JP2008131484A - Method and apparatus for generating random test bitstream without utilizing encoder for video codec - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for generating a random test bitstream without utilizing an encoder for video codic. <P>SOLUTION: The method includes processing for parsing a plurality of input parameters for bitstream properties according to a specified digital video codec standard, processing for checking a range of a plurality of input parameters according to the specified digital video codec standard and processing for checking the validity of the plurality of input parameters according to the specified digital video codec standard. The method includes also processing for inversely executing decoder functions according to the specified digital video codec standard, processing for generating raw bitstream data according to the specified digital video codec standard and processing for performing bitstream encapsulation of the raw bitstream data according to the specified digital video codec standard. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to random test bitstream generation for video codec device verification.

  With the progress in video processing technology, various different digital video codec standards and formats (eg, MPEG, VC1, AVS and other registered trademark technologies) are widely used in the field of home appliances. . Electronic systems and computer systems have been developed to perform the encoding and decoding of digital video data according to a specific digital video codec standard, whereby the digital video data is a video according to the specific digital video codec standard. It can be read by a decoding device.

  FIG. 1 shows a typical video digital encoding / decoding system. Raw video data is input to the encoder, and an encoded bitstream is generated as the output of the encoder. This encoded bit stream is placed in a storage medium or transmitted via streaming media (eg, the Internet, broadcast network). At the opposite receiver, this encoded bitstream needs to be decoded correctly by the decoder. The output from the decoder is raw video data, which can be input to a display device.

  In implementing a decoding function according to a specific digital video codec standard, a test and verification method has been introduced to ensure the normal operation of an electronic circuit or computer system. FIG. 2 shows a system outline of general digital video decoding verification. The encoded bit stream is input to a decoder serving as a device under testing (DUT) and a reference decoder. The reference decoder can be obtained from the respective digital video codec standard organization (or company). The DUT decoder generates a decoding result and the reference decoder generates an expected result. Then, the decoding result by the DUT decoder is compared with the expected result by the reference decoder. A comparison result summary is generated, which indicates whether the DUT decoder operates correctly as expected.

The testing and verification work is to ensure that the decoder performs its functions correctly according to a specific digital video codec standard, and is heavy but important. When performing random tests, some combinations of tests can result in invalid test cases, which is usually a waste of time and effort. However, the process of obtaining individual combinations of tests is easier because it can be generated in a simple random manner. In direct form testing, several test cases are developed according to specific digital video codec standards. However, this approach requires long working hours and high labor costs compared to random tests. Therefore, a verification method that can achieve high completeness with shorter working hours and low labor costs is required.
US Patent: US 5983022 ("System and Method For Using Profiles To Manage Data Streams For Device Verification"). US patent: US 6230295 ("Bitstream Assembler For Comprehensive Verification Of Circuits, Devices, And Systems"). US Patent: US2003 / 0172324 ("Bitstream Generation Tools For Bitstream Management System").

  Therefore, a test and verification method is devised in which a random test bit stream for generating a test and verification without using an encoder is generated by using an encoding / decoding algorithm of a digital video codec.

  As one aspect of the present invention, a method for generating a random test bitstream without using an encoder for a video codec is provided. The method includes analyzing a plurality of input parameters related to bitstream characteristics according to a particular digital video codec standard and checking a range of the plurality of input parameters according to a particular digital video codec standard. The method further includes checking the validity of the plurality of input parameters according to a particular digital video codec standard. The method also includes performing the reverse function of the decoder according to a specific digital video codec standard. The method further includes generating raw bitstream data in accordance with a particular digital video codec standard. In addition, the method includes performing bitstream encapsulation of the raw bitstream data according to a particular digital video codec standard.

