JP2000152178A - Disk and its recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the fast forwarding reproduction of a high double speed ratio with smooth movement by setting the transfer rate of encoded video data at the time of recording them in a disk by considering the double speed ratio at the time of the fast forwarding reproduction, recording the video data at a constant linear velocity on the outer peripheral side of the disk and reproducing them at a constant angular velocity. SOLUTION: At the time of recording high-efficiency encoded video data in this disk, for the transfer rate of the video data, STD image quality or LP image quality is set by considering recordable time and the double speed ratio of the fast forwarding reproduction based on the selection of a user. Also, between the inner periphery and outer periphery of the disk, a read-in area 22, a logical format definition area 24, a dummy data recording area 26, a reproduction dedicated data recording area 28 and a read-out area 30 are provided. The video data of the disk are recorded at the constant linear velocity and reproduced at the constant angular velocity. Thus, frames are dropped at a fixed ratio from all decoded video images and the fast forwarding reproduction of the smooth movement of the video images is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk and a recording method thereof, and more particularly to a disk suitable for fast-forward reproduction of a video signal and a recording method thereof.

[0002]

2. Description of the Related Art A DVD system is widely known as a system for encoding and recording video signals with high efficiency.
In the DVD system, a video signal is recorded by being encoded by the MPEG system, and a read-only disk is already on the market. This MPEG encoding method is a typical example of highly efficient encoding of a video signal.
15 frames per second is 1 GOP (Group Of Picture). A typical code transfer rate obtained by encoding the video signal by MPEG is 3 to 9 Mbps. On the other hand, a typical transfer rate in the relationship between the optical pickup and the disk is 10 Mbps.

[0003] Here, a case in which a video signal is fast-forward reproduced will be considered. One method of fast-forward playback is to decode all consecutive video frames and drop frames at a fixed rate from among them. For example, if the transfer rate of the coded video signal is 3 Mbps, the rate of fast-forward reproduction by dropping frames is 10/3 ≒ 3, which enables reproduction at about 3 times speed. Also, the transfer rate of the encoded video signal is 5 Mb.
In the case of ps, 2/5 speed reproduction is possible with 10/5 = 2. If the transfer rate of the encoded video signal is 9Mbps,
1/10 speed reproduction is possible at 10/9 再生 1.

The above is a case of fast-forward reproduction in which all continuous video frames are decoded and frames are dropped at a constant rate from among them. On the other hand, when fast forward reproduction is performed at a higher speed, it is impossible to decode all consecutive video frames and drop frames at a fixed ratio.
Therefore, the disc is traced and reproduced and displayed. In this case, due to the nature of the MPEG encoding method, usually only I (Intra) frames in one GOP are reproduced. The I frame typically exists in 15 frames, that is, one in one GOP. Therefore, all G
If it is possible to trace the I frame in the OP,
The same display as the case where frames are dropped at a fixed ratio of 1:14 becomes possible, and smooth 15 × fast forward reproduction can be performed.

[0005] However, the data amount of a typical I frame is about 1/3 of one GOP, not 1/15. It is very difficult in terms of time to trace an I-frame having such a data amount and to trace the next I-frame by accessing the next I-frame after waiting for rotation. That is, if access, rotation waiting, and tracing can be performed within 1/30 second for every I frame, 15-times speed reproduction in which the video progresses smoothly for each frame can be performed. Meeting this is very difficult in time.

As a countermeasure for compensating for such a problem, there is a method of giving up the N-times speed reproduction in which the image progresses smoothly for each frame and displaying one I frame 15 times in a typical example. Skip 14 GOPs following one I-frame,
Trace the I-frame of the 16th GOP and display it 15 times. By doing so, the ability of the playback device (player) and the movement of the displayed video regarding access, rotation waiting, and tracing are not smooth, but 15-times speed playback becomes possible.

