KR20130079884A - Method for prefetching multimedia data and multimedia player using the same - Google Patents

Abstract

PURPOSE: A video data prefetching method and a video playing device using the same are provided to reduce the power consumption of a disk by decoding and playing frames stored in a buffer. CONSTITUTION: A disk (100) stores a video file in which an acceptable minimum resolution level for each segment is set. A buffer (200) temporally stores the frames of the video file for playing. A carrying-in part (500) draws the frames of the video file out of the disk for storing in the buffer. A playing part (400) decodes and plays the frames stored in the buffer. A control part (600) controls the driving of the disk. The control part sets the power mode of the disk. [Reference numerals] (10) Video player; (100) Disk; (200) Buffer; (300) Preprocessing part; (400) Playing part; (500) Carrying-in part; (600) Control part

Description

Video data pre-loading method and video playback device using the same {METHOD FOR PREFETFETING MULTIMEDIA DATA AND MULTIMEDIA PLAYER USING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving picture playback method, and more particularly, to a moving picture data insertion method capable of reducing power consumption of a disc.

Recent advances in multimedia and network-related technologies have made it possible to use video services in real time on portable devices such as netbooks, laptops, PMPs and MP3 players. Because multimedia content requires a large amount of storage space, many portable multimedia devices adopt a high-performance disk as a storage medium. However, because disks consume a significant amount of power, techniques to reduce power consumption are very important. For example, micro drives used in PDAs are known to consume about 23% of the PDA's total power consumption.

To reduce disk power consumption, it is best to stay in the low power consumption standby mode for as long as possible. This can be done by reducing the need for the disk to process data requests. However, a large increase in the buffer capacity is not desirable, especially in a portable device, and excessively lowering the quality of the video also reduces the user's satisfaction.

Accordingly, the present invention proposes a method of designating the most appropriate resolution for each section within a range in which a user does not feel inconvenience using Scalable Video Coding (SVC).

In connection with SVC, Korean Patent Registration No. 10-0772868 ("Scalable video coding method and apparatus based on multiple layers") discloses a configuration of a video encoder for encoding a video sequence composed of a plurality of layers.

Regarding the disk standby mode, Korean Patent Registration No. 10-0780939 ("Method and control device for unloading wait time of hard disk drive") discloses a configuration for controlling an unload waiting operation of a hard disk drive.

Disclosure of Invention The present invention has been made to solve the aforementioned disc power consumption problem, and an object thereof is to provide a video data preloading method that can reduce power consumption of a disc without significantly lowering the quality of the video.

According to an aspect of the present invention, there is provided a video reproducing apparatus, comprising: a disc which is divided into a plurality of segments and stores a video file having a minimum resolution level set for each segment; A buffer in which frames of the video file are temporarily stored for playback; An import unit for retrieving frames of the video file from the disk and playing the frames in the buffer during playback; A playback unit for decoding and playing the frames stored in the buffer; And a disk controller configured to control the disk and to set a power mode of the disk, wherein the disk controller determines whether the first condition and the second condition are satisfied based on the resolution level information for each segment, and satisfies. The power condition of the disk to the standby mode, wherein the first condition is whether or not the maximum amount of frames have been loaded into the buffer, and the second condition is that the frames are loaded and the buffer is empty. And whether the remaining decoding time taken to lose is longer than the break-even time for bringing the disk into standby mode.

According to a second aspect of the present invention, a method of inserting data to reduce power consumed by a disc in accordance with a second aspect of the present invention is to (a) decode and reproduce frames stored in a buffer of the video. step; (b) selectively importing a frame of the video from the disk into a buffer according to the resolution level of each segment of the video in parallel with step (a); And (c) determining whether the first condition and the second condition are satisfied based on the resolution level information of each segment of the video, and if the first condition is met, entering the disk into the standby mode. Is the maximum amount of frames inserted into the buffer, and the second condition is the amount of gain and loss caused by the remaining decoding time taken for the buffered frames to be played back to empty the buffer. It is characterized in that it is longer than the branch time.

The present invention achieves the effect of reducing the power consumption of a disk storing a moving image in the moving image data preloading method.

You can also use buffers more efficiently.

In addition, the quality of the image can be adjusted within a range that is not recognized or acceptable to the user.

