JP2010041353A - Moving image decoding method, decoding device and decoding program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To randomly access and decode efficiently encoded moving image encoded signals by performing DPB (Decoded Picture Buffer) control holding a random access point there between while guaranteeing random access at the random access point. <P>SOLUTION: When DPB information is added to the header of an image obtained by performing decoding in an entropy decoding section 202, a DPB initialization section 203 initializes a DPB 207 according to the DPB information. The DPB information includes the image information (a number depending on a decoding order and a number depending on the display order of the image) of all the images present in the DPB inside the moving image encoding device at the point of time of detecting the random access point or the like. Thus, even when a DPB control signal for controlling the DPB holding the random access point there between is included in a bit stream, decoding is performed without a failure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a moving picture decoding method, a decoding apparatus, and a decoding program, and in particular, a moving picture decoding method having a function of controlling a decoded picture memory (DPB: Decoded Picture Buffer) used for motion compensation prediction of a moving picture, The present invention relates to a decoding device and a decoding program.

  In moving picture compression coding represented by MPEG (Moving Picture Experts Group), a correlation between neighboring pixels in a picture that is a frame image or a field image constituting one screen or a correlation between pictures is used. A method of compressing the code amount is used. Redundancy due to correlation between neighboring pixels in a picture can be reduced by performing orthogonal transformation represented by Discrete Cosine Transform (DCT). Redundancy due to correlation between pictures can be reduced by performing motion compensation prediction.

  In motion compensated prediction using correlation between pictures, prediction is performed between pictures using a reference image decoded before the current picture. Specifically, as shown in FIG. 11, motion compensation prediction is performed using a reference image stored in a decoded image memory 11 called a DPB (Decoded Picture Buffer). In the example of FIG. 11, the block of picture 1 among the plurality of reference images stored in the DPB 11 at the time of motion compensated prediction of the block 13 that is a rectangular area including a plurality of pixels set in advance in the encoding target picture 12. Is used.

  DPB is used not only for storing reference images but also for controlling the output order of pictures. Specifically, as in the example shown in FIG. 12, when the pictures encoded / decoded in the numerical order shown in FIG. 12B are displayed in the time order indicated by the arrows, the pictures are encoded. Since the decoding / decoding order is not the same as the picture display order, in order to reproduce each picture as a moving picture, the picture encoded / decoded before the display time is displayed until the picture display time is reached. As shown in A), the DPB 14 is temporarily held.

  Thus, the DPB is used for the purpose of accumulating reference images and waiting for output images. However, a DPB for storing picture pixel value data requires a very large amount of memory, and a memory with a large amount of memory is extremely expensive. In addition, in a video decoding device, there is a restriction on the amount of DPB memory. For this reason, on the moving image encoding side, it is necessary to generate a bitstream by controlling so that the number of pictures stored in the DPB does not exceed a predetermined number.

  Therefore, encoding methods such as MPEG-4 and AVC make it possible to control the DPB in detail in order to maximize the encoding efficiency under the condition that the number of pictures stored in the DPB is limited. ing. By controlling the DPB in detail, it is possible to accumulate the most suitable picture as the reference image in the DPB and perform highly accurate motion compensation prediction.

  However, in order to guarantee random access at a specific position (random access point) of the encoded video signal, not only the reference image is limited so that motion compensation prediction is not performed across the random access point. The signal that controls the DPB must also be limited.

  The random access at the random access point will be described with reference to FIG. In FIG. 13, five pictures 0 to 4 constitute group A, and subsequently displayed five pictures 5 to 9 constitute group B. Furthermore, picture 0 and picture 5 are random. It is an access point, and other pictures are not random access points. Here, the number of each picture indicates the decoding order of the picture. Therefore, FIG. 13 shows an example in which the decoding order and the display order of each picture are the same. A group refers to a picture from a random access point to a picture immediately before the next random access point picture in decoding order.

  Now, guaranteeing random access means that pictures after the random access point can be normally reproduced when decoding processing is started from the random access point. This is because when an appropriate picture as a reference image is stored in the DPB, if a memory operation is performed to control the DPB across the random access point, the memory operation is performed when decoding is started from the random access point. This is because there is a problem in decoding because there is no target picture in the DPB.

