 8. The document encoding apparatus according to claim 7, wherein the detection of the structure is switched from the analysis of the schema document to the analysis of the instance document based on the information on the appearance possibility of the element to be performed. An encoded document decoding apparatus that decodes an encoded document in which the same element is individually compressed and encoded based on difference information between elements,
Compression detection means for detecting that the element is differentially compressed;
Decoding means for decoding an element compressed based on the difference information;
A document decryption apparatus comprising: When decoding an encoded document in which consecutive identical elements are combined as one element and encoded,
The compression detecting means detects the compression of the elements and detects the coupling of the elements,
10. The document decoding apparatus according to claim 9, wherein the decoding means separates the combined elements and decodes the compressed elements based on the difference information. A similar structure is an encoded document decoding apparatus that decodes encoded documents that are individually compressed and encoded based on difference information between structures,
Compression detection means for detecting that the structure is differentially compressed;
Structure decoding means for decoding a structure compressed based on the difference information;
A document decryption apparatus comprising:   12. The document decoding apparatus according to claim 11, wherein the structure decoding unit recognizes a structure before compression by analyzing a first encoded structure output in the encoded document. .   12. The document decoding apparatus according to claim 11, wherein the structure decoding unit recognizes a structure before compression by analyzing structure information output in the encoded document at the time of encoding.   12. The document decoding apparatus according to claim 11, wherein the structure decoding unit recognizes a structure before compression by analyzing a schema document of an encoded instance document. An interpretation process for interpreting the document;
A detecting step of detecting whether or not the same element exists in the interpreted document;
When the same element exists according to the detection result, a difference calculation step for calculating a difference between the same elements;
A compression encoding step of compressing and encoding individual elements based on the calculated difference information;
A document encoding method comprising: An interpretation process for interpreting the document;
A structure detection step for detecting a structure of an element in the interpreted document;
A difference calculation step of calculating a difference between similar structures appearing in the document according to the detection result;
A compression encoding step of compressing and encoding individual structures based on the calculated difference information;
A document encoding method comprising: An encoded document decoding method for decoding an encoded document in which the same element is individually compressed and encoded based on difference information between elements,
A compression detection step of detecting that the element is differentially compressed;
A decoding step of decoding an element compressed based on the difference information;
A document decrypting method comprising: A similar structure is an encoded document decoding method for decoding encoded documents that are individually compressed and encoded based on difference information between structures,
A compression detection step of detecting that the structure is differentially compressed;
A structure decoding step of decoding a structure compressed based on the difference information;
A document decrypting method comprising: A document encoding program for encoding a document,
An interpretation step to interpret the document;
A detecting step for detecting whether or not the same element exists in the interpreted document;
If the same element exists according to the detection result, a difference calculating step for calculating a difference between the same elements;
A compression encoding step of compressing and encoding individual elements based on the calculated difference information;
A document encoding program characterized by comprising: A document encoding program for encoding a document,
An interpretation step to interpret the document;
A structure detection step for detecting a structure of an element in the interpreted document;
A difference calculating step for calculating a difference between similar structures appearing in the document according to the detection result;
A compression encoding step of compressing and encoding each structure based on the calculated difference information;
A document encoding program characterized by comprising: A document decoding program for decoding an encoded document in which the same element is individually compressed and encoded based on difference information between elements,
A compression detection step for detecting that the element is differentially compressed;
A decoding step of decoding an element compressed based on the difference information;
A document decryption program characterized by comprising: A document decoding program for decoding an encoded document in which the same element is individually compressed and encoded based on difference information between elements,
A compression detection step for detecting that the structure is differentially compressed;
A structure decoding step of decoding a structure compressed based on the difference information;
A document decryption program characterized by comprising:

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