1 illustrates a structure of a video reproducing apparatus according to the present invention.
Figure 2 shows the change in power consumption of the disk according to the power mode.
3 illustrates a structure of moving picture data according to the present invention.
4 illustrates an embodiment in which a video frame is inserted into a buffer according to the present invention.
5 is a flowchart illustrating a video data preloading method according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

1 is a block diagram showing a video reproducing apparatus 10 according to the present invention.

First, referring to FIG. 1, the video playback apparatus 10 according to the present invention includes a disk 100 storing a video file, a buffer 200 temporarily storing video data for playback, and a video data from the disk 100. Importer 500 to import and store in the buffer 200, the playback unit 400 to decode and play the video data stored in the buffer 200, the disk 100 to control and minimize the energy consumption of the disk 100 And a disk control unit 600 for setting the power mode of the disk 100 so that it can be used.

The video reproducing apparatus 10 according to the present invention is divided into a plurality of segments and plays a video in which the minimum allowable resolution level is set for each segment. In one embodiment, the video may be received from the outside. In another embodiment, the video reproducing apparatus 10 may further include a preprocessor 300 to process the same.

Before describing the details, let's first look at how the power consumption of the disk changes according to the power mode with reference to FIG.

In active mode, the head is reading or writing data while the disk is spinning. In idle mode, the disk is spinning but the data request cannot be processed. Standby mode The disk stops spinning completely and cannot process any data requests. Slowing down the rotation of the disk as it enters standby mode from active mode is called spin down, and spinning up from standby to return to active mode is called spin up.

As shown in the figure, the standby mode consumes much less power than the active / idle mode, but at the time of spin up and spin down the energy consumption is temporarily increased rather than the active / idle mode. Therefore, if the transition between standby mode and active / idle mode occurs too frequently, the power consumption may even go beyond when the active / idle mode remains. Therefore, to efficiently save the power consumed by the disk, the disk should be in standby mode for as long as possible, but not too often.

Therefore, the video playback apparatus 10 according to the present invention has a break-even time in which the energy gain that can be saved by switching to the standby mode is greater than the energy cost of switching to the standby mode when the disc power mode is switched. even time). That is, the disc controller 600 of the video player 10 according to the present invention waits for the disc 100 when determining whether to enter the standby mode in order to minimize energy consumption of the disc 100 during video playback. Determine if the time allowed to stay in mode is greater than the break-even time. To this end, it is checked whether the video data is inserted into the buffer 200 as much as possible, and whether the time when the data stored in the buffer 200 is decoded and reproduced is greater than the break-even time.

In particular, the video playback apparatus 10 according to the present invention is allowed for each section by dividing the video into sections so that the disc can stay in the standby mode as much as possible without increasing the size of the buffer or significantly reducing the playback quality of the video. Assign the lowest resolution level.

To this end, the video reproducing apparatus 10 according to the present invention uses scalable video coding (SVC) technology. This technology allows the same video to be represented in multiple quality temporal and spatial resolutions, making it easy to adjust the quality of service. In other words, scalable video coding converts a format so that one content can be used variably according to a service type. The scalable video coding divides the video into multiple layers, thereby bringing temporal and spatial scalability and quality scalability of an image.

In a particularly preferred embodiment, the video reproducing apparatus 10 according to the present invention is an extension of the H.264 / AVC standard to scalable video coding among various scalable video coding techniques. Use H.264 / SVC that is of interest.

Most people are unaware of the short interruptions of the video while watching the video, so it is possible to lower the time resolution slightly, as long as the user does not notice the degradation in the playback quality of the video. For example, in a 30fps frame rate, most people don't notice it when they skip one frame and play it back.

However, people tend not to notice a decrease in the frame rate for images with small movements, whereas people tend to feel a deterioration in image quality for images with large screen changes. Therefore, instead of applying a single temporal resolution to the entire video, dividing the sections according to the degree of change of the screen and applying the appropriate temporal resolution for each section ensures the quality of the image while reducing the power consumption of the disk. Volume is an efficient way to reduce.

Therefore, in order to balance the quality of the image and the power consumption of the disk, the image reproduced by the video reproducing apparatus 10 according to the present invention is divided into several segments, each having a different time resolution level. At this time, the resolution level means the lowest level within the range that the video viewer does not notice the deterioration of the image quality.

3 shows a structure of moving picture data according to the present invention.

