JP2009232370A - Moving image decoding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a moving image decoding apparatus which reduces the amount of data to be transferred even when performing image processing, prevents overflow of an input buffer section and further is adaptive to a plurality of output means. <P>SOLUTION: In a moving image decoding apparatus, when an image block is a skip block regardless of presence/absence of image processing, data transfer can be omitted. Furthermore, an input buffer section is constituted of a plurality of input buffers and the amount of bit streams is controlled by an unpacker section using a decoding end flag and priorities, thereby preventing overflow of the input buffer section. Moreover, a parameter storage area corresponding to a plurality of bit streams and a reference buffer are formed and further an output image buffer corresponding to the output means is formed, thereby outputting a plurality of moving images to a plurality of output means, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a moving picture decoding apparatus for decoding a moving picture bit stream compliant with the MPEG video standard, and more particularly to a moving picture decoding apparatus capable of reducing the data transfer amount of a skip block even when image processing is performed. It is.

  In recent years, with the widespread use of the Internet and DVD (Digital Versatile Disc) recorders, it has become common to transmit, record, and play back time-series image frames constituting a moving image as digital information. Techniques for efficiently converting image frames into digital information with a small amount of information include the MPEG-2 (Moving Picture Experts Group) standard shown in [Non-Patent Document 1] and the following [Non-Patent Document 2]. A moving picture coding system such as the MPEG-4 standard is generally widely used.

  In these moving image encoding methods according to the MPEG standard, intra-frame encoding in which one image frame is encoded using only spatial correlation, the current image frame is predicted in units of image blocks from past image frames, and By using inter-screen prediction differential encoding (inter-screen encoding) that encodes the difference between the predicted image frame and the current image frame, a moving image can be efficiently converted into digital information with a small amount of information. .

  When a certain image block constituting the current image frame is encoded and the image block to be encoded is the same as a past image block at the same position, the image block to be encoded is determined to be a past image. The block is encoded as a skip block with no motion or difference.

  When the skip block is decoded, an image block of the skip block is generated by copying a past image block at the same position as the skip block.

  Here, in the following [Patent Document 1], when decoding the digitalized bit stream data, it is determined whether or not there is a change in the content of the image block to be decoded, that is, whether or not it is a skip block. An invention relating to an image processing device that decodes an image block and updates an output image buffer (display frame memory in Patent Document 1) when the block is not a skip block is disclosed. This uses the fact that the image data of the image frame decoded immediately before remains in the output image buffer, and performs the decoding process only when the image block is not a skip block, thereby reducing the data transfer amount to the output image buffer. To reduce.

ISO / IEC 13818-2: 2000, Information technology-Generic coding of moving pictures and associated audio information: Video

ISO / IEC 14496-2: 2003, Information technology-Coding of audio-visual objects-Part 2: Visual JP 2007-67526 A

  However, the invention disclosed in [Patent Document 1] does not consider the case where image processing is performed on an image frame. In other words, since only the image data before image processing exists in the output image buffer, even if the image block is a skip block, the amount of data transferred to the output image buffer cannot be reduced when image processing is performed. .

  Further, since the input buffer unit of the invention disclosed in [Patent Document 1] is configured to acquire bit stream data in accordance with an instruction from the decoding unit, bit stream data exceeding the capacity of the input buffer unit is transmitted. In this case, there is a possibility that the input buffer unit overflows and the moving picture decoding process fails. In particular, when bit stream data is acquired via a network, the risk of occurrence of overflow is further increased because the transmission rate of the bit stream data is not constant. In addition, the above risk increases when a plurality of bit stream data is acquired and decoded in parallel.

  In the invention disclosed in [Patent Document 1], since the output image buffer unit is composed of one recording area, moving images of a plurality of bit stream data transmitted in parallel are transmitted to a plurality of output means. Each cannot be output.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a moving picture decoding apparatus capable of reducing the amount of data transfer even when performing image processing, preventing overflow of an input buffer unit, and capable of dealing with a plurality of output means. .

The present invention
(1) Variable length decoding is performed on a moving picture bit stream encoded in accordance with the MPEG video standard to obtain conversion coefficients and encoding information for each image block forming an image frame constituting the moving picture. In the moving picture decoding apparatus for decoding the image block data of the image block based on the transform coefficient and the encoding information, and outputting the output image data composed of the image block data to the predetermined output means 4,
An input buffer unit 22 having a plurality of input buffers;
The bit stream is acquired and divided into bit stream data for each image frame, and the bit stream data is selected and stored in the input buffer, and is also stored in the subsequent parameter storage unit 24 and the subsequent reference image buffer unit 26. An unpacker section 20 for forming a parameter storage area and a reference buffer corresponding to the bitstream,
A variable length decoding unit 10 that reads out the bitstream data instructed by the unpacker unit 20 from the input buffer, performs variable length decoding, and acquires the transform coefficient and the encoding information;
A parameter storage unit 24 for recording the encoded information in the parameter storage area corresponding to the bit stream of the encoded information;
An image block decoding unit 45 that performs predetermined decoding processing based on the encoding information and the transform coefficient to obtain image block data;
Two output image buffers corresponding to the output means 4 are formed for the output image buffer unit 32 for each output means 4, and the output image buffer for recording the image block data is indicated for each bit stream data, Furthermore, an output image handler unit 34 that alternately outputs output image data composed of the image block data recorded in the two output image buffers to the corresponding output means 4;
It is determined whether or not the image block data is a skip block based on the determination information included in the encoding information. If the image block data is a skip block, the next image block data is obtained. The image processing instruction for the bit stream is confirmed, and if there is an image processing instruction, the image block data obtained by performing predetermined image processing on the image block data, the image block data if there is no image processing instruction, the first temporary data An output image control unit 30 for outputting to the image buffer 28a and an output image buffer instructed by the output image handler unit 34;
A first temporary image buffer 28a that records image block data from the output image control unit 30, and a second block that records the image block data before image processing when the output image control unit 30 performs image processing. A temporary image buffer unit 28 provided with a temporary image buffer 28b,
The output image data recorded in one of the two output image buffers is output to the corresponding output means 4 based on the instruction of the output image handler unit 34, and the output image data recorded in the first temporary image buffer 28a. An output image buffer unit 32 for recording in the other of the two output image buffers;
The reference image data used for the decoding process of the image block is acquired from the second temporary image buffer 28b when the output image control unit 30 performs the image processing, and when the image processing is not performed, the output is performed. A reference image buffer unit 26 that acquires the output image buffer to be output to the means 4 and records it in the reference image buffer corresponding to the bit stream of the output image data
The above-mentioned problem is solved by providing a moving picture decoding apparatus 50 characterized by comprising:
(2) The unpacker portion 20 is
After giving priority according to the encoding format to the acquired bit stream data,
When bit stream data stored in a plurality of input buffers is sequentially confirmed, the acquired bit stream data is stored in an input buffer in which decoded bit stream data is stored, and all input buffers are undecoded. The moving image decoding apparatus according to (1), wherein the acquired bit stream data is stored in an input buffer in which bit stream data having a lower priority than the acquired bit stream data is stored. This solves the above problem.