By the way, on the outer peripheral side of the disk,
For example, JP-A-8-212708 and JP-A-10-1
As disclosed in Japanese Patent No. 24994, it is known that a high recording and reproducing data transfer rate can be ensured. In a known CD-ROM or DVD-ROM system, data is recorded / reproduced by rotating a disk at a so-called constant linear density, that is, at a CLV. In this case, the rotation speed of the disc changes according to the position of the pickup so that the linear velocity becomes constant.
The rotation speed of the disk becomes higher on the inner circumference side, and the rotation speed of the disk becomes lower on the outer circumference side of the disk.

On the other hand, there is also a method in which data is transferred by rotating a disk at a constant rotation angle (number of rotations), that is, at a CAV. As is well known, the DVD employs a variable rate system in which the amount of code after video signal encoding is changed according to the complexity of encoding to record and reproduce on a disk. At this time, a technique for simultaneously recording data transfer rate information on a disc is disclosed in, for example, Japanese Patent Application Laid-Open No. HEI 1-220073.

[0009]

As described above, in a typical MPEG code, 0.5 seconds and 15 frames correspond to 1 GO.
P. In this typical example, there is only one I frame that can be reproduced independently in one GOP. Furthermore, in DVDs, encoding at a variable rate is common as described above. For this reason, the destination address when accessing the I frame is not constant but changes. Therefore, this I
A device such as recording the destination address of the frame is employed.

However, in such a method, the destination address of the I frame must be known at the time of recording. Therefore, for example, when a movie or a sport is recorded on a disc by a home recording device, it is very difficult to record a destination address which is future information in time.

The present invention focuses on these points.
It is an object of the present invention to provide a disc capable of fast-forward reproduction of smooth video motion at a high speed ratio and a recording method thereof.

[0012]

According to the present invention, there is provided a disk recording method for recording video data encoded with high efficiency on a disk, wherein a transfer rate of the video data is set to a double speed ratio of a fast forward reproduction based on a user's selection. Is set in consideration of. According to one of the main modes, the video data is recorded at a constant linear velocity on an outer peripheral side of a disk reproduced at a constant angular velocity.

According to another aspect of the present invention, there is provided a disk having a lead-in area on the inner circumference side and a lead-out area on the outer circumference side, wherein data is recorded at a constant linear velocity and data is reproduced at a constant angular velocity. A dummy data area is provided on the inner peripheral side between the lead-in area and the lead-out area, and a reproduced data area is provided on the outer peripheral side.

[0014]

Embodiments of the present invention will be described below in detail. In order to perform fast-forward playback of smooth video motion, first, all continuous video frames are traced and read from the disk by an optical pickup.
Fast-forward playback, in which this is decoded and frame-removed at a fixed ratio among all the decoded videos and played back, is most preferable.

In this case, the double speed ratio F, which is the degree of fast forward, is used.
Is a value obtained by dividing the trace rate T at which the optical pickup traces the disk by the code transfer rate C after the high-efficiency encoding of the video signal, and F = T / C. DVD
In the standard, T = 10 Mbps and C = 5 Mbps.
At this time, the double speed ratio is F = 10/5 = 2. Therefore, up to double-speed playback, fast-forward playback of smooth video motion can be achieved by a technique of decoding all continuous video frames and playing back frames at a fixed ratio.

Here, in order to increase the fast-forward reproduction speed, the double speed ratio F may be increased. Double speed ratio F is
Since the T / C is used as described above, if the trace rate T at which the optical pickup traces the disk is increased and the code transfer rate C after the high-efficiency encoding of the video signal is decreased, the double speed ratio F is improved. However, if the code transfer rate C after the high-efficiency encoding of the video signal is reduced, the quality of the video is also reduced. Therefore, it is necessary to balance the technical constraints of the trace rate T and the code transfer rate C with the feeling of use of the double speed ratio F for fast-forward playback of smooth motion required by the user.