가 이를 의미한다.In the first drawing, the video is divided into several segments, and each segment has a minimum allowable resolution level within the range that does not cause quality deterioration. Assigned to the kth segment of the drawing

Means this.

인지 여부로 나타낼 수 있다. 값이 1이면 재생한다는 뜻이므로 버퍼로 반입하여 디코딩하고 0이면 건너뛴다는 뜻이므로 버퍼로 반입하지 않는다.Referring to the second drawing, it can be seen that each frame of each segment is determined to be played or not according to the resolution level of the segment. As shown in the figure, whether to play or skip the i-th frame of the k-th segment

It can be represented by whether or not. A value of 1 means to play, so it is imported into the buffer and decoded; a value of 0 means to skip, so it is not imported into the buffer.

For example, if the original video was produced at 24 fps and segment k was assigned a resolution level that would mean that the segment would be played at 12 fps, only half of the frames contained in segment k would be loaded into the buffer and played.

This lower time resolution reduces the total amount of data to be loaded into the buffer, which makes it possible to keep the disk in standby mode for a long time without employing a large buffer. This is because, even if the temporal resolution is lowered, the playback time itself does not change, and thus, the period of decoding the data loaded into the buffer is increased.

Let's take a look at Figure 4 which shows an embodiment in which a video frame according to the present invention is embedded in a buffer. 4 shows a simple but not realistic example for ease of explanation.

The first figure shows a video. Suppose the capacity of each frame is 2 bytes and the decoding time per frame is 1 second.

As a result of setting the minimum resolution level that is acceptable within the range that does not cause deterioration for each segment according to the criteria such as whether the motion is static or dynamic, the preprocessing unit 300 determines that the frame rate of the segment 0 from frame f0 to frame f3 is increased. Segment 1 from f4 to f9 frames skips one-half of all frames in the segment, so that frame rate skips two-thirds of all frames in the segment, f10 to f15 frames. Segment 2 assumes that the frame rate is set to skip one third of the frames of the segment. Given this level of temporal resolution, one can easily infer that segment 1 is the most static and segment 2 is the most dynamic.

Accordingly, as shown, whether to play each frame of segment 0 will be determined in order of 1, 0, 1, 0, ..., and whether to play each frame of segment 1 to 1, 0, 0, 1, 0. In this order, 0, ..., each frame of segment 2 will be determined in order of 1, 1, 0, 1, 1, 0, ....

The second figure shows a state where the original video is inserted into a 15-byte buffer without setting the time resolution level for each segment. The current state imported up to f6 is the state in which the maximum amount of frames is loaded into the buffer. Importing f7 further caused the buffer to overflow, so the import was aborted with 1 byte empty.

The third drawing shows a state in which a video when the segmented time resolution level is set in the same size buffer as in the first drawing according to the present invention. The current state loaded up to f13 is the state in which the maximum amount of frames is loaded into the buffer. Importing more f14 caused the buffer to overflow, so the import was aborted with 1 byte empty.

If you compare the second and third drawings, you can see that when the resolution level is lowered, more than seven frames are inserted in terms of the playback position. This means that the disc 100 may stay in the standby mode for longer. This is because there is no need to import data, and thus a time margin for not requiring a data request for the disk 100 is created.

This is because the playback time of the frames embedded in the buffer must be constant regardless of the temporal resolution difference. For example, it is evident that the playback time of a 30 second video played at 12 fps temporal resolution and a 30 second video played at 36 fps temporal resolution will be the same at 30 seconds. Since the decoding time per frame is 1 second, in the second drawing, all frames embedded in the buffer are decoded and it takes 6 seconds to empty the buffer, and in the third drawing, 13 seconds. In the case of the third drawing, the decoding time per frame is the same one second as the second drawing, but since the number of decoding decreases and the decoding period is longer, the remaining decoding time of the frames loaded in the same size buffer is longer than the second drawing. To lose.

Therefore, according to the present invention, the video having the time resolution level set by the segment has a time margin of about 7 seconds to insert data into the original video, and thus the time required for the disk to be in the standby mode is longer, which reduces the disk power. can do. But of course, you have to refill the buffer before it is empty, so it's only natural to reactivate the disk before 13 seconds have passed.

In this figure, two conditions for entering the standby mode can be derived. The first condition is that as many frames as possible are loaded into the buffer 200, and the second condition is that the remaining decoding time of the frames loaded into the buffer 200 breaks down when the disk 100 enters the standby mode. It must be longer than time.

