METHOD FOR RECORDING A DIGITAL DATA STREAM

Abstract: The present invention relates to a digital data stream recording method. The present digital data stream recording method creates an additional empty stream object unit (SOBU) with only stuffing packets, if transport packets, received before a counted incremental packet arrival time for a SOBU exceeds a predetermined maximum incremental packet arrival time defined in a provisional standard related with a treamer, do not compose a single complete SOBU because the inpt bit rate of transport packets is so low that a SOBU is not fully written with transport packets within the maximum incremental time, and writes the time difference between the counted incremental packet arrival time and the maximum time in a mapping list entry associated with the created empty SOBU. Accordingly, an incremental time sum calculated from the mapping list is exactly matched with real incremental time counted for associated SOBUs, therefore, a target position can be exactly found with the incremental time inforamtion written in the mapping list.

Description: D E S C R I P T I O N METHOD FOR RECORDING A DIGITAL DATA STREAM 1. Technical Field The present invention relates to a method for creating and recording time information used for search of recorded digital data streams while recording received digital data streams in a disk recording medium such as a digital versatile disk as grouping each of a certain size of the recorded digital data streams into a stream object unit (SOBU) . 2. Background Art With the recent rapid 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 digital broadcast. Digital broadcast offers several advantages that its analog counterpart cannot provide. For example, digital broadcast is capable of providing services with far more 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 digital broadcast, a plurality of programs encoded based upon the MPEG format are multiplexed into a transport stream before transmitted. The transmitted transport stream is received by a set top box at the receiver and demultiplexed into a plurality of 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 recorded digital broadcast signals can be edited and presented afterwards. For example, a digital data stream received by a set top box can be recorded in a streamer such as a digital video disk (DVD) through communication interfaces like an IEEE-1394 serial bus. Later, the recorded digital data stream can be edited and transmitted back to the set top box so that the original digital audio and video data can be presented. When recording the digital data stream of a single program in a streamer, the basic recording unit is the stream object (SOB) comprising a series of stream object units (SOBUs) . To record received digital broadcast signals in a streamer and reproduce the recorded signals 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 of a digital data stream can be employed. Fig. 2 depicts the process of recording the digital data stream and creating the navigation information in the system shown in Fig. 1. The system comprises a set top box 5 100, a communication interface (IEEE-1394), and a streamer 200. 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 0 tuned by a tuning unit 110, a control unit 140 outputs the decoded transport stream to an A/V output apparatus or to streamer 200 through an IEEE-1394 communication interface 130 and 210 so that the transmitted program can be recorded in streamer 200, depending upon a user's request. When 5 requested by a user, streamer 200 retrieves the recorded program and transmits the retrieved program through the IEEE-1394 communication interface back to set top box 100. In set top box 100, the received program is decoded by decoder 120 and outputted to an A/V output apparatus so that the 0 recorded program can be presented. A control unit 250 in streamer 200 controls the data stream transmitted from set top box 100 to be recorded as shown in Fig. 2 on a recording medium 230 by a recording stream processing unit 220. Each transport packet constituting the data stream is 5 recorded on the recording medium along with information on packet arrival time thereof, wherein the packet arrival time will be used as a time reference for transmitting the associated transport packet in playback. In streamer 200, the transport packets with packet arrival times are organized in sectors with each sector 0 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 organized 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 searching for and managing the stream object (SOB) and stream object units (SOBUs) is recorded together on the recording medium. Fig. 3 shows the way the received digital data stream is recorded in streamer 200. An application packet and a packet arrival time (PAT or time stamp) constitute a transport packet (TP) . A plurality of transport packets (TPs) and a header 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) created from recording operation at a time constitute a stream object (SOB) . Meanwhile, the stream object information (SOBI) , which is the navigation data for managing and searching for the recorded stream objects (SOBs) , comprises a stream object general information (SOB_GI) and a mapping list (MAPL) for managing stream object units (SOBUs) , as shown in Figs. 4 and 5. 