KR100192778B1 - A compatible encoder and decoder using ptsvq - Google Patents

Abstract

The present invention relates to a compatible code and decoder using a PTS VQ. The compatible coder according to the present invention is once stored in the first frame memory 10, the down sampler 11 to obtain a low resolution video sequence. Is converted into a low resolution video signal by the PTS VQ encoder 13 and then encoded by the PTS VQ encoder 13. On the other hand, the encoded low resolution image sequence is decoded again by the PTS VQ decoder 14 and then sampled up by interpolation in the up sampler 15. The subtractor 16 subtracts the sampled video signal from the original input video signal to obtain a difference video signal, and the second video signal is a discrete cosine transformer 17, a quantizer 18, and a variable length encoder 19. It is coded through and output as a high resolution video sequence.

Description

Compatible Encoders and Decoders Using PTS VQ

1 is a block diagram illustrating a compatible encoder according to the present invention.

2 is a block diagram illustrating a compatible decoder according to the present invention.

* Explanation of symbols for main parts of the drawings

10: first frame memory 11: down sampler

12: second frame memory 13: PTS VQ encoder

14: PTS VQ Decoder 15: Up Sampler

16: subtractor 17: discrete cosine converter (DCT)

18: Quantizer 19: Variable Length Coder (VLC)

21: PTS VQ Decoder 22: Up Sampler

23: adder 24: variable length decoder (VLD)

25 Inverse Quantizer 26 Inverse Discrete Cosine Converter (IDCT)

27: loss block processing unit

The present invention relates to a compatible encoder technology for separating and encoding a video signal into a high resolution video signal and a low resolution video signal. Particularly, the present invention relates to a low resolution video signal by subsampling a high resolution video signal. The present invention relates to a compatible encoder and decoder using PCT VQ, which encodes and decodes the low resolution video signal using PTS VQ (Pruned Tree Structured Vector Quantization) technique.

In general, digital image encoding technology is widely known as transform encoding, vector quantization, band division encoding, predictive encoding, and entropy encoding, and the encoding technology is established by international standardization standards for encoding still and moving images. Efforts have been made to study these techniques and obtain more advanced coding techniques.

On the other hand, compatible codes and techniques are widely studied for reasons different from the above-described encoding technique, the compatible encoder is a technique used to have compatibility between the existing TV technology and the later high definition (HD) TV.

Here, the compatibility refers to the ability to decode the compressed information of the image having a high resolution into an image having a given resolution, and this compatibility is further divided into an upward compatibility and a downward compatibility. Upward compatibility is that a high-resolution receiver decodes a bit string transmitted by a low-resolution encoder, and then up-samples and reproduces it on a screen or reproduces a portion of a screen by the size of a low-resolution signal. Downward compatibility means that a low resolution receiver decodes and reproduces a required portion of a bit string transmitted by a high resolution encoder.

In addition, if compatibility is divided based on resolution and image quality, compatibility of resolution and image quality can be divided into compatibility. Resolution compatibility is that the receiver of the high resolution receiver and the low resolution receiver receive the same bit string, and only some bit strings corresponding to the respective resolutions are used. It is the ability to decode and play the video, and the compatibility of image quality is that the receiver of the same resolution plays high quality video by decoding all the transmitted bit strings when the transmission network is in good condition. It is the ability to decode and play back images of basic quality.

The advantage of granting compatibility by the compatibility encoding technique is firstly that even a low-cost receiver can process a service corresponding to a high resolution signal, and as a result, a broadcast supporting multiple receivers is possible. This is useful in the middle of service improvement. A representative example thereof is compatibility with a TV in the field of HDTV.

Secondly, only a part of the entire bit string can be used. In a cable transmission network, the service can be connected to various data rates so that the user can select a service according to the cost.

In addition, another benefit of compatibility encoding is called graceful degradation, which guarantees the provision of basic video quality even when the transmission network is in a bad condition. Instead of leaving it unattended, an efficient error correction code is made in the low resolution part of the transmission data so that the corresponding low resolution video signal can be received on the HDTV. In other words, this may be considered to be a case where a low-resolution signal is sent to a high priority cell in an ATM network.

