KR102058333B1 - Method and apparatus for parsing bitstream, generic parsing apparatus - Google Patents

Abstract

A bitstream parsing method and apparatus are disclosed that can parse a bitstream by reconfiguring the parser during runtime. The bitstream parsing method includes reading bitstream syntax information for reconstruction of a parser; Determining whether the bitstream syntax information is valid; Reconfiguring a predefined parser based on the bitstream syntax information when the bitstream syntax information is valid; And parsing the input bitstream using the reconstructed parser.

Description

Bitstream parsing method and apparatus, general purpose parsing device TECHNICAL FIELD OF APPARATUS FOR PARSING

The following description relates to a framework of a reconfigurable codec and relates to a bitstream parsing method and a bitstream parsing apparatus for parsing an input bitstream.

In general, a video is converted into a bitstream form by an encoder. In this case, the bitstream is stored according to an encoding type satisfying the constraint of the encoder.

MPEG requires syntax and semantics ('semantics') as constraints of the bitstream. The syntax describes the structure, format, and length of the data, and in what order the data is represented. That is, the syntax indicates a grammar for performing encoding and decoding operations, and defines the order of each element included in the bitstream, the length of each element, and the data format. Semantics indicate what each bit of data means.

The framework of the reconfigurable codec currently standardized in MPEG is Bitstream Syntax Description (BSD), which describes the syntax structure of the bitstream through RVC-BSDL (Reconfigurable Video Coding-Bitstream Syntax Description, defined in ISO / IEC 23001-4). Create Regarding how to generate parsers, RVC-BSDL and Flaver focus on generating source code.

The conventional syntax parser is designed in a built-in manner, so the implementation of the parser is terminated at design time. In the reconfigurable multimedia coding (RMC) standardized in MPEG, there is no method for dynamically generating a parser. For efficient parsing of bitstreams, a parser description language capable of dynamically generating a parser at runtime and a method capable of dynamically generating a parser are required.

A bitstream parsing method according to an embodiment includes: reading bitstream syntax information for reconstruction of a parser; Determining whether the bitstream syntax information is valid; Reconfiguring a predefined parser based on the bitstream syntax information when the bitstream syntax information is valid; And parsing the input bitstream using the reconstructed parser.

In the bitstream parsing method according to an embodiment, the reconfiguring may include configuring an input port and an output port of the predefined parser based on the interface information; Setting a wait state for execution of an external function based on the plug-in function information; And loading the control information to control the predefined parser.

In the bitstream parsing method according to an embodiment, the determining may include determining whether a grammatical error exists in the bitstream syntax information; And determining whether there is a functional error related to the execution of an interface and an external function in the bitstream syntax information.

In one embodiment, a bitstream parsing apparatus includes a readout unit configured to read bitstream syntax information for reconstruction of a parser; A validity determination unit determining whether the bitstream syntax information is valid; A parser reconstructing unit configured to reconstruct a predefined parser based on the bitstream syntax information when the bitstream syntax information is valid; And a bitstream parser configured to parse the input bitstream using the reconstructed parser.

In one embodiment, a general parsing apparatus includes: a bitstream syntax information analyzer configured to analyze bitstream syntax information for reconstruction of a parser and classify the bitstream syntax information into control information, plug-in function information, and interface information; A controller for parsing the input bitstream based on the control flow indicated in the control information; And an interface unit configuring an input port and an output port based on the interface information.

The general purpose parsing apparatus according to an embodiment may further include an external function caller that calls an external function that performs a specific function based on the plug-in function information.

1 is a diagram illustrating an overall operation of a bitstream decoding system according to an embodiment.
2 is a diagram illustrating a detailed configuration of a bitstream parsing apparatus according to an embodiment.
3 is a diagram illustrating a detailed configuration of a general-purpose parsing apparatus according to an exemplary embodiment.
4 is a diagram for describing an operation of a general-purpose parsing apparatus, according to an exemplary embodiment.
5 is a diagram illustrating an XML language structure of an XML script based parser description language according to an embodiment.
6 is a flowchart illustrating an operation of a bitstream parsing method, according to an exemplary embodiment.
7 is a flowchart illustrating a detailed operation of determining whether bitstream syntax information is valid according to an embodiment.
8 is a flowchart illustrating a detailed operation of reconfiguring a parser, according to an exemplary embodiment.
9 is a flowchart illustrating a procedure of executing a reconfigured parser, according to an exemplary embodiment.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. The specific structural to functional descriptions below are illustrated for the purpose of describing embodiments of the invention only, and the scope of the invention should not be construed as limited to the embodiments set forth herein. The bitstream parsing method according to an embodiment may be performed by a bitstream parsing apparatus, and the same reference numerals shown in each drawing represent the same members.

