JP4447903B2 - Signal processing apparatus, signal processing method, recording medium, and program - Google Patents

Description

  The present invention relates to a signal processing device, a signal processing method, a recording medium, and a program, and is particularly suitable for use in a variable length encoding device that compresses and encodes still images and moving images.

  2. Description of the Related Art Conventionally, a method using entropy coding technology using run length / category coding and variable length coding is well known as part of compression coding technology for still images and moving images. This technique is also adopted in the JPEG (Joint Photographic Expert Group) encoding system and the MPEG-1 / -2 (Moving Picture Experts Group) encoding system, which are international standards. In these encoding methods, the variable length encoding event is a two-dimensional event called run length and level, and entropy encoding is realized by assigning a Huffman code to the two-dimensional event. ing. The two-dimensional event of run length and level is referred to as symbol data.

  Further, as a technique that has been attracting attention and used in a recent moving picture compression coding technique, there is a technique that assigns a Huffman code to a three-dimensional event. This technology has already been described in ITU-T Recommendation H.264. It is standardized by an encoding method called H.263 or MPEG-4.

  As the three-dimensional event, in addition to the run length and level used in the two-dimensional encoding method, what is called the last is considered. Here, the last indicates whether or not it is the last significant coefficient in a DCT (Discrete Cosine Transform) block. For this reason, even with the same run length and level value, the assigned Huffman code differs depending on whether or not it is the last significant coefficient in the DCT block. The run length, level and last three-dimensional events are also referred to as symbol data.

In the MPEG-4 encoding system, when a Huffman code corresponding to symbol data does not exist in a predetermined Huffman code table, a fixed-length code called an escape is assigned. The same applies to the MPEG-1 / -2 encoding method.
However, in the MPEG-4 encoding method, when the Huffman code corresponding to the symbol data does not exist in the Huffman code table, the maximum level existing in the Huffman code table is first determined from the value of the symbol data level. The Huffman code table is searched again using the symbol data obtained by subtracting the value as new symbol data.

  If the Huffman code corresponding to the symbol data exists in the Huffman code table as a result of the search, the corresponding Huffman code is assigned. On the other hand, if the Huffman code corresponding to the symbol data does not exist in the Huffman code table, symbol data obtained by further subtracting the maximum run length + 1 value existing in the Huffman code table from the run length value is newly added. As the symbol data, the Huffman code table is searched again. As a result of the search, if a Huffman code corresponding to the symbol data exists in the Huffman code table, the corresponding Huffman code is assigned, and if not, a fixed length code is assigned.

FIG. 6 shows the configuration of a conventional variable length coding apparatus corresponding to the MPEG-4 coding system.
Symbol data representing the above-described RUN (run length), LEVEL (level), and LAST (last) is input to the variable length coding apparatus shown in FIG.

  The level subtracting unit 100 outputs LEVEL + obtained by subtracting the maximum LEVEL (LMAX) value existing in the Huffman code table from the LEVEL value constituting the symbol data. The run-length subtraction unit 102 outputs RUN + obtained by subtracting the maximum RUN + 1 (RMAX + 1) value existing in the Huffman code table from the RUN value constituting the symbol data. The fixed length encoder 107 performs fixed length encoding on RUN, LEVEL, and LAST according to a predetermined format, and outputs the obtained fixed length code.

  First, in the first cycle, the control unit 108 controls the selectors 104 and 105 and inputs RUN, LEVEL, and LAST to the Huffman table 106. When Huffman codewords corresponding to the input RUN, LEVEL, and LAST are present in the Huffman table 106, the control unit 108 controls the selector 109 and the output control unit 110 to obtain the corresponding Huffman code. Output.

  On the other hand, if the Huffman code word corresponding to the RUN, LEVEL, and LAST input in the first cycle does not exist in the Huffman table 106, the control unit 108 causes the selectors 104 and 105 to operate in the second cycle. Control and input RUN, LEVEL +, and LAST to Huffman table 106. When the Huffman code word corresponding to the input RUN, LEVEL +, and LAST exists in the Huffman table 106, the control unit 108 controls the selector 109 and the output control unit 110 to change the Huffman code to the corresponding Huffman code. ESCAPE (escape) code “00000110” is added and output.

