JP2001076433A - Data reproducing method, and data reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease useless data processing by calculating a position on a recording medium, of a unit UV of original data being independently reproducible including a reproduction start position when a reproduction start position is specified, reading out and demodulating original data from a calculated position on a recording medium with post-recording data, and performing synchronizing-reproduction from a reproduction start position. SOLUTION: When reproduction is performed from the middle of a program in which post-recording is performed, a CPU 102 obtains a correspondent EUS (editable unit sequence) file and a reproduction start PTS(presentation time stamp) from a program and timing specified by a user, and sends it to a demultiplexer 111 and a decoder 112. Next, the CPU 102 calculates the leading address of the unit VU in which correspondent data is included and the leading address of a PRU(post recording unit) from the reproduction start PTS using an Address LUT(lookup table).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for reproducing video data and audio data on a randomly accessible recording medium such as a hard disk or an optical disk.

[0002]

2. Description of the Related Art Digital recording / reproducing apparatuses for video and audio using disk media are becoming popular. In those systems, there is a demand for a technology for realizing an after-recording (after-recording) function at a low cost similarly to the tape media. The post-recording function is a function of adding information, particularly audio, to the already recorded audio or video later.

A general data structure for realizing the after-recording function on a disk medium will be described below.

FIG. 10 shows a data structure on a disk as a recording medium. The disc is composed of a row of units of a predetermined reproduction time unit. When reading data, the reading is performed in units of this unit, and necessary data is extracted.

[0005] Video and audio are stored in the unit,
As shown in 0 (b), the audio block is arranged in the order of the after-recording audio block, the original audio block, and the original video block. Each block includes the dubbed audio, the original audio, and the original video corresponding to almost the same time. Note that the original audio block and the original video block are collectively referred to as an original block. When recording an original program (video before recording post-record audio), dummy data is written in the post-record audio block.

Next, the operation during dubbing in the prior art will be described with reference to FIG. In the figure, the upper graph shows each means and the relation between each means and the recording medium. The middle part schematically shows the position of the head in the disk, and the lower part schematically shows the ratio of the program data in the buffer memory.

Here, the program is s11 in the disk.
~ S18 ~ arranged in a continuous area, s11 ~ s13, s13 ~ s1
5, s15 to s17 correspond to one unit each, and s11 to
It is assumed that s12, s13 to s14, s15 to s16, and s17 to s18 respectively correspond to the post-record audio block.

At time t1, the area up to s13 has already been stored in the buffer memory, and the data recorded in s11 to s13 is decoded and presented (reproduced). , Encoding has been done.

At times t1 to t3, regions s13 to s15
Is read from the disk and stored in the buffer memory and the post-record buffer. The after-recording buffer directly stores the data of one unit that has been read, and has the same configuration as that of FIG. 10B.

Time t2 is the time at which the decoding and reproduction of the data recorded at s11 to s13 performed at time t1 ends. After time t2, times t1 to t3
The data of s13 to s15 read in is decoded and reproduced, and the dubbed sound of the data is input and encoded. The decoding and reproduction of the data of s13 to s15 are performed until t5.

[0011] The encoding of the after-recording sound input by t2 is completed at least by t3. At time t3, the after-recording sound input by t2 is recorded on the disk medium. At this time, when accessing s11, it takes time to wait for the rotation of the disk, but it is shorter than the time for reading and writing to the disk, so it is not considered here.

[0012] After-recording audio is written to the disc,
It is performed from time t3 to t4. When the writing to the disk is completed at t4, data from s15 to s17 from t4 is read from the disk. Thus, the same processing is repeated thereafter.

This conventional technique utilizes the fact that information reading is shorter than the data reproducing time by performing information compression, and the recording / reproducing means is used in a time-division manner for recording and reproducing. After-recording is realized with only one recording and reproducing means.

In such a data structure, when reproduction is performed from an arbitrary position, data is read out for each unit and reproduction is performed. When reproducing from the head position of the unit, the data of the entire unit can be read, decoded, and reproduced.

Next, consider a case where reproduction is desired to be performed from the middle of a unit. In this case as well, after reading and decoding the data of the entire unit, the position of the after-recording block and the original block corresponding to the position at which the reproduction is to be started is obtained, and reproduction is performed from that position, so that playback from the middle of the unit is started. Playback can be performed.