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 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 stream object (SOB) and stream object units (SOBUs) afterwards . The stream start 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 39-bit packet arrival time base (PAT__base) , as shown in Fig. 6A. 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 format of the stream start application packer arrival time (S_S_APAT) , the time stamp recorded along with the application packet shown in Fig. 3 is recorded as a 4-byte application time stamp (ATS) , shown in Fig. 6B, that is incremented at a rate of 27 MHz and can represent from 0 s up to 159 s (=232/27 MHz) . The method for searching a digital data stream corresponding to a requested search time using the navigation and time information regarding the stream objects (SOBs), stream object units (SOBUs) will be explained in detail with reference to an example. With reference to Fig. 2, suppose that the position (s) of a transport packet corresponding to a search time (ST) requested by a user is to be searched for. First, the stream start application packet arrival time (S_S_APAT) contained in the stream object general information (SOB_GI) of each stream object (SOB) is compared with the requested search time (ST) and a stream start application packet arrival time (S_S_APAT) that is closest to but does not exceed the request search time (ST) is detected. Referring to the mapping list (MAPL) of the stream object SOB #1 corresponding to the detected stream start application packet arrival time (S_S_APAT) , the incremental application packet arrival times (IAPAT 1~4) contained in entries of the mapping list (MAPL) are summed up. The sum value is multiplied by the unit time X and added to the detected stream start application packet arrival time (S_S_APAT) . The procedure is repeated until the calculated value (S_S_APAT+ XxΣIAPAT) approaches the requested search time (ST) without exceeding it. In Fig. 2, the summation and multiplication is repeated to include IAPAT 4 because the calculated value exceeds the search time (ST) if the calculation continues to IAPAT5. Then the entry in the mapping list (MAPL) corresponding to the calculated time (S_S_APAT+ XxΣIAPAT) is located and the index of the entry is multiplied by the number of sectors constituting a stream object unit, for example, 32 (sectors per a SOBU) to locate the desired stream object unit SOBU, for example, the SOBU 5 for the case of Fig. 2. From the start position A 1 of the searched stream object SOBU 5, the 4-byte application time stamp (ATS) , which is the time stamped at which the transport packet arrived, is detected. Recall that the stream start application packet arrival time (S_S_APAT) and the application time stamp (ATS) of a transport packet have different formats and therefore the two values cannot be compared directly. For this reason, the difference between the detected ATS and the ATS of the first transport packet of the stream object unit SOBU #5 is compared with the difference between the requested search time (ST) and the calculated value (S_S_APAT+ XxΣIAP T) for fine search of the transport packet corresponding to the requested search time (ST) . In the meantime, the size of each entry of the MAPL, namely, the size of the IAPAT is 12-bit as shown in Fig. 7. The IAPAT written in an entry is incremented every reset of the bit group from 19-th to 30-th, a shaded block in Fig. 6, of the 6-byte packet arrival time (PAT) of Fig. 6. The interval of this periodic reset is the aforementioned unit time X. Because the size of the IAPAT is 12-bit, the expressible numbers are 2 12 -1 (=4095) , however, in a provisional standard related with a digital data stream recorder (called streamer' ) , the expressible numbers are limited to 2 12 -2 (=4094) which is defined as a maximum incremental application packet arrival time, denoted IAPAT max . Therefore, the incremental time value, which will be written in an entry of the MAPL, counted while a SOBU is being packed with received TPs must not exceed the IAPAT max , namely, 2 12 -2 (=4094) . Thus, if the bit rate of input TPs received from the set top box is so low that a SOBU #n of 32 sectors is