  When the Huffman code word corresponding to RUN, LEVEL +, and LAST input in the second cycle does not exist in the Huffman table 106, the control unit 108 controls the selectors 104 and 105 in the third cycle. RUN +, LEVEL, and LAST are input to the Huffman table 106. When the Huffman code word corresponding to the input RUN +, LEVEL, and LAST exists in the Huffman table 106, the control unit 108 controls the selector 109 and the output control unit 110 to change the Huffman code to the corresponding Huffman code. ESCAPE code “000001110” is added and output.

  When the Huffman code word corresponding to RUN +, LEVEL, and LAST input in the third cycle does not exist in the Huffman table 106, the control unit 108 controls the selector 109 and the output control unit 110, The ESCAPE code “000001111” is added to the fixed length code from the fixed length encoder 107 and output.

  In the conventional variable length coding apparatus shown in FIG. 6 described above, one symbol data is used when there is no Huffman code corresponding to RUN, LEVEL, or LAST input to the variable length coding apparatus. There is a problem that it takes two or more cycles for the encoding process.

FIG. 7 shows the configuration of a conventional variable length coding apparatus that solves this problem. The variable-length encoding apparatus shown in FIG. 7 encodes one symbol data in one cycle, and has three Huffman tables 204, 205, and 206.
The level subtracting unit 200 and the run length subtracting unit 202 have the same functions as the level subtracting unit 100 and the run length subtracting unit 102 shown in FIG.

  The first Huffman table 204 searches for Huffman codewords corresponding to RUN, LEVEL, and LAST, and outputs any Huffman codewords. The second Huffman table 205 searches for Huffman codewords corresponding to RUN, LEVEL +, and LAST, and outputs any Huffman codewords. The third Huffman table 206 searches for Huffman codewords corresponding to RUN +, LEVEL, and LAST, and outputs any Huffman codewords.

The fixed length encoder 207 performs fixed length encoding on RUN, LEVEL, and LAST in a predetermined format, and outputs the obtained fixed length code.
The control unit 208 controls the selector 209 according to the search results of the Huffman tables 204 to 206, and selects one of the outputs of the Huffman tables 204 to 206 and the fixed length encoder 107. Select to output.

  That is, the variable-length encoding apparatus shown in FIG. 7 performs the processing that was sequentially performed for each cycle in the variable-length encoding apparatus shown in FIG. 6 using the three Huffman tables 204 to 206 at the same time. Thus, one symbol data is encoded in one cycle. There is Non-Patent Document 1 as a reference for the above contents.

ISO 14496-2

  However, the conventional variable-length encoding apparatus shown in FIG. 7 that encodes one symbol data in one cycle needs to include three Huffman tables 204 to 206, which increases the circuit scale. There's a problem. Further, as described in the conventional variable length coding apparatus shown in FIG. 6, when the variable length coding apparatus is configured using only one Huffman table 106, one symbol data is coded. There is a problem that the processing may take two or more cycles.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a signal processing apparatus capable of executing variable-length encoding processing at high speed with a small circuit scale.