  In order to prevent such decoding problems, it is not possible to perform a DPB memory operation for a picture in group A for a picture in group B in FIG. That is, in order to guarantee random access at a random access point, it is necessary to prohibit memory operations such as controlling the DPB across the random access point. For this reason, conventionally, an IDR picture is prepared at a random access point, and when the IDR picture is reproduced, the DPB is forcibly cleared, so that an arbitrarily separated picture can be encoded unless it crosses the IDR picture. The encoding can be performed by rearranging the order.

  However, since the encoded stream cannot be edited outside the IDR picture location, conventionally, information indicating that the order of pictures is discontinuous is added to the encoded stream, and it is composed of a plurality of pictures. A picture whose display order is later than the first intra-picture coded picture in a given coding unit is coded so that it is included in the coding unit, so that editing such as random access is possible without initializing the DPB. Is known in the art (for example, see Patent Document 1).

JP 2004-274732 A

  However, in the conventional moving image encoding / decoding device described in Patent Document 1, a stream that prohibits memory operation that controls DPB across a random access point is generated and decoded. DPB control cannot be performed across the access point, and as a result, a picture suitable as a reference image cannot be stored as a reference image in the DPB, resulting in a decrease in coding efficiency.

  The present invention has been made in view of the above points, and by performing DPB control across a random access point while guaranteeing random access at a random access point, an efficiently encoded moving image encoded signal can be obtained. It is an object of the present invention to provide a moving picture decoding method, a decoding apparatus, and a decoding program that can be decoded by random access.

  In order to achieve the above object, a moving picture decoding method according to the present invention includes a picture to be coded and a first decoded picture memory in coding of a moving picture signal in units of pictures as one picture. This is a bitstream including a coded signal in units of pictures obtained by performing entropy coding by performing motion compensation prediction using a reference image that has already been read and is a locally decoded picture. The decoding order of each picture stored in the first decoded image memory at the time of encoding a picture at a random access point set to one picture enabling reproduction of a picture after one picture is shown Control information including at least one of information and information indicating the playback / display order is added to the encoded signal of the picture of the random access point. An entropy decoding step for entropy decoding the received bitstream, and motion compensation using the already decoded picture read from the second decoded image memory as a reference image for the signal decoded by the entropy decoding step A picture of a moving image signal is decoded by performing prediction, and a picture to be a reference image in the decoded picture is included in information indicating the decoding order of the picture and information indicating a reproduction display order. A picture decoding step stored in the second decoded image memory together with at least one information, a detection step for detecting control information from the signal decoded by the entropy decoding step, and a point in time when the control information is detected in the detection step Information indicating the decoding order of each picture stored in the second decoded image memory And at least one of information of the information indicating the reproduction display order, characterized in that it comprises an initialization step for initializing the corresponding information including the detected control information.

  In order to achieve the above object, the moving picture decoding apparatus according to the present invention includes a picture to be coded and a first decoded picture in coding of a moving picture signal in units of pictures as one picture. It is a bitstream comprising a picture-unit coded signal obtained by entropy coding by performing motion compensation prediction using a reference picture that is a locally decoded picture read from a memory, and is reproduced and displayed at the time of decoding. Decoding order of each picture stored in the first decoded picture memory at the time of encoding a picture of a random access point set to one picture enabling reproduction of the picture after one picture in order Control information including at least one of the information indicating the display order and the information indicating the playback display order is included in the encoded signal of the picture of the random access point. Entropy decoding means for entropy decoding the added bitstream, a second decoded image memory for storing the decoded picture, and a second decoding for the signal decoded by the entropy decoding means A motion compensated prediction using the already decoded picture read from the image memory as a reference image is performed to decode a picture of the moving image signal, and a picture to be a reference image in the decoded picture is Control from the picture decoding means stored in the second decoded image memory together with at least one of the information indicating the picture decoding order and the information indicating the reproduction display order, and the signal decoded by the entropy decoding means Detecting means for detecting information and stored in the second decoded image memory at the time when the control information is detected by the detecting means; Initializing means for initializing at least one of the information indicating the decoding order of each picture and the information indicating the reproduction display order to the corresponding information included in the detected control information, To do.

