Coding instrument and methodology, decoding instrument and method, compiling apparatus and method, record medium, as well as program

[0001] [Technical field to which the invention belongs] The present invention<u style="single">Editing equipment and method</u>In particular, when transmitting and receiving image information (bitstream) compressed by orthogonal transform such as discrete cosine transform or Karhunen-Loève transform and motion compensation via network media such as satellite broadcasting, cable television broadcasting, and the Internet. Suitable for processing on storage media such as optical disks, magnetic disks, and flash memories.<u style="single">Editing equipment and method</u>Regarding. [0002] [Conventional technology] In recent years, image information has been treated as digital, and at that time, for the purpose of efficient transmission and storage of information, MPEG (PEG) that compresses by orthogonal transform such as discrete cosine transform and motion compensation by utilizing the redundancy peculiar to image information. Devices that comply with methods such as Moving Picture Expert Group) are becoming widespread in both information distribution by broadcasting stations and information reception in ordinary households. [0003] In particular, MPEG2 (ISO / IEC 13818-2) is a standard defined as a general-purpose image compression method, and is a standard that covers both skipped scanning images and sequential scanning images, as well as standard resolution images and high-definition images, for example. As represented by the DVD (Digital Versatile Disk) standard, it is widely used in a wide range of professional and consumer applications. [0004] By using this MPEG2 compression method, for example, 4 to 8 Mbps for a standard resolution jump scan image with 720 x 480 pixels and 18 to 22 Mbps for a high resolution skip scan image with 1920 x 1088 pixels. By allocating the code amount (bit rate) of, it is possible to realize a high compression rate and good image quality. [0005] MPEG2 was mainly aimed at high-quality coding suitable for broadcasting, but since it did not support coding methods with higher compression rates, the MPEG4 coding method was standardized. Regarding the image coding method, the standard was approved as an international standard as ISO / IEC 14496-2 in December 1998. [0006] Furthermore, in recent years, H.26L (ITU-T Q6 / 16) by the ITU-T (International Telecommunication Union-Telecommunication Standardization Sector), which is the telecommunications standardization division of the International Telecommunications Union, for the original purpose of image coding for video conferencing. The standardization of the standard called VCEG) is progressing. It is known that H.26L realizes higher coding efficiency than the coding methods such as MPEG2 and MPEG4, although a larger amount of calculation is required for its coding and decoding. [0007] In addition, as part of the activities of MPEG4, standardization of coding technology based on this H.26L that realizes higher coding efficiency is currently being carried out as a JVT (Joint Video Team) in collaboration with ITU-T. .. [0008] Here, image compression by orthogonal transform such as discrete cosine transform or Karhunen-Loève transform and motion compensation will be described. FIG. 1 is a diagram showing a configuration of an example of a conventional image information encoding device. [0009] In the image information coding device 10 shown in FIG. 1, the image information composed of the analog signal input from the input terminal 11 is converted into a digital signal by the A / D conversion unit 12. Then, the screen rearrangement buffer 13 rearranges the frames according to the GOP (Group of Pictures) structure of the image information supplied from the A / D conversion unit 12. [0010] Here, the screen rearrangement buffer 13 supplies the image information of the entire frame to the orthogonal conversion unit 15 for the image to be intra (in-image) coded. The orthogonal transform unit 15 performs orthogonal transform such as discrete cosine transform or Karhunen-Loève transform on the image information, and supplies the conversion coefficient to the quantization unit 16. The quantization unit 16 performs a quantization process on the conversion coefficient supplied from the orthogonal conversion unit 15. [0011] The lossless coding unit 17 determines the coding mode from the quantized conversion coefficient, the quantization scale, etc. supplied from the quantization unit 16, and variable-length coding or arithmetic coding for this coding mode. Lossless coding such as is performed to form information to be inserted in the header portion of the image coding unit. Then, the lossless coding unit 17 supplies the coded coding mode to the storage buffer 18 for storage. This coded coding mode is output from the output terminal 19 as image compression information. [0012] Further, the