KR100802180B1 - Method for controlling bit rate of MPEG-4 video signal according to dynamic network variation - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method of controlling the bit rate of an MPEG-4 video signal according to a dynamic communication capacity change.

2. The technical problem to be solved by the invention

The present invention provides a dynamic communication capacity of a bit rate of an MPEG-4 video signal, which allows MPEG-4 compression to be performed by controlling the bit rate of an MPEG-4 video signal according to a change in dynamic communication capacity while minimizing an effect on image quality. Its purpose is to provide a method of controlling according to the change.

3. Summary of Solution to Invention

The present invention provides a method for controlling the bit rate of an MPEG-4 video signal, comprising: an erase bit number calculating step of calculating the number of bits to be deleted for a predetermined group of the MPEG-4 video signal; A parsing step of parsing an enhancement bitstream to obtain a parameter; A cost calculation step of calculating a cost for each bit plane in a group using the obtained parameter; Deleting the bit plane having the smallest cost among the calculated costs; And repeating performing the above steps for all groups of the MPEG-4 video signal.

4. Important uses of the invention

The present invention is used in MPEG-4 video streaming system and the like.

MPEG-4 video signal, enhanced bitstream, rate control, dynamic communication capacity change, minimum cost

Description

Method for controlling bit rate of MPEG-4 video signal according to dynamic network variation}

1 is a configuration diagram of an MPEG-4 video streaming system to which a method of controlling a bit rate according to the present invention is applied;

2 is a flowchart of a method of controlling a bit rate of an MPEG-4 video signal according to a dynamic communication capacity change according to the present invention;

3 is an exemplary diagram illustrating a structure of input bitstream data;

4 is a diagram illustrating a result of deleting three FGST-VOPs per group.

* Explanation of symbols for the main parts of the drawings

10: encoder 20: extractor

30: decoder 40: display device

The present invention relates to a method of controlling the bit rate of an MPEG-4 video signal according to a dynamic communication capacity change. More particularly, the present invention relates to a method of controlling the bit rate of an MPEG-4 video signal while minimizing the effect on the visual quality. The present invention relates to a method of controlling a bit rate of an MPEG-4 video signal according to a change in dynamic communication capacity so that MPEG-4 compression is performed by controlling according to a change in dynamic communication capacity.

MPEG-4 (MPEG-4) is an object-based multimedia compression method for realizing interactive multimedia services using various multimedia contents. All contents are processed in units of objects. That is, scene description information including information related to the spatiotemporal arrangement of objects constituting the content, and object description information indicating the type of each content object included in the scene and the characteristic information of the bitstream. Express the overall composition and characteristics of the content. Separately, information related to the content of each content is obtained from the bitstream processed and transmitted for each content.

The advantage of the object-based encoding provided by MPEG-4 is that the multimedia streaming service can be provided in a situation where the transmission network and the player having very different characteristics are mixed. In other words, the structure of the content itself is scalable by layering the content composition information as well as the layering obtained by connecting different object bitstreams with the same content composition information so that different object bitstreams are transmitted according to characteristics of a transmission network or a player. You can also make it scalable.

For example, by layering scene description information, the movie clip object is included in the scene description information of the base layer, and the graphic object constituting the background is included in the scene description information of the enhancement layer. If the technical information is hierarchically structured in this form, it is possible to transmit only the base layer when the transmission bandwidth is low depending on the transmission environment, and thus the composition of the content itself can be layered.

In order to smoothly perform multimedia data streaming service in a situation where various types of transmission networks and terminals (players) are mixed, scalability is required because it is necessary to provide a service by setting an appropriate bit rate according to the user's environment. . Korean Patent Laid-Open Publication No. 10-2004-0091686 discloses a technique related to "FGST coding method using a higher query reference frame." According to this method, a reference frame in which a plurality of layers of a bidirectional or one-way prediction fine granular scalability time (FGST) frame includes at least one portion of base layer information and enhancement layer information. A fine granular scalability (FGS, hereinafter referred to as "FGS") coding scheme predicted from is disclosed.

However, even with this conventional method, although the bit rate can be reduced, it does not provide a means for reducing the bandwidth while effectively removing the bits having little effect on the visual quality.

