KR0169655B1 - Device for encoding moving picture signal - Google Patents

Abstract

The video encoder selectively divides the source input signal into N subbands and selectively selects subband signals encoded by the N subband encoders 10 and 20 and the N subband encoders to encode the subband signals. It consists of a switching unit 30 for outputting. This configuration can reduce the time required for encoding and can perform quantization for each frequency band densely, thereby improving the quality of the reconstructed image.

Description

Video encoder

1 is a block diagram showing the configuration of a general video encoder.

2 is a block diagram showing the configuration of a video encoder according to the present invention.

FIG. 3 is a detailed block diagram of the band division shown in FIG.

FIG. 4 is a diagram illustrating each subband signal divided by the band splitter shown in FIG.

* Explanation of symbols for main parts of the drawings

10, 20: subband encoder 30: switch

11, 21: band divider 12, 22, 15, 25: subtractor

13, 23: discrete cosine converter 14, 24: inverse discrete cosine converter

16, 26: quantizer 17, 27: inverse quantizer

18, 28: variable length encoder 19, 29: multiplexer

The present invention relates to a video encoder, and more particularly, to a video encoder for dividing a source input signal into N subband signals and performing encoding processing on each subband signal in parallel.

Information is one of the most important resources and is called the information society in modern times. As the amount of information to be accepted and processed is increasing day by day, data compression is indispensable to effectively use existing transmission bands.

In particular, since a digital video signal requires a lot of memory to express information, video information compression has an effect of more efficiently storing, retrieving, and transmitting information.

For this reason, many compression methods for image data have been developed, and the image data compression method can be classified into lossless coding method of lossy coding according to whether information is lost or not. And interframe encoding using temporal redundancy present in the video.

In addition, it is divided into the first generation coding method which has little information loss and the international standard is completed, and the second generation coding method which uses the characteristics of human visual structure and image. The first generation coding techniques include spatial coding such as Pulse Code Modulation (PCM), Differential PCM (Delta PCM), Delta Modulation (Delta Modulation), and conversion coding such as Karhunen-Loeve, Fourier, Cosine, Harr, Hadamard, and Sine, Hybrid coding combining the above two, and Motion Compensated Coding used for video. Second-generation coding techniques include pyramid coding, anisotropic nonnormal prediction coding, contour-texture-based techniques, and encoding techniques based on directional decomposition.

Since the transmission of video has more considerations than the still image and the compression effect is more prominent, the development of a technique to obtain a high compression ratio is of great interest. Motion compensation coding is used in the currently developed HDTV broadcasting system or MPEG. Motion compensation coding has a pixel cycling algorithm and a block matching algorithm. The block matching algorithm has a lower accuracy than the pixel cycling algorithm, but it is widely used in video systems because of its simple real-time processing and hardware implementation. Here, the block matching algorithm divides an image into blocks of a predetermined size, obtains a motion vector for each block, and performs a discrete cosine transform on the prediction error between the image obtained by the motion vector and the original image, and then the discrete cosine transform coefficient. It is a technique of transmitting together.

In general, video encoders which are widely used have the effect of data compression by removing temporal redundancy through motion processing and spatial redundancy through discrete cosine transform.

FIG. 1 is a block diagram showing the structure of a general video encoder, and is used in many standardized encoders such as H.261, MPEG-1, and MPEG-2.

Referring to FIG. 1, the subtractor 10 generates a difference image between frames by subtracting a motion compensation image of an original image of a current frame and a reconstructed image of a previous frame, which are input in units of frames.

The discrete cosine transforming unit (DCT) 12 outputs a discrete cosine transform coefficient by performing discrete cosine transforming of the inter-frame difference image into, for example, a block of 8x8 pixels in order to remove the correlation between pixels.

The quantizer Q 14 quantizes the discrete cosine transform coefficients of the interframe difference image output from the discrete cosine transforming unit 12 at a predetermined quantization interval and outputs the quantized interval.

The variable length encoder (VLC) 16 variably encodes the inter-frame difference image quantized by the quantizer 14 and transmits the variable length coder to a decoder (not shown) through a buffer (not shown).

That is, among the signals represented by 8 bits, for example, data with high frequency is represented by fewer bits, and data with less frequency is represented by many bits, thereby reducing the total number of bits representing the difference image.

An inverse quantizer (IQ) 18 is connected to the output terminal of the quantizer 14 and restores the quantized interframe difference image to a state before being input to the quantizer 14.

The inverse discrete cosine transform unit (IDCT) 20 is connected to the output terminal of the inverse quantizer 18 and before the inverse quantized inter-frame difference image is inputted to the discrete quantizer 18 by the inverse quantizer 18. Restore to state

The adder 22 adds the inter-frame difference image and the motion compensation image reconstructed by the inverse discrete cosine transform unit 20 and stores the reconstructed image of the previous frame in the frame memory 24.