lossless coding unit 17 applies lossless coding such as variable length coding or arithmetic coding to the quantized conversion coefficient, and supplies the coded conversion coefficient to the storage buffer 18 for storage. Let me. This encoded conversion coefficient is output from the output terminal 19 as image compression information. [0013] The behavior of the quantization unit 16 is controlled by the rate control unit 20 based on the amount of conversion coefficient data stored in the storage buffer 18. Further, the quantization unit 20 supplies the conversion coefficient after quantization to the inverse quantization unit 21, and the inverse quantization unit 21 dequantizes the conversion coefficient after quantization. The inverse orthogonal conversion unit 22 performs an inverse orthogonal conversion process on the inverse quantized conversion coefficient to generate decoded image information, and supplies the information to the frame memory 23 for storage. [0014] Further, the screen rearrangement buffer 13 supplies image information to the motion prediction / compensation unit 24 for an image to be inter-coded (between images). The motion prediction / compensation unit 24 takes out the image information referred to at the same time from the frame memory 23, performs motion prediction / compensation processing, and generates the reference image information. The motion prediction / compensation unit 24 supplies the generated reference image information to the adder 14, and the adder 14 converts the reference image information into a difference signal from the corresponding image information. Further, the motion prediction / compensation unit 24 simultaneously supplies the motion vector information to the lossless coding unit 17. [0015] The reversible coding unit 17 determines the coding mode from the quantized conversion coefficient and the quantization scale supplied from the quantization unit 16, the motion vector information supplied from the motion prediction / compensation unit 24, and the like, and determines the coding mode. The coded mode is subjected to reversible coding such as variable length coding or arithmetic coding to generate information to be inserted in the header part of the image coding unit. Then, the lossless coding unit 17 supplies the coded coding mode to the storage buffer 18 for storage. This coded coding mode is output as image compression information. [0016] Further, the lossless coding unit 17 performs lossless coding processing such as variable length coding or arithmetic coding on the motion vector information to generate information to be inserted into the header part of the image coding unit. [0017] Further, unlike intra-coding, in the case of inter-coding, the image information input to the orthogonal transforming unit 15 is a difference signal obtained from the adder 14. Since the other processes are the same as the image compression information to be intra-coded, the description thereof will be omitted. [0018] Next, FIG. 2 shows a configuration of an example of an image information decoding device corresponding to the above-mentioned image information coding device 10. In the image information decoding device 40 shown in FIG. 2, the image compression information input from the input terminal 41 is temporarily stored in the storage buffer 42 and then transferred to the reversible decoding unit 43. [0019] The lossless decoding unit 43 performs processing such as variable length decoding or arithmetic decoding on the image compression information based on the predetermined image compression information format, acquires the coding mode information stored in the header unit, and inversely quantizes the image compression information. It is supplied to the chemical unit 44 and the like. Similarly, the reversible decoding unit 43 acquires the quantized conversion coefficient and supplies it to the inverse quantization unit 44. Further, when the frame to be decoded is intercoded, the reversible decoding unit 43 also decodes the motion vector information stored in the header unit of the image compression information, and decodes that information into the motion prediction / compensation unit. Supply to 51. [0020] The inverse quantization unit 44 inversely quantizes the conversion coefficient after quantization supplied from the reversible decoding unit 43, and supplies the conversion coefficient to the inverse orthogonal conversion unit 45. The inverse orthogonal transform unit 45 performs inverse orthogonal transform such as inverse discrete cosine transform or inverse Karhunen-Loève transform on the conversion coefficient based on the predetermined image compression information format. [0021] [0021] Here, when the target frame is intra-encoded, the image information subjected to the inverse orthogonal conversion processing is stored in the screen rearrangement buffer 47, and the D / A conversion in the D / A conversion unit 48 It