According to the video decoding device according to the present invention,
(1) By recording image data before image processing in a second temporary image buffer provided in the temporary image buffer unit, output image data after image processing can be recorded in the output image buffer unit. In the case of a skip block, the output image data recorded in the output image buffer unit is used, so that data transfer to the output image buffer unit of the skip block is omitted even when image processing is performed. Can do.
(2) The input buffer unit for storing the bit stream data is composed of a plurality of input buffers, and the amount of bit stream data transmitted by the unpacker unit provided in the moving image decoding apparatus is stored in the input buffer. Control is performed using a decoding end flag indicating whether or not the stream data has been decoded and the priority assigned to each bit stream data. As a result, it is possible to prevent transmission of bit stream data exceeding the capacity of the input buffer unit, and avoid failure of the decoding process due to overflow of the input buffer unit.
(3) A parameter storage area and a reference buffer corresponding to a plurality of bit streams are formed in the parameter storage section and the reference image buffer section, respectively, and an output image buffer corresponding to the output means is formed in the output image buffer section. By associating the transmitted bit stream with the output image buffer, it is possible to output a plurality of moving images obtained from a plurality of bit streams transmitted in parallel to a plurality of output units, respectively.

  Hereinafter, embodiments of a moving picture decoding apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a moving picture decoding apparatus according to the present invention. FIG. 2 is a flowchart showing an input buffer selection operation by the unpacker unit constituting the moving picture decoding apparatus according to the present invention. FIG. 3 is a flowchart showing the operation of the video decoding apparatus according to the present invention. 4 and 5 are diagrams for explaining the display operation of the moving picture decoding apparatus according to the present invention. In FIG. 1, description and description of blocks that are not directly related to the present invention are omitted.

  In the unpacker section 20 constituting the moving picture decoding apparatus 50 according to the present invention shown in FIG. 1, a moving picture bit stream converted into digital information according to the MPEG video standard is reproduced by a reproducing apparatus such as a hard disk or an optical recording medium. 1a and the network 1b. At this time, when a plurality of bit streams are transmitted to the unpacker unit 20 in parallel, the unpacker unit 20 distinguishes each bit stream based on the IP address and port number of the data transmission source, a user instruction, etc. A stream index is assigned to each stream. For example, when two different moving image bit streams are transmitted to the unpacker unit 20, the unpacker unit 20 assigns stream indexes B1 and B2 to the respective bit streams. In the following description, bit streams to which stream indexes B1 and B2 are assigned are described as bit streams B1 and B2, respectively.

  Further, the unpacker unit 20 divides the recording areas of the parameter storage unit 24 and the reference image buffer unit 26 according to the number of bit streams to be transmitted, and sets the parameter storage area and the reference image buffer corresponding to each bit stream. Form. Then, the unpacker unit 20 assigns a parameter storage area index and a reference image buffer index corresponding to the stream index to the formed parameter storage area and reference image buffer. For example, when the bitstreams B1 and B2 are transmitted to the unpacker unit 20, the unpacker unit 20 divides the parameter storage unit 24 into two parameter storage areas corresponding to the bitstreams B1 and B2, and each parameter storage area Parameter storage area indexes J1 and J2 are assigned. Further, the unpacker unit 20 divides the reference image buffer unit 26 into two reference image buffers corresponding to the bit streams B1 and B2, and assigns reference image buffer indexes J1 and J2 to the respective reference image buffers. In the following description, the parameter storage areas to which the parameter storage area indexes J1 and J2 are assigned are referred to as parameter storage areas J1 and J2, respectively, and the reference image buffers to which the reference image buffer indexes J1 and J2 are assigned are respectively described. Reference image buffers J1 and J2 are described.

  Next, the unpacker unit 20 divides the transmitted bit stream into bit stream data for each image frame, decodes a part thereof, and confirms the encoding format of the bit stream data. If the bit stream data is for an intra-frame encoded image frame, the bit stream data is set to a higher priority. If the bit stream data is for an inter-frame encoded image frame, the priority of the bit stream data is set. Set the degree low.

