JP2007027848A - Reversible coding method and apparatus, and reversible decoding method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of immediately coding and decoding a digital signal by a simple processing method. <P>SOLUTION: A reversible coding apparatus disclosed herein includes: a buffering section 111 for temporarily storing digital signals of at least two frames; a conversion section 113 for converting the stored digital signals into a bit sequence in a code absolute value expression; a discrimination section 115 that discriminates whether or not each bit configuring the converted bit sequence has information by each bit location of the frames and generates omitted bit location information denoting bit locations of bits not including any information in all the frames; and a reversible coding section 129 that generates a coded bit sequence by omitting the bits of the bit locations and uses the coded bit sequence and the omitted bit location information for reversible coded signals. Applying reverse processing to the reversible coding to the reversible coded signal executes reversible decoding for the reversible coded signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to encoding that reduces the number of bits that represent various digital signals (for example, acoustic signals such as voice and music and image signals), and more specifically, to the bit that represents a digital signal. The present invention relates to a lossless encoding method for generating a lossless encoded signal by reducing the number, a lossless decoding method for decoding an original digital signal from a lossless encoded signal, these apparatuses, and a program thereof.

  Conventionally, lossless encoding is one of methods for encoding audio signals such as voice and music and image signals. This is a reversible compression method that can completely reproduce the original signal. For example, universal compression coding widely used for compression of computer files and texts is known. In this method, compression encoding is performed with reference to an input sequence signal, and any signal can be encoded. For example, in text or the like, the number of bits is reduced to about half.

  However, in the above-described compression coding, in order to reduce the number of bits, a method of collectively processing a large amount of signals is adopted and complicated processing is required, so that encoding and decoding take time. Had the problem. Therefore, for example, when the encoded sound data and music data are communicated from the DVD player to the speaker using the above-described compression encoding, the video and the sound are shifted due to the time required for encoding and decoding. It was. Therefore, there has been a demand for a lossless encoding method and a lossless decoding method capable of encoding and decoding without taking time.

  Here, Patent Literature 1 discloses an encoding method, a decoding method, these devices, and a program. However, in Patent Document 1, it is possible to prevent the quality of the decoded digital signal from being deteriorated so much even if bits are lost on the transmission path when performing encoding. It is not a lossless encoding method and a lossless decoding method capable of encoding and decoding.

JP 2003-332914 A

  It is an object of the present invention to provide a lossless encoding method, a lossless decoding method, an apparatus for the same, and a program thereof that can solve such drawbacks of the prior art and can be immediately encoded and decoded by a simple processing method. And

  In order to solve the above-described problem, the present invention solves the above-mentioned problem. If a bit located at the same position in all frames included in a digital signal does not have information, only the information indicating the position of the bit, that is, the bit position is required. Focusing on the fact that it can be omitted, this is a lossless encoding method that encodes a digital signal by omitting bits at bit positions that do not have information in all frames. More specifically, according to the present invention, it is determined for each bit position of a frame whether each bit constituting the bit string has information, and there is a bit having no information in all frames. For example, this is a lossless encoding method that creates information indicating the bit position, that is, omitted bit position information and omits the bit at the bit position indicated by the omitted bit position information from the bit string.

  In addition, the present invention pays attention to the fact that the number of bits having no information may increase by taking a difference between frames included in the digital signal, and taking a difference between frames included in the digital signal, It is determined for each bit position of the frame whether each bit constituting the bit string representing the difference has information, and if there is a bit position having no information in all the frames, the bit position is indicated. This is a lossless encoding method that creates information, that is, omitted bit position information, and reduces the number of bits by omitting the bit at the bit position indicated by the omitted bit position information from the bit string representing the difference.

  Furthermore, the present invention performs a lossless encoding method that does not take a difference and a lossless encoding method that takes a difference in parallel, calculates each coding rate, and adopts the higher coding rate as a lossless coding signal This is a lossless encoding method.

  The present invention is also a lossless decoding method for decoding a lossless encoded signal created by the above-described lossless encoding method into a substantially original digital signal by performing a process reverse to the encoding.

  According to the present invention, lossless encoding or lossless decoding can be performed with a very simple process. Therefore, it is possible to immediately perform lossless encoding or lossless decoding. Furthermore, according to the present invention, lossless encoding or lossless decoding can be performed with a very simple process, and lossless encoding or lossless decoding is possible without requiring a large calculation area.

  Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the lossless encoding apparatus and lossless decoding apparatus of the present invention, and FIG. 2 is a flowchart showing the processing procedure of the lossless encoding apparatus 101 shown in FIG. In FIG. 1, a time series of digital signals, that is, a digital signal series is input from the input terminal 103 to the lossless encoding apparatus 101. The lossless encoding apparatus 101 divides this digital signal sequence into a bit string including at least two frames, that is, a digital signal, and generates a lossless encoded signal 105 by reducing the number of bits of the digital signal. Output to 107. The lossless decoding device 107 decodes the original digital signal from the lossless encoded signal 105 output from the lossless encoding device 101. When a certain amount of digital signals are decoded, these are connected in time series order to reproduce the original digital signal series and output from the output terminal 109 of the lossless decoding device 107.

  In this embodiment, the lossless encoding device 101 and the lossless encoding device 107 are connected wirelessly, and the lossless encoded signal 105 is transmitted from the lossless encoding device 101 to the lossless decoding device 107 by an antenna (not shown). Note that the present invention is not limited to this, and the lossless encoding apparatus 101 and the lossless decoding apparatus 107 may be connected by wire. In this embodiment, music data is used for the digital signal series. However, the present invention is not limited to this, and various signals can be used. For example, in the case of image data, for example, encoding can be performed by determining the presence / absence of information for each bit position representing the amplitude of the luminance signal of a pixel and generating omitted bit position information. In addition, audio data, video data, image data, text data such as a character string, and the like can be used.