not completely packed with TPs until the incremental time value counted for that SOBU #n reaches to the IAPAT max of 2 12 -2 (=4094), the remaining area of the SOBU #n not written with TPs is padded with stuffing packets to be grouped into a complete SOBU the moment the incremental time value being counted exceeds the IAPAT max , then, the value IAPAT max is written in the MAPL entry associated with the SOBU #n. After that, the next TP received afterward is written in the next SOBU # (n+1) . The above-explained operation is described below in detail with reference to a concrete example. First, it is supposed that the size of the entry of MAPL is 4 so that the IAPAT max is 2 4 -2 (=14) and the input bit rate of TPs received from the set top box is too low. In this assumption, if a SOBU #1 is not fully packed with the received TPs and the incremental time value, namely, IAPAT reaches to 15 exceeding 2 4 -2 (=14) by 1 the moment a new TP arrives at 16 which is counted at the predetermined rate X, the remaining area of the SOBU #1 is padded with several stuffing packets to group the 32 sectors into a complete SOBU and the value 14 (=IAPAT max ) , marked Λ IAPAT #1' , is written in a MAPL entry associated with the SOBU #1. And then, the new TP is written in the next SOBU #2. The same as the SOBU #1, if the SOBU #2 is not fully packed with the received TPs and the counted IAPAT for the SOBU #2 reaches to 19 (=35-16) exceeding 2 4 -2 (=14) by five at the elapsing time 35 when a following TP arrives, the remaining area of the SOBU #2 is also padded with several stuffing packets to group the 32 sectors into a complete SOBU and the value 14 (=IAPAT max ) , marked λ IAPAT #2', is written in a MAPL entry associated with the SOBU #2. However, if the IAPATs have been written in the MAPL as above, an incremental time value sum (∑IAPAT) calculated from the MAPL is different from a real incremental time difference between packet arrival times of two associated start TPs. Considering the SOBUs #1 and #2, ∑IAPAT=IAPAT#1+IAPAT#2 is 28 whereas the real packet arrival time difference between two start transport packets of the first and the third SOBU is 34 (=35-1) . If this time difference mismatch frequently occurs, the calculated incremental time sum (ΣIAPAT) from the MAPL becomes much shorter than real time difference between arbitrary two TPs. Therefore, if the accumulated incremental time of IAPATs written in the MAPL is used for searching a location a user wants, the TPs recorded far ahead of real desirable location is searched, which inevitably results in search fails. 3. Disclosure of Invention It is an object of the present invention to provide a digital data stream recording method capable of always matching an incremental time sum calculated from a mapping list with real incremental time counted for corresponding stream object units even though the input bit rate of transport packets is so low that a stream object unit is not fully written with received transport packets until an incremental time counted for that stream object unit exceeds a maximum incremental time which is defined in a provisional standard related with a streamer, thereby preventing fails of search operation. It is another object of the present invention to provide a digital data stream recording method capable of minimizing the occurrences of empty stream object units with no received transport packets while guaranteeing the time match. The present invention is characterized in that a digital data stream recording method comprises the steps of measuring an incremental packet arrival time while recording received transport packets; grouping at least one transport packet, received before the measured incremental packet arrival time exceeds a predetermined maximum incremental packet arrival time, into a stream object unit if the measured incremental packet arrival time exceeds the maximum incremental packet arrival time; writing the maximum incremental packet arrival time in a mapping list entry associated with the grouped stream object unit, and allocating another stream object unit next to the grouped stream object unit without recording any transport packets therein; and writing an extra time, subtracted from the measured incremental packet arrival time by the maximum incremental packet arrival time, in another mapping list entry associated with said allocated stream object unit having no transport packet. The present invention is further characterized in that a digital data stream recording method comprises the steps of measuring an incremental packet arrival time while recording received transport packets; grouping at least one transport packet, received before the measured incremental packet arrival time exceeds a predetermined maximum incremental packet