KR100192510B1 - Speed reproducing apparatus and method of digital versatile disk - Google Patents

Abstract

The present invention relates to a double speed playback apparatus and method in a DVD system, and particularly to a B picture or a P on a disc in the case of a high speed mode using only an I picture by determining the type of double speed when playing a disc on which MPEG-coded data is recorded. When a picture is encountered, the track is jumped and then jumps back to the original track, and only the I picture data is read from the disc.In the low speed mode using the I and P pictures, when the B picture is encountered, the track is jumped to the original track again. By controlling the pickup so that only I and P picture data are read out from the disc by jumping, the high-speed reproduction is realized by reducing the amount of data to be processed by the MPEG decoder.

Description

Double speed playback device and method in digital multi-function disc (DVD) system

The present invention relates to double speed playback in a Digital Versatile Disc (DVD) system. In particular, a picture that skips during high speed playback of DVD data encoded and recorded with Moving Picture Experts Groups (MPEG) is recorded from a disc. The present invention relates to a double speed playback device and method in a DVD system.

In general, in a digital imaging system, each frame of an image is sampled in units of pixels. Since image information is very large, an image compression (or encoding) technique is required for efficient transmission or storage.

It mainly uses a method of removing redundant information in the space and time domain.

The redundancy in the spatial domain is due to the small degree of change between adjacent pixels in one frame, and the redundancy in the time domain is due to the slight change in object movement between adjacent frames.

1 is a diagram showing a prediction structure between each picture (I, P, B). In MPEG, one sequence of a moving picture is divided into a plurality of frames, that is, a GOP (Group of Picture) consisting of pictures, and encoding is performed. .

There are three types of image types to be encoded: I (intra code), P (forward prediction code), and B (bidirectional prediction code), and the relationship between them is shown in FIG. In other words, in MPEG, interframe prediction numbers and specific B pictures are introduced to secure a sufficient compression ratio, and an I picture (refresh frame) by intra-frame coding is inserted at appropriate intervals to overcome image quality degradation due to error measurement.

The GOP is composed of an I picture which is an intra-frame coded picture, a P picture that is a coded picture between frames that are already coded and temporally processed in a previous frame, and a B picture that is a bidirectional predictive interpolation picture that is predicted in two frames before and after.

Here, the I picture is coded using only the information of the frame itself, so that the compression rate cannot be very high, but can be based on random access from within the bit stream. The P picture is frame coded in the immediately preceding frame or with reference to the immediately preceding P frame. Since the P picture is coded using synchronous compensation, a compression ratio higher than that of the I picture can be obtained, but a coding error may be transmitted because there are times when the previous P frame is predicted. There is a number.

On the other hand, since the B picture is used as a frame with reference to past and future frames, the compression rate can be increased. If another picture or the P picture is not used as a reference frame, the above error may not be transmitted. After the MPEG bit stream is recorded on the DVD, the B picture is skipped or the B picture and the P picture are skipped and displayed during high-speed playback at n-times speed.

For example, in the 3x playback mode, the B picture is skipped and only the I and P pictures are displayed. In the 12x playback mode, the B and P pictures are skipped and only the I picture is displayed.

This does not mean that the disc spins at high speed and the data is decoded at high speed to reduce the display time, but the disc maintains the linear speed as it is and only selectively displays a specific picture among the read data. Therefore, the reproduction time in the double speed reproduction is the same as in the normal mode, resulting in the reduction of only the picture being viewed.

For example, when the normal mode playback time is 50 minutes, in the triple speed playback mode, the playback time is 50 minutes the same as the normal mode, and only the I and P pictures are displayed again.

This phenomenon occurs because all data recorded on the disc is continuously read even at n-times reproduction, and all of these signals are MPEG decoded, and then the header is detected to determine whether the picture is the required picture and to display only the required picture. That is, since all data recorded on the disk is read and MPEG decoded, it takes time to selectively display only the corresponding picture according to the double speed mode, thereby not obtaining a sufficient fast effect.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to read and decode only a corresponding picture from a disc according to a double speed mode, thereby reducing high-speed playback by reading out unnecessary picture data and decoding time. An apparatus and method for double speed playback in a DVD system are provided.

