KR100312420B1 - Video code method for esay reverse video play - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a video encoding method for facilitating reverse playback and a computer readable recording medium having recorded thereon a program for realizing the method.

2. The problem to be solved by the invention

In the present invention, when the moving picture is stored in a storage medium or the like using the MPEG encoding method, an image encoded by an intra frame method is stored as it is, so as to facilitate reverse playback. In parallel with this, a video encoding method for easily reproducing a video on a frame-by-frame basis even when the reverse video data is reproduced by encoding and storing a video of the currently encoded interframe method using the next encoded video as a previous video. To provide a computer readable recording medium having recorded thereon a program for realizing the method.

3. Summary of Solution to Invention

The present invention provides a video encoding method in a video encoding system, comprising: a first step of forward encoding an first intra video; A second step of forward encoding and storing the currently encoded interframe type image by encoding the next encoded image as a previous image when encoding by the interframe method; A third step of generating an encoded image of an interframe mode for backward reproduction every forward encoding; And a fourth step of reversely playing back the video using the encoded video in the interframe mode generated in the third step and the encoded video in the intra mode among the video stored in the second step.

4. Important uses of the invention

The present invention is used in a video encoding system.

Description

Video code method for facilitating reverse playback {Video code method for esay reverse video play}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video encoding method for facilitating reverse playback, and a computer readable recording medium having recorded thereon a program for realizing the method. In particular, the present invention relates to a digital storage medium such as MPEG-2. In a method of storing compressed image data, the present invention relates to a compression scheme and a reverse search scheme for facilitating backward search.

In general, the compression encoding method by the video encoding apparatus is a method commonly used in the ITU-T H.261, H.263 video telephone standards, or TV or HDTV video compression encoding standards such as ISO / IEC MPEG-2. .

Among these compression schemes, MPEG-1 (ie ISO / IEC 11172-2) and MPEG-2 (ie ISO / IEC 13818-2) schemes (hereinafter referred to as MPEG schemes) are the storage media as described above. This is a representative method aimed at.

In the MPEG method, as in the conventional video telephony standard such as H.261, the interframe compression method that compresses the video by estimating the motion from the previously encoded video and encoding the difference by using the discrete cosine transformation Regardless of the image, an intraframe compression method that compresses and encodes the current image itself using a discrete cosine transform method is used as a main compression means.

In addition, in MPEG, bidirectional motion compensation compression is basically possible to increase the efficiency of an encoding method.

In addition, in the video compression method for a storage medium, it is important that random access is possible in addition to the general performance such as the compression ratio or the image quality. In the MPEG method, an intra frame mode encoded image is periodically inserted for this purpose.

However, there is a problem in that a large amount of data must be read in reverse during reverse playback of a moving picture, and therefore, reverse playback is practically impossible in a tape device or the like.

The present invention has been proposed to solve the above problems, and when an image is stored in a storage medium or the like using the MPEG encoding method, an image encoded by an intra frame method is used to facilitate reverse playback. In the case of encoding by the interframe method, however, the encoded video is encoded and stored with the next coded video as the previous picture. It is an object of the present invention to provide a video encoding method for easily reproducing a moving picture and a computer-readable recording medium having recorded thereon a program for realizing the moving picture.

1 is an exemplary configuration diagram of a video encoding apparatus to which the present invention is applied.

2 is an exemplary explanatory diagram illustrating a video encoding sequence in a video encoding apparatus according to the present invention.

3 is a diagram illustrating an embodiment of reverse video playback in a video encoding apparatus according to the present invention;

Explanation of symbols on the main parts of the drawings

111: input processing unit 112: motion estimation and compensation unit

113: encoding mode determiner 114: two-dimensional discrete cosine transform unit

115: quantization unit 116: inverse quantization unit

117: two-dimensional inverse discrete cosine transform unit 118: previous image playback unit

119: previous image memory 120: scanner

121: variable length encoder

According to another aspect of the present invention, there is provided a video encoding method in a video encoding system, comprising: a first step of forward encoding an first intra video; A second step of forward encoding and storing the currently encoded interframe type image by encoding the next encoded image as a previous image when encoding by the interframe method; A third step of generating an encoded image of an interframe mode for backward reproduction every forward encoding; And a fourth step of reversely playing back the video by using the encoded video in the interframe mode generated in the third step and the encoded video in the intra mode among the images stored in the second step.