arrival time, into a stream object unit if the measured incremental packet arrival time exceeds the maximum incremental packet arrival time; writing the maximum incremental packet arrival time in a mapping list entry associated with the grouped stream object unit, and subtracting the maximum incremental packet arrival time from the measured incremental packet arrival time; determining how many stream object units with no received transport packet are to be allocated based on a time value obtained from the subtraction; and writing the maximum incremental packet arrival time in each mapping list entry associated with at least one stream object unit excluding one if the determined number of stream object units to allocate is above one. The present invention is further characterized in that a digital data stream recording method comprises the steps of measuring an incremental packet arrival time while recording received transport packets, and grouping at least one transport packet, received before the measured incremental packet arrival time exceeds a predetermined maximum incremental packet arrival time, into a stream object unit if the measured incremental packet arrival time exceeds the maximum incremental packet arrival time; writing the maximum incremental packet arrival time in a mapping list entry associated with the grouped stream object unit, and recording a transport packet, which arrived after the measured incremental packet arrival time exceeds the maximum incremental packet arrival time, in another stream object unit next to the grouped stream object unit based on a time remainder in a subtraction of the maximum incremental packet arrival time from the measured incremental packet arrival time; and writing another incremental packet arrival time, which the time remainder is added to, in another mapping list entry associated with said another stream object unit. The present invention is further characterized in that a digital data stream recording method comprises the steps of measuring incremental packet arrival time while recording received transport packets, and grouping at least one transport packet, received before the measured incremental packet arrival time exceeds a predetermined maximum incremental packet arrival time, into a stream object unit if the measured incremental packet arrival time exceeds the maximum incremental packet arrival time; writing the maximum incremental packet arrival time in a mapping list entry associated with the grouped stream object unit, and memorizing a time remainder in a subtraction of the maximum incremental packet arrival time from the measured incremental packet arrival time; and deciding on whether to group received transport packets into a new stream object unit based on the a newly-measured incremental packet arrival time for the new stream object unit plus the memorized time remainder. According to the digital data stream recording method in accordance with the present invention, an incremental time sum calculated from a mapping list is exactly matched with real incremental time counted for associated stream object units, therefore, a target position can be exactly searched for with the incremental time information written in the mapping list. In addition, the digital data stream recording method memorizes an incremental packet arrival time counted for a stream object unit subtracted by the maximum incremental packet arrival time, adds the memorized incremental time to another incremental packet arrival time counted for a next stream object unit when a transport packet arrives, and uses the added incremental time as an incremental packet arrival time for the next stream object. Accordingly, the number of empty stream object units, which are necessary for matching incremental packet arrival time written in the mapping list with real counted incremental time for stream object units, can be reduced. 4. Brief Description of Drawings The accompanying drawings, which are included to provide a further understanding of the present invention, illustrate the preferred embodiments of the invention, and together with the description, serve to explain the principles of the present invention, and wherein: Fig. 1 is a block diagram of a digital data stream recorder connected to a set top box; Fig. 2 is a pictorial representation of a general process of recording and searching digital data streams; Fig. 3 is a pictorial representation showing a general hierarchical structure of recorded digital data streams; Figs. 4 and 5 are tables showing general management information of recorded data streams; Figs . 