  As another aspect of the present invention, an apparatus for generating a random test bitstream without using an encoder for a video codec is provided. The apparatus comprises means for analyzing a plurality of input parameters relating to bitstream characteristics according to a particular digital video codec standard and checking a range of the plurality of input parameters according to a particular digital video codec standard. The apparatus further comprises means for checking the validity of a plurality of input parameters according to a specific digital video codec standard. The apparatus also has means for performing the functions of the decoder in reverse according to a specific digital video codec standard. The apparatus further comprises means for generating raw bitstream data according to a specific digital video codec standard. The apparatus also comprises means for performing bitstream encapsulation of raw bitstream data according to a specific digital video codec standard.

As a further aspect of the present invention, there is provided an apparatus for generating a random test bitstream without using an encoder for a video codec, which operates according to the method of the first aspect.
As yet another aspect of the present invention, a computer program product in which a computer program is recorded on a computer-readable medium, the program product for generating a random test bitstream without using an encoder for a video codec I will provide a. The computer program product comprises computer program code means for analyzing input parameters relating to bitstream characteristics according to a specific digital video codec standard and checking a range of a plurality of input parameters according to a specific digital video codec standard. Furthermore, the computer program product comprises computer program code means for checking the validity of a plurality of input parameters according to a specific digital video codec standard. The computer program product also has computer program code means for performing the functions of the decoder in reverse according to a specific digital video codec standard. The computer program product further comprises computer program code means for generating raw bitstream data according to a specific digital video codec standard. The computer program product further comprises computer program code means for performing bitstream encapsulation of raw bitstream data according to a specific digital video codec standard.

According to still another aspect of the present invention, there is provided a computer program product in which a computer program for generating a random test bitstream without using an encoder for a video codec is recorded on a computer-readable medium. A computer program product that operates according to the method of one aspect is provided.
Embodiments of the present invention can be used to provide an interactive interface to test and verification methodologies by specifying the characteristics of a random test bitstream, and for various combinations of test and verification of electronic devices and computer systems, A random test bitstream can be generated with specific characteristics that are within a user-specified range.

The present invention will now be described by way of non-limiting example with reference to the accompanying drawings.
The embodiment described here should be referred to as “random test bitstream generation without using an encoder for a video codec”. In this embodiment, a plurality of input parameters are used to determine the characteristics of the generated random test bitstream according to a specific digital video codec standard.

  A number of input parameters can be used to set the characteristics of the generated random test bitstream. These include at least the random test bitstream name, the frame width, the frame height, and the number of frames. Other specific random test bitstream characteristics can also be set based on specific digital video codec standards (eg, number of slices, number of reference pictures, interlace coding mode, etc.).

The embodiments described herein can be used to generate a random test bitstream for testing and verification purposes. The generated test bitstream is essentially random, but saves time and cost because it follows specific rules determined by the specific digital video codec standard that is set. Since there is no need to develop an independent encoder for creating a random test bitstream, the test and verification time required to achieve high completeness is reduced.
(General video decoding process)
FIG. 3 is a schematic flowchart illustrating a general digital video decoding process. In general, various digital video codec standards employ different algorithms in their decoding process, but the entire digital video decoding process can usually be divided into three main processes as shown in FIG. it can.

  Parsing (S100) according to a specific digital video codec standard is performed to decode all necessary parameters for the video bitstream being processed. After parsing, parameters and coefficients are decoded (S110), where some parameters for the block coefficients and the coefficients themselves are decoded from the video bitstream. Usually, in the digital video codec standard, variable length decoding or fixed length decoding is used for decoding block coefficients. In some implementation variations, there may be differences between digital video standards, but the coefficient decoding is still done by arithmetic decoding or context-based arithmetic decoding, depending on the particular digital video codec standard. Will be executed. Also, some prediction algorithms may be performed with the goal of keeping the bit rate low by determining block coefficients using adjacent block coefficients according to that particular digital video codec standard.