[0016]

As described above, when reproduction is performed from an arbitrary position, it is necessary to perform reading and decoding for each unit even if the position is intermediate between the above units. .

If the reproduction position is close to the head of the unit, there is not much waste, but if the reproduction position is in the latter half of the unit, even if the entire unit is read and decoded, most of it is useless. It becomes data.

If the above-mentioned unit is a sufficiently small unit, the portion which becomes useless data is reduced. However, if the unit becomes small, the number of units in a predetermined time increases. There is a problem that the ratio of the overhead of moving from the to the post-recording block occupies becomes large, and the reading of data cannot keep up with the display, and the reproduction of video and audio is interrupted.

Therefore, the present invention is to solve the above-mentioned problem, and the original data for the post-recording data is further divided into a plurality of small units, and the reproduction can be started for each of the small units, so that the unnecessary data can be reproduced. If you want to play back from a position near the beginning of the unit during playback without reading and decoding the unit, read and decode the entire unit, play it back, and play back from a position near the back end of the unit. The dubbing data is read out in its entirety, and the original data is read out in units of small units, so that the readout method is adaptively changed according to the reproduction start position so as to reduce useless readouts. Less.

[0020]

According to a first aspect of the present invention, original data consisting of video or audio and post-record data reproduced in synchronization with the original data are made into a unit called EU, A data reproducing method for a recording medium in which data is recorded as a set of VUs, which are independently reproducible units, wherein when a reproduction start position is specified, the VU including the reproduction start position is recorded on a recording medium. Calculating the position, reading out the original data from the position on the recording medium of the VU including the obtained reproduction start position together with the post-recording data, decoding the read original data and post-recording data, and starting the reproduction. The above problem is solved by performing synchronous reproduction from a position.

According to the second aspect of the present invention, the original data consisting of video or audio and the post-record data reproduced in synchronization with the original data are made into a unit called EU, and the original data is reproduced independently. A method of reproducing data of a recording medium recorded as a set of VUs that are possible units, wherein when a reproduction start position is specified, a position on the recording medium of the VU including the reproduction start position is calculated, Calculating a first read time for reading only the original data after the position on the recording medium of the VU including the obtained reproduction start position together with the after-recording data, and when the first read time is shorter than a predetermined time; ,
Along with the post-recording data, only the original data after the position on the recording medium of the VU including the obtained reproduction start position is read out, and the read original data and post-recording data are decoded to synchronize from the reproduction start position. The above problem is solved by performing reproduction.

According to the third aspect of the present invention, the original data composed of video or audio and the post-record data reproduced in synchronization with the original data are made into a unit called EU, and the original data is reproduced independently. A method of reproducing data on a recording medium recorded as a set of VUs that are possible units, wherein when a reproduction start position is specified, a position on the recording medium of the VU including the reproduction start position is calculated, A first read time for reading out only the original data after the position on the recording medium of the VU including the obtained reproduction start position together with the after-recording data;
A second method for reading the entire EU including the reproduction start position in the recording order
And when the first read time is shorter than the second read time, together with the post-recording data, the VU including the obtained reproduction start position on and after the position on the recording medium. A data reproducing method comprising: reading only original data; decoding the read post-record data and the original data; and performing synchronous reproduction from the reproduction start position.

According to the fourth aspect of the present invention, the original data composed of video or audio and the post-record data reproduced in synchronization with the original data are made into a unit called EU, and the original data is reproduced independently. A method of reproducing data on a recording medium recorded as a set of VUs that are possible units, wherein when a reproduction start position is specified, a position on the recording medium of the VU including the reproduction start position is calculated, The first time required to skip from the head position of the original data to the VU immediately before the VU including the determined playback start position, and the playback start position determined from the head position of the original data are included. Just before the VU
A second time required to read up to the VU is calculated, and when the first time is shorter than the second time, the obtained reproduction start position is included together with the after-recording data.
A data reproducing method comprising: reading out only the original data after the position of a VU on a recording medium, decoding the read out post-recording data and the original data, and performing synchronous reproduction from the reproduction start position.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described. FIG. 1 shows the configuration of a video disc recorder capable of post-recording in the first embodiment. As shown in the figure,
This device includes an operation unit 101, a CPU 102, a RAM 103, a ROM 104, a system clock 105, a buffer memory 108, an encoder 10
6, multiplexer 107, disk drive 109, bus 11
0, demultiplexer 111, decoder 112, disk 113
, And an ECC encoder / decoder 114.