The motion estimation unit (ME) 26 generally uses a block matching algorithm, estimates a similar portion between the input current image and the reconstructed image of the previous frame stored in the frame memory 24, and calculates the result of the position shift. Will output

The motion compensator (MC) 28 outputs the motion compensation image compensated by the motion vector to the subtractor 10 and the adder 22, respectively, by compensating the motion position of the reconstructed image of the previous frame stored in the frame memory 24, respectively. .

However, the above-described conventional video encoder has a problem that the processing time is relatively large because the amount of data to be processed is huge.

Accordingly, an object of the present invention is to provide a video encoder for dividing a source input signal into N subband signals and performing encoding processing on each subband signal in parallel.

In order to achieve the above object, a video incubator according to the present invention comprises: N subband encoders for encoding a sub-band signal by dividing a source input signal into N subbands; And a switching unit for selectively outputting the subband signals encoded and output by the N subband encoders. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing the configuration of a video encoder according to the present invention, comprising: N subband encoders 10 and 20 for encoding the sub-band signal by dividing the source input signal into N subbands; And a switching unit 30 for selectively outputting the subband signals encoded and output by the N subband encoders.

The subband encoders 10 and 20 further include: a band splitter 11 for dividing the N input subband signals into N source band signals; A first subtractor 12 for subtracting the subband signal outputted from the band splitter 11 and the reconstructed difference image signal; A discrete cosine transforming unit (13) for discrete cosine transforming the output signal of the first subtractor 912; An inverse discrete cosine transformer (14) for inverse discrete cosine transforming the output signal of the discrete cosine converter (13) to the first subtractor (12); A second subtractor 15 for subtracting the output signal of the discrete cosine converter 13 and the reconstructed difference image signal; A quantizer 16 for quantizing the output signal of the second subtractor 15; An inverse quantizer (17) for inverse quantizing the output signal of the quantizer (16); A variable length encoder (18) for variable length encoding the output signal of the quantizer (16); And a multiplexer 19 for selectively outputting one of the output signals of the first and second subtractors 12 and 15 and the output signal of the variable length encoder 18.

3 is a detailed block diagram of the band splitters 11 and 21 shown in FIG. 2, and the source input signal 31 is separated into N subband signals 33 and 34 by the source analyzer 32. FIG. . Here, the N subband signals are signals having a frequency spectrum for each band of signals separated into non-uniform bands.

Next, the operation of the present invention configured as shown in FIGS. 2 and 3 will be described.

In each of the subband encoders 10 and 20, the band dividers 11 and 21 decompose the source input signal into subband signals through a plurality of band pass filter processes. Here, each band divides signals into non-uniform bands. On the other hand, an example of separating a frequency band using a filter is shown in FIG.

The first subtractor 12, 22 subtracts the subband signal outputted from the band splitters 11, 21 and the output signal of the inverse discrete cosine converting parts 14, 24 to generate a difference image. Discrete cosine transformed in the discrete cosine converting section (13, 23) is applied to the inverse discrete cosine converting section (14, 24) and the second subtractor (15, 25), respectively.

The second subtractors 15 and 25 subtract the signals output from the discrete cosine converting units 13 and 23 and the output signals of the inverse quantizers 17 and 27 to quantizers 16 and 26 and the multiplexers 19 and 29. Are applied to the multiplexers 19 and 29 through the variable length encoders 18 and 28, respectively.

The multiplex 19, 29 quantizes the discrete cosine transform difference video signal of the previous frame and the current frame output from the first subtractor 12, 22 and the previous frame and the current frame output from the second subtractor 15, 25. The difference image signal and the variable length coded data are selectively output to the switching means 30.

The switching unit 30 selectively outputs one of the signals encoded and output by the N subband encoders 10 and 20, respectively.

As described above, the video encoder according to the present invention divides the source input signal into N subband signals for each frequency band and encodes the subband signals in parallel to reduce the time required for encoding. Since the quantization can be performed densely, the image quality of the reconstructed image can be improved.

Claims (1)

N subband encoding means (10, 20) for dividing the source input signal into N subbands for each subband signal and selectively outputting subband signals encoded and output by the N subband encoding means. A switching unit (30) for outputting, each of the N subband encoding means (10, 20) includes: a band dividing unit (11) for dividing the source input signal into N subband signals; A first subtractor 12 for subtracting the subband signal outputted from the band splitter 11 and the reconstructed difference image signal; A discrete cosine transformer (13) for discrete cosine transforming the output signal of the first subtractor (12); Inverse discrete cosine transformer 14 for outputting the output signal of the discrete cosine transformer 13 to the inverse discrete cosine converter and outputting it to the first subtractor 12: the output signal of the discrete cosine converter 13 and the reconstructed difference image A second subtractor (15) for subtracting the signal: a quantizer (16) for quantizing the output signal of the second subtractor (15); An inverse quantizer (17) for inverse quantization of the output signal of the quantizer (16); A variable length encoder (18) for variable length encoding the output signal of the quantizer (16); And a multiplexer (19) for selectively outputting one of an output signal of said first and second subtractors (12, 15) and an output signal of a variable length encoder (18).