On the other hand, in the case of a recording medium such as a disk, information can be recorded at the highest density by a recording method having a constant linear density (constant linear velocity) or a recording method based thereon. On the other hand, in reproducing recorded information, a method of rotating a disk at a constant angular velocity is generally used in order to obtain a high transfer rate and high-speed access. At this time, the information reproduction rate is relatively low on the inner circumference side of the disc and relatively higher on the outer circumference side of the disc. When recording a video signal on a disc, if it is required in advance to perform fast-forward playback of smooth video motion, it is convenient to positively use high transferability, which is a property on the outer peripheral side of the disc. is there. That is, since the reproduction rate is high on the outer peripheral side of the disk, the double speed ratio of the fast forward reproduction can be increased.

Therefore, in the present embodiment, the user selects recording conditions in consideration of fast-forward reproduction during recording. That is, at the start of recording, a screen for selecting the image quality and the reproduction speed is displayed. Then, information is recorded on the disc according to the selection of the user.

FIG. 1 shows an example of a recording condition selection screen. As shown in FIG.
D image quality "and low-quality" LP image quality ". Among these, the STD (Standard) image quality assumes a video coding rate of about 5 Mbps average rate of variable transfer. A total of 5.5 Mbps signal is added to this for about 5
When recording is performed using the entire surface of the G-byte disk, the total recording and reproducing time is 2 hours. The LP (Long Play) image quality is assumed to be a video coding rate of about 1.7 Mbps average rate of variable transfer. Add a voice, etc. to this, for a total of 1.9
When recording a Mbps signal using the entire surface of a disk of about 5 Gbytes, the total recording / reproducing time is 6 hours.

On the other hand, the trace rate during reproduction is usually
The reproduction rate is 10 Mbps at a position of a radius of 24 mm on the disk. When the disc is rotated at CAV and played, a radius of 4
At the position of 8 mm, the reproduction rate is 20 Mbps. Therefore, if the outer peripheral side of the disk is used, the transfer rate is high, and the double speed ratio of the fast forward reproduction can be improved.
However, when recording and reproducing at a position with a radius of 48 mm in the STD image quality, even if the video signal encoding rate is, for example, 5 Mbps for an average of 10 minutes, the average value for 1 minute is 9 Mbps.
, Fast-forward playback of smooth video motion is 2
0/9 ≒ 2, so that double-speed playback becomes the limit.

Therefore, if the maximum value of the short-time average rate of the video signal high-efficiency encoding is specified as 6 Mbps and the encoding is executed, it becomes 20/6 ≒ 3, and smooth fast-forward reproduction can be performed up to 3 × speed. Become. Here, "short time" means 1 to
It is set within the range of 10 GOP. Lower limit "1 GOP"
Corresponds to the basic unit of high-efficiency encoding of video signals,
The upper limit of “10 GOP” is usually 5 seconds, which corresponds to a typical buffer memory size of the reproducing circuit.

FIG. 2 shows an example of a recording area on the disk 10 in the present embodiment. As described above, in the present embodiment, the outer peripheral side of the disk having a high transfer rate is used. In the example shown in FIG. 2, the disk outer diameter is 60R (radius 6
0 mm), and the disk inner diameter is 7.5R. And it is divided into the inner peripheral area | region 12 from radius 24R to 41R, and the outer peripheral area | region 14 from radius 41R to 58R. The data recording area 13 is a combination of the inner peripheral area 12 and the outer peripheral area 14. In a mode in which fast forward reproduction is emphasized, the outer peripheral area 14 is used.

As described above, according to the present embodiment, the fact that the encoding rate of the video signal can be selected and that the reproduction rate of a disc recorded at a constant linear velocity and reproduced at a constant angular velocity differs between the inner and outer circumferences are used. Then, the conditions under which high-quality fast-forward playback is possible are presented to the user. That is, an upper limit value of the average code amount of N GOPs is set in accordance with a desired fast-forward playback speed, and video information is recorded on a disc at the upper limit value. At the time of this recording, the outer peripheral side of the disk with a high transfer rate is used. For this reason, when all consecutive video frames are traced and read from the disk by the optical pickup, and frames are skipped at a fixed ratio from all the video obtained by decoding the frames, and fast forward reproduction is performed at a predetermined double speed. However, a smooth reproduced image can be obtained. In particular, it is suitable for fast-forward playback of movies and sports.

