Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-05-29
2001-07-31
Nguyen, Huy (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06269218
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical disk data reproducing method, and more particularly to an optical disk data reproducing method by which a reproducing operation is performed in accordance with track characteristics and recording system.
2. Discussion of the Background
Currently, recording media are mainly divided into magnetic disks and optical disks, and particularly the optical disks are in great demand due to its massive information storage capacity.
FIG. 1
illustrates a typical optical disk of which a radius L
1
is 60 mm and a diameter of a center hall L
2
is 15 mm. The optical disk has a main storage area (MSA), including a lead-in area and a lead-out area, and an outer area.
As shown in
FIG. 4
, the lead-in area includes a table of contents (TOC) which shows location information of a track or a recording system of an MPEG bit stream, and a data track of MSA includes a plurality of tracks (track
1
, track
2
, . . . , track N).
FIG. 2
is a schematic block diagram of a disk data reproducing device for the optical disk of FIG.
1
.
As shown therein, the optical disk reproducing device includes an optical pickup
11
recording/reproducing data in an optical disk
10
, a high-frequency amplifier
12
amplifying a reproduction signal outputted from the optical pickup
11
, a digital signal processor (DSP)
13
digitalizing the amplified signal supplied from the high-frequency amplifier
12
, and performing demodulation and error-correction of the signal, an MPEG decoder
14
decoding the signal outputted from DSP
13
a D/A converting unit
15
converting the signal outputted from the MPEG decoder
14
to an analog signal and outputting audio and video signals, an MPEG microcomputer
16
analyzing/judging the signal from the MPEG decoder
14
, a microprocessor
17
performing a general control operation, a servo unit
18
performing a servo operation in accordance with control of the microprocessor
17
, a memory
19
storing information which have been processed in the microprocessor
17
, a display unit
20
displaying data, and a key input unit
21
receiving a key input signal from a user.
Now, the operation of the conventional optical disk data reproducing device will be described in detail with reference to
FIGS. 2 and 3
.
First, when a user reproduction instruction is supplied to the key input unit
21
after power is applied, the microprocessor
17
shifts the pickup
11
to the innermost part of the optical disk
10
and controls the servo unit
18
, thereby performing focusing control and tracking control (S
101
, S
103
). When the pickup
11
is positioned on the innermost part of the disk
10
, the microprocessor
17
controls the pickup
11
to move outward and determine whether the pickup
11
has reached the lead-in area of the MSA. (S
105
).
When the pickup
11
is in the lead-in area of MSA, the microprocessor
17
reads the TOC in the lead-in area (S
107
), and receives the TOC data which are passed through the high frequency amplifier
12
, to determine if the MPEG data recorded in the track is NTSC or PAL based.
After recognizing the type of the MPEG data, the microprocessor
17
checks whether a reproduction location designating key has been inputted (S
109
). If the reproduction key is inputted, the microprocessor
17
shifts the pickup
11
to the designated position and reproduces an MPEG bit stream therefrom (S
111
). If not the microprocessor
17
, reproduces the MPEG bit stream from the first end of the corresponding track (S
113
).
Next, when any reproduction location changing key is inputted over the key input unit
21
during the reproducing operation (S
115
), the microprocessor
17
shifts the pickup
11
to the location corresponding to the inputted reproduction location changing key and reproduces the MPEG bit stream from the changed track location (S
117
), and when the reproducing operation is completed or a reproduction interruption key is supplied from the user, the microprocessor
17
completes the reducing operation (S
119
).
The reproduced MPEG bit stream is amplified in the high-frequency amplifier
12
, then the amplified MPEG bit stream is demodulated and error is corrected in the DSP
13
and the resultant bit stream is inputted to the MPEG decoder
14
. The MPEG decoder
14
decodes the MPEG bit stream from the DSP
13
in accordance with parameters stored in the memory
21
and outputs the decoded MPEG bit stream to the D/A converting unit
15
and the microprocessor
17
.
Thereafter, the D/A converting unit
15
converts the output signal from the MPEG decoder
14
to the analog signal and outputs the audio and video signals, and the MPEG microcomputer
16
analyzes/judges the output signal from the MPEG decoder
14
and outputs the result to the microprocessor
17
, which processes various control operations on the basis of the output data from the MPEG microcomputer
16
, and the process result thereof is stored in the memory
19
and also displayed on the display unit
20
.
However, the conventional optical disk data reproducing method has a problem that video or audio data may not be normally reproduced when data of an optical disc in which information of the NTSC system and the PAL system coexist are reproduced by a scan or a random access or when characteristics of a present track are different from that of the previous track thereof, because the conventional optical disk data reproducing method uses information with respect to an NTSC or a PAL system until the completion time of the data reproducing operation without any change in the situation which either of the NTSC or PAL system is applied for recording data in an optical disk.
For example, when reproducing data of a track in which an NTSC bit stream is recorded by the scan or random access while data in the track in which a PAL bit stream is recorded are being reproduced, lower and upper parts of a picture may be cut off or the picture may be cracked.
Further, a hold in the picture may be occurred due to frame rate difference between the NTSC system and the PAL system.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an optical disk data reproducing method that obviates the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an optical disk data reproducing method that reproduces data in accordance with characteristics of tracks and a recording system by scanning or randomly accessing a video CD which has a plurality of tracks, thereby obtaining reliability of a data reproducing operation.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, in an optical disk data reproducing device for reproducing video and audio data of a video CD which has a plurality of tracks by a scan or a random access, an optical disk data reproducing method includes a first step for sensing a key input and judging whether the key input is for the scan or the random access, a second step for checking whether a track is changed, when the key input has been judged for the scan or the random access in the first step, a third step for reading a value of a sequence header in a reproduced bit stream and comparing the sequence header value with a sequence header value of a previous track, when the track is changed to another track, and a fourth step for newly setting up a sequence header value and parameters required for a decoding process when the compared sequence header value and sequence header value of the previous track value are not identical and performi
Kim Hyun Mok
Lim Gun Hwa
LG Electronics Inc.
Nguyen Huy
LandOfFree
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