According to the signal processing device of the present invention, in accordance with a variable length coding table storing variable length coded data corresponding to a combination of two input values to be input, and the first data constituting the symbol data, First subtraction means for subtracting a predetermined constant from second data constituting the symbol data different from the first data; and a predetermined subtraction from the first data according to the second data A second subtracting means for subtracting a constant; a combination of the first data and the second data; a combination of the first data and the output of the first subtracting means; and the second data. And the output of the second subtracting means, whether or not the corresponding variable length encoded data exists in the variable length encoding table is determined according to the input value in the combination and the input value. A determination unit that determines by comparing the magnitude relationship with a constant in parallel, and the input of the variable length coding table according to a determination result by the determination unit, the first data or the second Control means for selecting one of the outputs of the subtracting means and selecting one of the outputs of the second data or the first subtracting means.
In addition, the signal processing apparatus of the present invention includes a variable length coding table storing variable length coded data corresponding to a combination of three input values to be input, the first data constituting the symbol data, and the above-mentioned First subtracting means for subtracting a predetermined constant from second data constituting the symbol data different from the first data in response to third data different from the first data; Second subtraction means for subtracting a predetermined constant from the first data according to the second data and the third data, the first data, the second data, and the third data, A combination of the first data, the output of the first subtracting means, and the third data, and the second data, the output of the second subtracting means, and the third data. About combinations Whether or not variable-length encoded data to be present exists in the variable-length encoding table is determined by comparing in parallel the magnitude relationship between the input value in the combination and a predetermined constant corresponding to the input value. And selecting one of the first data and the output of the second subtracting means as the input of the variable length coding table according to the determination result by the determining means and the determination result by the determining means, And control means for selecting one of data and an output of the first subtracting means.
According to the signal processing method of the present invention, a first constant that subtracts a predetermined constant from the second data constituting the symbol data different from the first data in accordance with the first data constituting the symbol data. Subtracting step, a second subtracting step of subtracting a predetermined constant from the first data according to the second data, a combination of the first data and the second data, Corresponding variable length encoded data is input for the combination of the first data and the output in the first subtraction step, and the combination of the second data and the output in the second subtraction step. Whether or not the variable-length encoded data corresponding to the combination of two input values exists in the variable-length encoding table is determined by the magnitude of the input value in the combination and a predetermined constant corresponding to the input value. Relationship In accordance with the determination step that is determined by comparing in a row and the determination result in the determination step, the first data or the output in the second subtraction step is input as the variable length coding table. And a control step of selecting one of the second data and the output in the first subtraction step.
Further, the signal processing method of the present invention performs the symbol data different from the first data in accordance with the first data constituting the symbol data and the third data different from the first data. A first subtracting step for subtracting a predetermined constant from the second data to be configured; and a second subtracting a predetermined constant from the first data according to the second data and the third data. A combination of the subtraction step, the first data, the second data, and the third data, the first data, the output of the first subtraction step, and the third data, And, for the combination of the second data, the output in the second subtraction step, and the third data, the corresponding variable length encoded data has a variable length corresponding to the combination of three input values that are input. Encoded data is case A determination step of determining whether or not the variable length coding table is present by comparing in parallel the magnitude relationship between the input value in the combination and a predetermined constant according to the input value; and Depending on the determination result in the determination step, either the first data or the output in the second subtraction step is selected as the input of the variable length coding table, and the second data or the second And a control step for selecting one of the outputs in one subtraction step.
The program according to the present invention includes a first subtraction for subtracting a predetermined constant from the second data constituting the symbol data different from the first data in accordance with the first data constituting the symbol data. A step of subtracting a predetermined constant from the first data in accordance with the second data, a combination of the first data and the second data, the first data Two input values to which the variable length encoded data corresponding to the combination of the data and the output of the first subtraction step and the combination of the second data and the output of the second subtraction step are input Whether or not the variable-length encoded data corresponding to the combination exists in the variable-length encoding table storing the input value in the combination and a predetermined constant corresponding to the input value. A determination step for determining by comparing small relations in parallel, and an input to the variable length coding table according to a determination result in the determination step, the first data or the second subtraction step One of the outputs is selected, and the control step of selecting one of the second data or the output of the first subtraction step is executed by the computer.
The program of the present invention forms the symbol data different from the first data according to the first data constituting the symbol data and the third data different from the first data. A first subtracting step of subtracting a predetermined constant from the second data; and a second subtracting step of subtracting the predetermined constant from the first data according to the second data and the third data. A combination of the first data, the second data, and the third data, a combination of the first data, the output of the first subtraction step, and the third data, and the first data Variable length coding corresponding to a combination of three input values to which the corresponding variable length coded data is a combination of the data of 2 and the output of the second subtraction step and the third data The determination is made by comparing in parallel the magnitude relationship between the input value in the above combination and a predetermined constant corresponding to the input value. In accordance with the determination result in the step and the determination step, one of the first data and the output of the second subtraction step is selected as the input of the variable length coding table, and the second data Alternatively, the control step of selecting one of the outputs of the first subtraction step is executed by a computer.
The computer-readable recording medium of the present invention records the above program.

  According to the present invention, for different combinations of inputs, it is determined in parallel whether or not corresponding variable-length encoded data exists in the variable-length encoding table, and the variable-length encoding table is determined according to the determination result. The input to is appropriately selected. As a result, the encoding process can be performed in a short time, and it is not necessary to provide a variable length encoding table for each combination of inputs, and the variable length encoding process can be executed at high speed with a small circuit scale.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration example of a variable length coding device to which a signal processing device according to an embodiment of the present invention is applied. In FIG. 1, a variable-length encoding device corresponding to the MPEG-4 encoding method is shown as an example. Further, in the following description, in order to make the description easy to understand, the description will be made with the AC coefficient coding for the intra / macroblocks, but the present invention is not limited to this.