1 is a diagram illustrating an overall operation of a bitstream decoding system according to an embodiment.

Referring to FIG. 1, the operation of the bitstream decoding system may be described by dividing into a design section 170 and a runtime section 180.

In the design section 170, the general purpose parsing device 120 and other devices 160 for decoding the bitstream may be predefined. For example, the general purpose parsing device 120 may be a bitstream parser that may be reconfigurable or set in an operation manner, and may be predefined from a tool library.

In the runtime section 180, the bitstream parsing apparatus 110 may reconfigure the general purpose parsing apparatus 120 based on the bitstream syntax information 130 for reconfiguring the parser. For example, the bitstream syntax information 130 may be written in an extensible mark-up language (XML) script-based language. Details thereof will be described later with reference to FIG. 5.

The bitstream parsing apparatus 110 may classify the bitstream syntax information 130 into control information, plug-in function information, and interface information. The bitstream parsing apparatus 110 may set an input port and an output port of the general purpose parsing apparatus 120 based on the interface information, and load an external function for executing a specific function using the plug-in function information. Can be. The bitstream parsing apparatus 110 may compile and translate the finite state machine (FSM) structure into an executable form based on the control flow included in the control information. The bitstream parsing apparatus 110 may parse the bitstream based on the control flow. The bitstream parsing apparatus 110 may parse the bitstream efficiently by dynamically configuring the bitstream parser in the framework of the reusable codec.

After the decoder setting 155 step, a decoder may be generated 140 based on the reconstructed general purpose parsing device 120 and other devices 160. The decoder may output the decoded image by using the encoded bitstream as an input.

2 is a diagram illustrating a detailed configuration of a bitstream parsing apparatus according to an embodiment.

Referring to FIG. 2, the bitstream parsing apparatus 210 may include a reader 220, a validity determiner 230, a parser reconstructor 240, and a bitstream parser 250.

The reader 220 may read bitstream syntax information for reconstruction of the parser. The bitstream syntax information may include control information, plug-in function information, and interface information.

The control information may include information related to the control flow of the parser parsing the input bitstream. The control information is parsed into a parsing state indicating how to extract information from the input bitstream, an external function call state used to invoke an external function, an FSM call state used to invoke a finite state machine (FSM), and other states depending on the condition. At least one of the branch states for jumping may be defined.

The plug-in function information may include external function information for performing an external specific function. The plug-in function information may include parameter information related to the codec, and the external function may be parameterized by a codec-dependent value.

The interface information may include definitions for the input port and output port of the parser. The bitstream may be input through an input port, and a semantically decoded result may be output through an output port. For example, the output result may be used as a token of Reconfigurable Multimedia Coding (RMC). The interface information may include a list of all input and output ports associated with the parser.

The validity determiner 230 may determine validity of bitstream syntax information in order to prevent an unexpected error. The validity determiner 230 may determine whether the bitstream syntax information is valid and determine whether to reconfigure the predefined parser.

In detail, the validity determiner 230 may determine whether a grammatical error and a functional error exist in the bitstream syntax information.

When the bitstream syntax information is written based on XML, the validity determiner 230 may check a grammatical error of the bitstream syntax information by using XML verification tools using an XML schema. In addition, the validity determination unit 230 may check not only the XML grammar but also a description grammar regarding the parser configuration.

The validity determiner 230 may additionally determine whether there is a functional error when there is no grammatical error in the bitstream syntax information. The validity determination unit 230 may check a functional error to determine whether parsing operations of the bitstream can be performed properly.

The validity determiner 230 may perform functional verification of the parser interface based on the interface information included in the bitstream syntax information. For example, the validity determiner 230 may perform functional verification of the interface by comparing the parser interface declaration with the actual input and output ports currently connected.