Finally, after decoding all block coefficients in the picture, coefficient processing (S120) is performed according to the specific digital video codec standard applied (inverse quantization, inverse transform, intra-frame prediction, Inter-frame prediction or motion compensation, filtering, etc.). Various digital video codec standards may also use different algorithms for coefficient processing. The digital video decoding process continues until the last frame is decoded (S130). If it is not the last frame, the digital video decoding process continues and ends at the end of the decoding process as the last frame.
(Digital video decoding verification using random test bitstream)
FIG. 4 is a block diagram illustrating a digital video decoding verification system using a random test bitstream generator. Compared to FIG. 2, the random test bitstream generator (200) generates a random test bitstream to be input to the verification system. The generated random test bitstream (215,220) ensures that the digital video verification system can cover all valid test cases required based on the particular digital video codec standard implemented. Make things.

  The coverage function (205) is also used as an input to the random test bitstream generator (200) to determine what kind of coverage is required for the generated random test bitstream. Further, based on the coverage function (205) input to the random test bitstream generator (200), the generator creates a coverage result summary (210). The coverage function (205) and the coverage result summary (210) are used by the user to test whether the generated random bitstream already meets the required completeness.

  The random test bit stream (215) generated by the random test bit stream generator (200) is input to the DUT decoder (225). The same random test bit stream (220) generated by the random test bit stream generator (200) is also input to the reference decoder (230). The reference decoder (230) is a decoder with all decoding functions and produces the expected results for each input bitstream according to a specific digital video codec standard.

The decoding result (235) is generated by the DUT decoder (225), and the prediction result (240) is generated by the reference decoder (230). The decoding result comparison mechanism (245) is operated to check whether the decoding result (235) produced by the DUT decoder (225) and the prediction result (240) produced by the reference decoder (230) are the same. To do. The comparison mechanism includes comparison of decoded digital video data or comparison processing of digital video coefficient data (for example, coefficient data at the time of inverse quantization, inverse transform, motion compensation, or filtering) at each stage. included. The comparison result summary (250) is made as feedback to the user at the end of the verification system and indicates whether the subject DUT decoder is performing the decoding function correctly according to a particular digital video codec standard.
(Random test bitstream generation)
FIG. 5 is a flowchart regarding the operation when the embodiment of the present invention generates a random test bitstream without using an encoder for a video codec. First, a plurality of input parameters related to bitstream characteristics are provided (S300). The characteristics of the random test bitstream to be generated are specified by the plurality of input parameters. These include at least the random test bitstream name, the frame width, the frame height, and the number of frames. Other specific bitstream characteristics can also be realized according to the specific digital video codec standard to be implemented (eg, number of slices, interlaced coding mode, number of reference pictures, etc.).

  Next, the input parameter is checked and verified (S310). This is done to ensure that the input parameters are within a specific range and fall within the specific digital video codec standard implemented. Using the inverse decoder (S320), all syntax parameters and block coefficients are generated over the entire frame and the entire video duration. Reference is now made to FIG. For syntax analysis (S100), parameter and coefficient decoding (S110), and coefficient processing (S120), inverse processing is performed according to the input parameters to generate a valid random test bitstream. A valid raw bitstream (S330) is created at the end of the inverse decoding process (S320). Depending on the particular digital video codec standard implemented, a bitstream encapsulation process (S340) is performed on the raw bitstream (S330) to create an encapsulated bitstream (S350).

  FIG. 6 is a block diagram illustrating a modified decoder used to generate a random test bitstream without using video codec encoding. On the decoder side, there is a bit reading function unit (400) implemented for reading video bitstream parameters. The right side is an implementation of the inverse decoder (S320). The bit read function unit (400) in the decoder is replaced with a bit write function unit (410) in the inverse decoder (S320). By utilizing parameter range checking and verification, the generated parameter values are guaranteed to be valid based on a particular digital video codec standard.

  Reference is now made to FIG. The modified decoder (410) having the bit writing function performs the same function (ie, parsing (S100), parameter and coefficient decoding (S110), and coefficient processing (S120)) as a decoder. By implementing the bit write function (410) instead of the bit read function (400), the decoder is modified to produce a legitimate digital video bitstream according to a specific digital video codec standard. Yes.