  Furthermore, in order to achieve the above object, a moving picture decoding program of the present invention causes a computer to execute each step of the moving picture decoding method of the first invention.

  According to the present invention, the first decoded image memory at the time of encoding the picture of the random access point set to one picture that can reproduce the picture after the first picture in the reproduction display order at the time of decoding. A bit stream in which control information including at least one of information indicating the decoding order of each picture and information indicating the reproduction display order stored in the picture is added to the encoded signal of the picture of the random access point By detecting the control information from the entropy-decoded signal and initializing the corresponding information included in the control information on the basis of the detected control information, the random access is ensured at the random access point. DPB control can be performed with the point in between, and the encoded video signal is efficiently encoded. It can be decoded by the dam access.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  First, a moving picture decoding method, a decoding apparatus, and a moving picture coding method and a coding apparatus for generating a moving picture coded signal to be decoded by a decoding program according to the present invention will be described.

  FIG. 1 is a block diagram showing an example of a moving picture coding apparatus for generating a moving picture coded signal to be decoded according to the present invention. In FIG. 1, the moving image encoding apparatus 100 detects a motion vector from an input terminal 101 to which an image signal to be encoded is input, and the input image signal and a reference image stored in the decoded image memory 108. A motion vector detection unit 102; a motion compensation prediction 103 that performs motion compensation prediction using the detected motion vector; a subtraction unit 104 that subtracts the motion compensation signal from the input image signal; an orthogonal transform / quantization unit 105; Unit 106, inverse quantization / inverse orthogonal transform unit 107, decoded picture memory (DPB) 108, DPB information generation unit 109, random access point signal input terminal 110, entropy encoding unit 111, , And a bit stream output terminal 112. This moving image encoding apparatus 100 is characterized in that it includes a DPB information generation unit 109.

  Next, the operation of the moving picture coding apparatus 100 will be described. An image signal of a moving image input via the input terminal 101 is supplied to the subtraction unit 104 and is also supplied to the motion vector detection unit 102. The motion vector detection unit 102 is stored in the DPB 108 in units of a rectangular area (macroblock) composed of a predetermined number of pixels in a picture that is a frame image or a field image constituting one screen of an image signal of an input moving image. The motion vector is detected by moving within the search range of the reference image signal and performing block matching with the macroblock of the reference image signal.

  The motion compensation unit 103 performs motion compensation prediction based on the reference image signal supplied from the DPB 108 using the motion vector detected by the motion vector detection unit 102, and generates a motion compensation prediction signal. The subtracting unit 104 supplies an I picture obtained by performing intra prediction encoding without using a reference image signal as an input image signal to the orthogonal transform / quantization unit 105 without subtraction (in MPEG2, subtracting from the input image signal) (Intra-frame encoding is performed without MPEG, but in MPEG-4 AVC and the like, subtraction is also performed on I pictures to perform intra-frame predictive encoding.)

  On the other hand, the subtracting unit 104 obtains a P picture that performs predictive coding with reference to only one reference image, or two reference images that are arbitrarily combined among two reference images before or after in time. In the case of a B picture for which predictive encoding is performed with reference, subtraction is performed between the input image signal and the motion compensated prediction signal, and the difference signal is supplied to the orthogonal transform / quantization unit 105.

  The orthogonal transform / quantization unit 105 performs orthogonal transform such as discrete Fourier transform (DCT) on the signal input from the subtraction unit 104, and then quantizes the orthogonal transform coefficient obtained thereby. The inverse quantization / inverse orthogonal transform unit 107 performs inverse quantization on the quantized signal output from the orthogonal transform / quantization unit 105 and then performs inverse orthogonal transform to decode the difference signal and the like.

  The addition unit 106 decodes the picture of the input image signal by adding the motion compensated prediction signal from the motion compensation unit 103 and the signal after inverse orthogonal transform from the inverse quantization / inverse orthogonal transform unit 107, and decodes the decoded picture. The converted picture is stored in the DPB 108 as a reference image signal.

  When a signal indicating that the picture to be encoded is a random access point is input from the random access point signal input terminal 110, the DPB information generation unit 109 indicates DPB information indicating all stored pictures at that time in the DPB 108. Is generated. Here, the random access point is a point indicating a leading picture that enables playback of subsequent pictures in the display order.