is output from the output terminal 49 after processing. [0022] When the target frame is intercoded, the motion prediction / compensation unit 51 refers based on the motion vector information subjected to the reversible decoding process and the image information stored in the frame memory 50. An image is generated and supplied to the adder 46. The adder 46 synthesizes this reference image with the output from the inverse orthogonal transform unit 45. Since the other processing is the same as that of the intra-encoded frame, the description thereof will be omitted. [0023] By the way, in the coding method (hereinafter referred to as JVT Codec) standardized by the Joint Video Team mentioned above, various methods are being studied in order to improve the coding efficiency of MPEG2 and MPEG4. For example, as the conversion method of the discrete cosine transform, an integer coefficient transform of 4 × 4 block size is used. The block size at the time of motion compensation is variable, so that more optimal motion compensation can be performed. However, the basic method can be performed in the same manner as the coding method performed in the image information coding device 10 shown in FIG. [0024] Therefore, it is possible to decode by basically the same method as the decoding method performed in the image information decoding device 40 shown in FIG. [0025] By the way, in order to maintain compatibility between different decoding devices (decoders) and prevent the buffer from overflowing or underflowing, a buffer model is introduced in MPEG and ITU-T. The virtual decoder buffer model is defined as standard, and the encoder (encoder) encodes this virtual decoder buffer so as not to fail to prevent buffer overflow or underflow on the decoder side and maintain compatibility. Is possible. [0026] The virtual buffer model in MPEG will be described with reference to FIG. In the following description, the input bit rate to the decoder buffer is R, the size of the decoder buffer is B, the buffer occupancy when the decoder pulls out the first frame from the buffer is F, and the delay time at that time is D. Further, the bit amount of each frame at the time t0, t1, t2, ... Is b0, b1, b2 .... [0027] If the frame rate is M here, t_{i + 1}-t_i= 1 / M holds. [0028] B_i, Time t_iFrame bit amount in b_iThe following equation (1) holds when the buffer occupancy immediately before pulling out is used. B₀= F B_{i + 1}= min (B, B_iB_i+ R (t_{i + 1}-t_i)) (1) [0029] Here, in the case of the fixed bit rate coding method in MPEG2, the encoder must encode so as to satisfy the condition of the following equation (2). Bi B Bi-bi 0 (2) While such a condition is satisfied, it is said that the encoder does not perform encoding that causes a buffer overflow or underflow. [0030] Further, in the case of the variable bit rate coding method in MPEG2, the input bit rate R is the maximum bit rate defined by the profile and the level, and F = B. Therefore, Eq. (1) can be rewritten as Eq. (3) below. B₀= B B_{i + 1}= min (B, B_iB_i+ R_max(t_{i + 1}-t_i)) (3) [0031] At this time, the encoder must execute the encoding so as to satisfy the condition represented by the following equation (4). B_iB_i 0 (4) When this condition is satisfied, the encoder performs encoding so that buffer underflow does not occur on the decoder side. When the decoder buffer is full, it means that the encoder buffer is empty and no coded bitstream is occurring. Therefore, the encoder does not need to monitor the decoder for buffer overflow. [0032] In MPEG, encoding is performed based on each profile, the buffer size defined at the level, and the bit rate so as to comply with the buffer restrictions as described above. A decoder that conforms to each profile and level can decode the bitstream without breaking it. [0033] [Problems to be Solved by the Invention] However, it may be possible to decode the bitstream even if the profile, the buffer size specified for the level, and the bit rate are not actually used. [0034] For example, a bitstream encoded with bitrate R, buffer B, initial delay time F (R, B, F) can also be decoded by a decoder with a larger buffer size B'(B'&gt; B). .. It is also possible to decode at a higher bit rate R'(R'&gt; R). [0035] For example, even when the decoding bit rate of the decoder is lower than the coding bit rate, any decoder having a sufficiently large buffer size can decode the decoder. [0036] Thus, given a given bitstream, at each bitrate, the minimum buffer size B required to decode that bitstream._minExists. Such a relationship is shown in Fig. 4. [0037] In JVT Codec, standardization is being promoted so that not only decoding can be performed with a fixed bit rate and buffer size for each profile and level, but also decoding can be performed with a decoder having the conditions shown in FIG. The purpose is to be able to decode even if the encoder's coding bit rate, the buffer size and the decoder's decoding bit