In addition, the validity determination unit 230 may perform a functional verification of the external function based on the plug-in function information included in the bitstream syntax information. The validity determiner 230 may perform functional verification of the plug-in function by comparing an external function list with plug-in functions connected to the current parser.

The parser reconstructor 240 may reconstruct a predefined parser based on the bitstream syntax information when the bitstream syntax information is valid. At least one of an input port and an output port may be variably determined based on bitstream syntax information. The parser may be predefined at the design time, and the parser reconstructor 240 may reconfigure the parser defined at the design time to generate a new parser most suitable for bitstream parsing at runtime.

The parser reconstructor 240 may reconstruct a predefined parser based on control information, plug-in function information, and interface information extracted from bitstream syntax information. In detail, the parser reconfigurer 240 may configure an input port and an output port of a predefined parser based on the interface information. For example, the parser reconfigurer 240 may connect the input port and the output port of the predefined parser to the module network of the RMC framework according to the interface information.

The parser reconstructor 240 may set a wait state for the execution of an external function based on the plug-in function information. For example, the parser reconstructor 240 may configure a predefined parser to perform a complicated task such as entropy decoding using a predefined external function. The parser reconfigurer 240 may prepare plug-in function instances in a predefined parser and prepare them to be called by the controller. The parser reconstructor 240 may initialize the plug-in function instance by applying parameters shown in the bitstream syntax information to the plug-in function instance.

The parser reconstructor 240 may load control information to control a predefined parser when a waiting state for execution of an external function is set based on the plug-in function information. The parser reconstructor 240 may read the control flow included in the control information and induce the compilation of the FSM structure. FSM structures can be compiled at runtime and translated into an immediate executable form.

The bitstream parser 250 may parse the input bitstream using the reconstructed parser. When the parser reconstructor 240 reconstructs a predefined parser based on the bitstream syntax information passed through the reader 220 and the validity determiner 230, the bitstream parser 250 inputs the reconstructed parser. It is possible to control the reconfigured parser to parse the bitstream.

The bitstream parser 250 may control the operation of the reconfigured parser based on the type of each state in the control flow. The bitstream parser 250 may control the reconfigured parser to continuously perform the parsing process of the bitstream until the control flow ends or the input bitstream ends. In addition, the bitstream parser 250 may control a parser reconfigured to call a plug-in function in order to use an external function required for parsing the bitstream in the parsing process.

3 is a diagram illustrating a detailed configuration of a general-purpose parsing apparatus according to an exemplary embodiment.

Referring to FIG. 3, the general parsing apparatus 310 may include a bitstream syntax information analyzing unit 320, a controller 330, and an interface unit 340. In addition, the general purpose parsing apparatus 310 may further include an external function caller 350.

The bitstream syntax information analyzer 320 may analyze bitstream syntax information for reconstruction of the parser. The bitstream syntax information may include control information related to the control flow of the parser, plug-in function information related to external function information for performing a specific function outside the parser, and interface information related to the input / output port of the parser. The bitstream syntax information analyzer 320 may classify the bitstream syntax information into control information, plug-in function information, and interface information.

The controller 330 may reconfigure the general purpose parsing apparatus 310 based on the bitstream syntax information, and control the call of the interface and the external function according to the control information. In addition, when the reconstruction of the general purpose parsing apparatus 310 is completed, the controller 330 may perform a parsing process of the input bitstream based on the control flow indicated in the control information.

The interface unit 340 may configure an input port and an output port based on the interface information, and may connect to another network. For example, the interface unit 340 may connect the input port and the output port to the module network of the RMC framework.

The external function caller 350 may call an external function that performs a specific function based on the plug-in function information. The external function may be a function of a prototype loaded with a specific parameter set by the control flow indicated in the control information. The external function caller 350 may prepare the plug-in function instances to be called by the controller 330.

4 is a diagram for describing an operation of a general-purpose parsing apparatus, according to an exemplary embodiment.

In FIG. 4, a general purpose parsing device 410 is shown that can be reconfigured at runtime.

