KR100348791B1 - method for disk scheduling using acceptability control of writing/reading at the same time - Google Patents

Abstract

The present invention analyzes the performance factors that may occur under the worst-case environment of a disk when providing a general time shifting service and flows a service of accepting a time shifting operation according to a change in a playback rate with a simple calculation. Providing a time shifting operation by the user, physically calculating a distance between a read offset and a light offset from the request time point, and calculating a maximum time of a requestable pose, and calculating the requestable time. Determining whether to accept the recording task and the playback task for the user command according to the maximum time of the pause, and performing the simultaneous recording and playback in accordance with the determination of the acceptance, A disc can also satisfy the time shifting operation of the viewer.

Description

Method for disk scheduling using acceptability control of writing / reading at the same time}

The present invention relates to a time shifting application, and more particularly, to a disk scheduling method using simultaneous recording / playback acceptance control.

Recently, digital video recording (DVR) technology using high-performance, high-capacity hard disk drives (HDDs) instead of general magnetic tape-based storage devices (VCRs) has been in the spotlight.

In addition, there are companies such as Tivo and ReplayTV as the leaders in this field, and 'Personal Video Recorder (PVR)' introduced by Tivo, Replay TV, etc. By applying a hard disk drive (HDD) to TVs and STBs, it is possible to record programs that are broadcast on different stations simultaneously for up to 30 hours, allowing viewers to have fun.

In particular, they offer a technique for receiving broadcast analog data, digitizing it to MPEG-2 and storing it on disk.

In addition, there is an MbTV (Metabyte TeleVision) that provides a method of directly receiving broadcast digital data and storing it on a hard disk.

In this case, unlike the tape drive, since the HDD is capable of random access, a time shifting application according to simultaneous recording and playback is possible.

Thus, the time shifting application consists of at least one read request and one or more write requests.

In addition, the time shifting that the HDD needs to be equipped with recording and playback at the same time through the time shifting, at this time performance degradation should not occur during recording and playback.

In order to avoid performance degradation during recording, it must support the ability to store 19.4 Mbits per second, which is required for HD (High Definition) quality according to the North American ATSC standard.

Similarly, playback should support the ability to store 19.4 Mbits per second to avoid performance degradation.

Therefore, in order to record and play simultaneously, the performance of a hard disk that needs to process 38.8 Mbits per second is required.

However, the simultaneous recording / reproducing method according to the related art described above only refers to performance matters below that ratio according to a constant rate of reproduction.

For example, in the case of Tivo, a time shifting service is provided within a maximum allowable pause time.

Accordingly, the present invention has been made to solve the above problems, and analyzes the performance factors that may occur in the worst case of the disk when providing a general time shifting service, and time shifting according to a change in the playback rate. Its purpose is to provide a way to flow the service acceptance of operations with a simple calculation.

Another object of the present invention is to provide a method for doubling the maximum section that can be recorded when a user requests a pause.

1 is a configuration diagram of a software module for time shifting according to the present invention.

2 is a view showing a disk I / O method of a turn in accordance with the present invention

3 is a view showing a method of reusing disk space according to the present invention.

* Explanation of symbols for main parts of the drawings

10: remote control 20: admission control unit

30: recording task 40: playback task

50: HDD interface unit 60: Hard disk drive (HDD)

A feature of the disk scheduling method using the simultaneous recording / playback control according to the present invention for achieving the above object is the step of requesting a time shifting operation by the user, and the distance between the read offset and the write offset from the request time point. Physically calculating a maximum time of the requestable pose, determining whether to accept a recording task and a playback task for the user command according to the calculated maximum time of the requestable pose, and And performing simultaneous recording and playback in accordance with the determination.

Another feature of the present invention resides in the orderly alternating manner in which the order of leads and lights intersect with each other for one period.

According to an aspect of the present invention, when a program having an arbitrary playback rate is recorded and played simultaneously using a single disc, the simple operation of variably accepting or rejecting the time shifting operation according to the physical characteristics of the disc is performed. By inducing a calculation equation, the time shifting operation of the viewer can be satisfied using a low-performance disc.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Referring to the accompanying drawings, a preferred embodiment of a disk scheduling method using simultaneous recording / playback acceptance control according to the present invention will be described.

1 illustrates a configuration of a software module for time shifting according to the present invention.

Referring to FIG. 1, whenever a recording task 30 requesting storage of broadcast programs delivered through a broadcasting network, a playback task 40 reading the stored broadcast programs, and a new time shifting operation according to a viewer's command are received. An admission control unit 20 for controlling whether the recording task 30 and the reproduction task 40 accept or not process the user command, and an HDD for storing the SD program requested by the recording task 30. 60, and the HDD interface unit 500 for controlling the transfer of data between the recording task 30 or playback task 40 and the HDD (60).