In addition, the present invention provides a video encoding system having a processor for facilitating reverse playback, comprising: a first function of forward encoding an first intra video; A second function of forward coding the currently encoded interframe image and storing the encoded image as a previous image when encoding in the interframe method; A third function of generating an encoded image in an interframe mode for backward reproduction every forward encoding; And a program for realizing a fourth function of reversely playing back a moving picture using the encoded video in the interframe mode generated by the third function and the intramode encoded video stored in the second function. Provide a readable recording medium.

In the present invention, when the moving picture is stored in a storage medium or the like using the MPEG encoding method, in order to facilitate reverse playback, an image encoded in the intraframe method is stored as it is. By encoding the encoded video as a previous video and storing the currently encoded interframe video, the video is easily reproduced frame by frame even in reverse playback. Therefore, the present invention can effectively estimate the motion with a small amount of calculation in the motion estimation apparatus of the video encoder such as a portable video telephone.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary configuration diagram of a video encoding apparatus to which the present invention is applied, and includes an input processing unit 111, a motion estimation and compensation unit 112, an encoding mode determination unit 113, and a two-dimensional discrete cosine transform unit ( 114, the quantization unit 115, the inverse quantization unit 116, the two-dimensional inverse discrete cosine transform unit 117, the previous image reproduction unit 118, the previous image memory 119, the scanner ( 120 and a variable length encoding unit 121.

The operation of the video encoding apparatus to which the present invention having the structure as described above is applied is as follows.

When the input processor 111 receives image-related data from the outside and transfers the data to the motion estimation and compensation unit 112 and the encoding mode determiner 113, the motion estimation and compensation unit 112 is stored in the previous image memory 119. The image-related data is received from the input processor 111 by using the previous image, and is compensated with motion estimation to be transmitted to the encoding mode determiner 113.

Subsequently, the encoding mode determiner 113 encodes the image data transferred from the input processor 111 in units of macro blocks (MB) or macros the image data transferred from the motion estimation and compensation unit 112. It is determined whether to encode in units of blocks, and transmitted to the 2D discrete cosine transforming unit 114.

In this way, the image data having the encoding mode determined is sequentially subjected to a two-dimensional discrete cosine transform (DCT: Discrete Cosine Transform) (DCT) through the two-dimensional discrete transform unit 114 and the quantization unit 115, and then quantized to perform inverse quantization. 116 and the variable length encoder 120.

In this case, the image data transferred to the inverse quantization unit 116 is inversely quantized and then two-dimensional inverse discrete cosine transformed through the two-dimensional inverse discrete cosine transforming unit 117 and transferred to the previous image reproducing unit 118.

Subsequently, the previous image reproducing unit 118 receives the inverse discrete cosine transformed image data and the image data transferred from the motion estimation and compensation unit 112, reproduces the previous image, and stores the previous image in the previous image memory 119.

Meanwhile, the image data quantized by the quantization unit 120 and delivered to the scanner 120 are scanned in a zigzag form through the scanner 120 and then transferred to the variable length encoder 121.

Subsequently, the variable length encoder 121 receives the scanned image data and outputs the variable length encoding to the receiving end.

The compression coding method using the video encoding system is a method commonly used in the ITU-T H.261 and H.263 video telephone standards or in the TV or HDTV video compression coding standards such as ISO / IEC MPEG-2.

Among these compression schemes, MPEG-1 (ie ISO / IEC 11172-2) and MPEG-2 (ie ISO / IEC 13818-2) schemes (hereinafter referred to as MPEG schemes) are the storage media as described above. This is a representative method aimed at.

In the MPEG method, as in the conventional video telephony standard such as H.261, an interframe compression method for compressing an image by estimating a motion from a previously encoded image and encoding the difference using a discrete cosine transform method Regardless of the previous image, an intraframe compression method that compresses and encodes the current image itself using a discrete cosine transform method is used as a main compression means.

In addition, in MPEG, bidirectional motion compensation compression is basically possible to increase the efficiency of an encoding method.

In addition, in the video compression method for a storage medium, an important requirement is that random access should be possible in addition to the general performance such as the compression ratio and the image quality. In the MPEG method, an encoded image of an intraframe mode is periodically performed for this purpose. Put it.

For example, assuming that an image of 30 frames per second has been encoded, and that an encoded image of an intraframe mode (hereinafter referred to as I image) is inserted every 15 sheets, it is necessary to access from the middle of the encoded sequence. In this case, it takes a maximum of 0.5 seconds to meet the first decodable image, I image.

At this time, the time required can be changed by changing the insertion period of the I-image as necessary.