A feature of double speed playback in a DVD system according to the present invention for achieving the above object is that after a disc is recorded with MPEG-encoded data and a picture to be skipped in the double speed playback mode is detected, the track is jumped again. An optical pickup which jumps to a track and reads only data of the corresponding picture from the disk, a decoding unit for amplifying, waveform-shaping and decoding the signal read out from the optical pickup, and data of the disk according to the control and double speed reproduction mode of the decoding unit. And a control unit for outputting a signal for controlling reading, and a servo control unit for controlling tracking and focusing of the optical pickup by the control signal of the control unit.

A feature of the double speed playback method in the DVD system according to the present invention is a double speed playback method for reproducing data at high speed from a disc on which MPEG encoded data is recorded, wherein the type of double speed is determined when the double speed playback mode is selected from the outside. The first step of performing the step; and if the header of the picture to be skipped according to the double speed type is detected on the disc, the second step of performing track jump and then jumping back to the original track to read only the data of the picture that is not skipped from the disc; and And a third step of amplifying, waveform-shaping, and decoding the data read out from the same.

1 is a diagram showing a predictive structure between respective images in general.

2 is a block diagram of a double speed playback apparatus in a DVD system according to the present invention.

3 is a flowchart showing a method of double speed playback in a DVD system according to the present invention.

4 shows an example of track jump on an optical disc according to the invention;

* Explanation of symbols for main parts of the drawings

20: optical disc 21: optical pickup

22: digital signal processor 23: microcomputer

24: key input unit 25: MPEG decoder

26: memory 27: servo control unit

28: display unit

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing a playback apparatus in a DVD system according to the present invention. When a disc 20 in which MPEG encoded data is recorded and a picture to be skipped in the double speed playback mode is shown, the track is jumped and then returned again. An optical pickup 21 for reading only data of the picture from the disk 20, a digital signal processor (DSP) 22 for amplifying and waveform-shaping the signal read out from the optical pickup 21, and The microcomputer 23 for controlling the control of the DSP 22 and the data reading of the disk 20, the key input unit 24 for selecting the double speed playback mode, and the waveform-formed signal from the DSP 22 to the microcomputer 23. Control of the MPEG decoder 25 to decode by control, the memory 26 to store MPEG decoded data, the display unit 28 to encode and display the output signal of the MPEG decoder 25, and the control of the microcomputer 23. Tracking of the optical pickup 21 by And a servo controller 27 for controlling focusing.

3 is a flowchart for performing a double speed playback method in the DVD system according to the present invention.

The present invention configured as described above displays only I pictures or I, P pictures on the basis of MPEG encoding characteristics when a disc having data recorded as an MPEG bit stream is reproduced at a n-times speed in a DVD system.

For example, in the 3x playback mode, the B picture is skipped and only the I and P pictures are displayed. In the 12x playback mode, the B and P pictures are skipped and only the I picture is displayed.

Therefore, the present invention reduces the amount of data processed by the MPEG decoder 25 by controlling the optical pickup 21 to skip an area having unnecessary picture data on the disc 20 according to the double speed playback mode during double speed playback. have. That is, during the double speed playback, the section in which the B picture (or P picture) exists without continuing to follow the track is track jumped and then returned to the original track. At this time, the track jump is an operation of moving the optical pickup 21 because it is a jump to an adjacent track, which is performed by the servo controller 27 operating the optical pickup 21 under the control of the microcomputer 23.

Since no data is generated while the optical pickup 21 moves, no DSP processing or MPEG decoding operation is required. When the data section of the picture that is not required passes, the optical pickup 21 returns to the original track to read the data of the picture, and when the data of the picture is read, DSP processing and MPEG decoding are performed.

Typically, the linear velocity of the disc is 3.5 m / sec, and the time taken to jump to the same position of adjacent tracks during the jump operation is 2 msec. Eventually, it takes 4msec to perform the track jump to the next track and return one time. During this time, the disk is constantly rotating, so the pickup is the result of 14mm of the track of the disk.