  In FIG. 1 and FIG. 2, the digital signal sequence input to the input terminal 103 of the lossless encoding apparatus 101 is sent to the buffering unit 111. The buffering unit 111 temporarily stores a certain amount of digital signal series and temporarily stores an arbitrary number {eg, 16 × n (n is an integer of 2 or more)} so that at least two frames are included. Save in the buffer (step S1). In this embodiment, one frame is 16 bits, but the present invention is not limited to this, and one frame can have any number of bits according to the type of digital signal. The digital signal stored in the buffer is sent to the conversion unit 113.

  The conversion unit 113 converts the digital signal stored in the buffer from a bit string expressed in 2's complement to a bit string expressed in code absolute value (step S2). The bit string expressed by the code absolute value converted by the conversion unit 113 is sent to the determination unit 115. The discriminating unit 115 discriminates whether or not the bits constituting the bit string by the code absolute value expression have information. Here, the bit has information means that the bit has significant information, specifically, a bit whose value is “1”. Similarly, a bit having no information is a bit having a value of “0”. Therefore, the determination unit 115 determines whether the bit is “1” or “0” for each bit position in the frame, that is, for each bit position in the frame. As a result of the determination, if there is a bit that does not have information in all the frames, that is, there is a bit that is “0” in all the frames, abbreviated bit position information 119 indicating the bit position of the bit is created (step S3). .

  FIG. 3 is a diagram illustrating an example of processing in the determination unit 115 in FIG. First, the determination unit 115 arranges the bit string of the code absolute value expression in the order of the frames so that the positions of the bits in each frame are aligned. More specifically, in the case of the present embodiment, a matrix 117 is created in which a row, that is, a horizontal direction indicates a frame, and a column, that is, a vertical direction, indicates a bit position. Next, it is determined for each bit position of the frame whether or not there is a bit “1” in the bits constituting the column. If all bits that make up the column are "0", the omitted bit position information is "0", and if at least one bit is "1", the omitted bit position information is "1" and the omitted bit position is Create information 119. For example, in the rightmost column of the matrix, that is, the column 121 at the bit position 0 (the most significant bit of each frame), which is the most significant bit of all frames, the second frame, the fourth frame, the fifth frame, and the nth frame Since the bit of the frame is “1”, the rightmost bit of the omitted bit position information 119, that is, the most significant bit 123 is “1”. Also, for example, in column 125 at bit position 10 (the 11th bit from the most significant bit in each frame), which is the 11th column from the right of the matrix, all bits located in column 125 are `` 0 ''. Therefore, the eleventh 127 from the right of the omitted bit position information 119 is “0”. Similarly, all the bit positions are determined, and finally, from the most significant bit 123, "1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 , 1 ”, that is, omitted bit position information 119 is created. According to the abbreviated bit position information 119 according to the present embodiment, the portion where the abbreviated bit position information is “0”, that is, the bits at bit position 10 to bit position 14 are bits that do not have information in all frames. It can be seen that this is an optional bit.

  In the present embodiment, the omitted bit position information 119 is created as described above, but the present invention is not limited to this, and any method can be used as long as the omitted bit position information 119 can be created. It is possible to adopt. Also, the omitted bit position information 119 can adopt a form according to the creation method, and is not limited to the present embodiment. In addition, when the omitted bit position information is created using “0” and “1” as in this embodiment, the bit arrangement order of the omitted bit position information 119, that is, from the most significant bit to the least significant bit Is preferably aligned with the bit order in the frame because the correspondence with the omissible bit positions is easy to understand and the subsequent processing is simplified. However, the present invention is not limited to this.

  Referring back to FIG. 1 and FIG. 2, the bit string expressed by the code absolute value expression and the omitted bit position information 119 created by the determination unit 115 are both sent to the lossless encoding unit 129. Based on the omitted bit position information 119, the lossless encoding unit 129 creates the encoded bit string 131 by omitting the bit at the bit position indicated by the omitted bit position information 119 from the bit string in the code absolute value representation (step S4). The generated encoded bit string 131 and the omitted bit position information 119 are concatenated and output as the lossless encoded signal 105 (step S5).

  FIG. 4 is a diagram illustrating an example of processing in the lossless encoding unit 129 in FIG. In the example illustrated in FIG. 4, when the lossless encoding unit 129 identifies the “0” portion of the omitted bit position information 119, that is, the bit positions 10 to 14 in each frame as the bit positions 131 of the bits that can be omitted, The encoded bit string 131 is created by omitting the bits located at the positions 10 to 14 for each bit position. Specifically, bits are omitted for each column of the matrix 117. For example, in the case of bit position 10, the bits located at bit position 10 from the first frame to the nth frame are omitted at a time. The same applies to bit positions 11, 12, 13, and 14. The encoded bit string 131 and the abbreviated bit position information 119 created in this way are concatenated into a lossless encoded signal 105 and output from the lossless encoding unit 129. In this embodiment, the omitted bit position information 119 is concatenated before the encoded bit string 131 in time, and constitutes a lossless encoded signal 105. Note that the present invention is not limited to this. For example, the omitted bit position information may be concatenated after the encoded bit string 131 in time.

  In the present embodiment, the encoded bit string 131 is created by omitting bits that do not have information in all frames, but the present invention is not limited to this, and an arbitrary method is adopted for encoding. It is possible to create a normalized bit string 131. For example, the encoded bit string 131 can be created by extracting the “1” portion of the abbreviated bit position information 119, but is not limited thereto.

  FIG. 5 is a diagram showing another example of processing in the lossless encoding unit 129 in FIG. In FIG. 5, the encoded bit string 131 is created by omitting the bits at the optional bit positions 10 to 14 for each frame. Specifically, the encoded bit string 131 is created by omitting bits located at bit positions 10 to 14 in the first frame at a time. The same applies to the second to nth frames. The generated encoded bit string 131 is connected to the omitted bit position information 119 and output from the output terminal 109 as the lossless encoded signal 105, as in FIG. Note that the encoded bit string 131 in FIG. 3 and the encoded bit string 131 in FIG. 4 differ only in the way the bits are arranged, and the number of bits to be reduced is the same. It can be arbitrarily selected by a digital signal to be converted, a transmission means to the subsequent lossless decoding device 107, or the like.

