JP2008167380A - Moving image compression-coding method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compression-coding method and apparatus capable of easily compression-coding a logotype portion, in particular, of a moving image containing a partial image of a logotype or the like with high image quality without increasing coding costs. <P>SOLUTION: In a compression-coding apparatus of the present invention, when predictively coding a control block containing a partial image, intra-frame prediction is applied for a picture and an intra-picture first displaying the partial image and a quantization parameter thereof is corrected to be decreased rather than the prior art, thereby improving image quality. On the other hand, inter-frame prediction is applied for a picture displaying the partial image other than the first stage, and the quantization parameter is corrected to be increased rather than the prior art, thereby reducing coding costs. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a moving image compression coding method and apparatus, and more particularly, to a compression coding method and apparatus suitable for compression coding of a moving image into which a partial image such as a logo is inserted.

As a technique for inserting a partial image such as a logo into a moving image, Patent Documents 1 to 8 disclose techniques for partially inserting an image into a moving image that has been compression-encoded by an encoding method such as MPEG.
These methods are techniques that insert partial images after partially decoding a moving image and returning it to an uncompressed image, or on a conversion coefficient, both of which are essential in terms of reusing moving images. Although there is no technology, it is difficult to perform insertion control that minimizes the degradation of the image quality of the partial image to be inserted because the restriction caused by the amount of generated code in the encoded video before inserting the partial image is large. Met.
On the other hand, as a technique for guaranteeing the quality of partial images, a method of superimposing partial images on uncompressed moving images in advance and performing normal compression encoding processing, or compressing partial images by a procedure different from moving images (such as JPEG) There is known a method of superimposing a moving image on a moving image by performing still image coding or MPEG-4 object coding.
JP 2004-304231 A Special table 2003-532316 Special Table 2002-531019 Special Table 2002-531019 Japanese Patent Laid-Open No. 11-261966 JP 2001-268572 A JP 2000-78471 A Japanese Unexamined Patent Publication No. 2000-78468

  Especially for services such as mobile, the video resolution is low and the encoding bit rate is limited, so if you encode a character string that contains a logo or important information indicating an advertisement or copyright holder, it will be limited. Images such as important advertisements and logos often deteriorate due to the influence of encoding parameters.

  On the other hand, in services such as digital broadcasting, these logo images and important character strings are not encoded video content, but are added as additional data such as high-quality still images and text character codes. Quality is maintained by extending the system layer for multiplexing. However, these extended systems require a special receiver having a complex composition during reproduction and a function for controlling the timing.

  The object of the present invention is to solve the above-mentioned problems of the prior art and to easily compress and encode a moving image including a partial image such as a logo with high image quality, in particular, without increasing the coding cost. It is an object of the present invention to provide a compression encoding method and apparatus.

  In order to achieve the above object, the compression coding apparatus of the present invention, when coding a control block including a partial image, includes a control block including a partial image of an intra picture and a picture that initially displays the partial image. In (for example, a macroblock or motion compensation block in MPEG encoding), intra-frame prediction is applied, and the quantization parameter is reduced and reduced to improve the image quality. A control block including a partial image in an inter picture to be displayed is characterized in that inter-frame prediction is applied and that the quantization parameter is increased and corrected as compared with the prior art to reduce the coding cost.

  According to the present invention, since the quantization parameter is reduced and corrected in a macroblock with a large amount of generated codes, such as a picture that first displays a partial image or an intra picture, the image quality of the partial image is improved. In addition, when a partial image is a still image and the generated code amount of the prediction difference value of the region is ideally zero or sufficiently small, such as a picture that displays a partial image other than the first, quantization is performed. Since the parameter is increased and corrected to reduce the coding cost, the image quality of a partial image such as a logo can be maintained with a simple configuration while reducing the coding cost as a whole. In addition, if temporal fluctuation (noise) occurs for some reason in the pixel value of the inserted partial image that is a still image, this fluctuation is absorbed by increasing the quantization parameter, and subjective image quality is improved. The effect to improve is also acquired.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a moving image compression encoding apparatus according to the present invention. Here, illustrations of configurations unnecessary for the description of the present invention are omitted.

  The moving image compression encoding apparatus 10 of the present invention includes an uncompressed moving image Dm, an uncompressed partial image Dp such as a logo image, a mark, and an important character string inserted into the uncompressed moving image Dm, and this portion. As the attribute information Da of the image Dp, the shape and size of the partial image Dp, spatial and temporal arrangement information of the partial image Dp, and the like are input. The arrangement information of the partial image Dp includes an insertion position and an insertion timing on the reproduced image of the partial image Dp.

  In the moving image compression coding apparatus 10, the arrangement control unit 1 spatially displays the partial image Dp on the reproduced image based on the attribute information Da of the partial image Dp and the boundary information of each control block of the moving image Dm. In addition to correcting the correct insertion position, block attribute information indicating whether or not the partial image Dp is superimposed on each control block of the moving image Dm is extracted. The partial image insertion unit 2 inserts and outputs the partial image Dp at the insertion position of the uncompressed moving image Dm designated by the arrangement control unit 1.

  The encoding control unit 3 determines the encoding mode and motion vector MV of each control block based on the attribute information Da of the partial image Dp provided from the arrangement control unit 1 and the block attribute information of each control block. At the same time, the quantization parameter QP is determined based on the image parameters such as the encoding rate and the difficulty of encoding. The compression encoding unit 4 controls the non-compressed video Dm + p in which the partial image Dp is inserted based on the encoding mode, the quantization parameter QP, the motion vector MV, and the like notified from the encoding control unit 3. Compression encoding is performed for each block.

  FIG. 2 is a diagram schematically showing the control block of the uncompressed moving image Dm + p into which the partial image Dp is inserted and the boundary information of the partial image. Here, the control block is a macro block (MB) and a motion. A case where the compensation block (MC) is used will be described as an example.

  In the present embodiment, among MBs of moving images, as indicated by hatching in the figure, MBs that at least partially overlap the partial image Dp are expressed as MBlogo in particular. The insertion position of the partial image Dp is defined as an offset value from the reference point (in this embodiment, the upper left corner of the reproduced image).

  FIG. 3 is a diagram schematically representing the operation of the arrangement control unit 1. In this embodiment, the partial image Dp has a rectangular shape including a square, and the vertical and horizontal size is an integer of MB or MC. It is prescribed in advance twice. The partial image Dp is arranged so that its outline coincides with the MB boundary or the MC boundary.

  The arrangement control unit 1 first determines whether or not the contour of the partial image Dp matches the MB boundary. For the contour that does not match, the MC is changed from 16 × 16 pixels to 16 × 8 pixels, and further to 8 × 16. The pixel, 8 × 8 pixel, 8 × 4 pixel, 4 × 8 pixel, and 4 × 4 pixel are subdivided until the contour of the partial image Dp matches the MC boundary. Alternatively, the arrangement coordinates of the partial image Dp are corrected so that the contour of the partial image Dp matches the MC boundary. The amount of generated codes can be suppressed by matching the contour of the partial image with a larger block boundary.

  FIG. 4 is a block diagram showing the configuration of the main parts of the encoding control unit 3 and the compression encoding unit 4, and the compression encoding unit 4 responds to an instruction from the encoding control unit 3 with the moving image Dm. + p compresses and encodes.

  In the compression encoding unit 3, the quantization parameter deriving unit 301 derives the quantization parameter QP by a known method based on the image parameters such as the encoding rate and the difficulty of encoding. In the correction coefficient storage unit 302, a correction coefficient α for reducing the quantization parameter QP when applying intra-frame prediction to MBlogo to make the quantization step finer, and when applying inter-frame prediction to MBlogo A correction coefficient β for increasing the quantization parameter QP to roughen the quantization step is stored. The MV setting unit 303 sets all motion vectors for MBlogo prediction between frames to zero. In the present embodiment, the correction coefficients α and β are set such that the quantization parameter (QP2) that has been increased and corrected is always larger than the quantization parameter (QP1) that has been corrected and decreased.

  The motion prediction unit 401 generates a motion vector MV based on the uncompressed moving image Dm + p on which the partial image is superimposed and the reference image D7 stored in the image memory unit 410, and uses the motion vector MV to generate a frame The encoding cost Cinter when performing inter prediction is output. The motion compensation unit 402 performs inter-frame prediction based on the motion vector MV and the reference image D7 stored in the image memory unit 410, and outputs a prediction result as inter-frame prediction data D1.

  The subtractor 412 subtracts the prediction signal D8 selected by the selector 407 from the uncompressed moving image Dm + p to generate a prediction residual D2. The prediction residual D2 is orthogonally transformed in units of MB in the orthogonal transformation unit 403 to become an orthogonal transformation coefficient D3. The orthogonal transform coefficient D3 is quantized by the quantization unit 404 using the quantization parameter QP instructed from the encoding control unit 3.

  The orthogonal transform coefficient D4 quantized by the quantization unit 404 is output after being variable-length encoded by the entropy encoding unit 405 and dequantized by the inverse quantization unit 407. The output of the inverse quantization unit 407 is orthogonally inverse transformed by an orthogonal inverse transform unit 408. That is, the inverse quantization unit 407 and the orthogonal inverse transform unit 408 perform processing reverse to that of the quantization unit 404 and the orthogonal transform unit 403, and the output of the orthogonal inverse transform unit 408 approximates the prediction residual D2. A signal is obtained.

  The output of the orthogonal inverse transform unit 408 is added to the prediction signal D8 by the adder circuit 406 to generate a local decoded signal D5. The local decoded signal D5 is stored in the image memory 410 as a reference image signal D7 after block noise is removed by the deblocking filter unit 409.

  The intra-frame prediction unit 411 generates an intra-frame prediction signal D6 based on the local decoded signal D5, and outputs an encoding cost Cintra when intra-frame prediction is performed. The selector 407 selects one of the inter-frame prediction signal D1 and the intra-frame prediction signal D6 for each control block based on the comparison result between the coding cost of the intra-frame prediction and the coding cost of the inter-frame prediction. Is output as a prediction signal.

  FIG. 5 is a flowchart showing the setting procedure of the predictive coding method and the quantization parameter QP in the present embodiment, and mainly shows the operation of the coding control unit 3.

  In step S1, it is determined whether or not the current attention MB is MBlogo including the partial image Dp. If the MB of interest is a normal MB other than MBlogo, the process proceeds to step S10. In step S10, intra-frame prediction and inter-frame prediction are performed on the current MB of interest in the same manner as in the past, and the encoding prediction method is set to either one based on both encoding costs Cintra and Cinter. At this time, the quantization parameter QP derived by the quantization parameter deriving unit 301 is notified to the quantization unit 404 based on the encoding rate, the reproduction image quality, and the like. The selector 407 selects and outputs a prediction signal of the set prediction method.

  On the other hand, if the current attention MB is MBlogo, the process proceeds to step S2, and it is determined whether or not the partial image Dp is the MBlogo of the picture that appears first. If the partial image Dp is the MBlogo of the picture in which the partial image Dp first appears as in the nth picture shown in FIG. 6, the process proceeds to step S3, and the current attention MB (MBlogo) is the intra MB that is the target of intraframe prediction. Is set. In step S4, the quantization parameter QP1 at the time of intra-frame prediction is calculated based on the correction coefficient α (α is a non-negative value) from the QP value derived by the quantization parameter deriving unit 301 based on the coding rate, the reproduction image quality, and the like. (Integer) is subtracted and set to the corrected value (= QP-α).

  On the other hand, if it is determined in step S2 that the partial image Dp is not the MBlogo of the first appearing picture, that is, the MBlogo of the (n + 1) th or (n + 2) th picture in FIG. Go ahead. In step S5, it is determined whether or not the picture including the current MB of interest is an intra picture in which all MBs are forcibly encoded by intra-frame prediction. If it is not an intra picture, the process proceeds to step S6, and the current MB of interest is set as an inter MB to be subjected to inter-frame prediction. In step S7, the quantization parameter QP2 at the time of inter-frame prediction is converted to the QP value derived by the quantization parameter deriving unit 301 based on the coding rate, the reproduction image quality, etc., and the correction coefficient β (β is a non-negative value). It is set to a value (= QP + β) that has been increased and corrected by adding (integer).

  If it is determined in step S5 that the current attention MB is an intra picture, the process proceeds to step S8, where the current attention MB is set as the intra MB. In step S9, the quantization parameter QP1 of the current MB of interest is set to a value (= QP−α) obtained by subtracting the correction coefficient α from the QP derived based on the coding rate, reproduction image quality, and the like. Is done.

  In a frame in which inter-frame prediction is applied to a control block with a logo, each control block does not encode a transform coefficient (for example, a DCT coefficient) or a motion vector, and encodes using only predictable information. If the encoding is performed in the skip mode, the encoding efficiency can be further improved.

It is the block diagram which showed the structure of the principal part of the moving image compression encoding apparatus which concerns on this invention. It is the figure which showed typically the frame structure of the uncompressed moving image in which the partial image was inserted. It is the figure which expressed typically operation | movement of the arrangement | positioning control part. It is the block diagram which showed the structure of the principal part of a compression encoding part. It is the flowchart which showed the setting procedure of the prediction encoding system and a quantization parameter. It is the figure which showed the example of temporal insertion of a partial image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Arrangement | positioning control part, 2 ... Partial image insertion part, 3 ... Coding control part, 4 ... Compression encoding part, 10 ... Moving image compression encoding apparatus, 301 ... Quantization parameter deriving part, 302 ... Correction coefficient memory | storage part , 303 ... MV setting section

Claims (8)

In a compression encoding apparatus that compresses and encodes an uncompressed moving image in which a partial image is inserted into a partial region on an image by inter-frame prediction or intra-frame prediction based on a predetermined quantization parameter in units of control blocks.
Means for deriving quantization parameters based on image parameters;
Means for determining whether the control block to be encoded is a control block including a partial image;
Means for determining whether or not the control block including the partial image is a control block of a picture that first displays the partial image;
Intraframe prediction is applied to the control block that includes the partial image of the picture that first displays the partial image and the intra picture, and interframe prediction is applied to the control block that includes the partial image of the picture that displays the partial image other than the first Means to
Means for increasing and correcting a quantization parameter derived to compress and encode the control block including the partial image with inter-frame prediction;
Means for decorrecting a quantization parameter derived to compress and encode a control block including the partial image with intra-frame prediction;
A moving image compression encoding apparatus, wherein a control block including the partial image is quantized with the quantization parameter subjected to the increase / decrease correction.   The quantization parameter of the control block including the partial image is corrected to increase or decrease so that the increased correction quantization parameter is larger than the decreased correction quantization parameter. A moving image compression encoding apparatus according to claim 1.   3. The moving image compression coding apparatus according to claim 1, wherein a motion vector is set to zero in inter-frame prediction of a control block including the partial image. Means for inputting attribute information including the shape of the partial image and temporal and spatial insertion positions;
2. The moving image according to claim 1, further comprising: a unit configured to set an arrangement of the partial image based on the attribute information so that an outline of the partial image matches a boundary of the control block. 3. Compression encoding device.     5. The moving image compression coding according to claim 1, wherein each control block is predicted in a skip mode in a frame in which inter-frame prediction is applied to the control block including the partial image. apparatus. In a compression encoding method for compressing and encoding an uncompressed moving image in which a partial image is inserted into a partial region on an image by inter-frame prediction or intra-frame prediction based on a predetermined quantization parameter for each control block,
A procedure for determining whether or not the control block to be encoded is a control block including a partial image;
Determining whether the control block including the partial image is a control block of a picture that first displays the partial image;
A procedure for applying intra-frame prediction to a control block including a partial picture of the picture that first displays the partial image and an intra picture, and inter-frame prediction to a control block including a partial picture of the picture that displays the partial image other than the first The steps to apply,
A step of increasing and correcting a quantization parameter derived to compress and encode the control block including the partial image by inter-frame prediction;
A step of decorrecting a quantization parameter derived for compression-coding the control block including the partial image with intra-frame prediction;
A method for compressing and encoding a moving image, comprising: a step of quantizing a control block including the partial image with the quantization parameter subjected to the increase and decrease correction.   7. The quantization parameter of the control block including the partial image is corrected to increase or decrease so that the increased correction quantization parameter is larger than the decreased correction quantization parameter. 2. A method for compressing and encoding moving images according to 1.   The method according to claim 6 or 7, wherein a motion vector is set to zero in inter-frame prediction of a control block including the partial image.

Images