Next, an embodiment of a read-only disc will be described with reference to FIG. In the above-described embodiment, information is recorded in the outer peripheral area of the disk in consideration of the double speed ratio of the fast-forward reproduction.
This is an embodiment of a read-only disc such as an OM. In this embodiment, information is recorded at a constant linear recording density from the inner circumference to the outer circumference of the disk. That is, when the disk 20 is rotated at a constant rotation speed, the information is recorded such that the reproduction rate is higher on the outer peripheral side than on the inner peripheral side.

A lead-in area 22 is located on the inner peripheral side of the disk 20. In the logical format definition area 24 in or near the lead-in area 22, information on the configuration and arrangement of information in the disk 20 is recorded. On the outer peripheral side of the disk 20, a dummy data recording area 26 is placed. The dummy data recorded in the dummy data recording area 26 is meaningless data, but is data to be recorded due to the nature of the disk reproducing operation. This dummy data recording area 26
A read-only data recording area 28 is provided on the outer peripheral side of the area. In this area, MPEG-encoded video data is recorded. Further on the outer peripheral side of the read-only data recording area 28, a lead-out area 30 is provided.

When reproducing such a disc 20, tracing by an optical pickup is performed from the lead-in area 22 on the inner peripheral side in the same manner as a general reproducing operation. The dummy data in the dummy data recording area 26 is skipped because it is meaningless data. Then, the video data recorded in the reproduction-only data recording area 28 is reproduced. At this time, as described above, since the reproduction rate is high, the double speed ratio of the fast forward reproduction can be improved.

The present invention is not limited to the above embodiment. For example, the display contents shown in FIG. 1 may be appropriately set within a changeable range. For example, a screen display in which the fast-forward reproduction speed ratio is directly set may be used, and the code amount of the video data may be calculated in accordance with the value set by the user, and then recorded. Further, in the above-described embodiment, the present invention is mainly applied to an optical disk such as a DVD, but does not prevent application to other magnetic disks.

[0028]

As described above, according to the present invention,
The following effects are obtained. Since the transfer rate of the encoded video data at the time of recording on the disc is set in consideration of the double speed ratio at the time of the fast forward reproduction, the fast forward reproduction with a smooth motion and the high double speed ratio can be performed. Further, since the video data is recorded on the outer peripheral side of the disk at a constant linear velocity and reproduced at a constant angular velocity, the double speed ratio of the fast forward reproduction can be improved. Further, since the video data is recorded on the disk under the conditions according to the user's selection, it is possible to perform fast-forward reproduction at a desired image quality and a double speed ratio.

[Brief description of the drawings]

FIG. 1 is a diagram showing a recording condition selection screen which is a man-machine interface according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of division of an inner peripheral side and an outer peripheral side of a disk in the embodiment.

FIG. 3 is a diagram showing an arrangement of data areas on a disk in another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Disc 12 ... Inner circumference area 14 ... Outer circumference area 20 ... Disc 22 ... Lead-in area 24 ... Logic format definition area 26 ... Dummy data recording area 28 ... Reproduction-only data recording area 30 ... Lead-out area

Claims (3)

[Claims] 1. A disk recording method for recording high-efficiency encoded video data on a disk, wherein a transfer rate of the video data is set in consideration of a double-speed ratio of fast-forward playback based on a user's selection. Characteristic disk recording method. 2. The disk recording method according to claim 1, wherein said video data is recorded at a constant linear velocity on an outer peripheral side of a disk reproduced at a constant angular velocity. 3. A disc provided with a lead-in area on an inner circumference side and a lead-out area on an outer circumference side, wherein data is recorded at a constant linear velocity and data is reproduced at a constant angular velocity, respectively. A dummy data area is provided on the inner peripheral side between the readout area and the readout area, and a reproduced data area is provided on the outer peripheral side.