6A and 6B are formats of general packet arrival time information for recorded data streams; Fig. 7 is a format of the incremental packet arrival time information for recorded data streams; Fig. 8 is a pictorial representation of a conventional digital data stream recording method; Fig. 9 is a pictorial representation of an embodiment of a digital data stream recording method according to the present invention; and Figs. 10 and 11 are pictorial representations of other embodiments of a digital data stream recording method according to the present invention. 5. Modes for Carrying out the Invention In order that the present invention may be fully understood, a preferred embodiment thereof will now be described with reference to the accompanying drawings. A method of recording digital data stream according to the present invention is applicable to input TPs received from a set top box at such a low bit rate that a single SOBU of 32 sectors is not fully packed with received TPs until an incremental packet arrival time counted for the SOBU reaches to the maximum incremental packet arrival time IAPAT max , namely, 2 12 -2 (=4094) specified in the present provisional standard of a streamer, as mentioned above. If the input bit rate of TPs is that low, the present method pads a not-written remaining area of a SOBU #n with stuffing packets to group the 32 sectors, which is the size of a SOBU, into a complete SOBU when the IAPAT counted from the writing of the SOBU #n reaches to IAPAT max , namely, 2 12 -2 (=4094), and writes IAPAT max of 2 12 -2 (=4094) , marked IAPAT #n' , in a MAPL entry associated with the SOBU #n. And, the present method writes stuffing packets in entire 32 sectors to be allocated for the next SOBU #(n+l) , namely, makes the next SOBU #(n+l) empty with no valid TPs, and writes in the MAPL entry associated with the empty SOBU #(n+l) the incremental time remainder obtained from subtraction of the 2 12 -2 (=4094) written the MAPL entry for the SOBU #n from the incremental packet arrival time counted until a next TP, which will be written in another SOBU #(n+2), arrives. To describe these operations in more detail, recording conditions are simplified by the following assumption. It is assumed that the size of the entry of MAPL is 4 so that the IAPAT max is 2 4 -2 (=14) and the input bit rate of TPs received from the set top box is too low. In this assumption, as shown in Fig. 9, if a SOBU #1 is not fully packed with the received TPs and the incremental time value, namely, IAPAT reaches to 15 exceeding 2 4 -2 (=14) by 1 at the time when a new TP arrives at 16 which is counted at the predetermined rate X, the remaining area of the SOBU #1 is padded with necessary several stuffing packets to group the 32 sectors into a complete SOBU and the value 14 (IAPAT max ) , marked Λ IAPAT #1', is written in a MAPL entry corresponding to the SOBU -#1. And, the next 32 sectors are padded with only stuffing packets and they are grouped into an empty SOBU #2. The extra incremental time 1, marked IAPAT #2' which is a remaining incremental time obtained subtraction of IAPAT max , namely, Λ IAPAT #1' written in the MAPL entry for the SOUB #1 from the total incremental time 15 counted for the SOBU #1, is written in a next MAPL entry for the empty SOBU #2. And then, the TP arrived at 16 is written in a next SOBU #3 following the empty SOBU #2. For the SOBU #3, if the SOBU #3 is not fully packed with the received TPs and the counted IAPAT for the SOBU #3 reaches to 19 (=35-16) exceeding 2 4 -2 (=14) by five when a TP arrives at 35, the remaining area of the SOBU #3 is also padded with several stuffing packets as many as necessary for grouping the 32 sectors into a complete SOBU, and the maximum value 14 (IAPAT^ , marked IAPAT #3', is written in a MAPL entry associated with the SOBU #3. And, the next 32 sectors are padded with only stuffing packets and they are grouped into an empty SOBU #4. The extra incremental time 5, marked Λ IAPAT #4' which is an incremental time remainder obtained from subtraction of IAPAT max , namely, IAPAT#3' written in the MAPL entry for the SOUB #3 from the total incremental time 19 counted for the SOBU #3, is written in a next MAPL entry for the empty SOBU #4. According to the SOBU grouping and incremental time information writing method, the incremental time sum ∑IAPAT from IAPAT #1 to IAPAT #4 calculated from the MAPL is exactly equal to 34 which is real incremental time counted for the SOBUs #1 to #4 inclusive. Therefore, even though a searching operation is conducted based on an accumulated sum of the incremental time information written in the MAPL, a target location can be found without any fail. The following explanation is for the case that input TPs are received from a set top box at lower bit rate than the above. The illustrative example of Fig. 10 is for such lower bit rate. As described for the example of Fig. 9, if a SOBU #1 is not fully packed with the received TPs and