At this time, the recording task 30 and the reproduction task 40 share an index structure so that the position information of the recorded program can be known.

In addition, the time shifting operation is performed through the remote controller 10 in the user command.

The admission control unit 20 determines whether or not to accept the processing of the user command whenever a new time shifting operation such as pause, resume, fast forward, or the like is received. Should be.

The determination of the admission control unit 20 to be used at this time physically calculates the distance between the read offset and the write offset and determines whether to accept a new user command or not.

In general, the difference between the lead offset and the light offset is indicated by the user's request to pose, and the interval between the two offsets is decreased during the posing period.

Therefore, the distance between the read offset and the write offset is the maximum time of the pose that can be requested by the user, and the formula according to the maximum time is as follows.

The total time T required to read or write B bytes is expressed by Equation 1 below.

The time is all in milliseconds.

B: The number of bytes to read or write in one cycle

Tt: time to move from disc track to track

Tr: speed of rotation of the disc

Th: switching time of the disk head

N: roundup (B, Bv):

Ns: Rounddown (N, Nh): Number of head switching of the required disk:

The time it takes to read for one cycle is the time to read / write and the following conditions are satisfied.

P (eriod): Time (period) when one read and write operation takes place

d: distance between the track to be read and the disc track to be written

When the above equation 1 is substituted by the above condition, the maximum time of the pose that can be requested is as follows.

Bv: Number of bytes per disc track

Nh: number of disc heads

Rp: Refresh Rate (bps)

In Equation 2, the allocation of the P value is given according to the buffer demand of the embedded system currently used.

At this time, the disk seek time required for read / write to be processed in one cycle can be minimized by using an alternate rotation method.

In the sequential shift method, as shown in FIG. 2, when read and write for one period, the next write is performed after the last write and the offset is read after writing for the next period. .

By doing this, the seek time in the period is dependent on the distance between the two requests and the main seek time is zero.

The remaining values are fixed because they describe the characteristics of the disk.

In conclusion, using Equation 2, the time shift service is provided only within a time range between two read / write offsets.

Since Equation 2 is a quantitative calculation of the maximum poseable time of a viewer's currently playing program, when the user presses a pause remote control button for time shift, the following two service methods are provided.

The first is to record up to the maximum possible interval, and then reuse the previous section previously used for recording for the current recording.

The second method is to record up to the maximum possible section of the pause, and then stop the movement of the pose and automatically resume the resume state.

In case of the first method, when the viewer requests a pose at the time T (I) as shown in FIG. 3, the interval between the two possible offsets is calculated by using the maximum calculation of the pose described above, and the recording is continued based on this. When the maximum offset length is reached at the time T (j), the next recording position is positioned before the maximum offset distance of the current pose position at the time T (j + 1).

The above method doubles the recording period during the viewer's pause request period, but it does not support fast rewind or rewind, and after doubling the recording period, it is necessary to cope with the pose method in other ways. .

The second method is to allow a pose up to a certain interval, and it is simple to implement the pose by only posing for the maximum possible section and stopping the pose and automatically restarting the play without user's request. This is how it is implemented in the current TiVo model.

As described above, once the service of the time shifting operation is allowed, the time shifting operation of the disk can be guaranteed even under the worst circumstances.

Disc scheduling method using the simultaneous recording / playback acceptance control according to the present invention as described above has the following advantages.

First, when a viewer requests a time shifting operation, a decision formula according to the characteristics of the disc is used to determine whether to accept or reject the requested operation request, thereby satisfying the viewer's time shifting operation using a low-performance disc. Can be.

Second, by using the above-described A model, the maximum range of the poses that can be currently used can be increased up to 2 times with only a simple predefined equation.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (5)

The user requesting a time shifting action, Calculating a maximum time of a requestable pose by physically calculating a distance between a read offset and a write offset from the request time; Determining whether to accept a recording task and a playback task for the user command according to the calculated maximum time of the requestable pose; And performing simultaneous recording and reproducing according to the determination of the acceptance. The method of claim 1, Performing the simultaneous recording and playback, the disk scheduling method using the simultaneous recording / playback acceptance control, characterized in that recording up to the maximum possible interval, the previous section previously used for recording for the current recording . The method of claim 1, Performing the simultaneous recording and playback controls the simultaneous recording / playback acceptance control, characterized in that it poses only for the maximum time of the calculated requestable pose and stops the pose and starts playback again without a user's request. Disk scheduling method used. The method of claim 1, The calculation of the maximum time of the requestable pose is Wherein P (eriod) is the time (period) at which one read or write operation occurs, T is the total time required to read or write, Bv is the number of bytes per disc track, Nh Is the number of disc heads, Tt is the time to move from the disc track to the track, and Rp is the playback rate (bps). The method of claim 1, And performing the simultaneous recording and reproducing in a sequential alternating manner in which the order of reads and writes intersect with each other during one period.