Let's look at the first condition in detail. In the embodiment shown in the third drawing of Fig. 4, since 14 bytes, which is the sum of the capacities of the imported frames up to f13, is smaller than 15 bytes, which is the buffer size, when f14 is further loaded therein, it becomes 16 bytes and exceeds the buffer capacity. In this case, as long as the buffer 200 is emptied by one byte, the current state in which the import is stopped is possible. It would of course be more preferable if the sum of the capacities of the embedded frames is equal to the buffer size. Therefore, the first condition is that the sum of the frame capacities up to the last frame loaded into the buffer 200 is less than or equal to the buffer size, and whether the sum of the capacities of the first frame to be fetched after the last frame exceeds the buffer size. Can be determined to be satisfied.

However, as shown in the drawing, not all frames of the video from f0 to f13, but only the capacities of the frames actually loaded into the buffer 200 must be summed up, so whether to play by each frame is determined. Since it is determined according to the time resolution of each segment, the first condition may be to determine whether the disk 100 enters the standby mode based on the time resolution level of each segment.

When the first condition is expressed by a formula, it is as follows.

에 대해 최소한의 허용 가능한 해상도 레벨

를 설정하였을 때, 세그먼트

의

번째 프레임을 버퍼로 반입할지 건너 뛸지는

값에 의거하여 결정하게 된다.

이면 프레임

를 읽어오고 그렇지 않으면 프레임

는 제외된다.

를

번째 프레임의 크기,

를 버퍼의 크기라 하고,

를 프레임

에 해당하는 세그먼트의 번호, 프레임

가 버퍼의 마지막 프레임일 때,

를 버퍼 안에 있는 프레임들 중 첫 번째 프레임의 프레임 번호라고 하면, 제 1 조건의 충족 여부는 다음 두 수식을 모두 만족하는지 여부로 판단된다.As mentioned above, each segment

Minimum acceptable resolution level for

When is set, segment

of

Whether to import or skip the first frame into the buffer

It depends on the value.

Back frame

Reads the frame otherwise

Are excluded.

To

The size of the first frame,

Is the size of the buffer,

Frame

Number of segment corresponding to, frame

Is the last frame of the buffer,

When is the frame number of the first frame among the frames in the buffer, it is determined whether the first condition is satisfied whether the following two expressions are satisfied.

<Formula>

<Formula>

Now let's look at the second condition in detail. The remaining decoding time of the frames embedded in the buffer 200 used for the second condition has also been described in the drawing. Since the remaining decoding time also needs to know which frame is actually loaded based on whether each frame is played, the second condition may also be to determine whether the disk 100 enters the standby mode based on the time resolution level of each segment.

Break-even time means, as described above, the point in time at which the energy gain that can be saved by switching to standby mode is greater than the energy cost of switching to standby mode when transitioning the disk power mode. Break-even time calculations therefore require the power consumed in each mode and the energy and time required to spin up and spin down.

, 스핀다운(Spin-Down) 시에 필요한 에너지

, 디스크가 스핀업 하는데 걸리는 시간

, 스핀다운 하는데 걸리는 시간

, 유휴모드에서 소비되는 전력

, 및 대기모드에서 소비되는 전력

를 사용하여, 다음과 같은 세개의 수식으로 표현할 수 있다.That is, the second condition is energy required for spin-up of the disk 200.

Energy required for spin-down

, How long it takes for the disk to spin up

, The time it takes to spin down

, Power consumed in idle mode

, And power consumption in standby mode

By using, we can express the following three expressions.

<Formula>

<Formula>

<Formula>

5 is a flowchart illustrating a video data preloading method according to the present invention.

When the video playback starts, the import unit 500 imports the video data into the buffer 200 and the playback unit 400 decodes and plays the data stored in the buffer 200 (not shown). It is performed in parallel.

First, a frame is selectively loaded into the buffer 200 (S410). As described above, since playback is determined for each frame according to the resolution level of each segment, only the frame determined to be decoded is loaded into the buffer 200.

At this time, it is determined whether the conditions 1 and 2 are satisfied (S420), and when the condition is satisfied, the disk is entered into the standby mode (S430). As described above, the first condition is that the sum of the frame capacities up to the last frame loaded into the buffer 200 is less than or equal to the buffer size, and the sum of the capacities of the first frame to be fetched after the last frame is greater than the buffer size. The second condition is whether the remaining decoding time of the frames loaded into the buffer 200 is longer than the break-even time when the disk 100 enters the standby mode.