FIG. 2 is a diagram illustrating an example of a video encoding sequence in a video encoding apparatus according to the present invention, and illustrates a coding scheme in the case of using bi-prediction and periodically using an I-image for every nine pictures.

FIG. 3 is an explanatory diagram illustrating a video reverse playback order in the video encoding apparatus according to the present invention, and illustrates a coding scheme when the same I video period is used without bidirectional prediction.

In the figure, the GOP is a Group Of Picture.

The user may want to access an arbitrary position in the encoded data stored in this way, play in the forward direction, but sometimes play in the reverse direction.

This is usually included in analog VTRs and the like.

If you want to play the 12th image from the stored data as shown in Figures 2 and 3 suddenly reverse playback, unless you have stored all the previous image (this is practically impossible), first read the data corresponding to the 10th I image After playing the 10th, the 11th and 12th images are played in this order, and then, in reverse, 12, 11, 10 should be displayed.

However, in order to view the first to the ninth images in the reverse direction, the first I image must be decoded first, and then the ninth image must be decoded in turn and then displayed in reverse. This means that there must be a memory to store at least the frame of the I video, and the reverse direction cannot be seen until after decoding 9, and in the sequential recording method such as a tape device, the reverse direction is reversed, played back, stored and stored. While displaying a frame in reverse, there is a difficulty in rewinding backwards and so on to read previous data.

Therefore, since disks, semiconductor memories, and the like must be capable of random access, rewinding in the reverse direction is not necessary.

The present invention eliminates this complex process and proposes an encoding and decoding scheme for reproducing I-frames in the reverse direction. The encoding scheme proposed by the present invention is as shown in FIG.

The forward encoder encodes normally. First, the first intra image is encoded as it is (rI (0)). At this time, the reverse encoder does not operate. Here, the reverse coder does not operate even when encoding the encoded video of the first interframe mode (hereinafter referred to as P video).

Next, after encoding the second P-picture, the first P-picture is encoded using this as the previous video (rP (1)). Subsequently, after the third P picture is encoded, the second P picture is encoded using this (rP (2)).

Through this process, the encoding is performed until immediately before the next I image is encoded.

If the 9th image is an I image, after encoding I (9), the 8th P image is encoded using the previous image to form rP (8). Here, I (9) is rI (9) as it is.

The backward playback in the decoder is reproduced using the currently reproduced video and rI (n) or rP (n).

If reverse playback is selected while playback is being performed, for example while P (n) is being played back, rP (n-1) data after P (n) is read after P (n) is completed. It reads out, plays back P (n-1) and displays P (n) as a previous picture.

Also, P (n-2) data is reproduced using rP (n-2) data based on the reproduced P (n-1).

According to this process, it progresses by one frame and continues until an rI (k) frame is obtained. In this case, the rI (k) frame is the same as the I (k) frame, and since it is an intra mode image, the rI (k) frame can be reproduced without any other image.

Based on this, a P (k-1) image is reproduced from rP (k-1) data.

The method of the present invention as described above may be implemented as a program and stored in a computer-readable recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.).

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited to the drawing.

As described above, according to the present invention, a portable video is easily reversed by using an intra mode coded video of an interframe mode coded video generated for reverse playback and a video coded and stored in a forward code format for each reverse coded playback. There is an effect that the motion estimation apparatus of the video encoder in the telephone can effectively estimate the motion with a small amount of calculation.

Claims (3)

In the video encoding method in a video encoding system, A first step of forward encoding the first intra picture; A second step of forward encoding and storing the currently encoded interframe type image by encoding the next encoded image as a previous image when encoding by the interframe method; A third step of generating an encoded image of an interframe mode for backward reproduction every forward encoding; And A fourth step of reversely reproducing the video by using an intramode coded image of the interframe mode coded image generated in the third step and the image stored in the second step; Video encoding method for facilitating reverse playback comprising a. The method of claim 1, In the first step, Backward encoding is not performed, the video encoding method for facilitating backward reproduction. In order to facilitate reverse playback, in a video encoding system having a processor, A first function of forward encoding the first intra picture; A second function of forward coding the currently encoded interframe image and storing the encoded image as a previous image when encoding in the interframe method; A third function of generating an encoded image in an interframe mode for backward reproduction every forward encoding; And A fourth function of reversely playing back a video by using an intramode encoded video of the interframe mode encoded video generated by the third function and an image stored by the second function; A computer-readable recording medium having recorded thereon a program for realizing this.