KR19980061691A - Video encoding device - Google Patents

Abstract

The present invention relates to an encoding apparatus for processing digital image data input in units of segments, the encoding apparatus comprising: a coefficient memory for storing DCT coefficients of image data in units of segments, a class number of image data in units of segments, and A DCI memory for storing DCI information including mode information, a QNO latch unit for temporarily storing QNO information of the segment image data, and encoding and encoding data provided from the coefficient memory, the DCI memory, and the QNO latch. And encoding means for generating a codeword and multiplexing means for sequentially multiplexing the QNO information, the DCI information, and the coded codeword, thereby significantly reducing the capacity of a memory storing DCI information having a bit length shorter than coefficient data. It becomes possible.

Description

Video encoding device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoding device for encoding data used in an image encoding process of a digital CR, and more particularly, to an image encoding device for processing data of a segment unit input to an encoder for each type.

As is well known, the digitalized video signal can be transmitted as a higher quality video image than the analog signal. When a video signal composed of a series of video frames is represented in a digital form, a considerable amount of data is generated to transmit the digital video signal. However, since the available frequency bandwidth of a typical transmission channel is limited, it is necessary to compress the amount of data to be transmitted in order to transmit a large amount of digital data through the limited channel bandwidth.

Since a video signal has any correlation or redundancy between certain pixels in one frame or neighboring frames, it is possible to compress the video signal without seriously adversely affecting the whole of the video signal. Therefore, most conventional video signal encoding methods use various compression techniques developed based on the technical idea of using or eliminating the above-described redundancy.

Such a coding method relates to a transformation technique that takes advantage of redundancy existing in one frame, and includes a diagonal transformation method for transforming a digital image data block into transformation coefficients, for example, two-dimensional discrete cosine transform (DCT) coefficients. orthogonal transform method).

In particular, in the above-described diagonal conversion method such as DCT, a video signal of one frame is divided into non-overlapping same sized blocks, for example, 8 * 8 pixel blocks, each pixel block being a frequency in a spatial domain. Is converted to an area. As a result, each pixelblock will have a set of transform coefficients consisting of one DC coefficient and a plurality of (e.g., 63) AC coefficients. These transform coefficients represent the amplitude of the frequency component of each pixel in one block, in particular the DC coefficient of the block has the average brightness of the pixels in the block, while the remaining AC coefficients are the spatial frequency components of each pixel. Indicates the luminance.

The encoder used for the digital VCR is configured to process input DCT coefficients and information values related thereto in units of segments.

FIG. 1 shows a configuration of a segment that is a unit of video data processed in a digital VCR.

As shown, one segment contains five units (QNO1 to QNO6) each having QNOs to be treated identically. Each unit consists of six DCT blocks. Thus, one segment is shown as containing 30 DCT blocks.

Each DCT block is assigned one class number (class1 to class6) in accordance with the coefficient of the DCT block. In addition, each DCT block is composed of one DC coefficient value and 63 AC coefficient values, and is divided into four areas according to the zig-zag scan.

The image data having the above-described configuration is divided into DCT coefficients of the image data of each segment unit and information values (DCI and class number) related to the processing before the quantization and the variable length encoding process are performed in units of segments in the encoder. Stored in memory.

Referring to Fig. 2, a detailed configuration of the information / counting memory is shown, which includes 30 DCT blocks each composed of one DC value having 9 bits and 63 AC values having 9 bits. Is divided into a memory area 12 for storing the information, a memory area 14 for storing the number of 30 classes of 2 bits, and a memory area 16 for storing information about the mode of 1 bit.

The data stored in the information / counting memory 10 are classified into types, that is, DC values, modes, classes, and QNOs, and are quantized and variable length coded, and then stored in the output data memory in segments in the order of processing.

As such, AC coefficients stored in the information / coefficient memory used in the encoder of the prior art and ACI values, that is, AC having the maximum bit length even though the number of bits of DC values, class values, and mode values are different from each other. The bit storage width of the memory regions of the DCI should be set according to the number of bits of the coefficient. That is, the data width of the memory for storing class and mode information should be the same as the data width of the memory for storing AC coefficients. Thus, there is a problem that loss due to unnecessary memory capacity can be caused.

Therefore, an object of the present invention is to provide an encoder which can reduce the size of a memory by storing AC coefficients and DCI in separate memories.

1 is a diagram illustrating a configuration of video data in units of segments processed by a video encoding apparatus.

2 is a diagram showing the configuration of a memory used in a conventional video encoding apparatus.

3 is a block diagram of an encoding apparatus having a separate coefficient memory and an information memory for respectively storing coefficient information and DCI information of image data according to the present invention.

4A and 4B respectively show the configurations of the coefficient memory and the information memory shown in FIG.

FIG. 5 is a diagram showing the configuration of the output memory shown in FIG.

Explanation of symbols on the main parts of the drawings

30, 40; Coefficient memories 32, 42; Information memory

50; QNO latch section 56; DCI latch

60; Quantization unit 62; VLC Department

70; Multiplexer 80; Output memory

According to the present invention for achieving the above object, a coefficient memory for storing the DCT coefficients of the image data in units of segments, and a DCI memory for storing DCI information including class number and mode information of the image data in units of segments; And a QNO latch unit for temporarily storing QNO information of the segment image data, encoding means for encoding data provided from the coefficient memory, the DCI memory, and the QNO latch unit to generate an encoded codeword, and the QNO information. And a multiplexing means for sequentially multiplexing the DCI information and the coded codeword.