As such, video encoding of a video signal means a function of transmitting and receiving video signals of two or more standards or formats through the same channel, thereby providing the same service to users with different receivers. do. In other words, when the HDTV broadcast is introduced, expensive HDTV receivers cannot be purchased by all users at the beginning, so that the service provided by the HDTV can be provided as a general digital TV.

Such compatibility can be classified into spatial scalability technique and frequency scalability technique. Spatial scalability is a technique of dividing an image into spatial encoding and linking it to compatible encoding. There are techniques such as split band coding and pyramid encoding, and frequency scalability technique is to divide an image into a transform region and connect it to compatible encoding. As a technique, the existing block transformation encoding technique is applied to implement compatibility. The pyramid coding technique, which usually implements spatial scalability, can optimally encode TV signals, but it does not encode the excess signals used for reconstruction of HDTV signals, and the frequency scalability technique using transform coding applies HDTV signals. Although it can be optimally encoded, it has a disadvantage of poorly encoding TV signals.

Accordingly, an object of the present invention is to provide a compatible encoder using a PTS VQ that encodes a difference between a high resolution video signal and a low resolution video signal and transmits the same with a PTS VQ encoded low resolution video sequence.

Another object of the present invention is to provide a compatible decoder using a PTS VQ for receiving and decoding a PTS VQ compatible encoded video sequence as described above.

In order to achieve the above object, the compatible encoder of the present invention obtains a low resolution video signal by subsampling from an input video signal, and then outputs the low resolution video signal in a low resolution video sequence by performing PTS VQ encoding on the low resolution video signal. Decode and up-sample the encoded low-resolution video, compare the reproduced video with the input video signal, obtain the difference, and then transform the difference video signal into discrete cosine transform and variable length encoding to obtain a high-resolution video sequence. Output

In addition, in order to achieve the other object of the present invention as described above, the compatible decoder of the present invention decodes the received low resolution video sequence by the PTS VQ method, and enlarges the decoded video signal. On the other hand, the received high resolution image sequence is subjected to variable length decoding and inverse discrete cosine transform, and after processing the lost block, the adder outputs the reproduced video signal by adding the video decoded by the PTS VQ scheme.

In this way, the receiving side transmits the video sequence obtained by PTS VQ encoding the low resolution video signal of the input video and the video sequence encoded by the high resolution video signal (actually, the difference between the high resolution video signal and the low resolution video signal) of the input video. The sample may be stretched after the low resolution image sequence is rerun from the low resolution image sequence, and the image signal decoded from the high resolution image sequence may be added to the sample stretched low resolution image signal to improve the overall image quality of the received image.

Hereinafter, with reference to the accompanying drawings will be described in detail by dividing an embodiment of the present invention into a compatible encoder and decoder.

1. Embodiment of compatible encoder

As shown in FIG. 1, the compatible encoder according to the present invention includes: a first frame memory 10 for storing an input image; A down sampler 11 for down sampling the input image of the first frame memory 10 into a low resolution image signal; A second frame memory 12 for storing the low resolution video signal; A PTS VQ encoder (13) for outputting a low resolution image sequence by PTS vector quantization of the low resolution image of the second frame memory (12); A PTS VQ encoder (14) for decoding the encoded sequence of the PTS VQ encoder (13); An up sampler 15 for upsampling the output of the PTS VQ encoder 14; A subtractor 16 which subtracts an output of the upsampler 15 from an input video signal of the first frame memory 10; A discrete cosine transformer (DCT) for discrete cosine transforming the difference image of the subtractor 16; A quantizer (Q) 18 for quantizing the output of the discrete cosine transformer 17 and a variable length encoder 19 for variable length coding the output of the quantizer 18 are comprised.

Referring to the operation and effects of the compatible encoder according to the present invention configured as described above are as follows.

First, as described above, the compatible encoding means that an input video signal is separated into a low resolution and a high resolution video signal, and then encoded and transmitted in a different or the same manner, so that the receiving side decodes only a low resolution video sequence using a low resolution decoder to receive only a low resolution video. It is a technology that can satisfy both low resolution and high resolution services by receiving high resolution video by decoding both low resolution and high resolution video sequences with a high resolution decoder.