  Through the above processing, the lossless encoding apparatus 101 shown in FIG. 1 outputs the lossless encoded signal 105. After outputting the lossless encoded signal 105, the lossless encoding apparatus 101 determines whether or not the encoding is completed (step S6). If the encoding is completed, the lossless encoding is ended. If not, the process returns to step 1. The next digital signal is encoded.

  The lossless encoded signal 105 output from the lossless encoding apparatus 101 is losslessly decoded by performing a process reverse to that of the lossless encoding apparatus 101 by the lossless decoding apparatus 107 shown in FIG. FIG. 6 is a flowchart showing a processing procedure of the lossless decoding apparatus 107 shown in FIG. The lossless encoded signal 105 output from the lossless encoding apparatus 101 is first input to the bit string complementing unit 137 of the lossless decoding apparatus 107, and the bit string correcting unit 137 starts from the omitted bit position information 119 included in the lossless encoding signal 105. It is determined which bit position of the encoded bit string 131 is omitted, and the omitted bits are compensated (step S1). In this embodiment, since the bits at the bit positions 10 to 14 in each frame are omitted, the bit positions 10 to 14 are supplemented with “0” to create a bit string of the original code absolute value expression. Compensation can be performed for each bit position or for each frame in accordance with the input encoded bit string 131. The generated bit string of the code absolute value representation is sent to the lossless decoding unit 139.

  The lossless decoding unit 139 converts the bit string of the code absolute value expression into a bit string of 2's complement expression (step S2), and converts the converted bit string of 2's complement expression into the nth frame in time series order, that is, from the first frame to the nth frame. The digital signals are decoded in such a manner (step S3). The decoded digital signal is sent to the buffering unit 141. The buffering unit temporarily stores the decoded digital signal in a buffer (step S4), and when a certain amount of digital signal is stored, concatenates the digital signals in chronological order to reproduce the original digital signal sequence. To the output terminal 109. The output terminal 109 outputs a digital signal sequence. In addition, when the lossless decoding apparatus 107 sends the digital signal to the buffering unit 141, the lossless decoding apparatus 107 determines whether or not the decoding is finished (step S5), and if the decoding is finished, the decoding is finished. If not, the process returns to step S1 to decode the next lossless encoded signal.

  The digital signal is encoded and decoded as described above. According to the lossless encoding apparatus 101 and the lossless decoding apparatus 107 according to the present embodiment, it is possible to obtain the lossless encoded signal 105 with a reduced number of bits by simple processing. Furthermore, since lossless encoding and lossless decoding can be performed with simple processing, lossless encoding and lossless decoding can be performed immediately without requiring a large calculation area.

  FIG. 7 is a block diagram showing the configuration of another embodiment of the lossless encoding apparatus and the lossless decoding apparatus of the present invention, and FIG. 8 is a flowchart showing the processing procedure of the lossless encoding apparatus 151 shown in FIG. In FIG. 7, the same reference numerals as those in FIG. In FIG. 8, step S1 is the same process as step S1 of the process shown in FIG. In the lossless encoding device 151 in FIG. 7, the digital signal temporarily stored in the buffering unit is sent to the difference calculation unit 153. The difference calculation unit 153 calculates a difference between frames and creates a bit string representing the difference (step S2).

  FIG. 9 is a diagram illustrating an example of processing in the difference calculation unit 153 in FIG. In this embodiment, the difference calculation unit 153 calculates the difference between the bit string of the frame and the bit string of the frame located immediately before the frame, and creates a bit string representing the difference. For example, by calculating the difference between the bit string of the first frame 155 that is the first frame of the digital signal and the bit string of the second frame 157 that is positioned second, a frame consisting of a 16-bit bit string representing the difference, that is, A second difference frame 159 is created. The same applies to other frames.

  Here, when the digital signal sequence is a continuous signal and the digital signal stored in the buffer is present immediately before the digital signal currently stored in the buffer, the lossless encoding device 151 advances the previous one. The bit string of the nth frame 161, which is the last frame of the digital signal stored in the buffer, is stored in order to calculate the difference from the bit string of the first frame 155 of the digital signal stored in the buffer. Therefore, the difference calculation unit 153 calculates the difference between the bit string of the n-th frame 161 and the bit string of the first frame 155, and creates the first difference frame 163. If there is no nth frame 161 of the digital signal previously stored in the buffer, the first difference frame 163 is not calculated, and the second difference frame 161 is the first frame of the bit string representing the first difference. It becomes. By calculating the difference between frames in this way, the conversion unit 167 at the subsequent stage can increase the number of bits that are “0”, and can further reduce the number of bits.

  In the present embodiment, the bit string of the last nth frame 161 of the digital signal previously stored in the buffer is stored in the lossless encoding device 151, and this is then stored in the digital signal stored in the buffer. Although it is used to calculate a difference from the bit string of the first first frame 155 of the signal, the present invention is not limited to this, and the difference between frames is calculated to increase the number of “0” bits. If it is possible, it is possible to adopt an arbitrary difference method.

  When the difference is calculated between all frames to create n difference frames (n-1 if there is no nth frame 161 of the digital signal previously stored in the buffer), lossless encoding is performed. The device 151 stores the bit sequence of the last frame of the digital signal for which the current difference is calculated, i.e., the nth frame 165, in order to use the difference between the digital signal stored in the buffer and the first frame for calculation. (Step S3). Also, the difference calculation unit 153 sends all the created difference frames to the conversion unit 167.