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings.

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

Referring to FIG. 3, a block diagram of an encoding device according to a preferred embodiment of the present invention is shown.

As shown, the encoding apparatus of the present invention includes coefficient memory (30, 40) for storing the DCT coefficients of the image data in the unit of the segment shown in Figure 1, and includes class number and mode information of the image data of the unit of segment DCI memories 32 and 42 for storing DCI information, QNO latch sections 50 for temporarily storing QNO information of segment image data, coefficient memories 30 and 40, DCI memories 32 and 42, and QNO latches. A quantization unit 60 that quantizes the data provided by the wave 50 and a VLC unit 62 which generates an encoded codeword by variable length encoding the output of the quantization unit, the QNO information, the DCI information, and the encoded codeword. The multiplexer 70 sequentially multiplexes codewords, and an output memory 80 output from the multiplexer 70.

In addition, each time the QNO is latched to the QNO latch section 50, the information latch section 54 for temporarily storing six DCI information read out from the information memories 32 and 42, and the information latch section 54, respectively. A coefficient latch unit 52 for temporarily storing 64 DCT coefficients read from the coefficient memories 30 and 42 each time the DCI information is latched is further provided.

The operation of the present invention having the above-described configuration is described in detail as follows.

DCT coefficient values of DC and AC of each segment are stored in the coefficient memory 30, and class numbers and mode values corresponding to DCI are stored in the class storage area 34 and the mode storage area 36 of the information memory 32. When each segment of image data is stored in both the information memory 30 and the coefficient memory 32, the segment image data of the next rank is stored in the second coefficient memory 40 and the information memory 42. At this time, the coefficients stored in the coefficient memory 30 or 40 occupy a depth of 1920 (= 64 (number of coefficients) * 5 (number of units) * 6 (number of classes)) and the information memory 32 or (42). The information stored in occupies 30 depths. Thus, it is possible to use a size in which the capacity of the information memory is significantly reduced.

On the other hand, when a new segment is input to the encoder, the QNO value of the previous segment is calculated and stored in the QNO latch unit 50.

When 64 coefficient values are read sequentially from the coefficient memory 30, one mode and class information is read from the information memory 932. Thus, 384 coefficient values are read out while six classes are read, and one QNO is output from the QNO latch portion 50 when the 384 coefficient values are read out and provided to the quantizer 60 and the multiplexer 70. At this time, the count value and the DCI value stored in the count memory 30 and the information memory 32 are output and temporarily latched in the count latch 52 and the information latch 54, respectively.

The coefficient value latched in the coefficient latch unit 52 is provided to the quantization unit 60, and the DC coefficient value is provided to the DCI latch unit 56. The DCI value latched in the information latch unit 54 is provided to the DCI latch unit 56 and the quantization unit 60. The DCI latch unit 56 provides the multiplexer 70 with a DCI and a DC value to be passed without being encoded.

The quantization unit 60 determines the quantization step using the DCI value provided from the DCI latch unit 56 and the QNO value provided from the QNO latch unit 50, and coefficients provided from the coefficient latch unit 52 according to the quantization step. Quantize the value. The data quantized by the quantization unit 60 is provided to the VLC unit 62.

The VLC 62 performs variable length coding on the quantized data and outputs variable length coded code word data to the multiplexer 70.

The multiplexer 70 sequentially selects the QNO value from the QNO latch unit 50, the DCI value from the DCI latch unit 56, and the codeword from the VLC unit 62 under the control of the control unit 100. Output to (80). Data output from the multiplexer 70 is stored in the output memory 80.

FIG. 5 shows a detailed configuration of the output memory 80, in which one AC and six DCI information for one QNO value and 63 AC codewords sequentially for each DCI information are sequentially shown. Stored. The data stored in the output memory facilitates data processing in the next stage under the control of the controller 100.

As described above, according to the present invention, since image data in units of segments is divided into coefficient information and DCI and stored in different memories, the capacity of the memory for storing DCI information having a short configuration bit length can be selected to be small. By extracting and latching with class and mode information, the control logic that controls the quantizer and the VLC to pass through unprocessed is provided.

Claims (4)

In the encoding device for processing digital image data input in units of segments, A coefficient memory for storing DCT coefficients of the segment image data; A DCI memory for storing DCI information including class number and mode information of the segment image data; A QNO latch unit for temporarily storing QNO information of the segment image data; Encoding means for encoding data provided from said coefficient memory, said DCI memory, and said QNO latch to generate an encoded codeword; And multiplexing means for sequentially multiplexing the QNO information, the DCI information, and the coded codeword. The apparatus of claim 1, wherein the encoding apparatus comprises: a; An information latch unit for temporarily storing six DCI information read from the information memory whenever QNO is latched in the QNO latch unit; And a coefficient latch unit for temporarily storing 64 DCT coefficients read from the coefficient memory each time the DCI information is latched in the information latch unit. The encoding device of claim 2, wherein the DCI latch unit latches a DC coefficient value provided from the coefficient latch unit. The apparatus of claim 1, wherein the encoding apparatus comprises: a; And memory means for sequentially storing the QNO, the DCI, and the codeword output from the multiplexing means.