  Next, the operation of the DPB information generation unit 109 will be described in detail with reference to the flowchart of FIG.

  The DPB information generation unit 109 monitors whether or not a signal indicating that the picture to be encoded is a random access point is input (step S11), and a signal indicating that it is a random access point is input. When this is detected, all the picture information (numbers depending on the decoding order, numbers depending on the display order of pictures) in the DPB 108 at the time of detection is collected, and current DPB information is generated from these (step S12). .

  For example, as shown in FIG. 3, it is assumed that the current picture stored in the DPB 108 is a total of four pictures 31-34. The decoding order of the first picture 31 is “1”, the display order is “1”, the decoding order of the second picture 32 is “2”, and the display order is “4”. It is assumed that the decoding order of the picture 33 of the eye is “5”, the display order is “7”, the decoding order of the fourth picture 34 is “9”, and the display order is “8”.

  The DPB information generation unit 109 in FIG. 1 includes a signal indicating that it is a random access point, and picture information of all four pictures 31 to 34 in the DPB 108 at the time of detection of the random access point (numbers depending on the decoding order). , A number that depends on the display order of pictures), DPB initialization information, DPB control signals, and the like are supplied as DPB information to an entropy encoding unit 111, which will be described later, and added to the bitstream as a header. As a result, even when random access is performed to a portion where DPB control is performed across the random access point, decoding can be performed without any problem, and therefore, random access at the random access point can be guaranteed. A detailed description of random access will be given in a video decoding device to be described later.

  Returning to FIG. The entropy encoding unit 111 in FIG. 1 uses the DPB information generation unit 109 to generate the encoded data of each picture obtained by entropy encoding the quantized signal output from the orthogonal transform / quantization unit 105. Information is added as header information and entropy-coded.

  FIG. 4 shows an exemplary configuration of picture data in the bit stream output from the entropy encoding unit 111. As shown in FIG. 4, the picture data includes a flag (recovery point) 41 indicating whether or not it is a random access point, DPB information 42 generated by the DPB information generation unit 109, and other DPB control signals including a DPB control signal described later. In this configuration, the header 43 and the encoded data 44 are synthesized in time series. When the flag 41 has a predetermined value indicating a random access point, it is detected as a random access point signal.

  A bit stream, which is a time-series synthesized signal of the picture data output from the entropy encoding unit 111, is recorded on a recording medium by a known recording device (not shown) via the output terminal 112, or connected to a communication network. Delivered through.

  As described above, the encoding apparatus 100 having the configuration shown in FIG. 1 adds the DPB information related to the stored picture of the DPB 108 at that time to the bit stream at the random access point, as described later, and randomly Since DPB control can be performed across a random access point while ensuring random access at the access point, coding efficiency can be improved.

  Next, a DPB control method will be described. First, a detailed control method of a general DPB will be described with reference to FIG. In FIG. 5, parallelograms indicate pictures, and the numbers in the pictures indicate the decoding order. In the example of FIG. 5, it is assumed that the limit on the number of pictures stored in the DPB is four.

  FIG. 5A shows a state where encoding / decoding has been completed for pictures 0 to 3, and all the pictures are stored in the DPB. FIG. 5B shows a state where the encoding / decoding is further completed for the picture 4, and in order to store the picture 4 in the DPB, at least of the pictures 0 to 3 in the DPB. One picture needs to be erased from the DPB.

  In the conventional encoding method, the DPB is implicitly controlled by erasing from the DPB in order from the old picture in a method called FIFO (First In, First Out). However, this FIFO method cannot cope with the case where it is desired to leave the oldest picture, picture 0, as a reference image in the DPB.

  Therefore, it is possible to control the DPB in detail by adding information on the picture number to be erased to the bit stream. That is, by explicitly adding information that the picture to be erased is picture 1 to the bitstream, picture 0 in DPB is erased by erasing picture 1 in DPB as shown in FIG. Can be left in. Similarly, FIG. 5C shows a state in which encoding / decoding has been completed for picture 5, and shows a state in which picture 2 has been deleted in order to store picture 5 in the DPB.

  As described above, since it is possible to control the DPB in detail, an appropriate picture as a reference image can be stored as a reference image in the DPB, and as a result, motion compensation prediction with high accuracy can be performed. Efficiency can be improved.