  In the conversion unit 167, the bit string of the difference frame is converted from a bit string in 2's complement expression to a bit string in sign absolute value expression (step S4). The converted bit string based on the code absolute value representation is sent to the determination unit 169. The discriminating unit 169 discriminates for each bit position of the difference frame whether the bit constituting the bit string by the code absolute value expression is “1” or “0”. The abbreviated bit position information indicating the bit position of the bit "is created (step S5). In other words, the determination performed by the determination unit 115 shown in FIG. 1 for each frame is performed only by the determination unit 169 shown in FIG. 7 for each frame after the difference is calculated, that is, for each difference frame. 1 is the same as the determination unit 115 shown in FIG. The omitted bit position information generated by the determination unit 169 is sent to the lossless encoding unit 171. In the lossless encoding unit 171, as in the processing of the lossless encoding unit 129 shown in FIGS. 1, 3, and 4, the bit at the bit position indicated by the omitted bit position information is encoded based on the omitted bit position information. An encoded bit string is created by omitting every bit position or every frame from the bit string expressed in absolute value (step S6), and the generated encoded bit string and the omitted bit position information are concatenated to generate a lossless encoded signal 173. (Step S7). After outputting the lossless encoding signal 173, the lossless encoding device 151 determines whether or not the encoding is completed (step S8) .If the encoding is completed, the lossless encoding ends. If not, the process returns to step S1. Then, the next digital signal is encoded.

  Through the above processing, the lossless encoding device 151 shown in FIG. 7 outputs the lossless encoded signal 173. The output lossless encoded signal 173 is losslessly decoded by the lossless decoding device 175 shown in FIG. FIG. 10 is a flowchart showing a processing procedure of the lossless decoding apparatus 175 shown in FIG. In FIG. 10, steps S1 to S2, S4, and S6 to S7 are the same processes as steps S1 to S2, S3, and S4 to S5 shown in FIG.

  7 and 10, the lossless encoded signal 173 output from the lossless encoding device 151 is input to the bit string complementing unit 137 of the lossless decoding device 175, where the bit string of the original code absolute value representation is converted as in FIG. Created (step S1). The generated bit string of the code absolute position expression is sent to the conversion unit 177. The conversion unit 177 converts the bit string expressed in the code absolute value into a bit string expressed in 2's complement (step S2). This 2's complement bit string is a bit string representing a difference, that is, a bit string of a difference frame. The created difference frames are sent to the lossless decoding unit 179 in time series order, that is, in order from the first difference frame. The lossless decoding unit 179 returns the bit string of the original value to each original difference frame, that is, the frame (step S3). Specifically, the original bit string is created by adding to the bit string of the difference frame the bit string of the frame that has returned to the original value immediately before the difference frame. For example, in the case of the second difference frame which is the second difference frame, the bit string returned from the bit string of the first difference frame, that is, the bit string of the first frame is added to the bit string of the original second frame. Return. Similarly, the difference frames after the second difference frame also return to the original bit string based on the bit string restored from the previous bit string representing the difference, that is, the bit string of the previous frame.

  Here, in the case where the original digital signal sequence is a continuous signal and there is a digital signal that has been previously decoded by the lossless decoding unit 179, the lossless decoding device 175 determines that the last frame of the digital signal that was previously decoded Is stored in order to be added to the first difference frame input to the lossless decoding unit 179, that is, the bit string of the first difference frame. Therefore, the bit string of the first difference frame that is first input to the lossless decoding unit 179 returns to the original bit string based on the bit string of the nth frame. In the case of the first frame of the digital signal sequence, there is no previous frame that has been restored, but since all are zero bit strings, the original bit string is automatically restored.

  When the bit string representing all the differences returns to the original bit string, the lossless decoding unit 179 decodes the digital signal by concatenating the nth frame in time series order, that is, in order from the first frame (step S5). The decoded digital signal is sent to the buffering unit 141, reproduced as a digital signal sequence by the same processing as in FIGS. 1 and 6, and output from the output terminal 109. (Steps S6 and S7). Further, the lossless decoding apparatus 175 stores the bit sequence of the last frame decoded by the current lossless decoding unit 179, that is, the bit sequence of the nth frame for the first difference frame that is then decoded by the lossless decoding unit 179 ( Step S4).

  In this embodiment, the difference is calculated by storing the bit sequence of the last frame of the digital signal stored in the buffer by the lossless encoding device 151 one time before, and the lossless decoding device 175 is set in the previous one. Although the bit string of the last frame of the decoded digital signal is stored to restore the original value from the difference, the present invention is not limited to this, and any method can be adopted. . Also, the digital signal before calculating the difference including at least one frame in the lossless encoded signal 173 in the present embodiment, for example, the bit string or the difference of the last frame stored in the previous buffer is calculated. By including a bit string or the like, for example, even when a wrong signal is decoded by the previous lossless decoding unit 151 due to a transmission signal error or the like, the lossless input next to the lossless decoding unit 151 This is preferable because the encoded signal can be correctly decoded, but is not limited thereto.

  In this embodiment, the digital signal is encoded and decoded as described above. According to the lossless encoding device 161 and the lossless decoding device 175 according to the present embodiment, by calculating the difference, it is possible to increase the number of bits that are “0”, that is, the number of bits that do not have information. Thus, it is possible to obtain a lossless encoded signal with a higher encoding rate. Furthermore, since lossless encoding and lossless decoding can be performed with simple processing, lossless encoding and lossless decoding can be performed immediately without requiring a large calculation area.