The bitstream syntax information analyzer 420 receives the bitstream syntax information 480 and classifies the bitstream syntax information 480 into control information, external function information, and interface information. The bitstream syntax information analyzer 420 may provide the classified control information, external function information, and interface information to the controller 430, the external function caller 460, and an interface unit (not shown), respectively.

The bitstream syntax information analyzer 420 classifies the bitstream syntax information 480 and may induce a reconstruction process of the general purpose parsing apparatus 410. The bitstream syntax information analyzer 420 may use XML parser libraries such as MS-XML, Xerces, TinyXML, and the like to classify the bitstream syntax information 480.

The interface unit may configure and set the input port 440 and the output port 450 of the general purpose parsing device 410. General purpose parsing device 410 may communicate with other networks, such as RMC framework, through input port 440 and output port 450. The encoded bitstream 470 may be input through the input port 440, and the parsed or decoded data may be output through the output port 450. The input port 440 and the output port 450 of the general purpose parsing device 410 may be variably determined according to the interface information included in the bitstream syntax information 480. Thus, input port 440 and output port 450 can be dynamically controlled at runtime.

The controller 430 may reconfigure the general purpose parsing apparatus 410 based on the control information received from the bitstream syntax information analyzer 420, and control a call of an interface and an external function according to the control information. In addition, when the reconstruction of the general purpose parsing apparatus 410 is completed, the controller 430 may perform the parsing process of the encoded bitstream 470 based on the control flow indicated in the control information.

For example, the controller 430 may be a script engine that executes a control flow description included in the bitstream syntax information 480. The script engine can be based on runtime compilation methods for scripting languages such as run-time interpreters, just-in-time (JIT) compilers, and virtual machines.

The external function caller 460 may manage a plug-in function for calling external functions to perform a complex parsing function. The external function caller 460 may call an external function that performs a specific function based on the plug-in function information. The external function caller 460 may prepare the plug-in function instances to be called by the controller 430. Plug-in functions can be generated by plug-in function declarations and then loaded with a specific set of parameters by the control flow contained in the control information.

5 is a diagram illustrating an XML language structure of an XML script based parser description language according to an embodiment.

The bitstream parsing apparatus may use an XML Script-based Parser Description Language (XS-PDL) to reconstruct a predefined parser at runtime. The bitstream parsing apparatus may dynamically generate a parser in the framework based on the description of the parser defined in the XS-PDL.

The XS-PDL may be a model that describes a finite state machine (FSM). To describe the process of parsing the bitstream, the FSM can be modeled to be abstract and perform with minimal information through the XS-PDL. When modeling an FSM with minimal information, the FSM can be easily implemented and reused on a variety of other platforms.

In MPEG RMC, XML can be used as a language for writing decoder statements (eg, Functional Unit Network Language (FNL)). XS-PDL can be written based on XML to ensure compatibility with MPEG RMC decoder description. Through this, the bitstream parsing apparatus may perform document validation using an existing XML tool. XS-PDL may follow the syntax of W3C XML, and the overall structure is shown in FIG. Through the XS-PDL, a bitstream syntax description (BSD) that forms bitstream syntax information may be generated.

BSD can include control flow descriptions, parser interface declarations, and external function declarations.

Elements of the control flow description used in the XS-PDL may be represented as shown in Table 1 below.