  Then, the unpacker unit 20 stores the bit stream data to which the priority is given in the input buffer unit 22. Here, the input buffer unit 22 is composed of a plurality of input buffers, and the unpacker unit 20 selects an input buffer to be stored according to a procedure to be described later, and stores bit stream data. Then, an input buffer index is assigned to the stored input buffer. Note that the number of input buffers constituting the input buffer unit 22 is appropriately set according to the capacity of the input buffer unit 22, the amount of bit stream data, the decoding processing capability of the moving picture decoding apparatus 50, and the like.

  The unpacker unit 20 instructs the variable length decoding unit 10 that is a component of the decoding unit 40 to decode the stored bit stream data when the bit stream data is stored in the selected input buffer. At the time of this decoding instruction, the unpacker unit 20 outputs the input buffer index of the stored input buffer, the parameter storage area index corresponding to the stream index of the stored bit stream data, and the reference image buffer index to the variable length decoding unit 10. . For example, when the bit stream data of the bit stream B1 is stored in the input buffer I3, the unpacker unit 20 outputs the input buffer index I3, the parameter storage area index J1, and the reference image buffer index J1 to the variable length decoding unit 10. The bit stream data stored in the input buffer I3 is instructed to be decoded. The decoding unit 40 performs a decoding process of the bit stream data stored in the input buffer I3 instructed by the unpacker unit 20 according to a procedure described later. When the decoding process of the bit stream data is completed, a decoding end flag indicating that the stored bit stream data has been decoded is set for the input buffer storing the bit stream data for which the decoding process has been completed. .

  Here, the selection procedure of the input buffer by the unpacker unit 20 will be described with reference to the flowchart of FIG. FIG. 2 shows an example in which the input buffer unit 22 includes n input buffers from the input buffer I1 to the input buffer In.

  First, when the unpacker unit 20 acquires the bit stream data (step S100), the unpacker unit 20 confirms whether or not the bit stream data has been stored in each of the input buffers I1 to In (step S102). If there is an empty input buffer in which no bitstream data is stored, the acquired bitstream data is stored in the empty input buffer (step S110).

  If there is no empty input buffer in the input buffer unit 22, the unpacker unit 20 checks the presence or absence of a decoding end flag for each of the input buffers I1 to In (step S104). If there is an input buffer having a decoding end flag, the obtained bit stream data is stored in the input buffer (step S110).

  When all the bit stream data stored in the input buffer is undecoded and there is no decoding end flag in all the input buffers, the unpacker unit 20 determines the priority of the bit stream data stored in each of the input buffers I1 to In. It is checked and it is determined whether the priority of the stored bit stream data is lower than the priority of the acquired bit stream data (step S106). When the priority of the bitstream data stored is lower than the priority of the acquired bitstream data, the acquired bitstream data is stored in the input buffer storing the bitstream data with the lower priority ( Step S110).

  When the priority of all the bit stream data stored in the input buffer is higher than the priority of the acquired bit stream data, the unpacker unit 20 discards the acquired bit stream data (step S108). Then, it waits until the next bit stream data is input.

  As described above, the unpacker unit 20 controls the amount of bit stream transmitted to the input buffer unit 22 using the decoding end flag and the priority given to each bit stream data. Thereby, the overflow of the input buffer unit 22 can be prevented, and the failure of the decoding process due to the overflow of the input buffer unit 22 can be avoided.

  Next, the decoding process of the image block by the moving image decoding apparatus 50 is demonstrated. When the unpacker unit 20 outputs the input buffer index I3, the parameter storage area index J1, and the reference image buffer index J1, and instructs the decoding of the bitstream data stored in the input buffer I3, the variable length decoding unit 10 The bit stream data in the buffer I3 is read and a known variable length decoding process is performed. Thereby, the transform coefficient and the encoding information of each image block constituting the image frame of the bit stream data are acquired for each image block. Note that the encoding information here is motion vector information of each image block, type information of the image block, CBP (Coded Block Pattern) indicating the presence / absence of a transform coefficient, and the like. Then, the variable length decoding unit 10 records the acquired encoding information for each image block in the parameter storage area J1 of the parameter storage unit 24 corresponding to the bit stream B1. The variable length decoding unit 10 outputs the acquired transform coefficient for each image block to the inverse quantization unit 12.

  The inverse quantization unit 12 receives a transform coefficient from the variable length decoding unit 10 and performs a known inverse quantization process after performing an inverse scan process according to an image block prediction method. Then, the inverse quantized transform coefficient is output to an inverse DCT (Discrete Cosine Transform) unit 14.

  The inverse DCT unit 14 performs a known inverse DCT process on the transform coefficient inversely quantized by the inverse quantization unit 12. At this time, if the image block being decoded is an intra-picture encoded one, the data after inverse DCT processing is output to the output image control unit 30 as image block data.

  When the image block being decoded is of the inter-picture encoding, the MC (motion compensation) unit 16 uses the parameter storage region (here, the parameter storage region) corresponding to the stream index of the image block being decoded by the parameter storage unit 24. The motion vector information of the image block being decoded is acquired from J1). Further, the MC unit 16 acquires the reference image data recorded in the reference image buffer (here, the reference image buffer J1) corresponding to the stream index of the image block being decoded in the reference image buffer unit 26. The MC unit 16 generates predicted block data from the motion vector information acquired from the parameter storage unit 24 and the reference image data acquired from the reference image buffer unit 26. The prediction block data generated by the MC unit 16 is added to the prediction difference value after the inverse DCT process obtained by the inverse DCT unit 14 to become image block data, which is output to the output image control unit 30.