    FIG. 11 is a block diagram showing the configuration of another embodiment of the lossless encoding apparatus and lossless decoding apparatus of the present invention, and FIG. 12 is a flowchart showing the processing procedure of the lossless encoding apparatus 201 shown in FIG. In FIG. 11, the same reference numerals as those in FIGS. That is, the buffering unit 111, the conversion unit 113, the determination unit 115, and the lossless encoding unit 129 in the lossless encoding apparatus 101 illustrated in FIG. 1 are the first buffering unit 111 in the lossless encoding apparatus 201 illustrated in FIG. The first conversion unit 113, the first determination unit 115, and the first lossless encoding unit 129 correspond to the buffering unit 111, the difference calculation unit 153, and the conversion unit 167 in the lossless encoding device 151 shown in FIG. , A determination unit 169, and a lossless encoding unit 171 include a second buffering unit 111, a second difference calculation unit 153, a second conversion unit 167, and a second determination unit in the lossless encoding apparatus 201 illustrated in FIG. 169 and the second lossless encoding unit 171, respectively. 1 correspond to the first bit string compensation unit 137 and the first lossless decoding unit 139 in the lossless decoding apparatus 209 shown in FIG. 11, respectively. 7, the bit string compensation unit 137, the conversion unit 177, and the lossless decoding unit 179 in the lossless decoding device 175 shown in FIG. 7 are the second bit string compensation unit 137, the second conversion unit 177, and the second lossless decoding unit shown in FIG. 179 respectively. In FIG. 12, steps S1 to S4 are the same processes as steps S1 to S4 shown in FIG. 2, and steps S11 to S66 are the same processes as steps S1 to S6 shown in FIG. Therefore, explanation is omitted.

  In the lossless encoding apparatus 201 shown in FIG. 11, the digital signal sequence is input to the first buffering unit 111 and the second buffering unit 111, respectively, and the first buffering unit 111 (step S1), first The first lossless encoded signal is generated through the first conversion unit 113 (step S2), the first determination unit 115 (step S3), and the first lossless encoding unit 129 (step S4). Buffering section 111 (step S11), second difference calculation section 153 (step S22, step S33), second conversion section 167 (step S44), second determination section 169 (step S55), and second The second lossless encoded signal is generated through the lossless encoding unit 171 (step S66). That is, the lossless encoding apparatus 201 processes the digital signal sequence in parallel, and creates two encoded signals, a first lossless encoded signal and a second lossless encoded signal. The first lossless encoded signal is the same as the lossless encoded signal 105 created by the lossless encoding apparatus 101 shown in FIG. 1, and includes the first encoded bit string 131 and the first omitted bit position information 119. Are connected to each other. Also, the second lossless encoded signal is the same as the lossless encoded signal 173 created by the lossless encoding device 151 shown in FIG. 7, and the second encoded bit string and the second omitted bit position information. Are connected to each other. Both the first lossless encoded signal and the second lossless encoded signal are input to the specifying unit 203.

  The specifying unit 203 calculates and compares the coding rate of the first lossless coded signal and the coding rate of the second lossless coded signal, and specifies specific information 205 that identifies the higher coding rate. Create (step S7). For example, when the coding rate of the first lossless coded signal is higher than the coding rate of the second lossless coded signal, the specific information 205 is created as the specific information 205 of “1”. When the coding rate of the second lossless coded signal is higher than the coding rate of the first lossless coded signal, the specific information 205 of “0” is created. Here, the coding rate is the ratio of the number of bits of the original digital signal to the number of bits after coding. In the present embodiment, the specific information 205 is set to “0” and “1”. However, the present invention is not limited to this. Among the first lossless encoded signal and the second lossless encoded signal, As long as it is possible to specify the higher coding rate, it is possible to arbitrarily set.

  The specific information 205 generated by the specifying unit is connected to the first lossless encoded signal or the second lossless encoded signal specified by the specific information 205 and is generated by the lossless encoding device 201. It is output as 207 (step S8). In the present embodiment, the identification information 205 identifies the first lossless encoded signal, and is output as the lossless encoded signal 207 by concatenating with the first lossless encoded signal.

  FIG. 13 is a conceptual diagram of the lossless encoded signal 207 output by the lossless encoding apparatus 201 shown in FIG. In the present embodiment, the specific information 205 is connected between the first lossless bit sequence 131 and the first omitted bit position information 119 to constitute a lossless encoded signal 207. It is not necessary to limit to the present embodiment, and the specific information 205 can be connected at an arbitrary position.

  Through the above processing, the lossless encoding apparatus 201 shown in FIG. 11 outputs the lossless encoded signal 207. The output lossless encoded signal 207 is losslessly decoded by the lossless decoding device 209 shown in FIG. 11 by performing processing reverse to that of the lossless encoding device 201. FIG. 14 is a flowchart showing a processing procedure of the lossless decoding apparatus 209 shown in FIG. In FIG. 14, steps S2 to S4 are the same processes as steps S1 to S3 shown in FIG. 6, and steps S22 to S55 are the same processes as steps S1 to S4 shown in FIG. Is omitted.

  In FIG. 11, the lossless decoded signal 207 output from the lossless encoding device 201 is first input to the specifying unit 211 of the lossless decoding device 209. In the identifying unit 211, based on the identification information 205 included in the lossless encoded signal 207, whether the lossless encoded signal 207 includes the first lossless encoded signal or the second lossless encoded signal (Step S1). If it is determined that the lossless encoded signal 207 includes the first lossless encoded signal, the included first lossless encoded signal is output to the first bit string compensation unit 173.

  In the first bit string compensation unit 173, similarly to the bit string compensation unit 173 shown in FIG. 1, based on the first omitted bit position information 119, the bits of the first encoded bit string 131 are omitted at the omitted positions. The bit is supplemented, and a bit string representing the sign absolute value is created (step S2). The generated bit string of the code absolute value representation is sent to the first lossless decoding unit 113, and the first lossless decoding unit 113, like the lossless decoding unit 113 shown in FIG. Is converted into a bit string of 2's complement representation (step S3), and the converted bit sequence of 2's complement representation is connected in time series order, that is, from the first frame to the nth frame in order to decode the digital signal (step S3). S4).

  When the digital signal is decoded, the lossless decoding apparatus 209 stores the last frame of the decoded digital signal, that is, the bit string of the nth frame (step S6). In the case where the second lossless encoded signal 207 is included in the lossless encoded signal 207, the second lossless decoding unit 179 returns the previous bit string representing the difference to the original bit string. This is because the bit string of the nth frame of the digital signal decoded by the first lossless decoding unit 139 or the second lossless decoding unit 179 is required. When the bit string of the nth frame is stored, the digital signal is sent to the buffering unit 141, is reproduced into a digital signal sequence by the same processing as in FIGS. 1 and 6, and is output from the output terminal 109. (Steps S7 and S8).

