JP2002247586A - Image information conversion device and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the discrimination of a macro block mode by small operation quantity. SOLUTION: The image information conversion device 1 is provided with an intra/inter judging part 21 and an inter/inter 4V judging part 22 for determining which is to be used, an inter encoding mode or an inter 4V encoding mode on the basis of the moving vector of each encoding unit of the inter encoding mode and the moving vector of each encoding unit of the inter 4V encoding mode which are generated on the basis of moving vector information extracted from MPEG2 image compression information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image information conversion apparatus and an image information conversion method, and more particularly, to image information (bit stream) compressed by orthogonal transform such as discrete cosine transform and motion compensation, for satellite broadcasting, cable broadcasting, and so on. The present invention relates to an image information conversion device and an image information conversion method used when receiving via a network such as a TV or the Internet, or when processing is performed on a storage medium such as an optical disk, a magnetic disk, or a flash memory.

[0002]

2. Description of the Related Art In recent years, when image information is handled as digital data, for example, Discrete Cosine Transform (hereinafter, referred to as "discrete cosine transform") for the purpose of efficiently transmitting and storing information by utilizing the redundancy inherent in image information. DCT
It is written. 2. Description of the Related Art Apparatuses conforming to a method of performing compression by orthogonal transformation and motion compensation, such as), are becoming widespread in both information distribution at broadcast stations and the like and information reception in ordinary households.

In particular, MPEG (Moving Picture Experts)
MPEG2 standardized by ISO / IEC 13818-2 as a general-purpose image encoding method.
And covers both interlaced and progressively scanned images, as well as standard resolution images and high definition images. Therefore, it is expected that MPEG2 will be used for a wide range of applications from professional use to consumer use.

By using such an MPEG2 compression method, for example, in the case of a standard resolution interlaced scanning image having 720 × 480 pixels, a code amount of 4 to 8 Mbps (hereinafter, referred to as a bit rate) is 1920 × 108.
18 for a high-resolution interlaced scan image with 8 pixels
By assigning a bit rate of 22 Mbps, a high compression rate and good image quality can be realized.

[0005] MPEG2 is intended mainly for high-quality encoding suitable for broadcasting, but does not support an encoding system with a lower bit rate than MPEG1, that is, a higher compression rate. However, with the spread of portable terminals, the need for an encoding system with a higher compression ratio is expected to increase in the future, so that the MPEG4 encoding system has been standardized.
It was approved by the international standard as ISO / IEC14496-2 in January.

[0006] As described above, MPEG2 image compression information (hereinafter, referred to as "encoded") once encoded so as to correspond to digital broadcasting.
Described as an MPEG2 bit stream. 5) is converted into MPEG4 image compression information of a lower bit rate (hereinafter, referred to as an MPEG4 bit stream) for processing by a mobile terminal or the like, for example. Field-to-Frame Transcoding w
ith Spatial and Temporal Downsampling (Susie J.we
e, John G. Apostolopoulos, and Nick Feamster, ICIP'99)
Has been proposed.

[0007] In the image information conversion apparatus 100 shown in FIG.
The data of each frame in the G2 bit stream is
First, the image data is input to the picture type determination unit 111.

In the picture type discriminating section 111, input data of each frame is related to an I picture (intra-coded picture) and a P picture (forward predicted coded picture), or a B picture (bidirectional predicted coded picture). Then, only in the former case, information about the I and P pictures is output to the subsequent MPEG2 image information decoding unit (I / P picture) 112.

The processing in the MPEG2 image information decoding unit 112 is the same as that of a normal MPEG2 image information decoding device. However, since the data relating to the B picture is discarded by the picture type discrimination unit 111, the MPEG2
The function of the image information decoding unit 112 is only required to be able to decode only I / P pictures. The pixel value output from the MPEG2 image information decoding unit 112 is output from the thinning unit 113.
Is input to

The thinning section 113 performs a 1/2 thinning process in the horizontal direction, leaves only one of the first field and the second field in the vertical direction, and discards the other. , A progressively scanned image having a size of 1/4 of the input image information is generated. The progressive scan image generated by the thinning unit 113 is temporarily stored in the video memory 114 and then read out, and is read by the MPEG4 image information encoding unit (I / P-VO).
P) 115.