  Next, an example of DPB control capable of improving the encoding efficiency of the moving image encoding apparatus 100 will be described with reference to FIGS. 6 and 7. FIG. 6 shows a diagram in which pictures represented by parallelograms are arranged in the display order, and the numbers in the pictures indicate the decoding (decoding) order of the pictures. Here, for convenience, in the following description, the Nth picture in the decoding order is referred to as a picture N. In addition, a picture indicated by hatching indicates a reference image, and an arrow indicates a reference image used for motion compensation prediction. For example, an arrow indicates that picture 7 performs motion compensation prediction from picture 1 and picture 6.

  Pictures 0 and 5 are random access point pictures. In addition, five pictures of pictures 0, 3, 2, 4, 1 constitute group A, and four pictures of pictures 7, 6, 8, 5 displayed subsequently constitute group B. ing. Here, the group refers to a group of pictures from a picture at a random access point to a picture immediately before a picture at the next random access point in decoding order. Here, picture 0 of the random access point is a picture in the 0th decoding order, and picture 5 of the next random access point is a picture in the 5th decoding order. A is configured, and pictures 5 to 7 form group B. Therefore, groups A and B include one random access point picture 0 and picture 5, respectively. Further, in the example of FIG. 6, the moving image encoding apparatus 100 encodes the group B picture 7 and the picture 6 by performing motion compensation prediction using the picture 1 of the different group A as a reference image.

  FIG. 7 is an explanatory diagram of DPB control that enables motion compensation prediction indicated by an arrow in FIG. 6 when the size of the DPB 108 that stores the reference image is three. FIG. 7A shows the contents stored in the DPB 108 at the time when the encoding of the picture 2 is completed. As shown in FIG. 6, picture 2 is coded using motion compensation prediction using picture 0 and picture 1 as reference images, and coded picture 2 is also used for motion compensation prediction as a reference picture of another picture. It is done. Since these pictures 0, 1, and 2 are three or less, which is the size of the DPB 108, they are stored in the DPB 108 as reference images as shown in FIG.

  Subsequently, picture 3 is encoded using motion compensation prediction using pictures 0 and 2 in DPB 108 as reference pictures as shown in FIG. 6, but picture 3 is used as a reference picture as shown in FIG. Since it is not used, it is not stored in the DPB 108. Subsequently, as shown in FIG. 6, picture 4 is encoded using motion compensation prediction using picture 2 and picture 1 in DPB 108 as reference pictures, but picture 4 is used as a reference picture as shown in FIG. Since it is not used, it is not stored in the DPB 108.

  Subsequently, picture 5 of the random access point is encoded without using another picture as a reference picture as shown in FIG. As shown in FIG. 6, the picture 5 is used as a reference image for motion compensation prediction when the pictures 6 and 8 are encoded, and thus is stored in the DPB 108. However, at the end of encoding picture 5, since pictures 0, 1, and 2 are already stored in DPB 108 as shown in FIG. 7A, in order to store picture 5 in DPB 108 It is necessary to erase one picture from the three pictures already stored.

  Here, as shown in FIG. 6, picture 0 is not used for motion compensated prediction of picture 6 to picture 8 to be encoded after picture 5 has been encoded. Therefore, when picture 5 has been encoded, FIG. As shown in FIG. 4, picture 0 is deleted and picture 5 is stored in DPB 108. This erasure can be dealt with by the FIFO method because picture 0 is stored in DPB 108 earlier than pictures 1 and 2.

  Subsequently, as shown in FIG. 6, picture 6 is encoded using motion compensation prediction using pictures 1 and 5 in DPB 108 as reference images. As shown in FIG. 6, the picture 6 is used as a reference image for motion compensation prediction when the pictures 7 and 8 are encoded, and thus is stored in the DPB 108. However, at the end of encoding picture 6, pictures 1, 2, and 5 are already stored in DPB 108 to their full size as shown in FIG. 7B, so that picture 6 is stored in DPB 108. It is necessary to erase one picture from the three pictures already stored.