the incremental time value, namely, IAPAT reaches to 15 exceeding 2 4 -2 (=14) by 1 at the time when a new TP arrives at 16 which is counted at the predetermined rate X, TPs written in the SOBU #1 is grouped with several stuffing packets and the next 32 sectors are skipped to form an empty SOBU #2 while the value 14 (IAPAT max ) , marked IAPAT #1', and the incremental time remainder 1, marked IAPAT #2' are written in two successive MAPL entries for the SOBUs #1 and #2, respectively. And then, the TP arrived at 16 is recorded in a SOBU #3 following the empty SOBU #2. For the SOBU #3, if a counted IAPAT for the SOBU #3 ' reaches to 32 (=48-16) exceeding 2 4 -2 (=14) more than twice nevertheless the SOBU #3 is not fully written when a TP is arrived at 48, the remaining area of the SOBU #3 is padded with several stuffing packets as many as necessary for grouping the 32 sectors into a complete SOBU and the maximum value 14 (IAPAT max ) , marked IAPAT #3' , is written in a MAPL entry corresponding to the SOBU #3. Then, the counted IAPAT which the IAPAT max (=14) is subtracted from is memorized. This memorized incremental time value is 18 (=32-14) . And, the next 32 sectors are padded with only stuffing packets and they are grouped into a SOBU #4 and the maximum value 14 (IAPAT max ) , marked IAPAT #4', is written in a MAPL entry for the empty SOBU #4. After that, further next 32 sectors are padded again with only stuffing packets and they are grouped into a SOBU #5, and the extra incremental time 4, marked Λ IAPAT #5' which is an incremental time remainder obtained from subtraction of IAPAT max , namely, IAPAT #4' written in the MAPL entry for the SOUB #4 from the memorized incremental time 18, is written in a next MAPL entry for the empty SOBU #5. According to the SOBU grouping and incremental time information writing method for the above lower bit rate case, the incremental time sum ∑IAPAT from IAPAT #1 to IAPAT #5 calculated from the MAPL is exactly equal to 47 which is real incremental time counted for the SOBUs #1 to #5 inclusive. Therefore, even though a searching operation is conducted based on an accumulated sum of the incremental time information written in the MAPL, a target location can be exactly found. Fig. 11 illustrates another embodiment of a digital data stream recording method according to the present invention. The embodiment of Fig 11, which is to minimize the occurrences of empty SOBUs, is explained below. If a SOBU #1 is not fully packed with the received TPs and the incremental time value, namely IAPAT reaches to 15 exceeding 2 4 -2 (=14) by 1 at the time when a new TP arrives at 16 which is counted at the predetermined rate X because the input TPs received from a set top box is very low, the remaining area of the SOBU #1 is padded with necessary several stuffing packets to group the 32 sectors into a complete SOBU and the value 14 (IAPATmax) , marked Λ IAPAT #1', is written in a MAPL entry for the SOBU #1. The extra incremental time 1 (=15-14) is temporally stored in a memory, and the TP arrived at 16 is written in a SOBU #2 without creating an empty SOBU. After that, it is kept being checked whether the incremental packet arrival time counted for the SOBU #2 exceeds the maximum incremental time IAPATmax of 2 4 -2 (=14) every time a new TP arrives. If a new TP arrives at 27 after 16, the temporally stored incremental time 1 is added to the incremental time counted from 16 for the SOBU #2 to calculate real incremental time for the SOBU #2 elapsed before and after that TP arrives. The added incremental time becomes 12 (= (27-16) +1) . This time does not exceed the IAPATmax (=14) . If another TP arrives again at 48 as shown in Fig. 11, the real incremental time is 32+1 (=(48-16)+!) because of the temporally stored time 1. This real incremental time exceeds the IAPATmax (=14) . Because the real incremental time 33 exceeds the IAPATmax (=14) , the remaining area of the SOBU #2 not written with received TPs is padded with stuffing packets to group 32 sectors into a complete SOBU. And then, the maximum value 14 (IAPATmax) , marked IAPAT #2', is written in a MAPL entry associated with the SOBU #2. Because the incremental time 33 is also greater than 14 even if subtracted by 14 (IAPATmax) , an empty SOBU #3 is created following the SOBU #2 and the maximum incremental time 14, marked Λ IAPAT #3', is written in a MAPL entry for the SOBU #3. And, the time remainder 5 from 19 (=33-14) subtracted by 14 (IAPATmax) written in the MAPL entry of the SOBU #3 is temporally stored in a memory to be added to calculate real incremental packet arrival time counted for a next SOBU #4 as explained above. According to the SOBU grouping and incremental time information writing method, one empty SOBU can be removed in comparison