rate, and the buffer size are not the same. By achieving this purpose, for example, in a decoder having a high decoding bit rate, it is possible to reduce the buffer size. [0038] However, such information varies over time in the bitstream. Therefore, since the restrictions for decoder compatibility are relaxed, there is a problem that even if decoding is possible under a predetermined condition, decoding may not be possible under another condition. For example, when such characteristics of (R, B) fluctuate with time, there is a problem that even if decoding is possible at a predetermined time, decoding may not be possible at another time. [0039] There is a problem that decoding is not always possible even when moving to another scene or another channel due to random access or the like. In addition, when editing at the bitstream level such as splicing, there is a problem that the decoding possibility cannot be guaranteed. [0040] The present invention has been made in view of such a situation, and an object of the present invention is to efficiently determine the decryptability of a bitstream and to make it easy to edit a bitstream such as splicing. [0053] [Means for solving problems] The editing device of the present invention is used when decoding a bitstream contained in a header inserted at each predetermined interval that can be randomly accessed in an input bitstream.<u style="single">Of the buffer that stores the bitstream in</u>With buffer size<u style="single">With the input bitrate to the buffer</u>When determining whether a bitstream is decodable according to the combination of<u style="single">As a criterion for</u>Read the buffer characteristic information to be used, and based on the read information<u style="single">、</u>Bitstream<u style="single">Bitstream connected at edit point decodes without breaking the decoder buffer</u>By the judgment means to judge whether it is possible and the judgment means<u style="single">Decryption</u>Bitstream if determined to be possible<u style="single">Connect at edit points</u>Judgment means, including editing means for editing, are included in the buffer characteristic information contained in the header of the first bitstream.<u style="single">The first with the indicated buffer size and input bitrate as variables</u>The characteristic curve is included in the buffer characteristic information contained in the header of the second bitstream.<u style="single">A second variable with the indicated buffer size and input bitrate</u>First bitstream and second bitstream if they are always above or identical to the characteristic curve<u style="single">And the bitstream connected at the edit point decodes without breaking the decoder buffer</u>Judge that it is possible. [0054] The editing method of the present invention is used when decoding a bitstream included in a header inserted at each predetermined interval that can be randomly accessed in an input bitstream.<u style="single">Buffer to store the bitstream in</u>Buffer size and<u style="single">With the input bitrate to the buffer</u>When determining whether a bitstream is decodable according to the combination of<u style="single">As a criterion for</u>Read the buffer characteristic information to be used, and based on the read information<u style="single">、</u>Bitstream<u style="single">Bitstream connected at edit point decodes without breaking the decoder buffer</u>In the judgment step to judge whether it is possible and the processing of the judgment step<u style="single">Decryption</u>Bitstream if determined to be possible<u style="single">Connect at edit points</u>The processing of the judgment step, including the editing step for editing, is added to the buffer characteristic information included in the header of the first bitstream.<u style="single">The first with the indicated buffer size and input bitrate as variables</u>The characteristic curve is included in the buffer characteristic information contained in the header of the second bitstream.<u style="single">A second variable with the indicated buffer size and input bitrate</u>First bitstream and second bitstream if they are always above or identical to the characteristic curve<u style="single">And the bitstream connected at the edit point decodes without breaking the decoder buffer</u>Judge that it is possible. [0059] In the editing apparatus and method of the present invention, the header is included in the header inserted at each predetermined interval that can be randomly accessed in the input bit stream.<u style="single">Bitstream</u>When decoding<u style="single">Buffer to store the bitstream in</u>Buffer size and<u style="single">With the input bitrate to the buffer</u>When determining whether a bitstream is decodable according to the combination of<u style="single">As a criterion for</u>The buffer characteristic information to be used is read, and based on the read information, the buffer characteristic information included in the header of the bitstream is used.