  The variable length coding apparatus according to the present embodiment includes a level subtraction unit 11, a run length subtraction unit 13, a Huffman code determination unit 14, 15, 16, a fixed length coding unit 17, a control unit 18, and selectors 10, 12, 19 , 20, 22, Huffman table 21, and escape code connecting portion 23.

  When a RUN (run length), a LEVEL (level), and a LAST (last) constituting symbol data are input, the variable length coding apparatus executes processing described below. Here, RUN represents the number of consecutive zero coefficients in the DCT block, LEVEL represents a non-zero coefficient (non-zero coefficient, significant coefficient) in the DCT block, and LAST represents the DCT block. Represents the last non-zero coefficient.

  The selector 10 receives RUN and LAST, and outputs LMAX according to the value of RUN and the value of LAST. Here, LMAX is the maximum value of LEVEL corresponding to the input RUN value and LAST value, and is stored in the LMAX table 24 of FIG. 1, and is input as shown in FIG. The value of LMAX is determined according to the value of.

  The level subtracting unit 11 subtracts the LMAX value output from the selector 10 from the input LEVEL value, and outputs an operation result LEVEL +. That is, the level subtracting unit 11 subtracts the LMAX value determined according to the RUN and LAST values from the LEVEL, and outputs LEVEL +.

  The selector 12 receives LEVEL and LAST, and outputs a value (RMAX + 1) obtained by adding 1 to RMAX according to the value of LEVEL and the value of LAST. Here, RMAX is the maximum value of RUN corresponding to the inputted LEVEL value and LAST value, and is stored in the RMAX table 25 of FIG. 1, and is inputted as shown in FIG. The value of RMAX is determined according to the value of.

  The run-length subtracting unit 13 subtracts the RMAX + 1 value output from the selector 12 from the input RUN value, and outputs the result RUN +. That is, the run length subtraction unit 13 subtracts a value obtained by adding 1 to the RMAX value determined according to the LEVEL and LAST values from the RUN, and outputs RUN +.

  RUN, LEVEL, and LAST are input to the first Huffman code determiner 14. The second Huffman code determiner 15 receives RUN, LEVEL +, and LAST. The third Huffman code determiner 16 receives RUN +, LEVEL, and LAST.

  The Huffman code determiners 14 to 16 determine whether there is a Huffman code corresponding to the input symbol data, and output “1” to the control unit 18 when it is determined that the Huffman code exists. If it is determined that it does not exist, “0” is output to the control unit 18. The determination by the Huffman code determiners 14 to 16 is performed in parallel in the same clock cycle (within one cycle). Note that the Huffman code determiners 14 to 16 only determine the presence or absence of a Huffman code corresponding to the input symbol data, and do not output the Huffman code itself.

Here, a method for determining whether or not there is a Huffman code corresponding to the input symbol data will be described using the first Huffman code determiner 14 as an example.
The Huffman code determination unit 14 refers to the correspondence relationship (LMAX table 24) shown in FIG. 2 and extracts the maximum LEVEL value LMAX corresponding to the LAST and RUN values input to itself. Further, the Huffman code determiner 14 compares the input LEVEL value with the LMAX value, and determines that a Huffman code exists if LEVEL ≦ LMAX, and determines that no Huffman code exists otherwise. To do.

  For example, when LAST = 0, RUN = 3, and LEVEL = 2 are input, since the value of LMAX corresponding to LAST = 0 and RUN = 3 is 4 from FIG. 2, LAST = 0, RUN = 3, It can be seen that there is a Huffman code corresponding to LEVEL = 2. In the above description, the correspondence relationship shown in FIG. 2 is referred to, but the presence or absence of the Huffman code may be determined with reference to the correspondence relationship (RMAX table 25) shown in FIG.

  Thus, the Huffman code determiners 14 to 16 can determine whether or not there is a Huffman code corresponding to the input symbol data based on the correspondence shown in FIG. 2 or FIG. There is no need to have a Huffman table in the code determiners 14 to 16, and it can be implemented by a relatively small circuit.

  The selector 19 selects and outputs either LEVEL or LEVEL + based on an instruction from the control unit 18. Similarly, the selector 20 selects and outputs either RUN or RUN + based on an instruction from the control unit 18.

  The Huffman table 21 includes ISO / IEC 14496-2 Annex. B. Intra macroblock table B.B. All 16 Huffman codewords are stored hardwired. The Huffman table 21 receives the output of the selector 19 (LEVEL or LEVEL +), the output of the selector 20 (RUN or RUN +), and LAST, and the Huffman corresponding to the outputs of the selectors 19 and 20 and LAST. The code VLC is output.