Here, for example, an MPEG2 bit stream to be input is an NTSC (National Television System).
em Committee), ie 720x
In the case of an interlaced scan image of 480 pixels and 30 Hz, the image frame after the thinning out is 360 × 240 pixels, but the subsequent MPEG2 image information encoding unit 115
When encoding is performed in, the number of pixels in the horizontal direction and the vertical direction is 1 in order to perform processing in units of macroblocks.
Must be a multiple of six. Therefore, the pixels are supplemented or discarded in the thinning unit 113 at the same time. That is, at this time, the thinning section 113 discards the eight pixels at the right end or left end in the horizontal direction, for example, as 352 × 240 pixels as a supplement or discard of the pixels.

The MPEG2 image information encoding unit 115 encodes the input signals of the progressively scanned image to generate an MPEG2 image information.
A 4-bit stream is generated, and the MPEG4 image compression information is output from an output terminal 118 to a subsequent stage. that time,
The motion vector information in the input MPEG2 bit stream is mapped to a motion vector for the decimated image information in the motion vector synthesis unit 116, and the motion vector synthesized in the motion vector synthesis unit 116 is calculated in the motion vector detection unit 117. High-precision motion vectors are detected based on vector values. Note that, in MPEG4, a VOP (Video Object Plane) represents an area composed of one or more macroblocks surrounding an object, and corresponds to a frame in MPEG2. The VOP area is classified into one of an I picture, a P picture, and a B picture according to a coding method. I-VOP (V of I picture
OP) encodes (intra-encodes) an image (area) itself without performing motion compensation. P
-VOP (VOP of P picture) is basically forward predictive coded based on an image (I or P-VOP) located temporally ahead of itself. B-VOP (VOP of B picture) is basically bi-directionally predictive coded based on two pictures (I or P-VOP) temporally located before and after itself.

[0013] As described above, the document 1 describes that the input M
A technique relating to an apparatus for generating an MPEG4 bitstream of a progressively scanned image having a size of 1/2 × 1/2 of a PEG2 bitstream is described. That is, the input MPEG2 bit stream is, for example, NTSC
MPE that is output if it conforms to the standard
Although the G4 image compression information has the SIF size (352 × 240), according to the configuration of FIG. 5, by changing the operation of the thinning unit 113, other image frames, for example, the above example It is also possible to convert an image into a QSIF (176 × 112 pixel) size image which is an image frame of about １ ／ ××.

Reference 1 discloses, as processing in the MPEG2 image information decoding unit 112, decoding using all the 8th-order discrete cosine transform coefficients in an input MPEG2 bit stream in each of the horizontal and vertical directions. Although the apparatus for performing the processing is described, the apparatus shown in FIG. 5 is not limited thereto, and only the low-frequency component of the 8th-order discrete cosine transform coefficient is used only in the horizontal direction or in both the horizontal and vertical directions. It is possible to reduce the amount of calculation and the amount of video memory required for the decoding process while minimizing the image quality deterioration by performing the decoding process using.

By the way, in the image information conversion device shown in FIG.
When encoding a VOP, each macroblock is
Either encode as an Intra macroblock defined by EG4, encode as an 16 × 16 pixel Inter macroblock, or encode as an 8 × 8 pixel Inter4V (Inter4V) macroblock It is necessary to determine the type of encoding mode to be used.

Here, as a general method of mode determination, an MPEG-4 Video Verification Model (ISO / IEC JTC1 /
SC29 / WG11 N2932, hereafter referred to as Document 2).

Hereinafter, a method of mode determination (mode determination performed by the MPEG2 image information encoding unit 115 of FIG. 5) described in Reference 2 will be described with reference to FIG.

First, in step S101, an inter motion vector and an inter
Find the V motion vector.

Next, in step S102, predicted images generated by the inter motion vector and the inter 4V motion vector are respectively referred to as Ref _Inter and Ref _Inter .
_{It is assumed} that the _macroblock is represented by _Inter4V and the original picture is represented by Org. Further, in step S103, a prediction error ER when the macroblock is coded as an inter macroblock and an inter 4V macroblock.
R _Inter and ERR _{Inter4 V} are calculated by equations (1) and (2), respectively, and the average value of the pixels included in the macroblock is defined as Mean_MB, and the macroblock is coded as an intra macroblock. The prediction error ERR _Intra is defined as in Expression (3). ERR _Inter = SAD (Org-Ref _Inter ) (1) ERR _Inter4V = SAD (Org-Ref _Inter4V ) (2) ERR _Intra = SAD (Org-Mean_MB) Sum of Absolute
Difference).