Element Attributes  Of Children  Of Notes < control > Top Tag of XS-PDL Control Flow Description Children: <FSM> * < FSM > Tag that declares an FSM name = " FSM _ name " The identifier of an FSM. Children: <states> < states > Packed Tag to Declare State Children: (<parsing> | <plugin> | <FSM_call> | <branch>) * < parsing > Parsing State Declaration Tag name = " state _ name " State name (also used as variable name) bits = " expression " The length of bits to read from the bitstream source = " input _ port _ name " Input port name to use bytealign = "(true | false)" Byte alignment options peek = "(true | false)" Look-ahead parsing options expected = " expression " Expected value. If the value read does not match, an error occurs. value = " expression " Default. final = "(true | false)" Is the last state to exit FSM Children: {<process>, <output>} < plugin > External function call state declaration tag name = " state _ name " Same as parsing callee = " plugin _ instance _ name " Name of the external function to be called Children: (<parameters> | <process> | <output>)
Note: <parameters> < FSM _ call > An FSM call state. name = " state _ name " Same as parsing callee = " FSM _ name " FSM name to be invoked Children: {<process>, <output> *} < branch > A branch state based on a conditional jump among states .. name = " state _ name " Same as parsing condition = " expression " Branch conditions. A branch occurs if the evaluated value is true (nonzero) next = " operation _ name " Next state name when branch occurs Children: <process> < process > Description of an additional decoding operations. Children: (<operation> | <if>) * < output > Description of a port output of a parsed data. dest = " output _ port _ name " Output port name value = " expression " Value to be printed < operation > An operation for additional decoding process. name = " operation _ name " Name of the operation procedure target = " variable " Variable to be updated value = " expression " Value to be updated (calculation) < if > A flow control statement within additional decoding process using a conditional jump among operations. name = " operation _ name " same as <operation> condition = " expression " Branch conditions. A branch occurs if the evaluated value is true (nonzero) next = " operation _ name " Name of next operation procedure when branch occurs

The control flow of bitstream parsing in the XS-PDL may be described by the FSM. The description of the control flow may consist of one or more FSMs (including sub-FSMs). Each FSM (<FSM>) may be represented by a state (or state) of one of a parsing state, an external function call state, an FSM call state, and a branch state.

Each state has a name attribute used as an identifier, and a method of parsing a bitstream performed according to each codec type may be defined. The order in which each FSM is performed is in the order described in the control flow description, and the initial state of each FSM may be the first state that appears in the FSM.

The parsing state <parsing> may provide information related to how to parse information of a specific length of the input bitstream. The information to be provided can be described by declaring a parsing state as shown in Table 1. The method of extracting information from the bitstream can be defined by the bits, bytealign, and peek attributes. Bit length information to be parsed from the input bits can be defined in the bits attribute of type unsigned integer. Byte alignment information may be defined by the bytealign attribute. Parsing state declarations can define a look-ahead parsing process using the peek attribute. The input bitstream may be defined by a source attribute value. The source attribute value is optional and may be used when two or more multi-bitstreams need to be processed during the parsing process of the bitstream. The syntax element of a bitstream must be set to a special value. The validity can be checked using the value defined in the expected attribute.

The parsing state can be used to define data that is not parsed in the bitstream, which can be defined by the value attribute. In addition, the parsing state can be used to define the final state of the current FSM. For example, if the final attribute value is 'true', FSM may stop after the current state ends.

The parsed values can be stored and processed like regular variables in the rest of the parsing process. Each parsing state or external function call state can automatically create a variable with the same name. Thus, it is possible to read any bit from the bitstream without declaring a variable. If two states have the same name, one variable must be used.

An additional decoding process of the parsing state can be added via the <process> element. Additional decoding processes may include mathematical calculations, logic calculations, binary variable calculations, and the like. The <process> element may include a plurality of <operation> elements and <if> elements. <operation> and <if> elements may be labeled by the name attribute. The <operation> element performs the function of assigning a value. The target attribute indicates that a value is assigned (updated), and the value attribute can indicate a value to update. The value attribute can be a simple C-language mathematical expression. The <if> attribute can be used to describe a conditional branch statement. The value in the condition attribute can be described in the same way as the value attribute defined in <operation>. If the value in the condition attribute is 'true', the next action to be performed may be the one labeled by the next attribute. Otherwise, the next action to be performed may be performed in a sequential order.

The bitstream parsing apparatus may provide a decoded value to the reconfigurable codec network. In each parsing state, the output of the port can be described by the <output> element, and the output port can be specified by the dest attribute. The specified output port can be defined in the parser interface declaration (<interface>). The value of the parser interface declaration (<interface>) must be described by the value attribute and can be a fixed value or a variable.

The external function call state (<plugin>) can be used to call external functions. The called function can be described by the callee attribute, and one of the values included in the list (<plugin_list>) defining the external function can be specified. Parameters for external function calls can be described by the <parameters> element. <parameters> can have several other <parameters> elements as children. Each <parameters> element has a name attribute as an identifier and may also have a value attribute that describes the actual value of the parameter. The external function call state can specify additional decoding behavior.