  When there is no Huffman code corresponding to the symbol data (LEVEL or LEVEL +, RUN or RUN +, LAST), the Huffman table 21 outputs “0”. At this time, as will be described later, the selector 22 selects the output data (fixed length code) FLC of the fixed length encoder 17 as an output to the outside of the variable length encoding device in accordance with an instruction from the control unit 18. The “0” data output from the Huffman table 21 is not output to the outside.

  The fixed-length encoder 17 uses the fixed-length code table shown in FIG. 4 for the input RUN, LEVEL, and LAST, and outputs the fixed-length code FLC of the bit lane shown in FIG. In the RUN field of the fixed-length code FLC shown in FIG. 5, a code corresponding to the value of the inputted RUN is input according to the fixed-length code table shown in FIG. Similarly, a code corresponding to the input LEVEL value is input to the LEVEL field according to the fixed-length code table.

The selector 22 selects either the Huffman code VLC that is output data of the Huffman table 21 or the fixed length code FLC that is output data of the fixed length encoder 17 based on an instruction from the control unit 18. Output.
Based on an instruction from the control unit 18, the escape code linking unit 23 outputs the output data of the selector 22 as it is to the outside of the variable length encoding device or outputs a predetermined ESCAPE (escape) code of the output encoded data. Output at the beginning.

The control part 18 performs the process demonstrated below based on the determination result of the Huffman code | symbol determination devices 14-16.
(1) When the output of the first Huffman code determiner 14 is “1” The control unit 18 outputs “1” (the Huffman code corresponding to RUN, LEVEL, and LAST is the output of the first Huffman code determiner 14). If it exists, the selector 19 selects LEVEL, and the selector 20 outputs an instruction to select RUN. As a result, RUN, LEVEL, and LAST are input to the Huffman table 21.

Further, the control unit 18 outputs an instruction to the selector 22 to select the output data VLC of the Huffman table 21. In addition, an instruction to output the output data of the selector 22 as it is to the outside of the variable length encoding device is output to the escape code connecting unit 23.
Therefore, when the output of the first Huffman code determination unit 14 is “1”, the Huffman code VLC corresponding to RUN, LEVEL, and LAST is output to the outside of the variable length encoding device.

(2) When the output of the first Huffman code determiner 14 is “0” and the output of the second Huffman code determiner 15 is “1”, the control unit 18 outputs the first Huffman code determiner 14 Is '0' (the Huffman code corresponding to RUN, LEVEL, and LAST does not exist), and the output of the second Huffman code determination unit 15 is '1' (the Huffman code corresponding to RUN, LEVEL +, LAST exists) In the case of (Yes), the selector 19 selects LEVEL +, and the selector 20 outputs an instruction to select RUN. As a result, RUN, LEVEL +, and LAST are input to the Huffman table 21.

Further, the control unit 18 outputs an instruction to the selector 22 to select the output data VLC of the Huffman table 21. Further, the ESCAPE code “00000110” is concatenated to the head of the output data of the selector 22 to the escape code concatenation unit 23, and an instruction to output to the outside of the variable length coding apparatus is output.
Accordingly, when the output of the first Huffman code determiner 14 is “0” and the output of the second Huffman code determiner 15 is “1”, the RUN with the ESCAPE code “00000110” added at the head is provided. , LEVEL +, LAST corresponding to the Huffman code VLC is output to the outside of the variable length coding apparatus.

(3) When the outputs of the first and second Huffman code determiners 14 and 15 are “0” and the output of the third Huffman code determiner 16 is “1”, the control unit 18 performs the first Huffman code. The output of the determiner 14 is “0”, the output of the second Huffman code determiner 15 is “0” (the Huffman code corresponding to RUN, LEVEL +, LAST does not exist), and the third Huffman When the output of the code determination unit 16 is “1” (Huffman codes corresponding to RUN +, LEVEL, and LAST exist), the selector 19 selects LEVEL and the selector 20 selects RUN +. The instruction to be output is output. As a result, RUN +, LEVEL, and LAST are input to the Huffman table 21.