Next, as step S104, the prediction error ERR obtained by the above equations (1) and (2)
_{From the Inter} and ERR _Inter4V , it is determined which of the coding efficiency is better, that is, coding as an inter macroblock or coding as an _inter4V macroblock. That is, if equation (4) is satisfied, it is determined that coding as an inter macroblock has better coding efficiency, and if not, it is determined that coding as an inter 4V macroblock has better coding efficiency. ERR _Inter− Offset <ERR _Inter4V (4) In this equation (4), Offset is a parameter for making it easier to select an inter macroblock.
Reference 2 specifies 129.

Next, according to equation (4),
When the lock is selected, the parameter ERR is calculated according to the equation (5).
, While the inter 4V macroblock is selected.
In the case where the parameter ERR is defined, the parameter ERR is defined as in equation (6).
I do. ERR = ERR_Inter (5) ERR = ERR_Inter4V (6) Next, the average value of starvation included in the macroblock is
_MB as the macro block
Prediction error ERR when encoded as lock
_IntraIs defined as in equation (7). ERR_Intra= SAD (Org-Mean_MB) (7) Next, the parameter ERR and the equation (3) are used to determine
Defined error ERR_IntraFrom the macro
Encoding locks as intra macroblocks
And the macroblock mode selected by equation (4)
To determine which is more efficient than
Perform settings.

That is, if equation (8) is satisfied, it is considered that encoding as an intra macroblock is more efficient.
If not, it is assumed that coding in the macroblock mode selected by equation (3) is more efficient. ERR _Intra <ERR (8) That is, in step S105 of FIG.
And it is more efficient better to encode the intra macroblock mode in step S108 when _{the Inter <ERR Int ra} is not satisfied, when a condition is satisfied better be encoded in inter-macroblock mode in step S107 is to be more efficient. Step S10
6, ERR _Inter4V <ERR _Intra
If is not satisfied, it is assumed that the coding in the intra macroblock mode is more efficient as step S108, and that if it is satisfied, the coding is more efficient in the inter 4V macroblock mode as step S109.

Note that various methods can be considered for the operation principle of the motion vector synthesizing section 116 and the motion vector detecting section 117, but they are supplied to the input terminal 110 as in the image information converter 2 shown in FIG. MPE
M having 1/2 × 1/2 picture frame of G2 bit stream
When outputting a PEG4 bit stream, for example, it is conceivable to combine and detect motion vectors according to the flow shown in FIG.

That is, in the motion vector synthesizing section 116, first, in step S111, the input MPEG
The motion vector information is extracted from the 2-bit stream. Next, as step S112, the extracted MPEG
By performing scaling and time correction of the motion vector information on the two-image compression information, inter 4V motion vector information on the output MPEG4 bit stream is synthesized. Further, in the motion vector synthesis unit 116,
In step S113, the generated inter 4V
An average value or a representative value of the motion vectors is set as an inter motion vector.

Next, in step S114, the motion vector detecting unit 117 searches for several pixels around the inter motion vector and the inter 4V motion vector generated by the motion vector synthesizing unit 116, and searches for the inter motion vector and the inter motion vector. The accuracy of the inter 4V motion vector is improved. The motion vector whose accuracy has been improved in this way is the MPEG4 image information encoding unit 115 of FIG.
Sent to

[0026]

However, the macroblock mode discrimination method shown in FIG. 6 requires a large amount of calculation for performing motion compensation and calculating the sum of absolute value errors (SAD).

Therefore, the present invention has been made in view of such circumstances, and provides an image information conversion apparatus and an image information conversion method that can realize macroblock mode discrimination with a small amount of calculation. Aim.

[0028]

SUMMARY OF THE INVENTION The present invention provides an image information converter for converting at least first encoded image information comprising at least an intra-coded image and an inter-coded image into a second encoded image. In the apparatus, a motion vector generating means for generating motion vector information corresponding to each coding unit composed of a plurality of images constituting the second image coding information, and a motion vector storage means for storing the generated motion vector information , A motion vector of a coding unit of a first inter-picture prediction coding mode generated based on motion vector information extracted from the first picture coding information and a coding of a second inter-picture prediction coding mode A mode determining means for determining which of the first inter-picture prediction coding mode and the second inter-picture prediction coding mode to use based on the unit motion vector; To solve the above problems by having and.