Since the length of one physical sector is 5.16 mm of the disk and the physical sector time is 1.48 msec, a single track jump results in skipping 14 / 5.16 = 2.713 sectors. One sector consists of 2048 bytes of data, 16 bytes of headers, and 2064 bytes in total, resulting in a skipping of 2.713 × 2064 = 5600 bytes of data for each track jump. At this time, the image data recorded on the DVD is a variable rate MPEG coding method, but considering the average coding rate and the minimum coding rate, data that starts reading after one track jump is detected without missing a P picture or an I picture header that occurs next. This enables high speed playback. That is, when the normal speed playback mode is selected through the key input unit 24, the optical pickup 21 reads all data from the disk 20, and the DSP 22 amplifies and waveform-shapes the read data to the MPEG decoder ( 25) (step 301, step 302).

The MPEG decoder 25 decodes the waveform-shaped data and stores the I, P, and B pictures in the corresponding picture area of the memory 26 and simultaneously displays an image through the display unit 28. On the other hand, when the double speed playback mode is selected through the key input unit 24 (step 301), the microcomputer 23 determines the type of double speed playback (step 303). When the speed type determined in step 303 is a high speed mode in which the P and B pictures are skipped and only I pictures are used, the optical pickup 21 detects the picture header while reading data along the track of the disc 20 ( Step 304).

The picture header contains information for identifying the type of picture. Therefore, using the information of the picture header, it is determined whether the data of the track on which the optical spot is formed by the optical pickup 21 is an I picture, a P picture or a B picture (step 305). At this time, if it is determined that the picture is an I picture, the optical pickup 21 reads out data and outputs the data to the DSP 22. If it is determined that the picture is a P picture or a B picture, the optical jumper 21 jumps back to the track and returns again (step 306). That is, if the optical pickup 21 was B picture header data when reading the a point of the disc 20 as shown in FIG. 4, the optical pickup 21 jumps to the b point, which is the outer track, and then returns to the original track. The pickup 21 is returned. At this time, since the disk rotates at a constant linear velocity, when the optical pickup 21 jumps from point a to point b and then returns, the distance traveled by the disk 20 is about 14 mm. The time to move from to c is within 4msec. This time is equivalent to about 5600 bytes skipped in relation to the data amount of one sector.

At this time, even if the average code rate and the minimum code rate are taken into consideration, data to be read after one track jump is detected without missing a P picture or an I picture header to be generated next. Therefore, when the optical pickup 21 jumps to the adjacent track of the disc 20 in step 306 and returns to the original track, the picture header is detected again (step 308). At this time, the track jump of the optical pickup 21 is performed by the tracking control and the focusing control of the servo controller 27 in accordance with the control signal of the microcomputer 23.

If the header information detected in step 308 is determined to be a B picture or a P picture, the process returns to step 306 to perform track jump and return. If it is determined that the I picture is an I picture, the optical pickup 21 reads data and the DSP 22 reads the data. Will output

The DSP 22 amplifies and waveform-forms the data of the I picture read out from the optical pickup 21 under the control of the microcomputer 23, and outputs the data to the MPEG decoder 25. The MPEG decoder 25 outputs the I picture data. Is decoded and stored in the corresponding picture area of the memory 26 and output to the display unit 28 (step 309).

The display unit 28 converts the output of the MPEG decoder 25 into a form required for digital / analog (D / A) conversion and PAL or NTSC display and displays it (step 310).

In this way, high-speed playback that plays only I pictures without playing back B and P pictures performs one track jump when the B picture or P picture header is detected, skipping unnecessary B picture or P picture data, and playing back only the desired I picture data. To display. At this time, it is possible to perform faster and faster playback by skipping B and P picture data that will be generated for an appropriate time by jumping several tracks instead of one track and replaying only desired I picture data.

On the other hand, when the speed type determined in step 303 is a B-speed skip mode and the low-speed mode using I, P pictures, the optical pickup 21 reads the data along the tracks of the disc 20, and removes the picture header. (Step 311). Then, using the information of the picture header, it is determined whether or not the data of the track on which the optical spot is formed by the optical pickup 21 is a B picture (step 312). At this time, if it is determined that the picture is an I picture or a P picture, the optical pickup 21 reads out data and outputs the data to the DSP 22. If it is determined that the B picture is a B picture, the optical pickup 21 jumps to an adjacent track and returns again (step). 313).