  The inverse quantization unit 12, the inverse DCT unit 14, and the MC unit 16 correspond to the image block decoding unit 45.

  Next, processing of each unit for image block data will be described with reference to the flowchart of FIG. In FIG. 3, an example in which the image block data of the bit stream B1 is output to one output unit 4 will be described. In this case, the output image handler unit 34 divides the recording area of the output image buffer unit 32 into two output image buffers, and assigns, for example, output image buffer indexes K1 and K2, respectively. In the following description, the output image buffers provided with the output image buffer indexes K1 and K2 are referred to as output image buffers K1 and K2, respectively.

  First, when the output image control unit 30 acquires the image block data of the bit stream B1 from the image block decoding unit 45, the encoding information of the image block data is acquired from the parameter storage area J1 corresponding to the bit stream B1 (step S200). ).

  Then, the output image control unit 30 uses the acquired encoded information as determination information, and determines whether or not the acquired image block data is a skip block (step S202). As the determination method of step S202, for example, when the type information of the image block included in the encoded information is not coded, or when the motion vector of the image block is (0, 0) and CBP is 0, The image control unit 30 determines the acquired image block data as a skip block.

  If the acquired image block data is a skip block, the output image control unit 30 waits until the next image block data is input without performing image processing and recording on the image block data.

  If the acquired image block data is not a skip block, it is confirmed whether there is an instruction for image processing (step S204). If there is no instruction for image processing, the image block data is recorded in the first temporary image buffer 28a constituting the temporary image buffer unit 28 (step S210), and the output image handler unit 34 is instructed. It is recorded in one output image buffer, for example, the output image buffer K1 (step S212).

  When there is an instruction for predetermined image processing to the output image control unit 30, the output image control unit 30 records the image block data in the second temporary image buffer 28 b constituting the temporary image buffer unit 28. (Step S206), the designated image processing is performed on the image block data (Step S208). The image processing performed by the output image control unit 30 includes scaling processing such as image enlargement / reduction, image movement processing, noise removal processing, and the like. These image processing instructions are given by a user or a control unit of the moving image decoding apparatus 50 (not shown).

  Then, the output image control unit 30 records the image block data after image processing in the first temporary image buffer 28a constituting the temporary image buffer unit 28 (step S210), and is instructed by the output image handler unit 34. Recording in the output image buffer (step S212). In this case, image block data after image processing is recorded in the first temporary image buffer 28a. Note that the size of the second temporary image buffer 28b and the first temporary image buffer 28a constituting the temporary image buffer unit 28 is equal to one bit stream data, that is, one image frame, even when there are a plurality of bit streams. It doesn't matter in minutes.

  When the image block data is recorded in the output image buffer, the image handler unit 34 determines whether or not the decoding process of the bit stream data for one image frame is completed (step S214). Until this is done, the next image block data is processed.

  If the decoding process of bit stream data for one image frame has been completed, the image handler unit 34 determines whether image processing has been performed on the image block data (step S216). When the decoding process of bit stream data for one image frame is completed, output image data composed of image block data for one image frame is stored in the output image buffer K1 and the first temporary image buffer 28a. It is formed. When there is an instruction for image processing, the second temporary image buffer 28b is formed with image data for one image frame which is composed of image block data before image processing and which has not been subjected to image processing.

  If there is an instruction for image processing, the image data that has not been subjected to image processing recorded in the second temporary image buffer 28b is copied as reference image data to the reference image buffer J1 corresponding to the bit stream B1 (step S1). S218). If there is no instruction for image processing, the output image data formed in the output image buffer K1 is copied as reference image data to the reference image buffer J1 corresponding to the bit stream B1 (step S220). Thereafter, it is determined whether or not there is an instruction to decode the next bit stream data (step S222). If there is no instruction to decode, the process ends (step S224). If there is an instruction to decode the next bit stream data, the image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a to the other output image buffer of the output image buffer unit 32, in this case the output image buffer. Recording is performed in the image buffer K2 (step S226). And it waits until the input of the image block data of the next bit stream data.

  Here, the output means information of the output means 4 is acquired in advance in the image handler section 34, and the image handler section 34 uses the output image data recorded in the output image buffers K1 and K2 as time intervals according to the output means information. Are alternately output to the output means 4. At this time, the image handler unit 34 first outputs the latest output image data output from the output image control unit 30 to the output image buffer (currently output to the output image buffer K1) to the output unit 4. Thereafter, the image handler unit 34 instructs the output image control unit 30 to switch the output destination of the image block data from the output image buffer K1 to the output image buffer K2. Therefore, the output image control unit 30 outputs the image block data obtained from the next bit stream data to the output image buffer K2. As a result, the output image control unit 30 outputs the image block data by alternately switching the output image buffers K1 and K2 for each image frame.

  By repeating the above operation, when the output unit 4 is used as a monitor, the moving image of the bit stream B1 is displayed on the monitor of the output unit 4.

  As a result of the processing in step S226 described above, the output image data output to the output unit 4 is always present in the output image buffers K1 and K2 of the output image buffer unit 32 regardless of the presence or absence of image processing. Therefore, when the image block is a skip block, data transfer to the output image buffer unit 32 can be omitted.

  In addition, when image processing is performed in the reference image buffer unit 26 by the processing in step S218 and step S220 described above, the image data before image processing recorded in the second temporary image buffer 28b is copied, and the image When the process is not performed, the output image data recorded in the output image buffer is copied. Therefore, image data before image processing always exists in the reference image buffer unit 26 regardless of the presence or absence of image processing, and decoding of inter-screen coded bit stream data can be performed without any problem.