According to the present invention, there is provided an image information conversion method for converting first image encoded information comprising at least an intra-coded image and an inter-picture predicted encoded image into second image encoded information. A motion vector generating step of generating motion vector information corresponding to each coding unit including a plurality of images constituting the second image coding information; and a motion vector storing step of storing the generated motion vector information in a motion vector storage unit. And a motion vector of a coding unit of the first inter-picture prediction coding mode generated based on the motion vector information extracted from the first picture coding information and a code of the second inter-picture prediction coding mode Coding mode determination for determining which of the first inter-picture prediction coding mode and the second inter-picture prediction coding mode to use based on the motion vector of the coding unit. By having the over-de determination step, to solve the problems described above.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image information conversion apparatus shown as an embodiment of the present invention is a Moving Picture Experts Group (MPEG) comprising at least an intra-coded picture (I picture) and an inter-picture predictive coded picture (B picture). ) Is an image information conversion device for converting MPEG2 image compression information standardized by MPEG) into MPEG4 image compression information.
The motion vector of the coding unit of the inter-coding mode which is the first inter-picture predictive coding mode generated based on the motion vector information extracted from the EG2 picture compression information and the second inter-picture predictive coding mode A mode judging unit for judging whether to use the inter encoding mode or the inter 4 V encoding mode based on a motion vector of a coding unit of a certain inter 4 V encoding mode; Thus, the macro block mode determination can be realized with a smaller amount of calculation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the image information conversion device 1 mainly includes a picture type discriminating unit 13, a compression information analyzing unit 14, an MPEG2 image information decoding unit (I / P picture) 15, a thinning unit 16, , Video memory 17 and M
A PEG4 image information encoding unit (I / P-VOP) 18;
Motion vector synthesizing section 19 and motion vector detecting section 20
And the Intra / Inter determination unit 21 and the Inter
/ Inter4V determination unit 22 and an information buffer 23.

In the image information conversion device 1, the input terminal 1
The MPEG2 image compression information of the interlaced scanning (hereinafter, referred to as an MPEG2 bit stream) supplied to 1 is transmitted to the picture type determination unit 13.

The picture type discriminating section 13 discriminates a picture type. That is, the MPE from the input terminal 11
With respect to the G2 bit stream, information about I and P pictures is output and sent to the compressed information analysis unit 14, but information about B pictures is discarded. As a result, the frame rate is converted.

The compression information analysis unit 14 analyzes the syntax of the image compression information sent from the picture type discrimination unit 13 to extract information related to the encoding of the MPEG2 bit stream, and The related information is sent to the information buffer 23, the MPEG2 motion vector information is sent to the motion vector combining unit 19, and the image compression information is sent to the MPEG2 image information decoding unit 15. The details of the information extracted by the compression information analysis unit 14 will be described later.

The MPEG2 image information decoding unit 15
Is equivalent to that of the device shown in FIG. Since the information about the B picture has already been discarded in the preceding picture type discriminating unit 13, the MPEG2 image information decoding unit 1
The function of 0 may be any function as long as it can decode only information relating to I and P pictures. The pixel value output from the MPEG2 image information decoding unit 15 is output from the thinning unit 1
6 is input.

The thinning section 16 is halved in the horizontal direction.
By performing thinning-out processing, leaving only one of the data of the first field or the second field in the vertical direction and discarding the other, a sequential image having a size of 1/4 of the input image information is obtained. Generate a scanned image. Here, for example, the MPEG supplied to the input terminal 11
2 bit stream is NTSC (National Television)
System Committee) standards, that is, 72
In the case of an interlaced scan image of 0 × 480 pixels and 30 Hz, the image frame after the thinning out is 360 × 240 pixels. However, when performing encoding in the subsequent MPEG2 image information encoding unit 18, in order to perform processing in units of macroblocks, the number of pixels in both the horizontal and vertical directions needs to be a multiple of 16 pixels. Therefore, the thinning unit 16 sets the number of pixels to 16 at the same time as the thinning.
Pixels are complemented or discarded at the same time to make a multiple of. That is, the thinning unit 16 in this example discards, for example, the eight lines at the right end or the left end in the horizontal direction with respect to the above 360 × 240 pixels, for example, thereby
352 × 240 pixels, which is a multiple of .times. The progressively scanned image generated by the thinning unit 16 is temporarily stored in a video memory 17 and then stored in an MPEG
The two-image information encoding unit 18 or Intra / I described later
The data is read out in response to a request from the internet determination unit 21.