In the compatible encoder according to the present invention, the input video signal is once stored in the first frame memory 10, and is converted into a low resolution video signal by the down sampler 11 to obtain a low resolution video sequence, and then the PTS VQ encoder 13 Encoded by

On the other hand, the encoded low resolution image sequence is decoded by the PTS VQ encoder 14 again, the sample is increased by interpolation in the up-sampler 15. The subtractor 16 subtracts the sampled video signal from the original input video signal to obtain a difference video signal, and the second video signal is a discrete cosine transformer 17, a quantizer 18, and a variable length encoder 19. It is encoded through and output as a high resolution image sequence.

2. Example of compatible decoder

The compatible decoder according to the present invention includes a PTS VQ encoder 21 for decoding the PTS VQ decoder from the received low resolution image sequence as shown in FIG. An up sampler 22 which upsamples the decoded low resolution video signal to increase a sample; A variable length decoder (VLD) 24 for variable length decoding the received high resolution image sequence; An inverse quantizer (IQ) 25 which inversely quantizes the output of the variable length decoder 24; An inverse ideal cosine transformer (IDCT) for converting the output of the inverse quantizer 25 to an inverse ideal cosine transform (IDCT); A loss block processor 27 for restoring a block lost by an error during transmission at the output of the inverse cosine transformer 26 and an adder 23 for adding an error-corrected high resolution video signal to the stretched low resolution video signal. It consists of.

Referring to the operation and effects of the compatible decoder according to the present invention configured as described above are as follows.

First, as shown in FIG. 1, when a video signal sequence encoded and divided into a low resolution video sequence and a high resolution video sequence by a compatible encoder is received through a transport channel, the compatible decoder according to the present invention separately distinguishes the low resolution video sequence. Decoded by the PTS VQ method, the high resolution image sequence is decoded by the variable length decoder 24, the inverse quantizer 25, the inverse discrete cosine transformer 26. Subsequently, the video signals thus decoded are added by the adder 23 to restore the original video signals.

At this time, the loss block processing unit 27 restores the lost data from the neighboring block data using median filtering if the data is lost due to an error during transmission in the inverse discrete cosine transformed high resolution image block. To improve.

As described above, according to the present invention, by using the PTS VQ method for compatibility encoding and decoding, the compatibility of the reproduced video can be increased and the quality of the reproduced video can be improved. In particular, since the compatible decoder can handle lost blocks, there is a strong effect on errors during transmission.

Claims (2)

A compatible encoder for dividing an input video signal into high resolution and low resolution, the encoding apparatus comprising: a first frame memory 10 for storing an input video; A down sampler 11 for down sampling the input image of the first frame memory to generate a low resolution image signal; A second frame memory 12 for storing the low resolution video signal; A PTS VQ encoder (13) for outputting a low resolution image sequence by quantizing the PTS vector of the low resolution image of the second frame memory; A PTS VQ decoder (14) for decoding the encoded sequence of the PTS VQ encoder; An up sampler 15 for up-sampling the output of the PTS VQ decoder to restore the original image; A subtractor 16 for subtracting an output of the upsampler from an input video signal of the first frame memory; A discrete cosine transformer for discrete cosine transforming the difference image of the subtractor 16; A quantizer 18 for quantizing the output of the discrete cosine transformer 17; And a variable length encoder (19) for variable length coding the output of the quantizer and outputting a coded high resolution image sequence. A compatible decoder that receives a compatible encoded video sequence and divides the video into high resolution and low resolution, comprising: a PTS VQ decoder 21 for PTS VQ decoding the encoded low resolution video sequence; An up sampler 22 for up sampling the decoded low resolution video signal; A variable length decoder 24 for variable length decoding the encoded high resolution image sequence; An inverse quantizer 25 for inversely quantizing the output of the variable long decoder; An inverse discrete cosine transformer 26 for inverse discrete cosine transforming the output of the inverse quantizer; A loss block processing unit 27 for restoring a block lost due to an error in transmission at the output of the inverse cosine transformer; And an adder (23) for adding the low resolution video signal output from the upsampler to the high resolution video signal corrected by the loss block processor to output a reproduced video signal.