  For example, when the output image control unit 30 performs image processing for enlarging the image size from QVGA (320 × 240) to VGA (640 × 480) by the above processing, one skip block of a 16 × 16 macroblock is performed. 640/320 × 480/240 × 16 × 16 = 1024 bytes of data transfer amount can be reduced. By reducing the data transfer amount, the load on the decoding unit 40 can be reduced, and the speed of the decoding process can be increased. Note that the amount of reduction in the above data transfer varies depending on the image processing, and is basically (scaling size) × (image block size) per skip block. Note that the scaling size is an enlargement factor for enlargement processing, a reduction factor for reduction processing, and a scaling factor of 1 for noise removal processing and image movement processing.

  Next, a moving picture decoding apparatus in the case where reduced image processing is performed on two bit streams B1 and B2 transmitted to the unpacker unit 20 at different transmission rates using FIG. 50 display operations will be described. In this case, the unpacker unit 20 forms parameter storage areas J1 and J2 and reference image buffers J1 and J2 in the parameter storage unit 24 and the reference image buffer unit 26, respectively, and the image handler unit 34 outputs to the output image buffer unit 32. Image buffers K1 and K2 are formed. Here, the transmission rate of the bit stream B1 is 30 frames / sec, the transmission rate of the bit stream B2 is 15 frames / sec, and the display interval of the output means 4 is 30 frames / sec. Also, in FIG. 4 and FIG. 5 described later, K1 to K4 correspond to the recording area of the output image buffer, and Tmp corresponds to the recording area of the first temporary image buffer 28a corresponding to the display screen of the output means 4, respectively. It shall be shown in 4 and FIG. 5 indicate a buffer in which the output image control unit 30 outputs image block data, and an arrow in FIG. 4 and FIG. 5 indicates output image data of the first temporary image buffer 28a. Shows the operation of copying to the output image buffer.

  First, in the initial state shown at T0 in FIG. 4, the output image data is not recorded in the output image buffers K1 and K2 and the first temporary image buffer 28a (Tmp), and is empty.

  Next, when the unpacker unit 20 stores the bit stream data of the first frame of the bit stream B1 in the input buffer, the unpacker unit 20 instructs the decoding unit 40 to decode the bit stream data. In response to this decoding instruction, the decoding unit 40 performs the decoding process of the instructed bitstream data using the parameter storage area J1 and the reference image buffer J1 according to the above procedure. However, since the bit stream data of the first frame is generally encoded in the screen, the reference image buffer J1 is not actually used. In the decoding process, the output image control unit 30 performs a half reduction process, a leftward movement process, and a black painting process (shaded part in FIG. 4) for a blank portion accompanying the reduction process as an image process.

  As a result of the above processing, the image data B1 # 1 of the first frame is reduced and moved leftward, and the image data B1 is recorded in the recording areas of the output image buffer K1 and the first temporary image buffer 28a (Tmp). The output image data of # 1 is recorded as indicated by T1 in FIG. The output image handler unit 34 causes the output image data of the output image buffer K1 to be displayed on the display screen of the output unit 4, and the output destination of the image block data is output from the output image buffer K1 to the output image control unit 30. An instruction to switch to the buffer K2 is given.

  Next, the bit pack data of the second frame of the bit stream B1 is transmitted to the unpacker unit 20 before the bit stream data of the first frame of the bit stream B2. Therefore, the unpacker unit 20 instructs to decode the bit stream data of the second frame of the bit stream B1. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 stores the output image data recorded in the first temporary image buffer 28a (Tmp) in the output image buffer K2, as indicated by T1 ′ in FIG. make a copy.

  Then, the decoding unit 40 performs decoding processing and image processing of the bit stream data of the second frame of the bit stream B1 in accordance with an instruction from the unpacker unit 20. As a result, the output image control unit 30 outputs the output image data B1 # 2 of the second frame subjected to the image processing of the bit stream B1 to the output image buffer K2 and the first temporary image buffer 28a as indicated by T2 in FIG. Record in the left half of (Tmp). The output image handler unit 34 causes the output image data of the output image buffer K2 to be displayed on the display screen of the output unit 4, and the output destination of the image block data is output from the output image buffer K2 to the output image control unit 30. An instruction to switch to the buffer K1 is given.

  Next, the bit stream data of the first frame of the bit stream B2 is transmitted to the unpacker unit 20. Therefore, the unpacker unit 20 instructs to decode the bit stream data of the first frame of the bit stream B2. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a (Tmp) to the output image buffer K1, as indicated by T2 'in FIG. make a copy.

  Then, the decoding unit 40 performs the decoding process of the bit stream data of the first frame of the bit stream B2, the 1/2 reduction process, the rightward movement process, and the black process image process for the blank part according to the instruction of the unpacker unit 20. Do. In this decoding process, the parameter storage area J2 corresponding to the bit stream B2 and the reference image buffer J2 are used. However, since the bit stream data of the first frame is generally encoded in the screen, the reference image buffer J2 is not actually used.

  As a result of the above processing, the output image buffer K1 and the first temporary image buffer 28a (Tmp) store the image data B1 # of the second frame of the bit stream B1 recorded in the left half as shown at T3 in FIG. The image data B2 # 1 of the first frame of the bit stream B2 subjected to the image processing is recorded in the right half of the output image buffer K1 and the first temporary image buffer 28a (Tmp) without changing the number 2. As a result, in the output image buffer K1 and the first temporary image buffer 28a (Tmp), the image data B1 # 2 of the second frame of the bit stream B1 subjected to image processing in the left half is positioned, and image processing is performed in the right half. Output image data in which the image data B2 # 1 of the first frame of the bitstream B2 is located is formed. The output image handler unit 34 causes the output image data recorded in the output image buffer K1 to be displayed on the display screen of the output unit 4, and the output image control unit 30 sets the output destination of the image block data to the output image buffer K1. To switch to the output image buffer K2.