The present invention has been proposed to solve the above problems, while controlling the bit rate of the MPEG-4 video signal according to the dynamic communication capacity change while minimizing the effect on the image quality, MPEG-4 compression is performed, An object of the present invention is to provide a method of controlling a bit rate of a video signal according to a dynamic communication capacity change.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

According to an aspect of the present invention, there is provided a method of controlling a bit rate of an MPEG-4 video signal, comprising: an erase bit number calculating step of calculating a number of bits to be deleted for a predetermined group of the MPEG-4 video signal; A parsing step of parsing an enhancement bitstream to obtain a parameter; A cost calculation step of calculating a cost for each bit plane in a group using the obtained parameter; Deleting the bit plane having the smallest cost among the calculated costs; And repeating performing the above steps for all groups of the MPEG-4 video signal.

The method may further include: determining whether to use a cost to determine whether to delete a bit by using a cost in a state where the number of bits to be deleted is calculated in the erasing bit number calculating step; Proceeding to the parsing step if it is determined that the bit is to be deleted using a cost as a result of the determination; And if it is determined that the bit is not to be deleted using the cost, the step of constantly deleting each FGS VOP (Video Object Plane) by the same bit according to the target bit.

In addition, the method of the present invention comprises the steps of: using a predetermined condition to determine whether to reduce the frame rate by reducing the FGST while the number of bits to be erased is calculated in the erase bit number calculation step; An erasing FGST-VOP number calculating step of reducing the frame rate and calculating the number of FGST-VOPs to be deleted in the group; Deleting FGST-VOPs by the number of the calculated FGST-VOPs; And determining whether the number of bits of the deleted FGST-VOP is greater than or equal to the number of target bits to be extracted, and if so, proceeding to the repeating step, and if less, proceeding to determining whether to use the cost.

By controlling the bit rate in such a manner that the bit plane is erased by the method of the present invention, it becomes possible to control the bit rate of the video signal in a direction that minimizes the influence on the image quality.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating an embodiment of an MPEG-4 video streaming system to which a bit rate control method according to the present invention is applied.

As shown in FIG. 1, the MPEG-4 video streaming system to which the bit rate control method according to the present invention is applied includes an encoder 10, an extractor 20, a decoder 30, and a display device 40. .

Here, the encoder 10 receives an MPEG-4 video signal and compresses it to perform encoding.

The extractor 20 controls the bitstream generated by the encoder 10 at an appropriate bit rate in accordance with the communication capacity of the user. The method of controlling the bit rate of the MPEG-4 video signal according to the present invention to be described later is applied.

In addition, the decoder 30 is a part implemented in a terminal of a user side, and performs a function of decoding a signal input by streaming by controlling a bit rate through the extractor 20.

In addition, the display device 40 receives a signal decoded by the decoder 30 and performs a variety of additional signal processings known in the art so that the user of the terminal can display the signal.

2 is a flowchart illustrating a method of controlling a bit rate of an MPEG-4 video signal according to a dynamic communication capacity change according to the present invention.

First, the number of bits to be deleted for a specific group of MPEG-4 video signals (where the order of the groups has been previously determined) is calculated (200). That is, the number of bits to be extracted (deleted) per group is calculated.

For example, when the target bit amount (bit amount to be transmitted) of the current group is equal to Equation 1 below, the bit amount to be deleted from the current group is equal to Equation 2 below.

는 입력된 현재 그룹의 비트 양을 나타내고,

는 목표 비트율(target bit-rate)을 나타내며, fr은 입력된 영상의 프레임 레이트(frame-rate)를 나타내고, N은 그룹당 VOP(Video Object Plane) 개수를 나타낸다.In (Equation 1) and (Equation 2),

Indicates the bit amount of the current group entered,

Denotes a target bit rate, fr denotes a frame rate of an input image, and N denotes the number of VOPs per group.

Then, it is determined whether or not to use the FGST using a predefined condition (205). That is, it is determined using a predefined condition whether to reduce the frame rate by reducing the FGST. Of course, it can also be implemented in a manner that does not use FGST unconditionally. As a result of the determination 205, if it is determined that the FGST should be used, the process proceeds to "240", and if it is determined that the FGST is not used, the process proceeds to "210".