<u style="single">The first with the indicated buffer size and input bitrate as variables</u>The characteristic curve is included in the buffer characteristic information contained in the header of the second bitstream.<u style="single">A second variable with the indicated buffer size and input bitrate</u>First bitstream and second bitstream if they are always above or identical to the characteristic curve<u style="single">And the bitstream connected at the edit point decodes without breaking the decoder buffer</u>Bitstream if determined to be possible<u style="single">Connect at edit points</u>Editing is done. [0060] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 5 is a diagram showing a configuration of an embodiment of a coding device to which the present invention is applied. The coding device 70 shown in FIG. 5 is configured to include the image information coding device 10 shown in FIG. Here, since the configuration of the image information encoding device 10 and the like have already been described, the description thereof will be omitted as appropriate. [0061] The image information input to the image information coding device 10 is encoded and output to the buffer 71 and the bitstream analysis unit 72 as image compression information (BS: bitstream). The buffer 71 temporarily stores the input bit stream, and outputs the input bit stream to the buffer information addition unit 73 as needed. The bitstream analysis unit 72 examines a predetermined section in the bitstream, for example, the occupancy state of the buffer between GOPs and random access points, and supplies the information as buffer information BH to the buffer information addition unit 73. Here, the random access point refers to a predetermined section that can be randomly accessed in the bit stream in the JVT standard. Similarly, GOP refers to a predetermined section that can be accessed randomly in the MPEG2 / MPEG4 standard. [0062] The buffer information addition unit 73 adds the input buffer information BH to the input bit stream and outputs it. [0063] Here, as an example of the analysis performed by the bitstream analysis unit 72, a case where the buffer occupancy state is checked between each random access point and the buffer occupancy state information is encoded as header information in each random access point to form a bitstream. Will be described as an example. Although such an explanation is given here, it may be obtained in GOP units or in any other unit, and when other units are used as the units described below. Needless to say, the present invention can be applied. [0064] See Figure 6 (R)_min, B_min) Will be described below. Where R_minIndicates the minimum value of the input bit rate R to the buffer, B_minIndicates the minimum value of buffer size B. [0065] Given the bit rate R of a given bitstream, the minimum buffer size B that can be decoded by a decoding device (eg, having the configuration shown in FIG. 7) that decodes that bitstream at the decoding bit rate R._minIs determined, for example, as follows. [0066] Let N be the number of frames between predetermined access points. The amount of generated bits for each frame is b (i) (i = 1, N), the buffer occupancy immediately before extracting the data of each frame from the buffer is B (i), and the buffer occupancy immediately after extraction is B2 (i). And. If the buffer amount of the encoder is B, B2 (i) = B (i) b (i) B (i + 1) = B2 (i) + R / (Frame Rate) (5) However, if (B (i + 1)&gt; B) B (i + 1) = B, and the maximum value of B (i) is B. The delay amount F is F = B. [0067] At this time, B_minIs calculated by the following equation (6). B_min= Bmin (B2 (i)) (6) R at this time is R_minIf so, by the above method (R_min, B_min) Can be determined. [0068] Then (R_min, B_min, F_min) Will be described as an example of the method for determining. B = B_min, R = R_minAnd. Similar to equation (5), the following equation (7) holds. B2 (i) = B (i) -b (i) B (i + 1) = B2 (i) + R / (Frame Rate) (7) Will be. However, underflow is monitored based on the following conditions. if (B2 (i) &lt;0) { F_min= F_min+ (0B2 (i)); B2 (i) = 0;} [0069] F_minIs initialized to 0 at the beginning of each random access point. Similarly, monitoring for overflow is performed based on the following conditions. if (B (i + 1)&gt; B) B (i + 1) = B By performing the above inspection on all frames between random access points, (R_min, B_min, F_min) Is determined. [0070] Above (R_min, B_min, F_min) May be inspected in a predetermined number of predetermined numbers, or only independent combinations may be defined among them. The characteristics obtained as described above are shown in FIG. Linear interpolation is performed between each point. Obtained as above, (R_min, B_min, F_min), The buffer information BH is inserted at a predetermined position in the bit stream by the buffer information addition unit 