  Next, the bit pack data of the third frame of the bit stream B1 is transmitted to the unpacker unit 20. Therefore, the unpacker unit 20 instructs to decode the bit stream data of the third frame of the bit stream B2. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a (Tmp) to the output image buffer K2, as indicated by T3 ′ in FIG. make a copy.

  Then, the decoding unit 40 performs decoding processing and image processing on the bit stream data of the third frame of the bit stream B1 in accordance with an instruction from the unpacker unit 20. As a result, as shown at T4 in FIG. 4, the output image buffer K2 and the first temporary image buffer 28a (Tmp) store the image data B2 # 1 of the first frame of the bit stream B2 recorded in the right half. The third frame image data B1 # 3 of the bitstream B1 subjected to image processing is recorded in the left half of the output image buffer K2 and the first temporary image buffer 28a (Tmp) as it is. As a result, the output image buffer K2 and the first temporary image buffer 28a (Tmp) have the image data B1 # 3 subjected to image processing in the left half and the image data B2 # 1 subjected to image processing in the right half. Positioned output image data is formed. The output image handler unit 34 causes the output image data of the output image buffer K2 to be displayed on the display screen of the output unit 4, and the output destination of the image block data is output from the output image buffer K2 to the output image control unit 30. An instruction to switch to the buffer K1 is given.

  When the unpacker unit 20 issues an instruction to decode the next bit stream data, the output image handler unit 34 outputs the output recorded in the first temporary image buffer 28a (Tmp) as shown at T4 'in FIG. Copy the image data to the output image buffer K1.

  By sequentially performing the above operations, moving images of two bit streams B1 and B2 transmitted at different transmission rates can be displayed side by side on the left and right of one output means 4.

  As described above, according to the moving image decoding apparatus 50, the output image data recorded in the first temporary image buffer 28a is instructed to be output to the output means 4 before the bit stream data is decoded. Copy to the other output image buffer. As a result, when decoding bit stream data, the latest output image data always exists in both output image buffers, and a plurality of bit streams transmitted in parallel at different transmission rates are output to the same output means 4. Even if it is, it is possible to display the screen without a sense of incongruity. Further, when the image block is a skip block, data transfer to the output image buffer unit 32 can be omitted.

  In the above example, the output image data of the first temporary image buffer 28a is copied to a predetermined output image buffer. However, the output image buffer unit 32 outputs the output image data of the output image buffer of the copy destination. It is also possible to check and copy only the part that is not the latest image data. For example, since the image data B1 # 2 already exists in the output image buffer K2 at T3 ′ in FIG. 4, only the image data B2 # 1 is selected and copied from the first temporary image buffer 28a. May be.

  Next, the display operation of the video decoding device 50 when displaying the two bit streams B1 and B2 transmitted to the unpacker unit 20 at different transmission rates on the two output units 4 will be described with reference to FIG. . Also in this case, the unpacker unit 20 forms the parameter storage area indexes J1 and J2 and the reference image buffers J1 and J2 in the parameter storage unit 24 and the reference image buffer unit 26, respectively, and the image handler unit 34 outputs the first output means. Output image buffers K 1 and K 2 corresponding to 4 and output image buffers K 3 and K 4 corresponding to the second output means 4 are formed in the output image buffer unit 32. In this case as well, the transmission rate of the bit stream B1 is 30 frames / sec, the transmission rate of the bit stream B2 is 15 frames / sec, and the display interval of the first and second output means 4 is 30 frames / sec.

  First, in the initial state indicated by T0 in FIG. 5, the output image buffers K1 to K4 and the first temporary image buffer 28a (Tmp) are empty without output image data.

  Next, the bit stream data of the first frame of the bit stream B1 is transmitted to the unpacker unit 20, and the unpacker unit 20 instructs to decode the bit stream data. The decoding unit 40 receives the decoding instruction and performs decoding processing of the instructed bitstream data using the parameter storage area J1 and the reference image buffer J1. However, the reference image buffer J1 is not used when the bit stream data is the one encoded in the screen. As a result, as shown at T1 in FIG. 4, the image data B1 # 1 of the first frame of the bit stream B1 is recorded as output image data in the output image buffer K1 and the first temporary image buffer 28a (Tmp). . Then, the output image handler unit 34 displays the output image data of the output image buffer K1 on the display screen of the first output unit 4, and also instructs the output image control unit 30 to output the image block data of the bit stream B1. An instruction to switch from the output image buffer K1 to the output image buffer K2 is issued. Note that the bit stream data of the bit stream B2 has not been transmitted yet, and no output image data exists in the output image buffers K3 and K4. However, the output image handler unit 34 outputs the second image data to the output image buffer K3. The output unit 4 is instructed to output, and the output image control unit 30 is instructed to switch the output destination of the image block data of the bit stream B2 from the output image buffer K3 to the output image buffer K4.

  Next, when the bit stream data of the second frame of the bit stream B1 is transmitted to the unpacker unit 20, the unpacker unit 20 instructs to decode the bit stream data of the second frame of the bit stream B1. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a (Tmp) to the output image buffer K2, as indicated by T1 ′ in FIG. make a copy.