  The lossless decoding when the lossless encoded signal 207 includes the first lossless encoded signal has been described above. However, when the lossless encoded signal 207 includes the second lossless encoded signal, the second lossless encoded signal 207 includes the second lossless encoded signal. The bit loss compensation signal 207 is input to the bit compensation unit 137 of the second bit string compensation unit 137, and the second bit string compensation unit 137 (step S22), the second conversion unit 177 (step S33), as in FIG. 7 and FIG. The digital signal is restored through the second lossless decoding unit (steps S44 and S55). When the bit string of the nth frame of the digital signal decoded by the lossless decoding device 209 is stored, it is sent to the buffering unit 141 and reproduced as a digital signal sequence in the same manner as in the case of the first lossless encoded signal. Output from 109.

  In this embodiment, the digital signal is encoded and decoded as described above. According to the lossless encoding apparatus 201 and the lossless decoding apparatus 209 according to the present embodiment, the encoding rates of the first lossless encoded signal and the second lossless encoded signal are compared, and the higher encoding rate is obtained. Therefore, the lossless encoded signal 207 with a reduced number of bits can be obtained with a simple process. Furthermore, since it is possible to perform lossless encoding or lossless decoding with a simple process, it is possible to immediately perform lossless encoding or lossless decoding without requiring a large calculation area.

  It should be noted that the functions of the respective parts shown in the above embodiments can also be realized by causing a computer to decode and execute a program.

It is a block diagram which shows the structure of the Example of the lossless encoding apparatus and lossless decoding apparatus of this invention. It is a flowchart which shows the process sequence of the lossless encoding apparatus shown in FIG. It is a figure which shows an example of the process in the discrimination | determination part of FIG. It is a figure which shows an example of the process in the lossless encoding part of FIG. It is a figure which shows another example of the process in the lossless encoding part of FIG. It is a flowchart which shows the process sequence of the lossless decoding apparatus shown in FIG. It is a block diagram which shows the structure of another Example of the lossless encoding apparatus and lossless decoding apparatus of this invention. It is a flowchart which shows the process sequence of the lossless encoding apparatus shown in FIG. It is a figure which shows an example of the process in the difference calculation part in FIG. It is a flowchart which shows the process sequence of the lossless decoding apparatus shown in FIG. It is a block diagram which shows the structure of another Example of the lossless encoding apparatus and lossless decoding apparatus of this invention. It is a flowchart which shows the process sequence of the lossless encoding apparatus shown in FIG. It is a conceptual diagram of the lossless encoding signal output with the lossless encoding apparatus shown in FIG. It is a flowchart which shows the process sequence of the lossless decoding apparatus shown in FIG.

Explanation of symbols

101 lossless encoder
103 Input terminal
105 Lossless encoded signal
107 Lossless decoder
109 Output terminal

Claims (22)