73, encoded, and output. [0071] The bitstream analysis unit 72 performs (R) between each random access as described above._min, B_min, F_min) At the same time, the same analysis is performed for the entire bitstream, and the characteristics for the entire bitstream, (R_min, B_min, F_min) Global is determined, and this value is supplied to the buffer information addition unit 73 as buffer information BH. [0072] The bitstream BS output from the image information encoding device 10 is delayed by a predetermined time in the buffer 71, and then input to the buffer information addition unit 73. The buffer information addition unit 73 inserts the buffer information BH supplied by the bitstream analysis unit 72 at a predetermined position in the bitstream, and outputs the final output bitstream BS. [0073] Here, the buffer information BH (or buffer characteristic information) is, for example, (R)._min, B_min, F_min) And (R_min, B_min, F_min) Global. The buffer information addition unit 73 inserts the above information at a predetermined position in the bitstream BS. Here, an example of the syntax will be described below. [0074]<img file="JP4875285B2_D0001.tif" />[0075] Between random access points (R_min, B_min, F_min) Is recorded, for example, in the random access point header immediately before it, as in the above syntax. RAP_startcode is a code that indicates the start of the RAP header, which exists. [0076] closed_GOP is a flag indicating whether all the pictures in the GOP are independent without referencing the pictures of other GOPs, or whether there is a dependency of referencing the pictures of other GOPs. broken_link is a flag indicating whether or not the predicted reference image exists when the bitstream is replaced before and after the GOP by editing or the like. [0077] NumBuffer_Param is the obtained characteristic set (R)_min, B_min, F_min) Indicates the number. Rate [i], Buffer [i], F [i] are R_min, B_min, F_minShown. Here, for example, R_minAre recorded in ascending order. [0078] (R) for the entire bitstream_min, B_min, F_min) Global is recorded, for example, in the sequence header at the beginning of the bitstream as in the following syntax. [0079]<img file="JP4875285B2_D0002.tif" />[0080] [0080] Here, NumBuffer_Param is the obtained characteristic set (R)._min, B_min, F_min) Indicates the number of global. Rate [i], Buffer [i], F [i] are R_min, B_min, F_minIs shown. Here, for example, R_minAre recorded in ascending order. [0081] In the buffer information addition unit 73, after the above buffer information BH is added, the final output bitstream BS is output. [0082] In the embodiment of the invention, it has been described that all of the minimum bit rate Rmin, the minimum buffer size Bmin, and the minimum delay amount Fmin are added to the bit stream as the buffer information BH. However, not limited to this example, at least one of the minimum bit rate Rmin, the minimum buffer size Bmin, and the minimum delay amount Fmin may be added to the bitstream. For example, a combination of a minimum bit rate Rmin and a minimum buffer size Bmin may be added to the bitstream. [0083] FIG. 7 shows a configuration of an embodiment of a decoding device to which the present invention is applied. The decoding device 90 shown in FIG. 7 corresponds to the coding device 70 shown in FIG. 5, and includes the image information decoding device 40 shown in FIG. 2 inside. The bitstream BS input to the decoding device 90 is supplied to the bitstream analysis unit 91 and the decoding possibility determination unit 92. [0084] The bitstream analysis unit 91 decodes the buffer information BH in the bitstream and outputs it to the decoding possibility determination unit 92. The bitstream analysis unit 91 parses the bitstream and records it in the sequence header (R)._min, B_min, F_min) Decrypt global. Also, it is recorded in each random access point header, (R_min, B_min, F_min) Is decrypted. This information is output to the decodability determination unit 92. [0085] The decoding possibility determination unit 92 determines whether or not the input bit stream can be decoded without breaking the buffer based on the buffer information BH and the decoder information DI supplied from the image information decoding device 40. The decoder information DI is, for example, the decoder buffer size and the decoding bit rate. [0086] Decryptability determination unit 92 is (R_min, B_min, F_min) From global, create a characteristic curve as shown in Fig. 4. Linear interpolation is performed between each point. At this time, the buffer and decoding bit rate of the decoder (decoding device 90) are (R)._min, B_min, F_min) If it is located above the characteristic curve created by global, it is possible to determine that the input bitstream is decodable. Therefore, in such a case, the decoding possibility determination unit 92 determines that the decoding is possible and supplies the bit stream to the image