  Then, the decoding unit 40 decodes the bit stream data of the second frame of the bit stream B1 according to the instruction of the unpacker unit 20. As a result, as shown at T2 in FIG. 5, the image data B1 # 2 of the second frame of the bit stream B1 is recorded as output image data in the output image buffer K2 and the first temporary image buffer 28a (Tmp). . Then, the output image handler unit 34 displays the output image data of the output image buffer K2 on the display screen of the first output means 4, and the output image control unit 30 sets the output destination of the image block data to the output image buffer K2. To switch to the output image buffer K1. Further, the output image handler unit 34 instructs the output image buffer K4 to output the second output means 4, and the output image control unit 30 sets the output destination of the image block data of the bit stream B2 to the output image buffer K4. To switch to the output image buffer K3.

  Next, when the bit stream data of the first frame of the bit stream B2 is transmitted to the unpacker unit 20, the unpacker unit 20 instructs to decode the bit stream data of the first frame of the bit stream B2. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a (Tmp) to the output image buffer K1, as indicated by T2 'in FIG. make a copy.

  Then, the decoding unit 40 performs the decoding process of the bit stream data of the first frame of the bit stream B2 according to the instruction of the unpacker unit 20. In the decoding process, the parameter storage area J2 corresponding to the bit stream B2 and the reference image buffer J2 are used. (However, the reference image buffer J2 is not used when the bit stream data is intra-picture encoded.) As a result, as shown at T3 in FIG. 5, the output image buffer K3 and the first temporary image buffer 28a (Tmp ), Image data B2 # 1 of the first frame of the bit stream B2 is recorded as output image data. Then, the output image handler unit 34 displays the output image data of the output image buffer K3 on the display screen of the second output unit 4, and also sets the output destination of the image block data of the bit stream B2 to the output image control unit 30. An instruction to switch from the output image buffer K3 to the output image buffer K4 is issued. Further, the output image handler unit 34 displays the output image data of the output image buffer K1 on the display screen of the first output unit 4, and also instructs the output image control unit 30 to output the image block data of the bit stream B1. An instruction to switch from the output image buffer K1 to the output image buffer K2 is issued.

  Next, when the bit stream data of the third frame of the bit stream B1 is transmitted to the unpacker unit 20, the unpacker unit 20 instructs to decode the bit stream data of the third frame of the bit stream B1. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a (Tmp) to the output image buffer K4, as indicated by T3 ′ in FIG. make a copy.

  Then, the decoding unit 40 decodes the bit stream data of the third frame of the bit stream B1 according to the instruction of the unpacker unit 20. As a result, as shown at T4 in FIG. 5, the image data B1 # 3 of the third frame of the bit stream B1 is recorded as output image data in the output image buffer K2 and the first temporary image buffer 28a (Tmp). . Then, the output image handler unit 34 causes the output image data of the output image buffer K2 to be displayed on the display screen of the first output means 4, and the output destination of the image block data of the bit stream B1 to the output image control unit 30. An instruction to switch from the output image buffer K2 to the output image buffer K1 is issued. Further, the output image handler unit 34 displays the output image data of the output image buffer K4 on the display screen of the second output unit 4 and also sets the output destination of the image block data of the bit stream B2 to the output image control unit 30. An instruction to switch from the output image buffer K4 to the output image buffer K3 is issued.

  Next, when the bit stream data of the fourth frame of the bit stream B1 is transmitted to the unpacker unit 20, the unpacker unit 20 instructs to decode the bit stream data of the fourth frame of the bit stream B1. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a (Tmp) to the output image buffer K1, as indicated by T4 'in FIG. make a copy.

  Then, the decoding unit 40 decodes the bit stream data of the fourth frame of the bit stream B1 according to the instruction of the unpacker unit 20. As a result, as shown at T5 in FIG. 5, the image data B1 # 4 of the fourth frame of the bit stream B1 is recorded as output image data in the output image buffer K1 and the first temporary image buffer 28a (Tmp). . Then, the output image handler unit 34 displays the output image data of the output image buffer K1 on the display screen of the first output unit 4, and also instructs the output image control unit 30 to output the image block data of the bit stream B1. An instruction to switch from the output image buffer K1 to the output image buffer K2 is issued. Further, the output image handler unit 34 displays the output image data of the output image buffer K3 on the display screen of the second output unit 4, and also sets the output destination of the image block data of the bit stream B2 to the output image control unit 30. An instruction to switch from the output image buffer K3 to the output image buffer K4 is issued.

  Next, when the bit stream data of the second frame of the bit stream B2 is transmitted to the unpacker unit 20, the unpacker unit 20 instructs to decode the bit stream data of the second frame of the bit stream B2. When the unpacker unit 20 issues a decoding instruction, the output image handler unit 34 outputs the output image data recorded in the first temporary image buffer 28a (Tmp) to the output image buffer K2, as indicated by T5 'in FIG. make a copy.

  Then, the decoding unit 40 decodes the bit stream data of the second frame of the bit stream B2 according to the instruction of the unpacker unit 20. As a result, as shown at T6 in FIG. 5, the image data B2 # 2 of the second frame of the bit stream B2 is recorded as output image data in the output image buffer K4 and the first temporary image buffer 28a (Tmp). . Then, the output image handler unit 34 causes the output image data of the output image buffer K4 to be displayed on the display screen of the second output unit 4, and the output destination of the image block data of the bit stream B2 to the output image control unit 30. An instruction to switch from the output image buffer K4 to the output image buffer K3 is issued. Further, the output image handler unit 34 displays the output image data of the output image buffer K2 on the display screen of the first output unit 4, and also sets the output destination of the image block data of the bit stream B1 to the output image control unit 30. An instruction to switch from the output image buffer K2 to the output image buffer K1 is issued.