Here, the reference to the condition definition criteria for example as follows. In the case of 30 fps (frame per second), QCIF (Quarter Common Intermediate Format), or a low motion image, high quality / 25 fps may be more preferable to a user than low quality / 30 fps. The appropriate frame rate depends on the application. For example, 20 fps can be used as the minimum frame rate for low motion pictures (QCIF, CIF), and 25 fps can be used as the minimum frame rate when the motion is large and the image size is CIF (Common Intermediate Format). . In the case of a large moving image, it is desirable to maintain the frame rate at 30 fps.

On the other hand, if it is determined in step 205 that the FGST is not used, it is determined whether to delete the bit using the cost (210). That is, it is determined whether to extract (delete) a bit using a cost. Of course, it may be implemented in such a way that the bit is deleted using the cost without performing the determination process 210. As a result of the determination 210, if it is determined that the bit is to be deleted using the cost, the process proceeds to "215", and if it is determined that the bit is not to be deleted using the cost, the process proceeds to "235". .

Here, the cost is a measure that affects the quality of the image, and when the bit plane is deleted (extracted), it is preferable that the sum of the costs of the bit planes deleted in the group is the smallest.

Thereafter, the enhancement bitstream is parsed to obtain a parameter necessary for obtaining a cost (215). Here, the parameters required to obtain the cost may include the number of non-zero coefficients of a bit plane, the coefficients of each bit plane, and the level of the bit plane.

Thereafter, the priority to be deleted, that is, to be trimmed is calculated (220). That is, the cost is calculated for each bit plane in the group using the parameters obtained in the parsing process. At this time, an example of a formula for calculating the cost is as shown in Equation 3 or Equation 4 below.

Thereafter, the bit plane is deleted (225) so that the cost of the bit plane to be deleted in the group is the smallest. That is, the bit plane having the smallest cost among the calculated costs is deleted (extracted).

Then, it is determined whether the corresponding group is the last group (230), if the last group is terminated, otherwise proceeds to (200) process and repeats the subsequent process.

On the other hand, if it is not determined to extract (delete) using the cost in the process "210", after each FGS VOP (Video Object Plane) is constantly deleted by the same bit in accordance with the target bit (235) process "230" Proceed to

On the other hand, if it is determined that FGST should be used in step 205, the frame rate is reduced and the number of FGSTs and the number of bits to be deleted in the group are calculated (240). That is, the number of FGST-VOP to be deleted is calculated. Here, the method of calculating the number of FGST-VOP to be deleted is as shown in Equation 5 below.

는 그룹 내에서 삭제해야할 FGST-VOP의 개수를 나타내고,

은 FGST-VOP를 추출(삭제)하여 조절할 목표 프레임 레이트를 나타내며,

는 기본 계층의 프레임 레이트를 나타내고,

은 입력된 영상의 프레임 레이트(=기본 계층 프레임 레이트 + FGST 향상 계층 프레임 레이트)를 나타낸다.here,

Indicates the number of FGST-VOPs to delete in the group,

Indicates the target frame rate to be adjusted by extracting (deleting) the FGST-VOP.

Represents the frame rate of the base layer,

Denotes a frame rate of the input image (= base layer frame rate + FGST enhancement layer frame rate).

의 범위에서 조절할 수 있으며, 목표 프레임 레이트가 기본 계층의 프레임 레이트와 같음은 모든 FGST-VOP를 추출(삭제)함을 뜻한다. 또한, 목표 프레임 레이트를 현재 프레임 레이트와 같게 한다는 것은 FGST-VOP를 추출(삭제)하지 않음을 의미한다.The target frame rate is

The target frame rate is equal to the frame rate of the base layer, which means that all FGST-VOPs are extracted (deleted). Also, making the target frame rate equal to the current frame rate means not extracting (deleting) the FGST-VOP.

For example, if the current frame rate is 30 fps, the target frame rate is 20 fps, and the number of frames per group is 12, the number of frames to be deleted from the group is determined to be four.

As another example, in the input bitstream data having the structure as shown in FIG. 3, when the number of VOPs in the group is 9, the frame rate of the base layer is 10 fps, and the frame rate of the FGST enhancement layer is 20 fps, that is, The frame rate of the input image (= base layer frame rate + FGST enhancement layer frame rate) is 30 fps.

At this time, in order to delete the FGST-VOP such that the bitstream having the structure shown in FIG. 3 is 20 fps, three FGST-VOPs must be deleted per group (see Equation 5 above). The result of deleting the VOP is as shown in FIG.