If activation is required when in the standby mode (S440), the disk is released from the standby mode (S450), so that the data request can be processed. Therefore, the step S410 of selectively loading a frame into the buffer 200 is performed again.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

100: disk
200: buffer
300: preprocessing unit
400: playback unit
500: import
600: disk control unit

Claims (15)

In the video playback device,
A disk in which a video file is divided into a plurality of segments and a minimum resolution level for each segment is set;
A buffer in which frames of the video file are temporarily stored for playback;
An import unit for retrieving frames of the video file from the disk and playing the frames in the buffer during playback;
A playback unit for decoding and playing the frames stored in the buffer; And
And a disk controller configured to control driving of the disk and to set a power mode of the disk.
The disk control unit
Determine whether the first condition and the second condition are satisfied based on the resolution level information of each segment, and if the condition is satisfied, set the power mode of the disk to a standby mode,
The first condition is whether or not the maximum amount of frames has been loaded into the buffer,
And the second condition is whether the remaining decoding time taken for the preloaded frames to be played back and the buffer is empty is longer than the break-even time for bringing the disc into standby mode. The method of claim 1,
The video playback device
And a preprocessing unit for dividing the video file into a plurality of segments, setting an allowable minimum resolution level for each segment, and encoding the video file according to the resolution level information and storing the video file on the disk. . The method of claim 1,
The import unit determines whether each frame of the video is a frame to be decoded or a frame to be skipped according to the resolution level of each segment, and inserts only the frame to be decoded into the buffer. The method of claim 3, wherein
When the sum of the capacities of the frames embedded in the buffer is less than or equal to the buffer size, and the sum is greater than the buffer size when the sum is up to the capacity of the first frame to be decoded after the last frame embedded in the buffer. And determining that the first condition is satisfied. The method of claim 1,
And the remaining decoding time is a sum of decoding times of frames embedded in the buffer. The method of claim 1,
The break-even time is the energy required for spin-up of the disk.

Energy required for spin-down

, How long it takes for the disk to spin up

, The time it takes to spin down

, Power consumed in idle mode

, And power consumption in standby mode

In consideration of the above, a video reproducing apparatus is calculated using the following equation.

The method of claim 1,
The video playback apparatus of claim 1, wherein the segmented resolution level is set using a scalable video coding (SVC) technique. The method of claim 7, wherein
The video playback apparatus of claim 1, wherein the segment-level resolution level is set using the H.264 / SVC codec. In the method of pre-loading data to reduce the power consumed by the disc during movie playback,
(a) decoding and playing frames stored in a buffer of the video;
(b) selectively importing a frame of the video from the disk into a buffer according to the resolution level of each segment of the video in parallel with step (a); And
(c) determining whether the first condition and the second condition are satisfied based on the resolution level information of each segment of the video, and if the condition is satisfied, entering the disk into a standby mode.
The first condition is whether or not the maximum amount of frames has been loaded into the buffer,
And the second condition is whether the remaining decoding time taken for the preloaded frames to be reproduced to empty the buffer is longer than the break-even time for bringing the disc into standby mode. The method of claim 9,
In the step (a), it is determined whether each frame of the video is a frame to be decoded or a frame to be skipped according to the resolution level of each segment, and only the frame to be decoded is inserted into the buffer. 11. The method of claim 10,
In the step (c), the sum of the capacities of the frames embedded in the buffer is less than or equal to the buffer size, and the sum of the capacities of the frames to be decoded after the last frame embedded in the buffer is greater than the buffer size. And determining that the first condition is satisfied when large. The method of claim 9,
And the remaining decoding time is a sum of decoding times of frames embedded in the buffer. The method of claim 9,
The break-even time is the energy required for spin-up of the disk.

Energy required for spin-down

, How long it takes for the disk to spin up

, The time it takes to spin down

, Power consumed in idle mode

, And power consumption in standby mode

In consideration of the above, the video data prefetching method calculated using the following equation.

The method of claim 9,
And the video is set by the segment-level resolution level using a scalable video coding (SVC) technique. The method of claim 9,
The video data prefetching method, wherein the segment-level resolution level is set using an H.264 / SVC codec.

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