information decoding device 40. [0087] The image information decoding device 40 has basically the same configuration as the image information decoding device 40 shown in FIG. 2, performs the same processing, decodes the input bit stream, and displays the image information on a television (not shown). Output to John receiver, etc. [0088] Whether or not the entire bitstream can be decrypted is determined by (R) as described above._min, B_min, F_min) It can be determined by examining the global characteristic curve, decoder buffer size, and decoding bit rate. [0089] Further, when it is desired to decode only a specific section from a predetermined random access point by random access or the like, the decoding possibility determination unit 92 similarly performs (R._min, B_min, F_min) To create a characteristic curve as shown in Fig. 4. Linear interpolation is performed between each point. At this time, the decoder buffer and decoding bit rate are (R)._min, B_min, F_min) Is above the characteristic curve created by), the bitstream is decodable. Therefore, in such a case, the decoding possibility determination unit 92 determines that the decoding is possible and supplies the bit stream to the image information decoding device 40. [0090] Next, a description will be given when editing the bitstream. FIG. 8 is a diagram showing a configuration of an embodiment of an editing device 110 that edits a bit stream to which the present invention is applied. As an example of editing performed by the editing device 110, a case where a part of the input bit stream 1 is replaced with another input bit stream 2 will be described as an example. [0091] Here, to briefly explain the splice, the splice is to replace a predetermined bit stream with another bit stream at a random access point for editing. Such a splice is, for example, when inserting a commercial broadcast into a television broadcast program. In this case, the input bitstream 1 is the bitstream of the television broadcast program and the input bitstream 2 is the commercial bitstream. [0092] The input bitstream 1 is input to the bitstream analysis unit 111-1, and the input bitstream 2 is input to the bitstream analysis unit 111-2. The bitstream analysis units 111-1 and 111-2 decode the buffer information BH1 and 2 contained in the input bitstreams 1 and 2, respectively, and output the buffer information BH1 and 2 to the bitstream editing unit 112. [0093] The bitstream editing unit 112 determines whether or not the input bitstream 2 can be inserted into the input bitstream 1 at a predetermined editing point based on the buffer information BH1 and 2. At this time, in order for the edited bitstream to be able to be decoded without breaking the buffer of the decoder (decoding device 90), the condition that the value of the buffer occupancy immediately before the random access point is the same is the condition. is necessary. [0094] Decoders that use the MPEG2,4 method were supposed to operate at a specific bit rate and buffer size, but decoders that use the JVT method were supposed to operate at other bit rates and buffer sizes, as shown in Fig. 4. Even if there is (R_min, B_min, F_minIf it is above the characteristic curve of), the constraint on the buffer is relaxed so that it can be decoded. [0095] In order to prevent the decoding possibility from changing before and after editing a bitstream by editing the bitstream, (R) in the editing section_min, B_min, F_min) Is the same. Therefore, the bitstream editorial unit 112 has (R) in the random access point header located in the edit section._min, B_min, F_min) Characteristics are created for input bitstreams 1 and 2, and if these values match, the interval is replaced with bitstream 2. If they do not match, insert a padding bit for bitstream 1 or 2 and (R_min, B_min, F_min) Match, then replace with input bitstream 2. [0096] In JVT, restrictions on buffers have been relaxed, and this can be used to relax the conditions for buffer conformance in splices. In JVT, the decoder buffer size and decoding bit rate are (R)._min, B_min, F_minIf it is located above), it is known that it can be decrypted. Therefore, (R) of a given edit interval of the original input bitstream 1_min, B_min, F_min) For (R) of the predetermined edit interval of the input bitstream 2 to be inserted._min, B_min, F_minIf) is always below, a decoder that can decode the input bitstream 1 will be able to decode it even if the interval is replaced with bitstream 2. [0097] The relationship is illustrated in FIG. Curve 1 is the (R) in the edit interval of the input bitstream 1._min, B_min, F_min) Show characteristics. Curve 2 is the (R) in the edit interval of the input bitstream 2._min, B_min, F_min) Show characteristics. If the decoder buffer, the decoding bit rate, is above this curve, it is decodable, so it is guaranteed that it is decodable when curve 2 is always below curve 1, as shown in FIG. The curve. [0098] Therefore, the