  Here, for motion compensated prediction of picture 7 to picture 8 to be encoded after the encoding of picture 6, picture 2 is not used as shown in FIG. 6, but picture 1 is used as a reference image when picture 7 is encoded. In order to perform motion compensation prediction, it is necessary to accumulate in the DPB 108. Therefore, at the end of encoding picture 6, picture 2 is erased from DPB 108 before picture 1 and picture 6 is stored in DPB 108, as shown in FIG. Since this erasure cannot be handled by the FIFO method, it is handled by transmitting information for erasing picture 2 from the DPB 108 to the DPB control signal of picture 6.

  Here, since DPB control with a random access point as described above was prohibited in the past, reference images for motion compensation prediction before and after the random access point are limited, and the encoding efficiency cannot be improved. It was.

  On the other hand, in the moving picture coding apparatus 100, when the picture 5 at the random access point is detected, the DPB 108 includes three pictures 0, 1 in a group A different from the picture 5 as shown in FIG. 2 is stored, and DPB information including a number depending on the decoding order of the pictures 0, 1, and 2 and a number depending on the display order is added to the bitstream as header information. Therefore, it is possible to know the storage state of the DPB when decrypted from a random access point. Therefore, the DPB control information can be recognized without any problem by the decoding device, and DPB control with a random access point as shown in FIGS. 7B and 7C can be performed. Therefore, according to the present embodiment, it is possible to control the DPB across the random access points while guaranteeing random access at the random access points, and to improve the encoding efficiency.

  Next, an embodiment of the moving picture decoding apparatus of the present invention will be described with reference to the drawings.

  FIG. 8 shows a block diagram of an embodiment of a moving picture decoding apparatus according to the present invention. The moving picture decoding apparatus 200 according to this embodiment includes an input terminal 201 to which a bit stream generated by the moving picture encoding apparatus 100 in FIG. 1 is input via a recording medium or a distribution network, and entropy decoding. An entropy decoding unit 202, a DPB initialization unit 203 to which a signal from the entropy decoding unit 202 is supplied, a motion compensation unit 204, an inverse quantization / inverse orthogonal transform unit 205, an addition unit 206, and a decoded image And a memory (DPB) 207. The moving picture decoding apparatus 200 is characterized in that it includes a DPB initialization unit 203.

  Next, the operation of the moving picture decoding apparatus 200 will be described. The entropy decoding unit 202 performs entropy decoding of, for example, a bitstream generated by the moving image encoding apparatus 100 of FIG. 1 input from the recording medium or the distribution network via the input terminal 201, and obtains the result by decoding. The received signals are supplied to the DPB initialization unit 203, the motion compensation unit 204, and the inverse quantization / inverse orthogonal transform unit 205, respectively.

  The motion compensation unit 204 performs motion compensation prediction from the reference image signal supplied from the DPB 207 using the motion vector obtained by decoding by the entropy decoding unit 202, generates a motion compensation prediction signal, and adds the addition unit 206. Output to. The inverse quantization / inverse orthogonal transform unit 205 performs inverse quantization on the orthogonal transform quantization teacher obtained by decoding by the entropy decoding unit 202 to generate an orthogonal transform coefficient, and further inversely orthogonalizes the orthogonal transform coefficient. The data is converted and output to the adder 206.

  The adding unit 206 adds the signal output from the inverse quantization / inverse orthogonal transform unit 205 and the motion compensated prediction signal output from the motion compensation unit 204 to generate a decoded image signal, and outputs the decoded image signal. While outputting to the output terminal 208, it supplies to DPB207 as a reference image, and accumulate | stores it per picture.

  When DPB information (42 in FIG. 4) such as DPB initialization information is added to the header of the picture obtained by decoding by the entropy decoding unit 202, the DPB initialization unit 203 follows the DPB information according to the DPB information. Is initialized.

  Here, the operation of the DPB initialization unit 203 will be described in detail with reference to the flowchart of FIG.

  The DPB initialization unit 203 monitors whether or not DPB information is added to the header in the input picture data (step S21), and when it is detected that DPB information is added, at that time The DPB 207 is initialized as if there is a picture in the DPB 207 that matches the picture information stored in the DPB 207 (number depending on the decoding order, number depending on the display order of the pictures) (step S22).