Further, the control unit 18 outputs an instruction to the selector 22 to select the output data VLC of the Huffman table 21. Also, the ESCAPE code “000001110” is concatenated to the head of the output data of the selector 22 to the escape code concatenation unit 23, and an instruction to output to the outside of the variable length coding apparatus is output.
Therefore, when the outputs of the first and second Huffman code determiners 14 and 15 are “0” and the output of the third Huffman code determiner 16 is “1”, the ESCAPE code “000001110” is placed at the head. The added Huffman code VLC corresponding to RUN +, LEVEL, and LAST is output to the outside of the variable length coding apparatus.

(4) When the outputs of the first to third Huffman code determiners 14 to 16 are “0”, the control unit 18 outputs the first Huffman code determiner 14 to “0” and the second Select if the output of the Huffman code determiner 15 is '0' and the output of the third Huffman code determiner 16 is '0' (there is no Huffman code corresponding to RUN +, LEVEL, or LAST) An instruction to select the output data FLC of the fixed length encoder 17 is output to the unit 22. Furthermore, the control unit 18 outputs an instruction to connect the ESCAPE code “000001111” to the head of the output data of the selector 22 and output it to the outside of the variable length encoding device to the escape code connecting unit 23.
Therefore, when the outputs of the first to third Huffman code determiners 14 to 16 are “0”, the fixed-length code FLC based on RUN, LEVEL, and LAST with ESCAPE code “000001111” added to the head is generated. It is output outside the variable length coding device.

As described above, according to the present embodiment, the Huffman code determination units 14 to 16 to which different symbol data are input are provided, and whether or not there is a Huffman code corresponding to the input symbol data. Are determined by the Huffman code determiners 14 to 16 and the encoding process is executed by one Huffman table 21 based on the determination result.
This determines in parallel whether there is a Huffman code corresponding to the symbol data (RUN, LEVEL, LAST), symbol data (RUN, LEVEL +, LAST) and symbol data (RUN +, LEVEL, LAST). Therefore, since variable length coding can be performed in one cycle, encoding can be performed at a higher speed than the conventional variable length coding apparatus as shown in FIG. Since the long encoding device only needs to have one Huffman table, encoding can be executed with a smaller circuit than the conventional variable length encoding device as shown in FIG. That is, variable length coding can be executed at high speed with a small circuit scale.

  In the above embodiment, the encoding method in the three-dimensional event of RUN, LEVEL, and LAST is described. However, the present invention is not limited to this, and the encoding in the two-dimensional event of RUN and LEVEL is performed. The method can also be applied. When applied to a two-dimensional event encoding method, the correspondence between RUN and LMAX and LEVEL and RMAX is defined in the same manner as in the above embodiment, and the encoding process is performed assuming that there is no LAST in the above embodiment. Should be done.

(Other embodiments of the present invention)
In order to operate various devices in order to realize the functions of the above-described embodiments, a program code of software for realizing the functions of the above-described embodiments is provided to an apparatus connected to the various devices or a computer in the system. What is implemented by operating the various devices according to a program supplied and stored in a computer (CPU or MPU) of the system or apparatus is also included in the scope of the present invention.
In this case, the program code of the software itself realizes the functions of the above-described embodiments, and the program code itself constitutes the present invention. Further, means for supplying the program code to the computer, for example, a recording medium storing the program code constitutes the present invention. As a recording medium for storing the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.
Further, by executing the program code supplied by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) or other application software in which the program code is running on the computer, etc. It goes without saying that the program code is also included in the embodiment of the present invention even when the functions of the above-described embodiment are realized in cooperation with the embodiment.
Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the CPU provided in the function expansion board or function expansion unit based on the instruction of the program code Needless to say, the present invention includes a case where the functions of the above-described embodiment are realized by performing part or all of the actual processing.

For example, the signal processing apparatus shown in the above embodiment has a computer function 800 as shown in FIG. 8, and the CPU 801 performs the operation in the above embodiment.
As shown in FIG. 8, the computer function 800 includes a CPU 801, a ROM 802, a RAM 803, a keyboard controller (KBC) 805 of a keyboard (KB) 809, and a CRT controller (CRT) 810 serving as a display unit (CRT controller 810). A configuration in which a CRTC) 806, a hard disk (HD) 811 and a disk controller (DKC) 807 of a flexible disk (FD) 812, and a network interface card (NIC) 808 are connected to each other via a system bus 804. It is said.
The CPU 801 generally controls each component connected to the system bus 804 by executing software stored in the ROM 802 or the HD 811 or software supplied from the FD 812.
That is, the CPU 801 reads out from the ROM 802, the HD 811, or the FD 812 and executes a processing program for performing the above-described operation, thereby performing control for realizing the operation in the above-described embodiment.
The RAM 803 functions as a main memory or work area for the CPU 801.
The KBC 805 controls an instruction input from the KB 809 or a pointing device (not shown).
The CRTC 806 controls the display of the CRT 810.
The DKC 807 controls access to the HD 811 and the FD 812 that store a boot program, various applications, user files, a network management program, the processing program in the embodiment, and the like.
The NIC 808 exchanges data with other devices on the network 813 in both directions.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