More than one FSM may appear in the control flow description, and individual FSMs may be called by the FSM call state (<FSM_call>). The invoked FSM can be specified by the callee attribute, and the value of callee can be the FSM defined in the current control flow description. The FSM call state may have a description of additional decoding operations.

Branch state (<branch>) can be used to move to another state depending on the condition. The branch state can include a condition attribute indicating the condition of the branch and a next attribute specifying where to go. The condition of the branch may be described with the same syntax as the value attribute of the additional decoding descriptor. The branch state can perform the additional decoding operation described in the <process> attribute, and the result can be used as the condition of the branch.

The parsing of bitstreams defined for each state may follow the priority defined in Table 2 below. Table 2 shows the processing priority for each tag.

(One) Parsing State (2) External Function Call State Precedence
Level Element Attribute Precedence
Level Element Attribute One <parsing> source One <parameter> name 2 <parsing> peek 2 <parameter> value 3 <parsing> bytealign 3 <plugin> callee 4 <parsing> bits 4 <plugin> name 5 <parsing> value 5 <operation> value 6 <parsing> expected 6 <operation> target 7 <parsing> name 7 <if> condition 8 <operation> value 8 <if> next 9 <operation> target 9 <output> value 10 <if> condition 10 <output> dest 11 <if> next 12 <output> value 13 <output> dest 14 <parsing> final (3) FSM Call State (4) Branch State One <FSM_call> <callee> One <operation> value 2 <operation> value 2 <operation> target 3 <operation> target 3 <if> condition 4 <if> condition 4 <if> next 5 <if> next 5 <branch> condition 6 <output> value 6 <branch> next 7 <output> dest

In general, reading a bitstream, calling an external function, or calling a FSM may take precedence over additional decoding operations and sending results to the output port. The condition used for the branch state may be executed after performing an additional decoding operation to update the value of the conditional statement. The final attribute, which terminates the currently running FSM, can be triggered after additional decoding operations and all results are sent to the output port.

The external function used for the control flow description may be defined in the external call function declaration unit (<plugin_list>). Table 3 below shows the elements of the external function declaration syntax.

Element Attributes  Of Children  Of Notes < plugin _ list > Top-level tag in XS-PDL external function declaration Children: <instance> * < instance > External function instance declaration tag name = " plugin _ instance _ name " Instance name prototype = " plugin _ prototype _ name " External function prototype name to be used Children: <parameters> < parameters > Parameter declaration bundle tag Children: <parameter> * < parameter > Individual Parameter Declaration Tag name = " plugin _ parameter _ name " Parameter name value = "( value | array _ value )" Parameter value (fixed value or array type)

First, the prototype for an external function that has an identifier string that can be used by the bitstream parser must be valid. Prototype functions can be instantiated by <instance> elements. One prototype can be instantiated in plural by different parameters. Each external call function can be instantiated with parameters by the <parameters> element.

Input port and output port interfaces can be declared in BSD. Table 4 below shows the elements of the interface declaration syntax.

Element Attributes  Of Children  Of Notes < interface > Top-level tag of parser interface declaration in XS-PDL Children: (<input> | <output>) * < input > Input port declaration tag name = " input _ port _ name " Port name token_type = " token _ type " Token type < output > Output port declaration tag name = " output _ port _ name " Port name token_type = " token _ type " Token type

Input ports and output ports can be defined as <input> and <output> elements, respectively. These two elements can have the same attribute structure. Each port name is defined by the name attribute, and the data type of each port can be defined by the token_type attribute. The token_type attribute is optional and can follow the format defined in the existing MPEG RMC standard.

6 is a flowchart illustrating an operation of a bitstream parsing method, according to an exemplary embodiment.

In step 610, the bitstream parsing apparatus may read bitstream syntax information for reconstruction of the parser. The bitstream syntax information may include control information related to the control flow of the parser, plug-in function information related to external function information for performing a specific function outside the parser, and interface information related to the input / output port of the parser.

In operation 620, the bitstream parsing apparatus may determine whether the bitstream syntax information is valid in order to prevent an unexpected error. For example, the bitstream parsing apparatus may determine whether there are grammatical errors and functional errors in the bitstream syntax information. The bitstream parsing apparatus may determine whether the bitstream syntax information is valid and determine whether to reconfigure the predefined parser. When an error 640 exists in the bitstream syntax information, the bitstream parsing apparatus may terminate the process without reconfiguring the parser.