  FIG. 7 is a block diagram illustrating a possible implementation of bit reading in a video decoding system. First, the number of bits to be read (S500) is provided. According to the number of bits to be read (S500), bit reading (S510) is performed according to a specific digital video codec standard that is either a little endian format or a big endian format. After the parameter value is obtained, a range check (S520) is performed to confirm that the decoded value conforms to the range specified by the digital video codec standard. The implementation of the bit read function in a digital video decoding system may vary depending on the particular digital video codec standard and system requirements.

  FIG. 8 is a block diagram illustrating a form of realization of random bit generation in the modified video decoding system used in the random test bitstream generator. First, the number of bits to be written is provided (S600). A random number generator (S610) generates a random number. The random number generator (S610) can be realized using a general method (for example, a uniform dispersion method, a non-uniform dispersion method, a linear congruence method, or the like) based on a desired complexity and a required randomness.

  The random number generator (S610) performs masking (S620) on the generated random number, and the resulting value becomes the maximum value according to the number of bits to be written (S600). However, in a specific digital video codec standard, some values that are valid according to the number of bits to be written (S600) are reserved or prohibited. Thus, a range check (S630) is performed to ensure that the generated value is within an acceptable range based on a particular digital video codec standard. Finally, a bit representing the generated value is written to generate a valid random test bit stream (S640).

  The apparatus and process of the exemplary embodiment can be implemented in a computer system (700), such as the system schematically shown in FIG. The present embodiment is implemented as software such as a computer program that is executed inside the computer system (700) and instructs the computer system (700) to execute the method of the present embodiment. .

The computer system (700) includes a computer module (701), input modules such as a keyboard (702) and a mouse (703), and a plurality of output devices such as a display (704) and a printer (705).
The computer module (701) is connected to a computer network (706) via an appropriate receiving device (707), so that it can be connected to, for example, the Internet or other network systems (eg local area network (LAN), wide area network). Area network (WAN)) can be accessed.

  The computer module (701) of this example includes a processor (708), a random access memory (RAM) (709), and a read only memory (ROM) (710). The computer module (701) also includes a number of input / output (I / O) interfaces (eg, an I / O interface (711) to a display (704), an I / O interface (712) to a keyboard (702), a mouse An I / O interface (715) to (703) and an I / O interface (716) to the printer (705). The keyboard (702) and mouse (703) are used by the user, for example, for the purpose of specifying random test bitstream characteristics according to the particular digital video codec standard implemented.

The components of the computer module (701) typically communicate via the interconnection bus (713) in a manner known to those skilled in the art.
The application program is usually encoded on a data storage medium such as a CD-ROM or a floppy (registered trademark) disk and provided to the user of the computer system (700), and the data storage medium drive corresponding to the data storage device (714) Is read out using. The application program is read and controlled by the processor (708) in its execution. The intermediate storage of program data may be realized using the RAM (709).
(The invention's effect)
The method and apparatus for generating a random test bitstream without using an encoder for a video codec uses a plurality of input parameters. Random test bitstream generation that does not utilize an encoder for a video codec can significantly reduce test and verification time because it eliminates the need for encoder development. By testing the decoder (device under test) using random test bitstream generation, it can be adapted to a specific digital video codec standard. Short testing and verification times also reduce costs. This eliminates the need for property testing and verification tools. Further, since a random value is generated for each of the parameters according to a specific digital video codec standard, high completeness can be achieved.

  The above embodiment has been described in relation to the generation of a random test bitstream without using an encoder for a video codec. However, the described process generates a random test bitstream without the use of an encoder with other purposes (eg, image encoding / decoding, communication transmitter / receiver, and compression / decompression). Could also be used for this purpose. This can be easily understood by those skilled in the art.

  As described above, a method and apparatus for generating a random test bitstream without using an encoder for a video codec is disclosed. Although only some embodiments have been described, it will be apparent to those skilled in the art that many changes and modifications can be made without departing from the scope of the invention, provided that the disclosure of the document is viewed.