In a lossless encoding method for encoding a digital signal to create a lossless lossless encoded signal,
A buffering process for temporarily storing the digital signal of at least two frames in a buffer;
A conversion process for converting the digital signal into a bit string of a sign absolute value representation;
Abbreviated bit position information indicating whether or not the bits constituting the bit string of the code absolute value representation have information for each bit position of the frame and indicating the bit positions of the bits having no information in all frames Discriminating process to create
A bit of the bit position indicated by the abbreviated bit position information is omitted from the bit string of the code absolute value representation to generate an encoded bit string, and the lossless encoded signal is used as the lossless encoded signal. A lossless encoding method comprising: an encoding process. In a lossless encoding method for encoding a digital signal to create a lossless lossless encoded signal,
A buffering process for temporarily storing the digital signal of at least two frames in a buffer;
A difference calculation process for calculating a difference between a bit string of the frame and a bit string of a frame located immediately before the frame, and creating a bit string representing the difference for each frame;
A conversion process of converting the bit string representing the difference into a bit string of a code absolute value expression;
Abbreviated bit position information indicating whether or not the bits constituting the bit string of the code absolute value representation have information for each bit position of the frame and indicating the bit positions of the bits having no information in all frames Discriminating process to create
A bit of the bit position indicated by the abbreviated bit position information is omitted from the bit string of the code absolute value representation to generate an encoded bit string, and the lossless encoded signal is used as the lossless encoded signal. A lossless encoding method comprising: an encoding process. In a lossless encoding method for encoding a digital signal to create a lossless lossless encoded signal,
A first buffering process for temporarily storing the digital signal of at least two frames in a buffer;
A first conversion step of converting the digital signal into a bit string of sign absolute value representation to create a first code absolute value representation bit string;
It is determined for each bit position of the frame whether or not the bits constituting the first code absolute value expression bit string have information, and the bit positions of the bits having no information in all frames are indicated. A first discriminating process for creating one abbreviated bit position information;
The first encoded bit string is generated by omitting the bit at the bit position indicated by the first omitted bit position information from the first encoded absolute value expression bit string, and the first encoded bit string and the first encoded bit string A first lossless encoding process using the abbreviated bit position information of the first lossless encoded signal,
A second buffering process for temporarily storing the digital signal including at least two frames in a buffer;
A difference calculation process for calculating a difference between a bit string of the frame and a bit string of a frame located immediately before the frame, and creating a bit string representing the difference for each frame;
A second conversion step of converting the bit string representing the difference into a bit string of a code absolute value expression to create a second code absolute value expression bit string;
It is determined for each bit position of the frame whether or not the bits constituting the second code absolute value expression bit string have information, and the bit positions of the bits having no information in all the frames are indicated. A second discriminating process for creating 2 abbreviated bit position information;
A bit of the bit position indicated by the second abbreviated bit position information is omitted from the second code absolute value expression bit string to create a second encoded bit string, and the second encoded bit string and the second abbreviated bit string are generated. A second lossless encoding process using bit position information as a second lossless encoded signal;
A specification for identifying one of the first lossless encoded signal and the second lossless encoded signal by comparing the coding rates of the first lossless encoded signal and the second lossless encoded signal Including the specific process of creating information,
A lossless encoding method in which the specific information and the first lossless encoded signal or the second lossless encoded signal specified by the specific information are used as the lossless encoded signal.   The lossless encoding method according to any one of claims 1 to 3, wherein the lossless encoding step is configured to change a bit at a bit position indicated by the omitted bit position information for each bit position from a bit string of the code absolute value expression. A lossless encoding method, characterized in that an encoded bit string is created by omitting the above.   The lossless encoding method according to any one of claims 1 to 3, wherein the lossless encoding step is configured to change the bit at the bit position indicated by the omitted bit position information from the bit string of the code absolute value representation for each frame. A lossless encoding method characterized in that an encoded bit string is created by omitting. In a lossless decoding method for losslessly decoding a digital signal from an encoded lossless encoded signal,
The lossless encoded signal is
An encoded bit sequence with bits omitted, and
Abbreviated bit position information indicating a bit position of a bit omitted in the encoded bit string,
The lossless decoding method includes:
Based on the abbreviated bit position information, a bit string complementing process of creating a bit string of a code absolute value representation by supplementing the omitted bits at the bit position where the bits of the encoded bit string are omitted
A lossless decoding method comprising: a lossless decoding step of converting the bit string of the code absolute value expression into a bit string of 2's complement expression and losslessly decoding the digital signal. In a lossless decoding method for losslessly decoding a digital signal from an encoded lossless encoded signal,
The lossless encoded signal is
An encoded bit sequence of at least one frame with bits omitted;
Abbreviated bit position information indicating a bit position of a bit omitted in the encoded bit string,
The lossless decoding method includes:
Based on the abbreviated bit position information, a bit string complementing step of creating a bit string of a code absolute value representation by supplementing the omitted bit position to the bit position where the bit of the encoded bit string is omitted;
A conversion process of converting the bit string of the sign absolute value representation into a bit string of 2's complement representation;
A reversible decoding process for reversibly decoding the digital signal by converting the bit string converted into the two's complement representation for each frame based on the bit string of the frame located immediately before the frame. A lossless decoding method. In a lossless decoding method for losslessly decoding a digital signal from an encoded lossless encoded signal,
The lossless encoded signal is
A first lossless encoded signal including a first encoded bit string in which bits are omitted and first omitted bit position information indicating a bit position of a bit omitted in the first encoded bit string, or A second encoded bit sequence of at least one frame in which bits are omitted, and second abbreviated bit position information indicating a bit position of the bits omitted in the second encoded bit sequence One of the lossless encoded signals of
Including specific information for specifying one of the first lossless encoded signal and the second lossless encoded signal;
The lossless decoding method includes:
With the specifying information, it is specified whether the lossless encoded signal includes the first lossless encoded signal or the second lossless encoded signal;
If it is specified that the first lossless encoded signal is included, the bits omitted in the bit positions where the bits of the first encoded bit string are omitted based on the first omitted bit position information To generate a bit string of a sign absolute value representation, convert the bit string of the sign absolute value representation into a two's complement representation, and reversibly decode the digital signal;
If it is specified that the second lossless encoded signal is included, the bits omitted in the bit positions where the bits of the second encoded bit string are omitted based on the second omitted bit position information To generate a bit string of sign absolute value representation, convert the bit string of sign absolute value representation to a bit string of 2's complement representation, and convert the bit sequence converted to 2's complement representation for each frame A lossless decoding method characterized in that the digital signal is losslessly decoded based on a bit string of a frame located immediately before the digital signal.   The lossless decoding method according to any one of claims 6 to 8, wherein a bit string representing a code absolute value is created by supplementing a bit omitted in the coded bit string for each bit position. A lossless decoding method.   The lossless decoding method according to any one of claims 6 to 8, wherein a bit string representing a code absolute value is created by supplementing the bits omitted in the coded bit string for each frame. A lossless decoding method. In a lossless encoding device that encodes a digital signal to create a lossless lossless encoded signal,
A buffering unit for temporarily storing the digital signal of at least two frames in a buffer;
A conversion unit for converting the digital signal into a bit string of a code absolute value expression;