  Here, as described above with reference to FIG. 3, the DPB information is the picture information of all pictures in the DPB 108 in the moving picture coding apparatus 100 at the time of detection of the random access point (numbers depending on the decoding order, display of pictures) (Number depending on the order) and DPB initialization information. Therefore, for example, when the picture data has the configuration shown in FIG. 4, data (DPB information) as shown in FIG. 10 is added to the header 42 indicating the DPB initialization information and the like.

  The data (DPB information) shown in FIG. 10 is based on the DPB initialization flag, the number of initializations, and the picture information (number depending on the decoding order, number depending on the display order of pictures) for the number of initializations. Become. The first DPB initialization flag means that DPB initialization is necessary when the value is “1”, and that DPB initialization is not necessary when the value is “0”. Here, since the value of the DPB initialization flag is “1”, it means that the DPB needs to be initialized.

  Next, the value of the initialization number shown in FIG. 10 being “4” means that DPB information for four pictures has been added. Therefore, as shown in FIG. 10, four sets of decoding order and display order are added following the number of initializations. Among them, since the value of the first set of decoding order and display order is “1”, these indicate that the decoding order of the first picture is “1” and the display order is “1”. Show. The subsequent set of the second decoding order and the display order indicates that the decoding order of the second picture is “2” and the display order is “4”. Similarly, the third set of decoding order and display order indicates that the decoding order of the third picture is “5” and the display order is “7”, and the fourth decoding order and display order are displayed. The order set indicates that the decoding order of the fourth picture is “9” and the display order is “8”. That is, the DPB information is such that the four pictures existing in the DPB 207 at the time of picture detection at the random access point are the four pictures whose decoding order and display order are set to the above values. Is initialized.

  Since such DPB information indicates the storage state of the DPB 207 when decryption is performed without performing random access, decryption is performed without performing random access when random access is performed. In this case, the storage state of the DPB 207 can be known. Therefore, even when a DPB control signal for controlling DPB with a random access point sandwiched in the bit stream is included, decoding can be performed without any problem.

  As described above, in the moving picture decoding apparatus 200 according to the present embodiment, DPB control can be performed across a random access point while guaranteeing random access at the random access point. A moving image encoded signal can be randomly accessed and decoded.

  In the moving picture decoding apparatus 200 according to the present embodiment, the storage state of the DPB 207 can be quickly confirmed at the random access point. Therefore, when the continuous decoding is performed across the random access point, the actual DPB By providing a section that compares the state and information on the DPB state added to the header, it becomes possible to quickly detect a DPB error.

  Further, the present invention is not limited to the above embodiment, and includes a moving picture decoding program for causing a computer to realize the functions of the moving picture decoding apparatus 200, for example. The moving picture decoding program may be read from a recording medium and taken into a computer, or may be transmitted via a communication network and taken into a computer.

  In the above embodiment, the DPB information has been described as including information indicating both the number depending on the decoding order of each picture in the DPB and the number depending on the display order, but at least one of the numbers May be included.

  The present invention relates to a moving picture decoding apparatus and program, and in particular, performs random access to a moving picture coded signal that has been coded efficiently so as to enable random access while improving coding efficiency. It is very useful when you want.

It is a block diagram of an example of the moving image encoding apparatus which produces | generates the moving image encoding signal decoded by this invention. 3 is a flowchart for explaining the operation of a DPB information generation unit in FIG. 1. It is explanatory drawing which shows an example of DPB information generation. It is a figure which shows the structure of an example of the picture data containing DPB information. It is explanatory drawing which shows an example which controls DPB in detail. It is explanatory drawing (the 1) which shows an example of the DPB control method which improves encoding efficiency. It is explanatory drawing (the 2) which shows an example of the DPB control method which improves encoding efficiency. It is a block diagram of one embodiment of a moving picture decoding apparatus of the present invention. FIG. 9 is a flowchart for explaining the operation of the DPB initialization unit in FIG. 8. FIG. It is explanatory drawing which shows an example of DPB information. It is explanatory drawing of DPB which accumulate | stores a reference image. It is explanatory drawing of DPB for waiting for an output image. It is explanatory drawing about the guarantee of the random access in a random access point.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Moving image encoder 101 Image signal input terminal 102 Motion vector detection part 103,204 Motion compensation part 104 Subtraction part 105 Orthogonal transformation / quantization part 106,206 Addition part 107,205 Inverse quantization / inverse orthogonal transformation part 108, 207 Decoded image memory (DPB)
109 DPB Information Generation Unit 110 Random Access Point Signal Input Terminal 111 Entropy Coding Unit 112 Bit Stream Output Terminal 200 Video Decoding Device 201 Bit Stream Input Terminal 202 Entropy Decoding Unit 203 DPB Initialization Unit 208 Decoded Image Signal Output Terminal