In the motion vector synthesizing section 19, the MP
The MPEG2 motion vector information extracted from the EG2 bit stream is mapped to a motion vector for the decimated image information, and the next-stage motion vector detecting unit 20 further calculates the motion vector value synthesized by the motion vector synthesizing unit 19 and the video Based on the image information stored in the memory 17, a highly accurate motion vector is detected.
The detected motion vector is sent to the MPEG2 image information encoding unit 18 and the Intra / Inter determination unit 21.

The MPEG2 image information encoding section 18 includes information relating to the encoding of the MPEG2 bit stream held in the information buffer 23, the motion vector information from the motion vector detection section 20, and I
ntra / Inter determination unit 21 and Inter / In
In obtained by the determination processing in the ter4V determination unit 22
Using the ter / Inter4V mode information, the progressive scan image signal supplied from the video memory 17 is encoded to generate an MPEG4 bit stream. The MPEG4 bit stream is output from the output terminal 12 to a subsequent stage.

Information buffer 23, Intra / Inte
r determination unit 21, Inter / Inter4V determination unit 22
Will be described with reference to FIGS. 2 and 3 below. First, the operation principle of mode determination for a normal P-VOP other than the P-VOP converted from an I picture will be described with reference to the flowchart of FIG. 2 and FIG.

The Intra / Inter determination unit 21 extracts information related to the above-described encoding from the input MPEG2 bit stream stored in the information buffer 23 (step S1), and based on the extracted information related to the encoding. First, an Inter mode determination is performed (step S2).

Here, when outputting a progressively scanned MPEG4 bit stream having an image frame of about 1/2 × 1/2 of the interlaced MPEG2 bit stream, for example, as shown in FIG. STR2 constituting the MPEG2 bit stream supplied to
Macro blocks MB included in
_{MPEG2, i} (i = 1,2,3,4) is MPEG4
A case will be described as an example in which a macro block MB _MPEG4,1 in an image STR4 forming a bit stream is supported.

For example, as shown in FIG.
Four macroblocks MB _{MPEG2, i} (i = 1,2,3,4) of the image STR2 in the EG2 bit stream
4) corresponds to the macro block MB _{MPE G4, i} in the output MPEG4 bit stream,
_{MB MPEG2, i (i = 1,2,3,4} ) encoded the number of macro blocks are _{N an In tra} as intra macroblocks among the number of macro blocks that are coded as inter macroblock N
_If the following equation (9) is satisfied,
In step S2, this macro block is determined and encoded as an intra macro block, and step S6
In, the macro block of the image STR4 constituting the output MPEG4 bit stream is determined as an intra macro block. N _Intra ≧ N _Inter (9) When Expression (9) is not satisfied, that is, the number of macro blocks coded as intra macro blocks is larger than the number of macro blocks coded as inter macro blocks. If it is less than the above, it is determined that this macroblock is to be encoded as an inter macroblock or an inter 4V macroblock, and the process proceeds to step S3.

Here, the mode determination using the residual may be performed as in the above equation (8). Alternatively, the quantization scale for each of the macroblocks MB _{MPEG2, i} is Q _{MPEG2, i} (i = 1,2,3,4),
The code amount (bit number) assigned to each is B
_{When MPEG2, i} (i = 1,2,3,4), the complexity X _{MPEG2, i} (i = 1,2,3,4) for the macroblock MB _{MPEG2, i}
May be calculated by Expression (10), and a mode that is considered to have good coding efficiency may be selected using this complexity. X _{MPEG2, i} = Q _{MPEG2, iB MPEG2, i} (10)

Next, in step S2 of the above Intra / Inter determination, regarding the macroblock determined to be an inter macroblock or an inter 4V macroblock, the inter motion vector corresponding to the VOP stored in the motion vector detector 15 is determined. And the inter / inter 4 using the inter 4 V motion vector
Determine V. That is, in step S3, the mode determination unit 16 converts the x-direction component and the y-direction component of the inter motion vector of the macroblock into mv ₁₆ ×
_{16_x} , mv ₁₆ × _{16_y,} and the x-direction and y-direction components of the inter 4V motion vector are respectively mv ₈ ×
_{8_x, i} , mv ₈ × _{8_y. i} (i = 1, 2, 3,
As 4), the variance Dist of the motion vector information is calculated by the following equation (12) or (13).