  Next, when the unpacker unit 20 issues an instruction to decode the next bit stream data, the output image handler unit 34 is recorded in the first temporary image buffer 28a (Tmp) as shown at T6 'in FIG. The output image data is copied to the output image buffer K3.

  By sequentially performing the above operations, moving images of two bit streams B1 and B2 transmitted at different transmission rates can be displayed on the two output units 4, respectively.

  In the above example, the output image data to be copied to the output image buffer is acquired from the first temporary image buffer 28a, but copied from one output image buffer set as the output destination of the output image control unit 30. By doing so, the first temporary image buffer 28a becomes unnecessary, and the capacity of the temporary image buffer unit 28 can be reduced.

  As described above, according to the video decoding device 50 according to the present invention, the output image buffer unit 32 always has the output image data output to the output unit 4 regardless of the presence or absence of image processing. Therefore, when the image block is a skip block, data transfer to the output image buffer unit 32 can be omitted.

  Further, according to the moving picture decoding apparatus 50 according to the present invention, the input buffer unit 22 for storing the bit stream data is constituted by a plurality of input buffers, and the unpacker unit 20 adds the decoding end flag and each bit stream data. The amount of the bit stream stored in the input buffer unit 22 is controlled using the determined priority. As a result, overflow of the input buffer unit 22 can be prevented, and failure of the decoding process due to overflow of the input buffer unit 22 can be avoided.

  Further, according to the video decoding device 50 according to the present invention, the unpacker unit 20 forms a parameter storage area and a reference buffer corresponding to a plurality of bit streams in the parameter storage unit 24 and the reference image buffer unit 26, respectively. Further, the output image handler unit 34 forms an output image buffer corresponding to the output unit 4 in the output image buffer unit 32 and associates the bit stream with the output image buffer, so that a plurality of moving images obtained from the plurality of bit streams can be obtained. An image can be output to each of the plurality of output means 4.

It is a block diagram which shows one Embodiment of the moving image decoding apparatus which concerns on this invention. It is a flowchart which shows the selection operation | movement of the input buffer by the unpacker part which comprises the moving image decoding apparatus which concerns on this invention. It is a flowchart which shows operation | movement of the moving image decoding apparatus which concerns on this invention. It is a figure explaining the display operation of the moving image decoding apparatus which concerns on this invention. It is a figure explaining the display operation of the moving image decoding apparatus which concerns on this invention.

Explanation of symbols

4 Output means
10 Variable length decoder
20 Unpackers
22 Input buffer section
24 Parameter storage
26 Reference image buffer
28 Temporary image buffer
28a First temporary image buffer
28b Second temporary image buffer
30 Output image controller
32 Output image buffer
34 Output Image Handler
45 Image block decoder
50 Video decoding device

Claims (2)

A variable length decoding is performed on a bit stream of a moving image encoded in accordance with the MPEG video standard to obtain a conversion coefficient and encoding information for each image block forming an image frame constituting the moving image, and In the moving picture decoding apparatus for decoding the image block data of the image block based on the transform coefficient and the encoding information, and outputting the output image data composed of the image block data to a predetermined output unit,
An input buffer unit having a plurality of input buffers;
The bitstream is acquired and divided into bitstream data for each image frame, and the bitstream data is selected and stored in the input buffer, and the bitstream data is stored in a subsequent parameter storage unit and a subsequent reference image buffer unit. An unpacker unit that forms a parameter storage area and a reference buffer corresponding to the stream, and
A variable length decoding unit that reads out the bitstream data instructed to be decoded by the unpacker unit from the input buffer, performs variable length decoding, and acquires the transform coefficient and the encoding information;
A parameter storage unit that records the encoded information in the parameter storage area corresponding to the bit stream of the encoded information;
An image block decoding unit that performs predetermined decoding processing based on the encoding information and the transform coefficient to obtain image block data;
Two output image buffers corresponding to the output means are formed for the output means for the output image buffer unit, the output image buffer for recording the image block data is designated for each bit stream data, and the 2 An output image handler unit that alternately outputs output image data composed of the image block data recorded in one output image buffer to a corresponding output unit;
It is determined whether or not the image block data is a skip block based on the determination information included in the encoding information. If the image block data is a skip block, the next image block data is obtained. The image processing instruction for the bit stream is confirmed, and if there is an image processing instruction, the image block data obtained by performing predetermined image processing on the image block data, the image block data if there is no image processing instruction, the first temporary data An output image control unit for outputting to an image buffer and an output image buffer instructed by the output image handler unit;
A first temporary image buffer that records image block data from the output image control unit, and a second temporary image that records the image block data before image processing when the output image control unit performs image processing A temporary image buffer unit comprising a buffer,
The output image data recorded in one of the two output image buffers is output to a corresponding output unit based on an instruction from the output image handler unit, and the output image data recorded in the first temporary image buffer is output to the second output image buffer. An output image buffer unit for recording in the other one of the output image buffers;
The reference image data used for the decoding process of the image block is acquired from the second temporary image buffer when the output image control unit performs image processing, and to the output unit when the image processing is not performed. A reference image buffer unit obtained from the output image buffer to be output and recorded in a reference image buffer corresponding to the bit stream of the output image data;
A moving picture decoding apparatus comprising: The unpacker part is
After giving priority according to the encoding format to the acquired bit stream data,
When bit stream data stored in a plurality of input buffers is sequentially confirmed, the acquired bit stream data is stored in an input buffer in which decoded bit stream data is stored, and all input buffers are undecoded. The moving image decoding apparatus according to claim 1, wherein the acquired bit stream data is stored in an input buffer in which bit stream data having a lower priority than the acquired bit stream data is stored.

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