In step 313, when the optical pickup 21 jumps to the adjacent track of the disc 20 and returns to the original track, the picture header is detected again (step 314). If the header information detected in step 314 is again determined as a B picture, the process returns to step 313 to perform track jump and return. If it is determined that the picture is an I picture or a P picture, the optical pickup 21 reads out data and the DSP 22 Will output The DSP 22 amplifies and waveform-forms the data of the I picture or the P picture read out from the optical pickup 21 under the control of the microcomputer 23, and outputs the data to the MPEG decoder 25. The MPEG decoder 25 The data of the I picture or the P picture is decoded, stored in the corresponding picture area of the memory 26 and output to the display unit 28 (step 309).

The display unit 28 converts the output of the MPEG decoder 25 into a form necessary for D / A conversion and PAL or NTSC display, and then displays it (step 310).

In this way, high-speed playback of playing I picture and P picture without playing B picture performs one track jump when the B picture header is detected, skipping unnecessary B picture data, and displaying only the desired I and P picture data. . At this time, it is possible to perform faster and faster playback by skipping B picture data that will be generated for an appropriate time by jumping several tracks instead of 1 track and reproducing only desired I and P picture data.

As described above, according to the double speed playback apparatus and method of the DVD system according to the present invention, in the high speed playback mode, a track jump is performed when a B picture or a P picture is encountered on a disc in all cases of high speed using only an I picture. After jumping back to the original track to read only I picture data, and in the low speed mode using I and P pictures, when a B picture is encountered on the disc, the player jumps back to the original track after jumping to the original track. By controlling the pickup so that only data is read, high-speed playback is realized by reducing the amount of data to be processed by the MPEG decoder.

Claims (7)

When a disc on which MPEG-coded data is recorded, a key input unit for selecting a double speed playback mode, and a picture to be skipped according to the double speed playback mode are detected, the track is skipped and then jumped back to the original track and not skipped. An optical pickup for reading only data of the picture from a disc, decoding means for amplifying, waveform-shaping and decoding the signal read out from the optical pickup, and control for controlling data reading in accordance with the control of the decoding means and a double speed reproduction mode. And a servo controller for controlling the tracking and focusing of the optical pickup based on a control signal of the controller. 2. The optical pickup according to claim 1, wherein the optical pickup is a high speed mode in which the determined double speed type skips a P picture and a B picture and uses only an I picture. A double speed playback apparatus in a digital multi-functional disc system, characterized in that returning to a track of < RTI ID = 0.0 > I < / RTI > The original track according to claim 1, wherein the optical pickup skips only the B picture and the original track after the track jump in the B picture area under the control of the servo control unit in the low speed mode using the I and P pictures. And a read / write device in the digital multifunction disc system, wherein only data in the I picture and P picture areas are read from the disc. A double speed reproduction method for reproducing data at a high speed from a disc on which MPEG encoded data is recorded, the first step of determining a type of double speed when a double speed reproduction mode is selected from the outside, and skipping according to the double speed type. When a picture header is detected on the disc, the second step of performing track jump and then jumping back to the original track and not skipping only the data of the picture from the disc, and amplifying and waveform-shaping the data read from the disc A double speed playback method in a digital multi-functional disc system, comprising the third step. 5. The method of claim 4, wherein the second step determines picture data by detecting a picture header on a disc. 5. The method of claim 4, wherein in the second step, when the determined speed type is a high speed mode in which the P picture and the B picture are skipped and only the I picture is used, the P and B picture areas return to the original track after the track jump. A double speed playback method in a digital multifunctional disc system, characterized in that only data in a picture area is read from a disc. The method of claim 4, wherein in the second step, when the determined speed type is skipped only the B picture, and in the low speed mode using the I and P pictures, the B picture area returns to the original track after the track jump. A method of double speed playback in a digital multifunctional disc system, characterized in that only data in a P picture area is read from a disc.