The disk 113 is a detachable optical disk on which recording and reproduction are performed spirally from the outer periphery to the inner periphery. One sector is 2048 bytes, and an ECC block is composed of 16 sectors for error correction. When rewriting the data in the ECC block, it is necessary to read the entire ECC block containing the data, correct the error, rewrite the target data, add the error correction code again, construct the ECC block, and record it on the recording medium There is.

FIG. 2 shows the structure of the disk 113. At the head of the disc is file system management information, and the rest is a user area managed by the file system in file units. The user area is divided into a management information area and an AV stream area. The management information area includes a file related to management information, and the AV stream area includes an EUS (editable unit sequence) file. The EUS file is a file in a data stream unit that records a series of video and audio data from the start of video recording to the end thereof. On the other hand, the file in the management information area includes an EUS Management file storing information on the EUS file and the like.

In this embodiment, each file is accessed through a file system managed by file system management information. Therefore, it is possible to access a file distributed and arranged in the disk like the EUS file # 2 in the figure by using a continuous logical address. The unit at the time of access by a logical address is a sector unit. In this embodiment, the description of the file system is omitted because it is not directly related to the invention. Also,
An address in the following description refers to a logical address unless otherwise specified.

An encoding method used in this embodiment will be described. Original video is 5Mbps by MPEG-2 encoding
The audio is sampled at 48 kHz for both the original and audio dubbing, with MPEG-1 /
Coding is performed at a fixed rate of 256 kbps for two channels by Layer II coding.

The EUS file is a file for storing EUS, which is a unit of a multiplexed data stream of video and audio information. Figure 3 shows the general configuration of EUS. The main elements that make up EUS are summarized below.

Block: A fixed-length unit of 2048 bytes corresponding to a sector. The video data specified by ISO / IEC 13818-2, the audio data specified by ISO / IEC 13818-3, and other data VU (Video Unit) composed of packetized PES Packets specified in / IEC 13818-1: A unit of random access during playback, even if in the middle of EUS if accessed from the beginning of VU Audio and video are guaranteed to be decoded correctly. PRU (Post Recording Unit) composed of Blocks: An area for recording post-recording data (post-recording data) related to a plurality of VUs. EU (Editable Unit) composed of Blocks: composed of multiple VUs and 0 or 1 PRUs corresponding to them. One EU is a unit corresponding to an EUS (Editable Unit Sequence): Rec Start-Stop or Pause section that is continuously recorded on the disc, and is composed of an integer number of EUs.

The block in the figure is a unit of a fixed length of 2048 bytes, and one block is stored in one sector. One block is basically composed of one packet. The packet here conforms to the PES packet specified in ISO / IEC 13818-1. Figure 4 shows the structure of the packet. A packet is composed of a packet header that stores attributes and the like related to the packet and packet data that stores actual data such as video data. The main information included in the packet header is as follows. packet-start-code-prefix is ISO / IE
This is the start code of the packet specified in C 13818-1. s
tream-id indicates the type of this packet. PES-packet-l
“ength” indicates the size of data following this field. PES-header-data-length indicates the size of the packet header. PTS (presentation time stamp) is synchronization information between elementary streams such as multiplexed audio and video, and the timing at which the access unit (one frame in the case of video) whose head is included in the packet is reproduced at 90 kHz Is represented by 33 bits. The DTS (Decoding Time Stamp) represents the timing at which the access unit having the head in the packet is decoded on the same time axis as the PTS. stuffing-by
tes is used to adjust the size of the packet as described below.

If the packet is less than 2048 bytes and the shortage is less than 7 bytes, a stuffing byte is inserted in the packet header. On the other hand, when the shortage is 8 bytes or more, a padding packet corresponding to the shortage is placed after the packet. These stuffing bytes and padding packets are so-called dummy data that are not actually processed. The packets used in this embodiment are summarized below.

V-PKT (Video Packet): ISO / IEC 13818-2
A-PKT (Audio Packet): A packet storing video data specified in ISO / IEC 13818-3 P-PKT (Padding Packet): A packet storing audio data specified in ISO / IEC 13818-1 VH-PKT (VU Header Packet): A packet containing a header related to VU PH-PKT (PRU Header Packet): A packet containing a header related to PRU V-PKT, A-PKT and P-PKT format Is ISO / IEC 138
Conform to the provisions of 18-1. Other packet formats will be described later. The blocks that make up EUS are summarized below.