Claims (3)

In the encoding of a moving image signal in units of pictures, which is a single image, motion compensation using a picture to be encoded and a reference image that has already been locally decoded and read from the first decoded image memory It is a bitstream including the encoded signal in units of pictures obtained by performing prediction and entropy encoding, and is set to the one picture that enables playback of the pictures after the first picture in the playback display order at the time of decoding Information indicating the decoding order of each picture stored in the first decoded image memory and information indicating the reproduction display order at the time of encoding the picture of the random access point to be performed Control information including the entropy of the bit stream added to the encoded signal of the picture of the random access point And entropy decoding step for No. of,
For the signal decoded by the entropy decoding step, motion compensated prediction using the already decoded picture read from the second decoded image memory as a reference image is performed to decode the picture of the moving image signal In addition, the second decoded image is used as a reference image in the decoded picture, together with at least one of information indicating the decoding order of the picture and information indicating the reproduction display order. A picture decoding step stored in memory;
A detection step of detecting the control information from the signal decoded by the entropy decoding step;
At least one of the information indicating the decoding order and the reproduction display order of each picture stored in the second decoded image memory at the time when the control information is detected in the detection step. And an initialization step of initializing to corresponding information included in the detected control information. In the encoding of a moving image signal in units of pictures, which is a single image, motion compensation using a picture to be encoded and a reference image that has already been locally decoded and read from the first decoded image memory It is a bitstream including the encoded signal in units of pictures obtained by performing prediction and entropy encoding, and is set to the one picture that enables playback of the pictures after the first picture in the playback display order at the time of decoding Information indicating the decoding order of each picture stored in the first decoded image memory and information indicating the reproduction display order at the time of encoding the picture of the random access point to be performed Control information including the entropy of the bit stream added to the encoded signal of the picture of the random access point And entropy decoding means for No. of,
A second decoded image memory for storing the decoded picture;
For the signal decoded by the entropy decoding means, a motion compensated prediction using an already decoded picture read from the second decoded image memory as a reference image is performed to decode a picture of the moving image signal And the second decoding of the picture to be a reference image of the decoded picture together with at least one of information indicating the decoding order of the picture and information indicating the playback display order. Picture decoding means for storing in an image memory;
Detecting means for detecting the control information from the signal decoded by the entropy decoding means;
At least one of the information indicating the decoding order of each picture and the information indicating the reproduction display order stored in the second decoded image memory at the time when the control information is detected by the detecting means And an initialization means for initializing the corresponding information included in the detected control information. On the computer,
In the encoding of a moving image signal in units of pictures, which is a single image, motion compensation using a picture to be encoded and a reference image that has already been locally decoded and read from the first decoded image memory It is a bitstream including the encoded signal in units of pictures obtained by performing prediction and entropy encoding, and is set to the one picture that enables playback of the pictures after the first picture in the playback display order at the time of decoding Information indicating the decoding order of each picture stored in the first decoded image memory and information indicating the reproduction display order at the time of encoding the picture of the random access point to be performed Control information including the entropy of the bit stream added to the encoded signal of the picture of the random access point And entropy decoding step for No. of,
For the signal decoded by the entropy decoding step, motion compensated prediction using the already decoded picture read from the second decoded image memory as a reference image is performed to decode the picture of the moving image signal In addition, the second decoded image is used as a reference image in the decoded picture, together with at least one of information indicating the decoding order of the picture and information indicating the reproduction display order. A picture decoding step stored in memory;
A detection step of detecting the control information from the signal decoded by the entropy decoding step;
At least one of the information indicating the decoding order of each picture and the information indicating the reproduction display order stored in the second decoded image memory at the time when the control information is detected in the detection step. And an initialization step of initializing the corresponding information included in the detected control information.

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