[0045]

(Equation 1)

[0046]

(Equation 2)

Subsequently, in step S4, the variance (Dist) obtained by the above equation (12) or (13) is obtained.
ribution: Dist) and the obtained threshold Th, when the following equation (14) is satisfied, this macro block is determined to be an inter macro block in step S5, and when not satisfied, the inter 4V macro is determined in step S7. Determine that it is a block. Dist ≦ Th (14) Therefore, as described above, the image information conversion device 1
Since it is not necessary to calculate the absolute value error sum (SAD) as calculated by the equations (1), (2) and (6), the amount of calculation can be greatly reduced while minimizing the image quality deterioration. Is possible.

FIG. 4 shows an image information conversion apparatus 2 according to a second embodiment of the present invention. Image information converter 2
Has a basic structure similar to that of the image information conversion device 1 shown in FIG. 1, but the image information conversion device 1 uses an inter motion vector and an inter 4V motion vector that have been made highly accurate by the motion vector detection unit 20. Inter / In
In contrast to the determination of ter4V, the image information conversion device 2 illustrated in FIG. 4 performs the determination of Inter / Inter4V using the inter motion vector and the inter 4V motion vector generated in the motion vector synthesis unit 31. It has features. In the image information converter 2 shown in FIG. 2, the same components as those of the image information converter 1 shown in FIG.

In the image information conversion apparatus 2 shown in FIG. 4, prior to performing the high precision of the inter motion vector and the inter 4V motion vector generated by the motion vector detecting section 32, the Inter / Inter 4V determining section 34 It is possible to determine Inter / Inter4V.

For this reason, for example, Inter / Inte
In the r4V determination unit 34, the macro block is
If it is determined that r, the motion vector detection unit 32 performs the accuracy improvement only on the inter motion vector, and there is no need to increase the accuracy of the inter 4V motion vector. This makes it possible to reduce the amount of computation involved in detecting a motion vector.

In the above description, MPE is used as an input.
Take G2 bit stream as an example and output MPEG
An example of a 4-bit stream was given.
The output is not limited to this, and may be, for example, MPEG1 or H.264. 263
Image compression information (bit stream).

[0052]

As described above, the image information conversion apparatus according to the present invention provides a motion vector for generating motion vector information corresponding to each coding unit composed of a plurality of images constituting the second image coding information. Generating means, a motion vector storing means for storing the generated motion vector information, and a code of a first inter-picture predictive coding mode generated based on the motion vector information extracted from the first picture coding information Either the first inter-picture prediction coding mode or the second inter-picture prediction coding mode is used based on the motion vector of the coding unit and the motion vector of the coding unit of the second inter-picture prediction coding mode. And mode determination means for determining an encoding mode for determining whether to perform coding.

Therefore, according to the image information conversion apparatus according to the present invention, it is possible to realize a great reduction in the amount of calculation involved in detecting a motion vector while minimizing image quality deterioration.

Also, the image information conversion method according to the present invention
A motion vector generating step of generating motion vector information corresponding to each coding unit composed of a plurality of images constituting the second image coding information; and a motion vector storage for storing the generated motion vector information in a motion vector storage unit. Process and
The motion vector of the coding unit of the first inter-picture prediction coding mode generated based on the motion vector information extracted from the first picture coding information and the coding unit of the second inter-picture prediction coding mode A mode determining step of determining which of the first inter-picture predictive coding mode and the second inter-picture predictive coding mode to use based on the motion vector.

Therefore, according to the image information conversion method according to the present invention, it is possible to realize a significant reduction in the amount of calculation involved in detecting a motion vector while minimizing image quality deterioration.

[Brief description of the drawings]

FIG. 1 is a structural diagram illustrating a configuration of an image information conversion device shown as an embodiment of the present invention.

FIG. 2 shows an information buffer of an image information conversion apparatus, Intra / Inter shown as one configuration example of an embodiment of the present invention.
It is a flowchart which shows operation | movement in a determination part and an Inter / Inter4V determination part.

FIG. 3 shows an image S constituting an MPEG2 bit stream.
Four macroblocks MB included in TR2
Macroblock MB in image STR4 forming MPEG4 bit stream with _{MPEG2, i}
FIG. 4 is an explanatory diagram illustrating correspondence with _MPEG4 and _MPEG1 .

FIG. 4 is a structural diagram illustrating a configuration of an image information conversion device shown as a second embodiment of the present invention.

FIG. 5 is a structural diagram illustrating a configuration of a conventional image information conversion device.

