Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
2000-02-09
2004-09-07
Homere, Jean R. (Department: 2177)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C386S349000, C386S349000
Reexamination Certificate
active
06789072
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for creating time information for searching digital data streams to be recorded on a recording medium and a method and apparatus for searching for requested data using the created time information.
2. Description of the Related Art
In the conventional analog television broadcast, video signals are transmitted over the air or through cables after being AM or FM modulated. With the recent advance of digital technologies such as digital image compression or digital modulation/demodulation, standardization for digital television broadcast is in rapid progress. Based upon the Moving Picture Experts Group (MPEG) format, satellite and cable broadcast industry also moves towards the digital broadcast.
The digital broadcast offers several advantages that its analog counterpart cannot provide. For example, the digital broadcast is capable of providing services with far ore improved video/audio quality, transmitting several different programs within a fixed bandwidth, and offering enhanced compatibility with digital communication media or digital storage media.
In the digital broadcast, a plurality of programs encoded based upon the MPEG format are multiplexed into a single transport stream before transmitted. The transmitted transport stream is received by a set top box at the receiver and demultiplexed into original programs. If a program is chosen from among the demultiplexed programs, the chosen program is decoded by a decoder in the set top box and original audio and video signals are retrieved. The retrieved audio and video signals can be presented by an A/V output apparatus such as a TV.
It is also possible to record the received digital broadcast signals on a storage medium instead of directly outputting the received broadcast signals to A/V output devices. The stored digital broadcast signals can be edited and retrieved afterwards. For example, a digital data stream received by the set top box can be transmitted to a streamer such as a digital video disk (DVD) recording apparatus through communication interfaces like an IEEE-1394 serial bus and stored on a recording medium by the streamer. The recorded digital data stream can be edited and transmitted back to the set top box so that the digital audio and video data can be presented.
When recording the digital data stream of a single program on a recording medium in a streamer, the basic recording unit is a stream object (SOB) comprising a series of stream object units (SOBUs). To record received digital data streams on a recording medium and to reproduce the recorded data afterwards, it is necessary to explore how to group and record stream objects (SOBs) and stream object units (SOBUs) and how to create search information for managing and searching for the recorded stream objects (SOBs) and stream object units (SOBUs). Also, it is required to investigate how to search a specific data stream corresponding to a search time requested by a user.
A conventional method for recording digital data streams and creating and recording navigation information will now be explained with reference to the accompanying drawings.
FIG. 1
depicts a block diagram of an apparatus in which the conventional method for creating and recording the navigation information for recorded digital data streams can be employed.
FIG. 2
depicts the process of recording digital data streams and creating the navigation information in the system shown in FIG.
1
. The system comprises a set top box
100
, a communication interface (IEEE-1394), and a streamer
200
. The set top box
100
receives transport streams encoded by system encoders and broadcast by a plurality of broadcast stations and demultiplexes the received transport streams. After a decoder
120
decodes the transport stream of a program tuned by a tuning unit
110
, a control unit
140
outputs the decoded transport stream to an A/V output apparatus or to the streamer
200
through the IEEE-1394 communication interface
130
and
210
so that the transmitted program can be recorded on a recording medium
230
by the streamer
200
, depending upon a user's choice When requested by a user, the streamer
200
retrieves the recorded program and transmits the retrieved program through the IEEE-1394 communication interface back to the set top box
100
. In the set top box
100
, the received program is decoded by the decoder
120
and then outputted to an A/V output apparatus so that the recorded program can be presented.
A control unit
250
of the streamer
200
controls a stream recording unit
220
to record the data stream transmitted from the set top box
100
on the recording medium
230
, as shown in FIG.
2
. The received data stream consisting of transport stream packets is recorded on the recording medium along with the packet arrival time (PAT) of each transport stream packet. The transport stream packets with packet arrival times are organized in sectors on the recording medium, with each sector having a predetermined size. A predetermined number of sectors, for example 32 sectors, are grouped into a stream object unit (SOBU). If the recording process is stopped or suspended by a user, the recorded stream object units (SOBUs) are grouped into a stream object (SOB). Additionally, navigation data such as the stream start application packet arrival time (S_S_APAT) and incremental application packet arrival time (IAPAT) for managing and searching for the stream object (SOB) and stream object units (SOBUs) is recorded together with the transport stream packets on the recording medium.
FIG. 3
shows the way the received digital data stream is recorded on the recording medium
230
. An application packet and its packet arrival time (PAT or time stamp) constitute a transport stream packet (TSP). A plurality of transport stream packets (TSPs) and header information are organized into a sector and a predetermined number of sectors, for example 32 sectors, constitute a stream object unit (SOBU). A series of stream object units (SOBUs) constitutes a stream object (SOB). Meanwhile, the stream object information (SOBI), which is the navigation data for managing and searching the recorded stream object (SOB), comprises stream object general information (SOB_GI) and a mapping list (MAPL) for managing stream object units (SOBUs) contained in the stream object (SOB), as shown in FIGS.
4
(
a
),
5
(
b
) and (
b
). The stream object general information (SOB_GI) includes the stream start application packet arrival time (S_S_APAT) indicative of the start time of the associated stream object (SOB). As shown in
FIG. 2
, the incremental application packet arrival time (IAPAT), which is a count value counted at constant time intervals (x) between two consecutive stream object units (SOBUs), is included in the mapping list (MAPL) and used as information for searching for the associated stream object units (SOBUs).
The stream start application packet arrival time (S_S_APAT) contained in the stream object general information (SOB_GI) is recorded as a 6-byte packet arrival time (PAT) comprising a 9-bit packet arrival time extension (PAT_ext) and a 39-bit packet arrival time base (PAT_base), as shown in FIGS.
6
(
a
) and
6
(
b
). The packet arrival time extension (PAT_ext) is a modulo-300 counter that is incremented at a rate of 27 MHz, whereas the packet arrival time base (PAT_base) is incremented at a rate of 90 kHz. Unlike the stream start application packet arrival time (S_S_APAT), the time stamp recorded along with the application packet shown in
FIG. 3
is recorded as a 4-byte packet arrival time (PAT) that is incremented at a rate of 27 MHz and thus can represent from 0 s up to 159 s (=2
32
/27 MHz).
The method for searching for a transport stream packet corresponding to requested search time using the navigation and time information regarding the stream object (SOB), stream object units (SOBUs) will be explained in detail with reference to an example.
Suppose that the position (s) of a tra
Kang Ki Won
Kim Byung-Jin
Seo Kang-Soo
Yoo Jea-Yong
Homere Jean R.
LG Electronics Inc.
Wong Leslie
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