Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data streaming
Reexamination Certificate
1999-12-16
2002-06-18
Sheikh, Ayaz (Department: 2155)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data streaming
C386S349000, C386S349000, C386S349000, C386S349000, C386S349000, C386S349000, C386S349000
Reexamination Certificate
active
06408338
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application Nos. 98-55499, filed Dec. 16, 1998, and 99-839, filed Jan. 14, 1999, in the Korean Patent Office, the disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to fast searching of digital data, and more particularly, to a method of generating additional information used to quickly search for a desired position in a data stream, after storing data which is packetized (hereinafter, called “packet data”) in a recording medium, a recording medium for storing the information and a recording and/or playback apparatus using the same.
2. Description of the Related Art
Recording and/or playback apparatuses which store and/or reproduce packet data, which is used in digital satellite broadcasting or in digital high definition broadcasting, in a one dimensional recording medium such as a tape and which implement special playback such as trick-play, have been developed. Moreover, an optical recording and/or playback apparatus or multimedia equipment using optical disks requires the function of recording packet data in a two dimensional recording medium such as an optical disk and quickly accessing a desired position during special playback such as time search to play back only necessary data.
FIG. 1
shows the basic form of recorded data including input packet data and its arrival time and the conceptional relation between the recorded data and data output time intervals during playback. When recording input data, an arrival time stamp (ATS), which is arrival time information, is added to the input data and the data is output based on the added ATS during playback. Here, the input data is packetized data which is obtained by dividing data such as video or audio into units of a predetermined size. The packetized data is transmitted through satellites, cables or local area networks (LANs). The size of the unit is 188 bytes when data is transmitted using a Moving Picture Experts Group (MPEG)-2 transport stream defined by the International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) 13818-1 standard, and is 53 bytes when data is transmitted using an asynchronous transfer mode (ATM) standard.
In digital broadcasting, packet data is transmitted at irregular time intervals. The transmitted packet data is usually received by a receiving party having a decoder. In the receiving party, the transmitted data is input into the decoder via a buffer and decoded by the decoder so that users can watch the broadcasting.
When a user sets a playback mode to reproduce, at a desired time, packet data, which has been stored in a recording medium, is sent to the decoder by a playback apparatus. When sending the data to the decoder, the irregular time intervals at which the packet data was originally transmitted to the receiving party are significant because the buffer of the receiving party overflows or underflows if the irregular time intervals are not obeyed. This is because, when transmitting data, an original transmitting party (a broadcasting station) adjusts the time intervals between packet data taking into account the state of the buffer of a receiving party having a decoder. For this reason, it is assumed that information on the arrival time of each packet of data is added to each corresponding packet of input data when a recording apparatus records data, and each packet of data is output by a playback apparatus based on the arrival time information thereof.
FIG. 2
is a block diagram showing a recording and playback apparatus for the packet data shown in FIG.
1
. In
FIG. 2
, a counter
102
, which operates according to a system clock signal, usually uses a system clock signal of 27 MHz because the MPEG-2 system generates time stamps on the basis of a clock signal of 27 MHz. It is needless to say that a system clock signal of another frequency can be used.
An ATS generator
104
adds an ATS to each packet of input data. The input packet data together with the added ATSs is converted into a signal suitable for recording by a recording controller
106
and then recorded in a recording medium
108
. A playback controller
110
plays back to which ATSs have been added, which is recorded in the recording medium
108
and sends the playback data to an ATS processor
112
. The ATS processor
112
outputs the data according to the added ATS of the playback data. Here, the ATS generator
104
and the ATS processor
112
each includes an internal buffer. Alternately, the buffers of the ATS generator
104
and the ATS processor
112
may be separately provided on the outside.
In the method of adding an ATS, during recording, the ATS generator
104
reads a count value of the counter
102
at the time when packet data is input, and adds the count value to the packet as an ATS. The packet data with the added ATS is temporarily stored in the internal buffer of the ATS generator
104
and then recorded in the recording medium
108
via the recording controller
106
. As mentioned above, the internal buffer can be separately provided on the outside of the ATS generator.
During playback, the playback controller
110
plays back the packet data with the added ATS from the recording medium
108
and sends the playback data to the ATS processor
112
. The ATS processor
112
, which includes a buffer of a predetermined size, temporarily stops reading data when the buffer overflows, and restarts the reading when the buffer is empty, repeatedly. The ATS processor
112
reads the ATS and corresponding packet data of a first packet, from its internal buffer, and sets the counter
102
based on the ATS while outputting the packet data. The output data of the ATS processor
112
is pure packet data from which the ATS has been removed. Thereafter, packet data is output only when the added ATS of the packet is determined to have the same value as the count value of the counter
102
by comparing the ATS with the count value. The buffer included in the ATS processor
112
may also be separately provided on the outside. Due to such configuration and operation as described above, data can be transmitted to a receiving party having a decoder while the original time intervals of packet data are maintained during playback so that decoding can be smoothly performed.
In addition to simple playback functions in which recorded data is sequentially played back from beginning to end, special playback functions, which are provided in analog recording and playback apparatuses such as existing video cassette recorders (VCRs) and in digital audio and video (AV) apparatuses which record or play back data in or from two dimensional recording media such as video CD and DVD, must be supported. Accordingly, a fast search function is used in playing back of data starting from an arbitrary position of a data stream. For example, time searching is representatively used to perform playback starting from data corresponding to a desired time or data soon after the desired time, instead of starting from the beginning. In this case a fast search function is desired. In addition, it is necessary to quickly search for desired positions when a user collects data streams from various positions on a recording medium to make a new playback order of the collected data streams and plays back the data streams in the new order.
FIG. 3
is a diagram for explaining a time search in a case where data with an ATS is recorded without a special information structure. Referring to
FIG. 3
, if it is assumed that a specified target time is ATS
1
, every ATS is quickly read starting from the beginning of a data stream, and the values of ATSs, which are added to packets, are compared with the value of ATS
1
in order to find out the position of data corresponding to the time slot of ATS
1
. As the result of the comparison, data packets having ATS values smaller than the value of ATS
1
are all discarded, and playback is performed starting from the packet
Bak Bong-gil
Kang Jung-suk
Moon Seong-jin
Park Pan-gie
Park Sung-wook
Jean Frantz B.
Samsung Electronics Co,. Ltd.
Sheikh Ayaz
Staas & Halsey , LLP
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