1 is a diagram illustrating a general digital video encoding / decoding system. FIG. It is a figure which shows the outline of the general system of digital video decoding verification. It is a flowchart which shows a normal digital video decoding process. 1 is a block diagram illustrating a digital video decoding verification system that uses a random test bitstream generator. FIG. It is a flowchart which shows the random test bit stream production | generation process which does not use an encoder. FIG. 5 is a block diagram illustrating a modified decoder used in a random test bitstream generator. FIG. 6 is a block diagram illustrating a possible implementation of bit reading in a video decoding system. FIG. 2 is a block diagram illustrating an embodiment of a modified video decoding system used in a random test bitstream generator. FIG. 2 illustrates a computer system for performing apparatus and processes in accordance with an exemplary embodiment.

Claims (31)

A method for generating a random test bitstream without using an encoder for a video codec,
(A) analyzing a plurality of input parameters related to bitstream characteristics according to a particular digital video codec standard;
(B) checking a range of the plurality of input parameters according to a particular digital video codec standard;
(C) checking the validity of a plurality of input parameters according to a particular digital video codec standard;
(D) performing the function of the decoder in reverse according to a specific digital video codec standard;
(E) generating raw bitstream data according to a specific digital video codec standard; and
(F) performing bitstream encapsulation of the raw bitstream data according to a particular digital video codec standard;
A method characterized by comprising: The step of analyzing the plurality of input parameters related to the bitstream characteristics according to the specific digital video codec standard includes a process of analyzing the plurality of input parameters indicating characteristics of the random test bitstream to be generated according to the specific digital video codec standard. Included,
The method of claim 1, wherein: The steps of analyzing a plurality of input parameters relating to bitstream characteristics according to a specific digital video codec standard include at least a random test bitstream name, a random test bitstream frame width, a random test bitstream frame height, and a total number of random test bitstream frames. Includes processing to parse the fixed bitstream syntax elements,
The method according to claim 2. The random test bitstream name is a name of a random test bitstream to be generated,
The method according to claim 3. The random test bitstream frame width is a frame width of a random test bitstream to be generated;
The method according to claim 3. The random test bitstream frame height is a frame height of a random test bitstream to be generated;
The method according to claim 3. The total number of random test bitstream frames is the total number of intraframes and interframes of the random test bitstream to be generated;
The method according to claim 3. The additional analysis step of multiple input parameters for bitstream characteristics based on a specific digital video codec standard may include additional input file or configuration file analysis processing,
The method according to claim 2. The additional parsing of multiple input parameters for bitstream characteristics based on a particular digital video codec standard includes the parsing of multiple input arguments via command line parameters;
The method according to claim 2. The additional parsing of multiple input parameters for bitstream properties based on a particular digital video codec standard includes interactive parsing of multiple input arguments via a graphic user interface;
The method according to claim 2. The step of checking a set value range of a plurality of input parameters based on a specific digital video codec standard includes a process of checking a minimum value of input parameters based on a specific digital video codec standard;
The method of claim 1, wherein: The step of checking a set value range of a plurality of input parameters based on a specific digital video codec standard includes a process of checking a maximum value of input parameters based on a specific digital video codec standard;
The method of claim 1, wherein: The step of checking a set value range of a plurality of input parameters based on a specific digital video codec standard includes a process of checking a range of values between a maximum value and a minimum value of input parameters based on a specific digital video codec standard. Is included,
The method of claim 1, wherein: Checking the validity of a plurality of input parameters based on a specific digital video codec standard includes the process of checking for the presence of input parameters based on a specific digital video standard;
The method of claim 1, wherein: The step of checking a range of a plurality of input parameters according to a specific digital video codec standard and the step of checking the validity of the plurality of input parameters include a dependency of one input parameter on another input parameter. Including a process to check,
15. A method according to any of claims 2 to 14, characterized in that Reversing the functions of the decoder according to a specific digital video codec standard includes the process of replacing the bitstream parsing function with the bitstream configuration function in the decoder to obtain the bitstream syntax parameters;