Thereafter, the FGST-VOP is deleted (extracted) by the number of the calculated FGST-VOP (245). Thereafter, it is determined whether the number of bits of the extracted FGST-VOP is greater than or equal to the number of target bits to be extracted (250). If the number of bits of the extracted FGST-VOP is greater than or equal to the target number of bits to be extracted, the process proceeds to "230". If the number of bits of the extracted FGST-VOP is less than the number of target bits to be extracted, the process proceeds to step “210” and repeats the following process.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

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

As described above, the present invention has an effect of controlling the bit rate of the MPEG-4 video bitstream while minimizing the image quality in accordance with various communication environments and terminals.

That is, the present invention has the effect of reducing the bandwidth by performing MPEG-4 compression by controlling the bit rate of the MPEG-4 video signal according to the dynamic communication capacity change while minimizing the influence on the image quality.

Claims (8)

In the method for controlling the bit rate of an MPEG-4 video signal, An erase bit number calculation step of calculating the number of bits to be erased for the predetermined group of the MPEG-4 video signal; A parsing step of parsing an enhancement bitstream to obtain a parameter; A cost calculation step of calculating a cost for each bit plane in a group using the obtained parameter; Deleting the bit plane having the smallest cost among the calculated costs; And An iteration step of repeatedly performing each step for all groups of the MPEG-4 video signal Method for controlling the bit rate of the MPEG-4 video signal comprising a dynamic communication capacity change. The method of claim 1, A cost usage determining step of determining whether to delete a bit using a cost in a state where the number of bits to be deleted is calculated in the erasing bit number calculating step; Proceeding to the parsing step if it is determined that the bit is to be deleted using a cost as a result of the determination; And If it is determined that the bit is not to be deleted using the cost, the step of constantly deleting each FGS VOP (Video Object Plane) by the same bit in accordance with the target bit And controlling the bit rate of the MPEG-4 video signal according to the dynamic communication capacity change. The method of claim 2, In a state in which the number of bits to be deleted in the erasing bit number calculation step is calculated, determining whether to reduce the FGST to reduce the frame rate using a predefined condition; An erasing FGST-VOP number calculating step of reducing the frame rate and calculating the number of FGST-VOPs to be deleted in the group; Deleting FGST-VOPs by the number of the calculated FGST-VOPs; And Determining whether the number of bits of the deleted FGST-VOP is greater than or equal to the number of target bits to be extracted, and if so, proceeds to the repeating step; if less, proceeds to determining whether to use the cost And controlling the bit rate of the MPEG-4 video signal according to the dynamic communication capacity change. The method of claim 3, wherein The step of calculating the number of deleted FGST-VOP, A method of controlling the bit rate of an MPEG-4 video signal according to a dynamic communication capacity change, comprising calculating the number of FGST-VOPs to be deleted as shown in [Equation 5] below. [Equation 5]

(here,

Indicates the number of FGST-VOPs to delete in the group,

Indicates the target frame rate to be adjusted by deleting FGST-VOP,

Represents the frame rate of the base layer,

Indicates the frame rate of the input video (= base layer frame rate + FGST enhancement layer frame rate). The method according to any one of claims 1 to 4, The erasing bit number calculation step, If the target bit amount (bit amount to be transmitted) of the current group is equal to (Equation 1) below, the MPEG is characterized by calculating the amount of bits to be deleted from the current group as shown in (Equation 2) below. -4 A method of controlling the bit rate of a video signal according to dynamic communication capacity change. [Equation 1]

[Equation 2]

(here,

Indicates the bit amount of the current group entered,

Represents the target bit rate, fr represents the frame rate of the input video, and N represents the number of VOPs per group.) The method of claim 5, wherein In the parameter, Control the bit rate of an MPEG-4 video signal according to dynamic communication capacity changes, including the number of non-zero coefficients of the bit plane, the coefficients of each bit plane, and the level of the bit plane. How to. The method of claim 5, wherein The cost calculation step, A method of controlling the bit rate of an MPEG-4 video signal according to a dynamic communication capacity change, wherein the cost is calculated as shown in Equation 3 below. [Equation 3]

The method of claim 5, wherein The cost calculation step, A method of controlling the bit rate of an MPEG-4 video signal according to a dynamic communication capacity change, wherein the cost is calculated as shown in Equation 4 below. [Equation 4]

Images