FIG. 6 is a flowchart illustrating an operation of mode determination in an MPEG2 image information encoding unit in a conventional image information conversion device.

FIG. 7 is a flowchart illustrating operations of a motion vector synthesis unit and a motion vector detection unit in a conventional image information conversion device.

[Explanation of symbols]

1, 2 image information converter, 11 input terminal, 12 output terminal, 13 picture type discriminating unit, 14 compression information analyzing unit, 15 MPEG2 image information decoding unit, 16 decimation unit, 17 video memory, 18 MPEG4 image information encoding Section, 19, 31 motion vector synthesis section, 20,
32 motion vector detector, 21, 33 Intra / I
inter, 22/34 Inter / Inter
4V judgment unit, 23 information buffer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teruhiko Suzuki 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Yoichi Yagasaki 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 5C059 KK41 LB05 MA00 MA05 NN01 NN21 NN28 PP05 PP06 PP07 SS02 SS13 TA17 TA21 TB04 TC03 TC12 TD04 TD12 UA02 UA38 5J064 AA02 BA01 BB03 BC01 BC14 BD02 BD03

Claims (8)

[Claims] 1. An image information conversion device for converting at least first image encoding information including at least an intra-image encoded image and an inter-image predictive encoded image into second image encoded information, wherein the second image Motion vector generating means for generating motion vector information corresponding to each coding unit consisting of a plurality of images constituting the coding information; motion vector storing means for storing the generated motion vector information; and the first image A motion vector of a coding unit of the first inter-picture prediction coding mode and a motion vector of a coding unit of the second inter-picture prediction coding mode generated based on the motion vector information extracted from the coding information; Mode determining means for performing an encoding mode determination for determining which of the first inter-picture prediction encoding mode and the second inter-picture prediction encoding mode to use, based on An image information conversion device comprising: 2. The method according to claim 1, wherein the mode determining unit obtains a variance value between the first inter-picture prediction coding mode and the second inter-picture prediction coding mode, and compares the variance value with a preset threshold value. 2. The image information conversion apparatus according to claim 1, wherein a coding mode for the coding unit forming the second image coding information is determined based on the coding mode. 3. The mode determination means, if a condition that the variance value is equal to or less than the threshold value is satisfied, sets the coding mode of the coding unit constituting the second image coding information to the first image. If the condition is satisfied that the variance value is larger than the threshold value, the coding mode of the coding unit constituting the second image coding information is set to the second inter-picture prediction mode. 3. The image information conversion device according to claim 2, wherein the encoding mode is determined. 4. The method according to claim 1, further comprising:
Determining means for determining the first inter-picture prediction coding mode, the second inter-picture prediction coding mode, and the intra-picture coding mode based on motion vector information extracted from the picture coding information of The image information conversion device according to claim 1, further comprising: 5. An image information conversion method for converting first image coding information comprising at least an intra-picture coding image and an inter-picture prediction coding image into second image coding information, wherein the second image A motion vector generation step of generating motion vector information corresponding to each coding unit composed of a plurality of images constituting the coding information; anda motion vector storage step of storing the generated motion vector information in a motion vector storage unit. The motion vector of the coding unit of the first inter-picture prediction coding mode generated based on the motion vector information extracted from the first picture coding information and the coding of the second inter-picture prediction coding mode Coding mode determination for determining which of the first inter-picture predictive coding mode and the second inter-picture predictive coding mode to use based on a unit motion vector And a mode determining step of performing image processing. 6. In the mode determination step, a variance value of the first inter-picture prediction coding mode and the second inter-picture prediction coding mode is obtained, and the variance value is compared with a preset threshold value. 6. The image information conversion method according to claim 5, wherein a coding mode for the coding unit constituting the second image coding information is determined based on the coding mode. 7. In the mode determining step, if a condition that the variance value is equal to or less than the threshold value is satisfied, the coding mode of the coding unit constituting the second image coding information is changed to the first image. If the condition is satisfied that the variance value is larger than the threshold value, the coding mode of the coding unit constituting the second image coding information is set to the second inter-picture prediction mode. 7. The image information conversion method according to claim 6, wherein the encoding mode is determined. 8. The method according to claim 1, further comprising:
Determining the image first inter-picture prediction coding mode, the second inter-picture prediction coding mode, and the intra-picture coding mode based on motion vector information extracted from the picture coding information of 6. The image information conversion method according to claim 5, comprising: