Abstract: Decimating MPEG or other video data by subsampling the output of an inverse discrete cosine transform (IDCT) module. The decimation process is useful for reducing the volume of data that must be processed to display images on a display device, particularly when the volume of video data received at the decoder is greater than the amount needed to take advantage of the resolution of the display device. For example, high definition television data can be decimated for display on a standard television display device or in a picture-in-picture window, thereby reducing the amount of processing resources needed at the decoder and reducing the size of the frame buffers. Subsampling the output of the IDCT module reduces the volume of data and, for relatively static or constant pans, there is not a significant compounded loss of image quality as successive frames are decoded.

Abstract: A motion picture decoding apparatus according to the invention includes: a coefficient reducing circuit for removing orthogonal transform coefficients for high horizontal frequencies from a certain sized block of orthogonal transform coefficients obtained from an input signal, thereby reducing the number of transform coefficients to half; an inverse orthogonal transformation circuit for performing an inverse orthogonal transform operation by using the transform coefficients reduced by the coefficient reducing circuit, thereby obtaining, on a block-by-block basis, reconstructed image data or time-axis prediction error data horizontally compressed to ½; an adder for generating reconstructed image data horizontally compressed to ½, based on the time-axis prediction error data provided by the inverse orthogonal transformation circuit and on predetermined reference image data; and one or more than one reference image memories for storing reconstructed image data which is included in the reconstructed

Abstract: A method and apparatus for the selective peaking of portions of a video signal is provided. The video signals, such as those transmitted in compressed form, in accordance with MPEG Standards, can be presented as blocks of data encoded using Discrete Cosine Transforms (DCT). The Discrete Cosine Transform coefficients corresponding to the chrominance values of the signal can be obtained and analyzed. The analysis and corresponding amounts of enhancement (peaking) can be performed on a block-by-block, I-frame by I-frame, basis to selectively peak portions of a video signal. If the DCT coefficients for a portion of the signal exceed or fall within a pre-selected value or range, that portion of the signal can be subjected to peaking. For example, if the high frequency horizontal DCT coefficients exceed (or fall within) a pre-set threshold value or range, a horizontal peaking circuit can be set to peak that portion of the signal.

Abstract: When a real-time MPEG video encoding is performed, null frames are used to compensate lost frames. Or, when a performance of the real-time MPEG video encoding is insufficient, the encoding is performed in accordance with a predetermined frame-type output sequence, in which the null frames are uniformly distributed in the predetermined frame-type output sequence. The null frames are encoded by transforming a null predictive frame with a pixel value of 0 into a discrete cosine transform coefficient through a discrete cosine transform algorithm. The discrete cosine transform coefficient is then transformed into a quantized discrete cosine transform coefficient by quantization. The quantized discrete cosine transform coefficient is then encoded with a null motion vector of (0,0) by variable length coding.

Abstract: A system, method, and apparatus for improved and faster block processing structure for MPEG decoders is presented herein. The decoder receives compressed images at a Huffman decoder. The Huffman decoder decodes the variable length code, resulting in quantized DCT coefficients. The Huffman decoder also records the matrix position of non-zero coefficients. The Huffman decoder provides the quantized DCT coefficients and the matrix positions of the non-zero coefficients to an inverse quantizer. The inverse quantizer uses the non-zero coefficients to access and inverse quantize only the non-zero quantized coefficients. The quantizer provides the coefficients and positions of the non-zero coefficients to an inverse zig-zag scanner. The inverse zig-zag scanner creates an all zero DCT matrix and calculates the positions of the non-zero coefficients in the DCT matrix. The non-zero coefficients are added to the DCT matrix at the calculated positions.

Abstract: An apparatus and method of decoding coded video bitstreams is disclosed. The apparatus comprises a first processor and a second processor configured to operate in parallel. The main processor receives the coded video bitstream, parses it, and calls the second processor to decode the coded video bitstream to retrieve macroblock data. If an error occurs during decoding, the second processor signals the first processor, which can instruct the second processor to perform an error recovery routine. The first processor the performs dequantization and inverse DCT to recover digital pixel data from the macroblocks so that an image formed from the digital pixel data can be later displayed on a monitor.

Abstract: The invention concerns a method and system for generating a dummy bidirectional predictive (dummy B) field picture. The method includes the steps of setting at least a portion of a first indicator of the dummy B field picture to indicate that no encoding of a residual signal will occur and setting at least a portion of a second indicator of the dummy B field picture to indicate that the dummy B field picture will be predicted from at least one field among a first field and a last field of a reference picture to control a vibration artifact. The dummy B field picture can be a forward or a backward predicted field picture, and the at least one field from which the dummy B field picture is predicted can be a first or last field of the reference picture.

Abstract: A programmable video encoding accelerator having a substantially hardware-based transform coder that has at least a first video input and a second video input. In a preferred embodiment, the first video input is operably coupleable to an integral native difference computer and the second video input is operably coupleable to an external video feed that does not pass through the native difference computer.

Abstract: A method of encoding moving pictures using a plurality of quantization matrices. The method involves selecting one of the plurality of quantization matrices in consideration of an at least one characteristics of an input image; transforming the input image; and quantizing the transformed input image using the selected quantization matrix.

Abstract: Input MPEG compressed data is input into a partial decoder and a logo insertion controller. A block DCT coefficients (a) output from the partial decoder is divided into a logo insertion region (c) and a non-logo insertion region (d) in a logo insertion region separator. Logo data (e) supplied from a logo information supply section is combined into the logo insertion region (c) with an arbitrary mixing ratio in a logo information insert section. In a logo region partial re-encoder, intra-frame coding of an image insertion region is executed when a starting frame for inserting an image is an intra-coded frame or a predictive coded frame, and, when the starting frame is a bidirectionally predictive-coded frame, inter-frame coding of the image insertion region is executed, and intra encoding of the image insertion region is executed in a frame to which the starting frame for inserting the image can refer.

Abstract: Digital multimedia includes intraframe information and interframe information. In addition to sending separate complete intraframes that are referenced by interframes, some interframes (“hybrid” frames) contain partial intraframe information, so that if a complete intraframe is lost, referencing interframes can obtain at least some intraframe information from the hybrid frames.

Abstract: Decomposition of deblocking filters used in block-based video compression allows reduction of computational redundancies.

Abstract: An apparatus and method for encoding quantized frequency represented data, the data comprising zero and non-zero represented data is claimed. For zero represented data, a zero run length is determined. A Golomb parameter is determined as a function of the zero run length. A quotient is encoded as a function of the zero run length and the Golomb parameter. A remainder is encoded as a function of the zero run length, the Golomb parameter and the quotient. The coded quotient and the coded remainder are concatenated. For non-zero represented data, the nonzero data is encoded as a function of the non-zero data value and the sign of the non-zero data value.

Abstract: At the time of coding input image and audio data, and decoding coded video and audio data by using a computer, the amount of computation required per unit time becomes enormous, whereby it has been very difficult to carry out coding and decoding in real time.

Abstract: A phase plane correlation motion vector determination method of a invention embodiment identifies images areas in which motion took place. A reference image is shifted by the candidate motion vectors obtained from the phase plane correlation. The shifted reference image is correlated to determine similarity with the current image and to eliminate spurious motion vectors. Candidate motion vectors are validated to determine valid motion vectors and identify problem areas. In a preferred embodiment, a correlation resolution is to a sub-block size. Sub-blocks of the reference image are shifted by candidate motion vectors for corresponding blocks. Shifted sub-blocks are correlated with sub-blocks of a current image using a sub-block neighborhood to determine valid vector assignments. Where an assignment proves invalid, global motion parameters are determined to assign motion vectors to sub-blocks where correlation fails.

Abstract: A reversible Discrete Cosine Transform (DCT) is described. The reversible DCT may be part of a compressor in a system. The system may include a decompressor with a reversible inverse DCT for lossless decompression or a legacy decompressor with an inverse DCT for lossy decompression.

Abstract: A system and corresponding method for adjusting the brightness and color of MPEG encoded video images. A digital versatile disk player capable of decoding a previously encoded MPEG video signal and adjusting the brightness and color of the entire previously encoded MPEG video signal based on a subset of information contained in the encoded input signal. The brightness and color adjustments are performed while the encoded MPEG video signal is in the frequency (dct) domain before motion compensation is performed. The digital versatile disk player also determines whether the particular block to be decoded is of a predetermined type and decodes such block accordingly.

Abstract: A method and apparatus for perceptual model based video compression calculates a bitrate value that follows with stabilizing delay the actual bitrates of previous frames. A current quantization coefficient is determined with the calculated bitrate value and a perceptual model. The current quantization coefficient's rate of change is limited based on a previous quantization coefficient. After the current quantization coefficient has been calculated and limited, a current frame is encoded with the limited current quantization coefficient.

Abstract: A method for decompressing digital image data to improve the speed of decompression is disclosed. More specifically, the present invention improves image decompression time by operating upon a subset of the original data and by performing a modified discrete cosine transform on a subset of the originally provided data. The subset is determined by examining the compressed data and looking for a particular pattern of zero values and/or and “end of block” statement.

Abstract: A fine-grain scalable video data apparatus, system, method and data structure is disclosed. An encoder (110) for encoding input video data as minimum bitrate macroblock data to produce DCT data having DCT coefficients representing a minimum bitrate version of the macroblock data. The encoder (110) also encodes the input video data as intermediate bitrate macroblock data to produce DCT data having DCT coefficients representing an intermediate bitrate version of the macroblock data. An adaptive motion compensator (132) (whether incorporated within the encoder or externally) communicates with the encoder for predicting whether a decoded version of the intermediate bitrate macroblock data has an accumulated predicted error frame energy exceeding a maximum threshold (228).

Abstract: A method and apparatus for redundant image encoding and decoding, in which using a slice structure used for image encoding part of an image is redundantly encoded and decoded are provided. The apparatus for redundant image encoding includes a slice modeling unit which determines the structures of slices to be used in encoding the image and regions to be redundantly encoded so that image data of a predetermined region of the image to be redundantly encoded is contained in a plurality of slices, a slice allocation unit which allocates image data of each region of an image to the plurality of slices, a picture header encoding unit which encodes information required to decode the plurality of encoded slices and generates picture information, and a slice encoding unit which encodes the image in units of slices according to the picture header information.

Abstract: A method for encoding video data to reduce blocking artifacts is provided. The method initiates with identifying a macro-block as being associated with a blocking artifact. For example the macro-block may be identified as a low activity macro-block or a high activity macro-block. Then, blocking artifacts introduced through a compression operation are mitigated by adjusting both a quantization parameter and an amount of bits generated from the quantization parameter. A video encoder and a system for processing image data associated with block based compression are provided.

Abstract: Provided are a video encoding/decoding method, in which a motion between interlaced video frames is estimated and/or compensated, and a video encoding/decoding apparatus. In this method, first, a macroblock and a search range are received, and a frame motion vector for each integer pixel is estimated. Next, if the vertical component of the estimated frame motion vector is an odd value, the bottom field pixels in the received macroblock are matched with top field pixels in a reference frame that correspond to motion vectors obtained by scaling the vertical component of the original motion vectors depending on a field-to-field distance. If the vertical component of the original frame motion vector is an even value, the top or bottom field pixels in the received macroblock are matched with the top or bottom field pixels in the reference frame that correspond to the original frame motion vector.

Abstract: The invention relates to a scalable video transcoding method for transcoding an input video signal coded in accordance with the MPEG-2 video standard. It is an object of the invention to provide a method and device for modifying data in a coded data signal through the use of standard motion compensation processing steps used in MPEG-2 video decoders and encoders. To this end, an adding and a subtracting sub-step are inserted into the prediction loop for shifting the dynamic of the coding error so that it can be stored in a standard memory device dedicated to storing 8-bit unsigned values. Secondly, said subtracting sub-step allows to use a standard prediction step while reducing the quality drift resulting from data interpolation.

Abstract: Methods and apparatus are provided for selecting a cut-off index to filter transform coefficients associated with an input bitstream to provide filtered transform coefficients associated with a rescaled output bitstream. An arrangement of transform coefficients associated with an input data sequence (e.g. an audio segment or a video image block) is filtered using a cut-off index to provide modified transform coefficients associated with a modified output data sequence. Information including information about the input data sequence and the modified output data sequence can be used to update the filter cut-off index for reduction of future data sequences.

Abstract: A processor changes frames of a videostream according to how an MPEG (Motion Picture Expert Group) encoder will encode them so that the output of the MPEG encoder has a minimal number of bits but a human eye generally does not detect distortion of the image in the frame.

Abstract: An information insertion/detection system for detecting and inserting DCT coefficients in image signals includes a resolution analyzer for receiving image code data and outputting the image code data and image size information of the image code data, an insertion pattern determining unit for receiving the image code data and the image size information and outputting the image code data and pattern information, an information inserter for receiving the image code data and the pattern information and producing image code data by inserting information of the DCT coefficients into the image code data and a video analyzer for receiving the image code data and producing information of insertion strength of the DCT coefficients. The information is inserted in DCT coefficients so that the information can be detected by referring to an image size of MPEG data inputted to the system when the image data is converted into a reference image size.

Abstract: A method adaptively encodes a video including a sequence of images, where each image is a picture of two fields. Each image is first separated into a top-field and a bottom-field. Motion activity is extracted from the top-field and the bottom-field, and each image is encoded using either frame encoding or field encoding depending on the extracted motion activity.

Abstract: The invention relates to a method for transmitting video information, in which at least a first bit-stream (510) and a second bit-stream are formed. The first bit-stream (510) comprises at least one video frame, and the second bit-stream (520) comprises at least one predictive video frame (524). At least partly different encoding parameters are used with encoding of the frames of said first bit-stream (510) and said second bit-stream (520). At least one frame of said first bit-stream (510) is being transmitted, and the transmission is switched over from said first (510) to said second bit-stream (520). In switching the transmission over from said first (510) to said second bit-stream (520), a secondary switching frame (550) is transmitted, which have been encoded using the encoding parameters of the second bit-stream (520), and at least one reference frame from the first bit-stream (510).

Abstract: The present invention describes a method and an arrangement for coding transform coefficients in picture and/or video coders and decoders and a corresponding computer program and a corresponding computer-readable storage medium, which can particularly be employed as a novel efficient method for binary-arithmetic coding transform coefficients in the field of video coding.

Abstract: A method to predict visual quality of a DCT (discrete cosine transform) based compressed image or video stream without referring to its source. When applied to an MPEG video stream, the method is based on (1) an estimation of quantization errors using MPEG quantization scales and statistics of the inverse quantized DCT coefficients, (2) a blind estimation of the 8×8 and 16×16 blocking effect, and (3) an adaptive combination of the quantization error estimation and the blocking effect estimation using the MPEG motion vector information. The method may be used in many applications, such as network video servers, switches and multiplexers for automatic quality monitoring and control of video services, video encoders, decoders, transcoders, and statistical multiplexers for picture quality optimization.

Abstract: Occurrence of mosquito noise of a macro block that contains even a small plain region is suppressed. One macro block is subdivided into sub blocks each of which is composed of four pixels×four lines. The average value of luminance levels of each sub block is calculated. The absolute values of the difference values between the luminance levels and the average value are obtained for each sub block. The minimum value of the average difference values of the 16 sub blocks of one macro block is selected and decided as an activity of the macro block. Corresponding to the decided activity, a quantizer scale of the macro block is decided. With the decided quantizer scale, the macro block is quantized. According to this method, since the size of each sub block is smaller than the size of a conventional sub block of eight pixels×eight lines, the average difference value of each sub block is more emphasized.

Abstract: A video decoding method and apparatus receives a motion compensation shader command, such as a packet, for a programmable shader of a 3D pipeline, such as programmable vertex shaders and pixel shaders, to provide motion compensation for encoded video, and decode the encoded video using the programmable shader of the 3D pipeline. As such, the programmable shader of a 3D pipeline is used to provide motion compensated video decoding as opposed to, for example, dedicated hardware, thereby, among other advantages, eliminating the need for the dedicated hardware.

Abstract: An apparatus and method is described for performing texture-decoding within a video decoder processing a series of macroblocks within a video bit-stream. The inventive texture decoding is particularly well suited for implementation within decoders incorporating multiple processors. The method separates data independent operations from data dependent (sequential) operations wherein multiprocessing may be efficiently utilized for processing data independent macroblocks. The method preferably makes an assumption as to prediction direction within the set of data dependent operations. A prediction determination is then made and the assumption corrected if necessary with a transposition within the data independent operations operating on the macroblocks. The method reduces the computational overhead and provides for efficiently segmenting operations within a multiprocessing decoder.

Abstract: Adaptive DCT/IDCT apparatus based on energy and method for controlling the same. The adaptive DCT/IDCT apparatus relates to a coding unit of a MPEG4/H.263 video coder, and performs an image processing operation with a high image quality at a high speed by calculating energy values for respective blocks and a mean energy value of the whole image.

Abstract: Apparatus and methods are provided for encoding video data in a manner which significantly reduces the computation performed by the video encoder and the video decoder without suffering any degradation in the perceived quality of the compressed video data. In particular, apparatus and methods are provided for determining which blocks might be zeroed out after quantization. This determination is performed after motion estimation, the classification of the frame as either an I frame, P frame, or a B frame, and the determination of a quantization step size (QP) for the block, but before DCT. If a given block is determined to be a “zero” quantized block, then the DCT, quantization, zig-zag scan and variable length coding steps are omitted, and a variable length code output is provided indicating that the block B is a “zero” quantized block.

Abstract: A video decoder system having a scalable IDCT system. Included is a system for determining a complexity level based on a complexity budget inputted from a local resource controller; and an IDCT system that selects a scaling algorithm from a plurality of scaling algorithms, wherein the selected scaling algorithm corresponds to the determined complexity level. Each of the plurality of scaling algorithms provides a unique data-pruning pattern for processing DCT data.

Abstract: The present invention relates to an image processing apparatus capable of reducing noise contained in input image data. By determining whether or not, among the absolute values of the AC components of luminance Y, there is at least one value greater than a threshold value A, it is determined whether the components are effective edge components of the image or noise components. When it is determined that the components are effective edge components of the image, a suppress_flag is set to “0” so that a suppression process is not performed. When it is determined that the components are noise components, the suppress_flag is set to “1” so that a suppression process is performed. The present invention can be applied to a video camera for capturing an image of a subject.

Abstract: An MPEG-2 video decoding system simultaneously decodes two or more HD-class MPEG sequences using a single video decoder, and reduces memory capacity and bandwidth. According to the video decoding system, a buffer size is reduced by efficiently sharing a video buffer, and a great reduction of a gate size can be obtained by integrating a VLD unit and a picture controller, and by integrating a motion compensation unit and a memory interface, respectively. Also, two or more HD-class MPEG sequences are displayed in the form of a PIP or a split screen. In the case of the PIP display, a DTV main picture is displayed in a non-compression mode, and a DTV sub-picture is displayed in a ¼-compression mode. In the case of the split-screen display, the DTV main picture and the DTV sub-picture are displayed in a ½-compression mode.

Abstract: Provided are a filtering method and apparatus for removing blocking artifacts and/or ringing noise. The filtering apparatus includes (a) performing one-dimensional discrete cosine transform (1D DCT) on video data on a block-by-block basis in a horizontal or vertical direction; (b) performing 1D DCT in the other direction of (a) and quantization on at least one of 1D DCT coefficients for a pixel obtained by performing 1D-DCT on the video data, the pixel being selected according to pixel position; and (c) generating filtering information based on the quantized pixel coefficient obtained from (b). According to the filtering method and apparatus, it is possible to reduce the amount of calculation when obtaining filtering information to remove the blocking artifacts and/or ringing noise.

Abstract: Methods and apparatus for performing 2:1 downscaling on video data are provided. At least one input matrix of N×N (e.g., N=16) Discrete Cosine Transform (DCT) coefficients is formed from the video data by combining four N/2×N/2 field-mode DCT blocks. Vertical downsampling and de-interlacing are performed to the input matrix to obtain two N/2×N/2 frame-mode DCT blocks. An N×N/2 input matrix is formed from the two frame-mode DCT blocks. Horizontal downsampling is performed to the N×N/2 matrix to obtain one N/2×N/2 frame-mode DCT block.

Abstract: A method of encoding an input video signal for communication over a computer network, the method comprising the steps of: i) dividing each frame into a two-dimensional array of macroblocks; ii) detecting motion between each macroblock of a current frame and the corresponding macroblock of a previous frame, and coding only those macroblocks where motion is detected; iii) replacing all coefficients of non-coded macroblocks with zero coefficients; iv) applying discrete cosine transformation to coded macroblocks; v) reorganizing coefficients into a multi-resolution representation; vi) quantizing the coefficients with a uniform scalar quantizer to produce a significance map; and vii) adaptive arithmetic coding of said signal by encoding the motion information, encoding the significance map, encoding the signs of all significant coefficients, and encoding the magnitudes of significant coefficients, in bit-plane order starting with the most significant bit.

Abstract: In methods and systems consistent with the present invention, the process of inverse quantization is performed by determining class number and quantization number for each block of received quantized DCT coefficients, determining a first shift value based on the class number and quantization number and a second shift value based on the class number and a combination type, and shifting the entire block of DCT coefficients based on the first and second shift values. Alternatively, the inverse quantization may be combined with inverse weighting step by pre-shifting a set of weighting tables, one for each area number combination. A pre-shifted weighting matrix is then selected based on the second shift value and multiplied by the shifted matrix of DCT coefficients. In another embodiment, a pre-shifted weighting table is selected based on the class number and combination type and then multiplied by the shifted matrix of DCT coefficients.

Abstract: A Fine Granular Scalability (FGS) encoding system and method having a base layer encoder and an enhancement layer encoder, wherein the base layer encoder comprises: a discrete cosine transform (DCT) system for generating a DCT signal having a Y component and a U/V component; and a quantizer system for separately quantizing the Y component and U/V component such that more bits can be assigned to the Y component than the U/V component.

Abstract: An encoding apparatus includes: (a) input circuitry for inputting image data including luminance component data and chrominance component data; (b) block forming circuitry for dividing the image data input by input circuitry into blocks so as to divide the respective component data into the blocks separately, each of the blocks being formed by a same predetermined amount of the input image data; and (c) encoding circuitry for encoding the input image data divided into the blocks by the block forming circuitry. The encoding circuitry includes code amount control circuitry for controlling a code amount of encoded data on a unit basis of a predetermined number of blocks, the predetermined number of blocks being formed so as to include at least one of the blocks of each type of component data.

Abstract: This invention relates to systems and methods for increasing image compression. The systems and methods are improvements applicable to encoder/decoders which compress images by, inter alia, transforming non-overlapping independent blocks of pixels into a frequency domain and then quantizing the resulting frequency domain coefficients. The invention achieves increased compression by predicting low frequency coefficients of a block from, preferably, the average intensities, or zero frequency coefficients, of the block and its adjacent blocks. In an encoder, the low frequency coefficients are predicted, are then subtracted from the actual transform coefficients, and the difference coefficients are transmitted to a decoder. In the decoder, the low frequency coefficients are again predicted, are added to the received difference coefficients, and the resulting actual transform coefficients are used to reconstruct an image.

Abstract: Data is discrete cosine transformed and streamed to a processor where quantized and inverse quantized blocks are generated. A second streaming data connection streams the inverse quantized blocks to an inverse discrete cosine transform block to generate reconstructed prediction error macroblocks. An addition circuit adds each reconstructed prediction error macroblock and its corresponding predictor macroblock to generate a respective reconstructed macroblock. The quantized macroblocks are zig-zag scanned, run level coded and variable length coded to generate and encoded bitstream.

Abstract: Received frame and field coded DCT coefficient blocks are downconverted to lower resolution reconstructed pixel field blocks so that, for example, HDTV programs can be played on NTSC receivers. The frame and field coded DCT coefficient blocks have motion vectors associated therewith. Specifically, the received frame coded DCT coefficient blocks are converted to converted field coded DCT coefficient blocks and an IDCT module is performed on the converted field coded DCT coefficient blocks to produce downconverted field residual or pixel blocks. Also, an IDCT is performed directly on the received field coded DCT coefficient blocks to produce downconverted field residual or pixel blocks. Reference pixel blocks are selected based upon the motion vectors, the reference pixel blocks are upsampled, and the upsampled reference pixel blocks are downsampled.

Abstract: The variable bitrate coding method according to the invention comprises an iterative process including a first analysis pass and a second prediction pass and followed by a last control step for adjusting said stepsize with respect to said target bitrate. According to the invention, a picture re-arrangement step is provided between the analysis and prediction steps of one iteration, in order to encode with an improved quality the picture sequence.

Abstract: In a bitstream transcoder, the computational cost and the memory area are suppressed so that stream transcoding is performed with a reduced number of times of computing and a reduced memory area. The transcoder includes a VLD portion 11 for performing VLD on a bitstream encoded in MPEG-2 to output quantized DCT coefficients; an IQ portion 12 for receiving the coefficients, and outputting inverse-quantized DCT coefficients; a coefficient table 132 for storing a transformation matrix obtained by multiplying transformation matrices for operating band-limiting filter, IDCT, down-sampling and DCT, respectively, together in advance; a DCT scaling portion 13 for performing down-sampling on the DCT coefficients by use of the transformation matrix; a Q portion 15 for outputting quantized DCT coefficients down-sampled horizontally and vertically; and a VLC portion 16 for encoding the quantized DCT coefficients in MPEG-4 to output a bitstream.