bitstream editorial unit 112 has (R) in the random access point header located in the edit section._min, B_min, F_min) A characteristic is created for bitstreams 1 and 2, and if the characteristic curve of bitstream 2 is below the characteristic curve of bitstream 1, the interval is replaced with bitstream 2. [0099] Conversely, if they do not match, insert a padding bit into bitstream 1 or 2 to get bitstream 2 (R)._min, B_min, F_min) After changing the characteristic curve so that it is located below the characteristic curve of bitstream 1, replace it with input bitstream 2. [0100] When splicing is performed so as to satisfy such a condition, the decoder capable of decoding the bitstream 1 will not be disrupted. The bitstream editorial unit 112 outputs the final bitstream after splicing. [0101] In this way, in the header of the point where random access is possible in the bitstream, (R_min, B_min, F_minBy including information such as the minimum bit rate, minimum buffer size, minimum initial delay time, etc., the decoding side can efficiently judge the decipherability of the bitstream, and the bitstream such as splicing. It is possible to easily edit the data and always perform decoding without breaking the buffer on the decoding side. [0102] FIG. 10 is a diagram showing an example of the internal configuration of a general-purpose personal computer. The CPU (Central Processing Unit) 211 of the personal computer executes various processes according to the program stored in the ROM (Read Only Memory) 212. The RAM (Random Access Memory) 213 appropriately stores data and programs necessary for the CPU 211 to execute various processes. The input / output interface 215 is connected to an input unit 216 composed of a keyboard and a mouse, and outputs a signal input to the input unit 216 to the CPU 211. An output unit 7 composed of a display, a speaker, and the like is also connected to the input / output interface 215. [0103] Further, the input / output interface 215 is also connected to a storage unit 218 composed of a hard disk and the like, and a communication unit 219 that exchanges data with other devices via a network such as the Internet. The drive 220 is used when reading or writing data from a recording medium such as a magnetic disk 231, an optical disk 232, a magneto-optical disk 233, or a semiconductor memory 234. [0104] As shown in FIG. 10, the recording medium is a magnetic disk 231 (including a flexible disk) on which the program is recorded and an optical disk 232 (CD-), which are distributed to provide the program to the user separately from the personal computer. ROM (Compact Disc-Read Only Memory), DVD (Digital Versatile) Not only composed of packaged media consisting of (including Disc), magneto-optical disc 233 (including MD (Mini-Disc) (registered trademark)), or semiconductor memory 234, but also pre-installed in a computer. It consists of a ROM 212 for storing programs and a hard disk including a storage unit 218 provided to the user. [0105] In the present specification, the steps for describing the program provided by the medium are processed in chronological order according to the order described, and are not necessarily processed in chronological order, but are arranged in parallel or individually. It also includes the processing to be executed. [0106] Further, in the present specification, the system represents an entire device composed of a plurality of devices. [0109]<u style="single">[Effect of the invention]</u><u style="single">The present invention</u>According to the editing device and method of the above, it is possible to reduce the processing related to editing such as splices and to easily determine whether or not editing is possible. [Simple explanation of drawings] FIG. 1 is a diagram showing a configuration of an example of a conventional image information coding device. FIG. 2 is a diagram showing a configuration of an example of a conventional image information decoding device. FIG. 3 is a diagram illustrating a buffer amount. FIG. 4 is a diagram illustrating a relationship between a bit rate and a buffer amount. FIG. 5 is a diagram showing a configuration of an embodiment of a coding device to which the present invention is applied. FIG. 6 is a diagram illustrating a buffer amount. FIG. 7 is a diagram showing a configuration of an embodiment of a decoding device to which the present invention is applied. FIG. 8 is a diagram showing a configuration of an embodiment of an editing device to which the present invention is applied. FIG. 9 is a diagram illustrating a relationship between a bit rate and a buffer amount. FIG. 10 is a diagram illustrating a medium. [Explanation of symbols] 70 Encoding device, 71 Buffer, 72 Bitstream analysis unit, 73 Buffer information addition unit, 90 Decoding device, 91 Bitstream analysis unit, 92 Decoding possibility determination unit, 111 Bitstream analysis unit, 112 Bitstream editorial department