with the previous embodiments of Figs. 9 and 10. In spite of this advantage of recording efficiency, the incremental time sum ∑IAPAT up to IAPAT #3, excluding the last SOBU #4 which is accepting input TPs at present, calculated from the MAPL is exactly equal to 42 which is a real incremental time counted for the SOBUs #1 to #3 inclusive. Therefore, even though a searching operation is conducted based on an accumulated sum of the incremental time information written in the MAPL, a target location can be exactly found. The present invention may be embodied in other specific forms without departing from the sprit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims: C L A I M S 1. A digital data stream recording method, comprising the steps of: (a) measuring an incremental packet arrival time while recording received transport packets; (b) grouping at least one transport packet, received before the measured incremental packet arrival time exceeds a predetermined maximum incremental packet arrival time, into a stream object unit if the measured incremental packet arrival time exceeds the maximum incremental packet arrival time; (c) writing the maximum incremental packet arrival time in a mapping list entry associated with the grouped stream object unit, and allocating another stream object unit next to the grouped stream object unit without recording any transport packets therein; and (d) writing an extra time, subtracted from the measured incremental packet arrival time by the maximum incremental packet arrival time, in another mapping list entry associated with said allocated stream object unit having no transport packet. 2. The method set forth in claim 1, wherein said (b) records stuffing packets with null data in a remaining area after recording said at least one transport packet in the stream object unit. 3. The method set forth in claim 1, wherein said step (c) pads stuffing packets with null data in an entire area of said allocated stream object unit. 4. The method set forth in claim 1, wherein the maximum incremental packet arrival time has been determined based on the size of a field for writing an incremental time length from a start to an end transport packet in a single stream object, the incremental time length being counted with a pre-defined unit time. 5. The method set forth ' in claim 4, wherein the maximum incremental packet arrival time is 2 12 -2 (=4094). 6. The method set forth in claim 1, wherein the size of a stream object unit is 32 sectors. 7. A digital data stream recording method, comprising the steps of: (a) measuring an incremental packet arrival time while recording received transport packets; (b) grouping at least one transport packet, received before the measured incremental packet arrival time exceeds a predetermined maximum incremental packet arrival time, into a stream object unit if the measured incremental packet arrival time exceeds the maximum incremental packet arrival time; (c) writing the maximum incremental packet arrival time in a mapping list entry associated with the grouped stream object unit, and subtracting the maximum incremental packet arrival time from the measured incremental packet arrival time; (d) determining how many stream object units with no transport packet are to be allocated based on a time value obtained from the subtraction; and (e) writing the maximum incremental packet arrival time in each mapping list entry associated with at least one stream object unit excluding one if the determined number of stream object units to allocate is above one. 8. The method set forth in claim 7, wherein said step (d) allocates at least two stream object units with no transport packets if the measured incremental packet arrival time exceeds the maximum incremental packet arrival time more than twice. 9. The method set forth in claim 7, wherein said step (e) writes a remainder in a division of the time value by the maximum incremental packet arrival time in a mapping list entry associated with the excluded one stream object unit. 10. The method set forth in claim 7, wherein the maximum incremental packet arrival time has been determined based on the size of a field for writing an incremental time length from a start to an end transport packet in a single stream object, the time length being counted with a pre-defined unit time.

Inventors: KIM BYUNG JIN, KIM MI HYUN, SEO KANG SOO, UM SOUNG HYUN, YOO JEA YONG, KIM, BYUNG, JIN, KIM, MI, HYUN, SEO, KANG, SOO, UM, SOUNG, HYUN, YOO, JEA, YONG
Applicants: KIM BYUNG JIN, KIM MI HYUN, LG ELECTRONICS INC, SEO KANG SOO, UM SOUNG HYUN, YOO JEA YONG, KIM, BYUNG, JIN, KIM, MI, HYUN, LG ELECTRONICS INC., SEO, KANG, SOO, UM, SOUNG, HYUN, YOO, JEA, YONG
Application year: 2001
Main classification: G11B20
IPC codes: G11B20, G11B27, H04N5