In operation 630, when the bitstream syntax information is valid, the bitstream parsing apparatus may reconfigure the predefined parser based on the bitstream syntax information. The bitstream parsing apparatus may reconfigure a predefined parser based on control information, plug-in function information, and interface information extracted from the bitstream syntax information. The parser may be predefined at the design time, and the bitstream parsing apparatus may reconfigure the parser defined at the design time to generate a new parser most suitable for the bitstream parsing at runtime.

In operation 650, the bitstream parsing apparatus may parse the input bitstream using the reconstructed parser. In detail, the bitstream parsing apparatus may control the reconfigured parser so that the reconstructed parser parses the input bitstream. The bitstream parsing apparatus may control the operation of the reconfigured parser based on control information, plug-in function information, and interface information extracted from the bitstream syntax information. The bitstream parsing apparatus reconfigures the bitstream to be continuously performed until the bitstream is parsed according to the control flow included in the control information and the parsing process is completed until the control flow ends or the input bitstream ends and parsing is completed. The old parser. In addition, the bitstream parsing apparatus may control a parser reconfigured to call a plug-in function in order to use an external function required for parsing the bitstream during parsing.

7 is a flowchart illustrating a detailed operation of determining whether bitstream syntax information is valid according to an embodiment.

In operation 710, the bitstream parsing apparatus may determine whether a grammatical error exists in the bitstream syntax information. When the bitstream syntax information is written based on XML, the bitstream parsing apparatus may check a grammatical error of the bitstream syntax information using XML verification tools using an XML schema. In addition, the bitstream parsing apparatus may check not only the XML grammar but also the descriptive grammar regarding the parser configuration. When the bitstream parsing apparatus determines that the validity error 740 exists due to a grammatical error in the bitstream syntax information, the bitstream parsing apparatus may terminate without proceeding to the next step.

In operation 720, if the grammatical error does not exist in the bitstream syntax information, the bitstream parsing apparatus may determine whether a functional error exists. First, the bitstream parsing apparatus may perform functional verification of a parser interface based on interface information included in bitstream syntax information. For example, the bitstream parsing apparatus may perform functional verification of the interface by comparing the parser interface declaration with the actual input and output ports currently connected. The bitstream parsing apparatus may determine whether there is a functional error for all interfaces, and in the case where there is a functional error in the bitstream syntax information, the bitstream parsing apparatus may determine a validity error 740 and terminate the process.

In operation 730, the bitstream parsing apparatus may perform functional verification of the external function based on the plug-in function information included in the bitstream syntax information. The bitstream parsing apparatus may perform functional verification of the plug-in function by comparing an external function list with plug-in functions connected to the current parser. The bitstream parsing apparatus may determine whether there is a functional error for all external functions, and if there is a functional error in the bitstream syntax information, determine that it is a valid error 740 and terminate the process.

8 is a flowchart illustrating a detailed operation of reconfiguring a parser, according to an exemplary embodiment.

In operation 810, the bitstream parsing apparatus may configure and connect an input port and an output port of a predefined parser based on the bitstream syntax information. For example, the bitstream parsing apparatus may set an input port and an output port of a predefined parser according to a parser interface declaration included in the bitstream syntax information. The bitstream parsing device can connect the input port and the output port to the module network of the RMC framework.

In operation 820, the bitstream parsing apparatus may set a wait state for execution of an external function based on the plug-in function information. The bitstream parsing apparatus may configure a predefined parser to perform a complicated task such as entropy decoding using a predefined external function. The bitstream parsing device may prepare plug-in function instances in a predefined parser and ready to be called.

In operation 830, the bitstream parsing apparatus may load control information to control a predefined parser when a waiting state for execution of an external function is set based on the plug-in function information. The bitstream parsing apparatus may read the control flow included in the control information and induce compilation of the FSM structure. FSM structures can be compiled at runtime and translated into an immediate executable form.

9 is a flowchart illustrating a procedure of executing a reconfigured parser, according to an exemplary embodiment.