Abbreviated bit position information indicating whether or not the bits constituting the bit string of the code absolute value representation have information for each bit position of the frame and indicating the bit positions of the bits having no information in all frames A discriminator for creating
The bit of the bit position indicated by the abbreviated bit position information is omitted from the bit string of the code absolute value representation to create an encoded bit string, and the lossless encoded signal is used as the lossless encoded signal. A lossless encoding apparatus comprising: an encoding unit. In a lossless encoding device that encodes a digital signal to create a lossless lossless encoded signal,
A buffering unit for temporarily storing the digital signal of at least two frames in a buffer;
A difference calculation unit that calculates a difference between a bit string of the frame and a bit string of a frame positioned immediately before the frame, and creates a bit string representing the difference for each frame;
A conversion unit that converts the bit string representing the difference into a bit string of a code absolute value expression;
Abbreviated bit position information indicating whether or not the bits constituting the bit string of the code absolute value representation have information for each bit position of the frame and indicating the bit positions of the bits having no information in all frames A discriminator for creating
The bit of the bit position indicated by the abbreviated bit position information is omitted from the bit string of the code absolute value representation to create an encoded bit string, and the lossless encoded signal is used as the lossless encoded signal. A lossless encoding apparatus comprising: an encoding unit. In a lossless encoding device that encodes a digital signal to create a lossless lossless encoded signal,
A first buffering unit for temporarily storing the digital signal of at least two frames in a buffer;
A first converter that converts the digital signal into a bit string of a sign absolute value representation to create a first sign absolute value representation bit string;
It is determined for each bit position of the frame whether or not the bits constituting the first code absolute value expression bit string have information, and the bit positions of the bits having no information in all frames are indicated. A first discriminating unit that creates one abbreviated bit position information;
The first encoded bit string is generated by omitting the bit at the bit position indicated by the first omitted bit position information from the first encoded absolute value expression bit string, and the first encoded bit string and the first encoded bit string A first lossless encoding unit using the abbreviated bit position information as a first lossless encoded signal;
A second buffering unit for temporarily storing the digital signal including at least two frames in a buffer;
A difference calculation unit that calculates a difference between a bit string of the frame and a bit string of a frame positioned immediately before the frame, and creates a bit string representing the difference for each frame;
A second conversion unit that converts the bit string representing the difference into a bit string of a code absolute value expression to create a second code absolute value expression bit string;
It is determined for each bit position of the frame whether or not the bits constituting the second code absolute value expression bit string have information, and the bit positions of the bits having no information in all the frames are indicated. A second discriminating unit that creates the omitted bit position information of 2;
A bit of the bit position indicated by the second abbreviated bit position information is omitted from the second code absolute value expression bit string to create a second encoded bit string, and the second encoded bit string and the second abbreviated bit string are generated. A second lossless encoding unit that uses the bit position information as a second lossless encoded signal;
A specification for identifying one of the first lossless encoded signal and the second lossless encoded signal by comparing the coding rates of the first lossless encoded signal and the second lossless encoded signal Including a specific part that creates information,
A lossless encoding apparatus that uses the specific information and the first lossless encoded signal or the second lossless encoded signal specified by the specific information as the lossless encoded signal.   14. The lossless encoding apparatus according to claim 11, wherein the lossless encoding unit converts a bit at a bit position indicated by the omitted bit position information from a bit string of the code absolute value expression for each bit position. A lossless encoding apparatus characterized in that an encoded bit string is created by omitting.   14. The lossless encoding apparatus according to claim 11, wherein the lossless encoding unit converts a bit at a bit position indicated by the abbreviated bit position information for each frame from a bit string of the code absolute value expression. A lossless encoding apparatus, characterized in that an encoded bit string is omitted. In a lossless decoding apparatus for losslessly decoding a digital signal from an encoded lossless encoded signal,
The lossless encoded signal is
An encoded bit sequence with bits omitted, and
Abbreviated bit position information indicating a bit position of a bit omitted in the encoded bit string,
The lossless decoding device includes:
Based on the abbreviated bit position information, a bit string complementing unit that creates a bit string of a code absolute value representation by supplementing the omitted bits at the bit position where the bits of the encoded bit string are omitted;
A lossless decoding apparatus comprising: a lossless decoding unit that converts the bit string of the code absolute value expression into a bit string of 2's complement expression and losslessly decodes the digital signal. In a lossless decoding apparatus for losslessly decoding a digital signal from an encoded lossless encoded signal,
The lossless encoded signal is
An encoded bit sequence of at least one frame with bits omitted;
Abbreviated bit position information indicating a bit position of a bit omitted in the encoded bit string,
The lossless decoding device includes:
Based on the abbreviated bit position information, a bit string complementing unit that creates a bit string of a code absolute value representation by supplementing the omitted bits at the bit position where the bits of the encoded bit string are omitted;
A conversion unit that converts the bit string of the sign absolute value representation into a bit string of 2's complement representation;
A reversible decoding unit that reversibly decodes the digital signal by converting the bit string converted into the two's complement representation for each frame based on the bit string of the frame located immediately before the frame. A lossless decoding device characterized. In a lossless decoding apparatus for losslessly decoding a digital signal from an encoded lossless encoded signal,
The lossless encoded signal is
A first lossless encoded signal including a first encoded bit string in which bits are omitted and first omitted bit position information indicating a bit position of a bit omitted in the first encoded bit string, or A second encoded bit sequence of at least one frame in which bits are omitted, and second abbreviated bit position information indicating a bit position of the bits omitted in the second encoded bit sequence One of the lossless encoded signals of
Specific information for specifying one of the first lossless encoded signal and the second lossless encoded signal;
The lossless decoding device includes:
A specifying unit for specifying whether the lossless encoded signal includes the first lossless encoded signal or the second lossless encoded signal according to the specifying information;
Based on the first abbreviated bit position information, a bit string of the first code absolute value expression is generated by supplementing the omitted bit position to the bit position where the bit of the first encoded bit string is omitted. The bit string compensation part of
A first lossless decoding unit that reversibly decodes the digital signal by converting the bit string of the first code absolute value expression into a bit string of 2's complement expression;
Based on the second abbreviated bit position information, a second bit string representing the second code absolute value is generated by supplementing the omitted bit position to the bit position where the bit of the second encoded bit string is omitted. The bit string compensation part of
A second conversion unit for converting the bit string of the second code absolute value expression into a bit string of 2's complement expression;
A second lossless decoding unit for losslessly decoding the digital signal by converting the bit string converted into the two's complement representation for each frame based on the bit string of the frame located immediately before the frame; Including
When the specifying unit specifies that the first lossless encoded signal is included, the digital signal is decoded by the first bit string compensation unit and the first first lossless decoding unit, and the specifying unit When it is specified that the second lossless encoded signal is included, the digital signal is decoded by the second bit string compensation unit, the second conversion unit, and the second lossless decoding unit. A lossless decoding device.   The lossless decoding apparatus according to any one of claims 16 to 18, wherein the bit string complementing unit generates a bit string representing a code absolute value by supplementing a bit omitted in the encoded bit string for each bit position. A lossless decoding apparatus characterized by the above.   19. The lossless decoding apparatus according to claim 16, wherein the bit string complementing unit generates a bit string representing a code absolute value by supplementing the bits omitted in the encoded bit string for each frame. A lossless decoding apparatus characterized by the above.   A program for causing a computer to execute each step of the lossless encoding method according to any one of claims 1 to 5.   A program for causing a computer to execute each step of the lossless decoding method according to any one of claims 6 to 10.

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