The method of claim 1, wherein: The process of replacing the bitstream analysis function with the bitstream configuration function in the decoder includes generating a candidate number and changing the candidate number according to the word width of the candidate number defined according to a specific digital video codec standard. Including masking, checking a range of values, and writing the candidate number to obtain a bitstream syntax parameter;
The method according to claim 16. The process of generating the number of candidates includes a process of creating a random number, or a process of copying a predetermined constant from the additional file or the configuration file.
The method of claim 17, wherein: The step of reversing the function of the decoder in accordance with a specific digital video codec standard includes the process of replacing the bitstream parsing function with a bitstream configuration function in the decoder to obtain a bitstream syntax parameter, and the bitstream syntax parameter And a process of obtaining a parameter after decoding, and a process of obtaining a parameter after processing by processing the parameter after decoding,
The method of claim 1, wherein: In the process of replacing the bitstream analysis function with the bitstream configuration function in the decoder, a process for generating the number of candidates and the number of candidates according to the word width of the number of candidates defined by a specific digital video codec standard are used. A masking process, a process of checking a value range to provide a presentation bit indicating the validity of the value range, and if the presentation bit indicates a valid value range, the candidate number is written Processing to obtain a bitstream syntax parameter at, while updating the number of candidates if the presentation bit indicates a range of invalid values,
The method according to claim 19. Generating raw bitstream data in accordance with a particular digital video codec standard includes generating a valid digital video bitstream in accordance with the particular digital video codec standard;
The method of claim 1, wherein: The step of generating raw bitstream data according to a specific digital video codec standard includes the step of checking a range of a plurality of input parameters according to a specific digital video codec standard, and within an inverse decoder according to a specific digital video codec standard Including the step of checking the validity of a plurality of input parameters at
The method of claim 1, wherein: The step of performing bitstream encapsulation of the raw bitstream data according to a specific digital video codec standard is to insert a plurality of bytes into the bitstream so that a start code within the digital video bitstream according to the specific digital video codec standard Including processing to prevent emulation, long “0” sequences, or long “1” sequences from occurring,
The method of claim 1, wherein: A method for generating a random test bitstream without using an encoder for a video codec;
24. A method according to any one of claims 1 to 23.   A method for generating a random test bitstream without using an encoder for a video codec, substantially as described above, with reference to the accompanying drawings or as illustrated therein Method. An apparatus for generating a random test bitstream without using an encoder for a video codec,
Means for analyzing a plurality of input parameters relating to bitstream characteristics according to a particular digital video codec standard;
Means for checking a range of multiple input parameters according to a particular digital video codec standard;
Means for checking the validity of multiple input parameters according to a specific digital video codec standard;
Means for performing the functions of the decoder in reverse according to a specific digital video codec standard;
Means for generating raw bitstream data according to a specific digital video codec standard;
Means for performing bitstream encapsulation of raw bitstream data in accordance with a particular digital video codec standard;
A device characterized by comprising:   26. An apparatus operating according to the method of any of claims 1-25. Operating according to the method of any of claims 1 to 27;
27. The apparatus of claim 26.   An apparatus for generating a random test bitstream without using an encoder for a video codec, which is configured so as to substantially operate with reference to the accompanying drawings or in the manner shown in the drawings so far And said device arranged. A computer program product for recording a computer program on a computer readable medium for generating a random test bitstream without using an encoder for a video codec,
Computer program code means for analyzing input parameters relating to bitstream characteristics according to a particular digital video codec standard;
Computer program code means for checking a range of a plurality of input parameters according to a particular digital video codec standard;
Computer program code means for checking the validity of a plurality of input parameters in accordance with a particular digital video codec standard;
Computer program code means for performing the functions of the decoder in reverse according to a particular digital video codec standard;
Computer program code means for generating raw bitstream data in accordance with a particular digital video codec standard; and
Computer program code means for performing bitstream encapsulation of raw bitstream data in accordance with a particular digital video codec standard;
A computer program product comprising:   27. A computer program product in which a computer program operating according to the method of any one of claims 1 to 26 is recorded on a computer readable medium for generating a random test bitstream without using an encoder for a video codec.

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