9 illustrates in detail the operation performed by the bitstream parsing apparatus after the predefined parser is reconfigured. The bitstream parsing apparatus may parse the bitstream according to the state type of each state in the control flow. For example, the bitstream parsing apparatus determines whether the state is a parsing state, an external function call state, an FSM call state, and a branch state. Can perform the operation according to the state.

The operation according to each state may be continuously performed until a value indicating the end of file (EOF) appears. The parsing process of the input bitstream may continue until the control flow ends or the input bitstream ends.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts.

Examples of computer readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine code, such as produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different manner than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims (20)

Reading bitstream syntax information for reconstruction of the parser;
Determining whether the bitstream syntax information is valid;
Reconfiguring a predefined parser based on the bitstream syntax information when the bitstream syntax information is valid; And
Parsing the input bitstream using the reconstructed parser
Including,
The reconstructing step,
Extracting control information, plug-in function information, and interface information from the bitstream syntax information;
Prepares plug-in function instances containing external function information for performing a specific function outside of the parser in a state that can be called by a controller in the predefined parser, and bitstreams the plug-in function instance. And initializing the plug-in function instance by applying the parameters shown in the syntax information, thereby setting a wait state for execution of an external function based on the plug-in function information.

delete The method of claim 1,
The control information,
A parsing state that indicates how to extract information from the input bitstream, an external function call state used to invoke an external function, an FSM call state used to invoke a finite state machine (FSM), and other states depending on the condition A bitstream parsing method comprising at least one of the branch states to jump to.
The method of claim 1,
The plug-in function information,
Bitstream parsing method comprising external function information for performing a specific function outside the parser.
The method of claim 1,
The interface information,
A bitstream parsing method comprising definitions for input ports and output ports.
The method of claim 1,
The reconstructing step,
Configuring an input port and an output port of the predefined parser based on the interface information; And
Loading the control information to control the predefined parser
Bitstream parsing method comprising a.
The method of claim 1,
The determining step,
Determining whether there is a grammatical error in the bitstream syntax information; And
Determining whether there is a functional error related to an interface and an external function in the bitstream syntax information;
Bitstream parsing method comprising a. The method of claim 1,
The predefined parser,
And at least one of an input port and an output port is variably determined based on the bitstream syntax information. The method of claim 1,
The bitstream syntax information is
Extensible Mark-up Language (XML) A bitstream parsing method written in a script-based language. A reading unit that reads bitstream syntax information for reconstruction of the parser;
A validity determination unit determining whether the bitstream syntax information is valid;
A parser reconstructing unit configured to reconstruct a predefined parser based on the bitstream syntax information when the bitstream syntax information is valid; And
A bitstream parser configured to parse the input bitstream using the reconstructed parser
Including,
The parser reconstruction unit,
Extract control information, plug-in function information, and interface information from the bitstream syntax information, and include plug-in function instances in the predefined parser including external function information for performing a specific function outside of the parser. Preparing to be called by a controller, and initializing the plug-in function instance by applying parameters indicated in bitstream syntax information to the plug-in function instance, thereby waiting for execution of an external function based on the plug-in function information. Bitstream parsing device to set up.
The method of claim 10,
The parser reconstruction unit,
And reconfiguring a predefined parser based on the control information, the plug-in function information, and the interface information extracted from the bitstream syntax information.
The method of claim 11,
The parser reconstruction unit,
Configure an input port and an output port of the predefined parser based on the interface information, and after setting a standby state for execution of an external function based on the plug-in function information, to control the predefined parser. And a bitstream parsing device for loading the control information. The method of claim 11,
The control information,
Parsing states that indicate how to extract information from the input bitstream, external function call states used to call external functions, FSM call states used to load finite state machines (FSMs), and jump to different states depending on conditions. And at least one of the branch states for the device. delete The method of claim 11,
The interface information,
Bitstream parsing device comprising definitions for input ports and output ports. The method of claim 10,
The validity determination unit,
And determining whether there is a grammatical error or a functional error in the bitstream syntax information. The method of claim 10,
The predefined parser,
And at least one of an input port and an output port is variably determined based on the bitstream syntax information. delete delete delete

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