It is a block diagram which shows the structural example of the variable length coding apparatus to which the signal processing apparatus by embodiment of this invention is applied. It is a figure which shows an example of the correspondence of the value of last and run length, and the maximum value of a level in this embodiment. It is a figure which shows an example of the correspondence of the last and level value in this embodiment, and the maximum value of run length. It is a figure which shows the fixed length code table in this embodiment. It is a figure which shows the bit lane of the fixed length code in this embodiment. It is a block diagram which shows the structure of the conventional variable length coding apparatus. It is a block diagram which shows the other structure of the conventional variable length coding apparatus. It is a block diagram which shows the structural example of the computer function which can implement | achieve the signal processing apparatus in this embodiment.

Explanation of symbols

10, 12, 19, 20, 22 Selector 11 Level subtractor 13 Run length subtractor 14, 15, 16 Huffman code determiner 17 Fixed length encoder 18 Controller 21 Huffman table 22 Escape code concatenation unit

Claims (14)

A variable-length coding table storing variable-length coded data corresponding to a combination of two input values to be input;
First subtracting means for subtracting a predetermined constant from the second data constituting the symbol data different from the first data in accordance with the first data constituting the symbol data;
Second subtracting means for subtracting a predetermined constant from the first data according to the second data;
A combination of the first data and the second data, a combination of the first data and the output of the first subtracting means, and an output of the second data and the second subtracting means. For combinations, whether or not the corresponding variable-length encoded data exists in the variable-length encoding table is compared in parallel with the magnitude relationship between the input value in the combination and a predetermined constant according to the input value. Determining means for determining by
According to the determination result by the determination means, one of the first data and the output of the second subtraction means is selected as the input of the variable length coding table, and the second data or the first data is selected. And a control means for selecting one of the outputs of the subtracting means. The determination means is
First code determination means for determining whether variable-length encoded data corresponding to a combination of the first data and the second data exists in the variable-length encoding table;
Second code determination means for determining whether variable-length encoded data corresponding to a combination of the first data and the output of the first subtracting means exists in the variable-length encoding table;
Third code determining means for determining whether or not variable length encoded data corresponding to a combination of the second data and the output of the second subtracting means exists in the variable length encoding table; The signal processing apparatus according to claim 1, further comprising: The first data is data representing the number of consecutive zero coefficients in a block that is orthogonally transformed and quantized with image data divided into blocks of a predetermined size,
The signal processing apparatus according to claim 1, wherein the second data is data representing a non-zero coefficient in the block. A variable-length coding table in which variable-length coded data corresponding to a combination of three input values to be input is stored;
In accordance with the first data constituting the symbol data and the third data different from the first data, a predetermined constant from the second data constituting the symbol data different from the first data First subtracting means for subtracting
Second subtracting means for subtracting a predetermined constant from the first data according to the second data and the third data;
A combination of the first data, the second data, and the third data, a combination of the first data, the output of the first subtracting means, and the third data, and the second data For the combination of the data, the output of the second subtracting means, and the third data, whether the corresponding variable length encoded data exists in the variable length encoding table, the input value in the combination, and Determination means for determining by comparing in parallel the magnitude relationship with a predetermined constant according to the input value;
According to the determination result by the determination means, one of the first data and the output of the second subtraction means is selected as the input of the variable length coding table, and the second data or the first data is selected. And a control means for selecting one of the outputs of the subtracting means. The determination means is
First code determination for determining whether variable-length encoded data corresponding to a combination of the first data, the second data, and the third data exists in the variable-length encoding table Means,
A second unit for determining whether variable-length encoded data corresponding to a combination of the first data, the output of the first subtracting means, and the third data exists in the variable-length encoding table; Sign determination means of
A third unit for determining whether variable-length encoded data corresponding to a combination of the second data, the output of the second subtracting means, and the third data exists in the variable-length encoding table; The signal processing apparatus according to claim 4, further comprising: The first data is data representing the number of consecutive zero coefficients in a block that is orthogonally transformed and quantized with image data divided into blocks of a predetermined size,
The second data is data representing a non-zero coefficient in the block,
6. The signal processing apparatus according to claim 4, wherein the third data is data representing the last non-zero coefficient in the block.   7. The signal processing apparatus according to claim 6, wherein the output of the signal processing apparatus is a bit stream encoded by an MPEG-4 encoding method. A fixed-length encoding means for encoding the symbol data into a fixed-length code;
8. The control unit according to claim 1, wherein the control unit selects one of the output of the variable length coding table and the output of the fixed length coding unit according to a determination result by the determination unit. 2. The signal processing device according to item 1.   9. A code adding unit for adding a predetermined code to encoded data obtained by encoding the symbol data according to a determination result by the determining unit. The signal processing device according to claim 1. A first subtraction step of subtracting a predetermined constant from the second data constituting the symbol data different from the first data in accordance with the first data constituting the symbol data;
A second subtraction step of subtracting a predetermined constant from the first data according to the second data;
A combination of the first data and the second data, a combination of the first data and the output in the first subtraction process, and an output in the second data and the second subtraction process Whether or not the corresponding variable-length encoded data exists in the variable-length encoding table storing the variable-length encoded data corresponding to the combination of two input values that are input. A determination step of determining by comparing in parallel the magnitude relationship between the input value in the combination and a predetermined constant according to the input value;
According to the determination result in the determination step, one of the first data and the output in the second subtraction step is selected as the input of the variable length coding table, and the second data or the above And a control step of selecting one of the outputs in the first subtraction step. In accordance with the first data constituting the symbol data and the third data different from the first data, a predetermined constant from the second data constituting the symbol data different from the first data A first subtraction step of subtracting
A second subtraction step of subtracting a predetermined constant from the first data in accordance with the second data and the third data;
A combination of the first data, the second data, and the third data, a combination of the first data, the output in the first subtraction step, and the third data, and the second data Variable length encoded data corresponding to the combination of the three input values to be input is the variable length encoded data corresponding to the combination of the first data, the output in the second subtraction step, and the third data. A determination step of determining whether or not the stored variable-length encoding table exists by comparing in parallel the magnitude relationship between the input value in the combination and a predetermined constant according to the input value;
According to the determination result in the determination step, one of the first data and the output in the second subtraction step is selected as the input of the variable length coding table, and the second data or the above And a control step of selecting one of the outputs in the first subtraction step. A first subtracting step of subtracting a predetermined constant from the second data constituting the symbol data different from the first data according to the first data constituting the symbol data;
A second subtraction step of subtracting a predetermined constant from the first data in accordance with the second data;
A combination of the first data and the second data, a combination of the first data and the output of the first subtraction step, and an output of the second data and the second subtraction step. For the combination, whether or not the corresponding variable-length encoded data exists in the variable-length encoding table storing the variable-length encoded data corresponding to the combination of two input values to be input A determination step for determining by comparing in parallel the magnitude relationship between an input value and a predetermined constant according to the input value;
Depending on the determination result in the determination step, either the first data or the output of the second subtraction step is selected as the input of the variable length coding table, and the second data or the second A program for causing a computer to execute a control step of selecting one of outputs of one subtraction step. In accordance with the first data constituting the symbol data and the third data different from the first data, a predetermined constant from the second data constituting the symbol data different from the first data A first subtraction step for subtracting
A second subtracting step of subtracting a predetermined constant from the first data according to the second data and the third data;
A combination of the first data, the second data, and the third data, a combination of the first data, the output of the first subtraction step, and the third data, and the second data For the combination of the data, the output of the second subtraction step, and the third data, the corresponding variable length encoded data is stored, and the variable length encoded data corresponding to the combination of the three input values to be input is stored. A determination step of determining whether or not the variable length coding table exists by comparing in parallel the magnitude relationship between the input value in the combination and a predetermined constant according to the input value;
Depending on the determination result in the determination step, either the first data or the output of the second subtraction step is selected as the input of the variable length coding table, and the second data or the second A program for causing a computer to execute a control step of selecting one of outputs of one subtraction step.   14. A computer-readable recording medium on which the program according to claim 12 or 13 is recorded.

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