V-BLK (Video Block): block storing V-PKT A-BLK (Audio Block): block storing A-PKT P-BLK (Padding Block): block VH- storing P-PKT BLK (VU Header Block): block storing VH-PKT PH-BLK (PRU Header Block): block storing PH-PKT First, the EU will be described. Figure 5 shows the EU structure. EU
Contains one or more integer VUs and zero or one PRU. 1
The presentation time of the VUs constituting each EUS is the same. However, the last VU of the EUS may be shorter than other VUs. That is, the VU playback intervals in one EUS are always the same. When the VU includes video data, the presentation time of the VU is defined as the number of video fields or video frames included in the VU multiplied by the video field period or video frame period, respectively.

The EUs constituting one EUS include either all PRUs or no PRUs. The number Nvu of VUs constituting the EU is constant in the EUS except for the last EU in the EUS. That is, in one EUS, the presentation time interval of the EU is always constant. For EUS without PRU,
Nvu = 1. On the other hand, in the case of EUS with PRU, the presentation time per VU is Tpv, the rotation waiting time is Tv, the time to jump from the track currently being read to the track with the dubbing area is Tk, the data transfer speed from the disk is Rs, The overall EUS bit rate is Ro, the bit rate per channel of post-record audio is Ra, and the number of post-record audio channels is Nc
h

[0036]

(Equation 1)

Assume that: Note that ceiling (x) is a function for obtaining a minimum integer equal to or larger than x, and floor (x) is a function for obtaining a maximum integer equal to or smaller than x. The reason for setting the minimum value of Nvu based on data transfer speed etc. in the case of EUS with PRU is that if the time per EU is not large enough, the head will be This is because the proportion of the overhead of moving from the reading position to the post-recording area occupies a large portion, and the reading of data cannot keep up with the display, and the reproduction of video and audio is interrupted.

Next, the VU will be described. VU, sequ
video data consisting of one or more integer GOPs (groups of pictures) immediately preceding the ence-header and the following GOP-header, and an integer number of AAUs (audio access units) synchronized with it Audio data. The GOP is a unit of MPEG video compression and is composed of a plurality of fields or frames. AAU
Is obtained by segmenting audio samples every 0.024 seconds and compressing each segment. GOP, AAU
In both cases, it is necessary to decode from the head of each unit, but since each VU includes an integer number of them, independent reproduction is possible in VU units. N video fields per VU
For TSC, the range is from 24 to 60 fields, and for PAL, the range is from 20 to 50 fields.

The VU has a VU Header Bloc at the beginning as shown in FIG.
k (VH-BLK), then AB containing the audio data
LK column, and finally the V-
Arrange in BLK column order. The number of A-BLKs is required and sufficient to store the above-mentioned audio data. If there is a surplus in the last A-BLK, adjust with P-PKT or stuffing byte as described above. V-BLK has the same configuration.

A unit that can be independently reproduced as described above.
By configuring the EU with a set of VUs, overhead when starting playback from the middle of the EU is reduced. If the transfer speed has no margin compared to the data bit rate, Nv
It is necessary to set u large, that is, to set the presentation time per EU long, but in this case, if a unit such as VU is not provided, for example, even if playback is started near the end of the EU,
The data must be read from the beginning of the EU, resulting in poor response to the user. Also, by configuring the VU with an integer number of blocks, that is, sectors, access to the head of the VU is simplified.

FIG. 7 shows the structure of VH-PKT. BP (byte position) in the figure is a relative byte position from the head, and the number of bytes indicates the number of bytes of each field. packet-start-code-prefix, stream-id, PES-packe
t-length is as described above. VU Property is a 1-byte bit field and stores information on the VU including this VU header. One of them, First VU of EU
Is set to 1 if the VU including the VH-PKT is the first VU in the EU, and is set to 0 otherwise. This field is used for synchronization at the time of post-recording, as described later. Length of
VU indicates the number of blocks in the VU including this VU header.
Start RLBN of Video Data indicates the number of blocks from the beginning of the VU to the start of video data.

Next, the PRU will be described. PRU is 1
This is an area for storing audio for an integer number of VUs, and there are 0 or 1 in one EU. The PRU size is the smallest integer number of ECC blocks that can include audio data and PRU header blocks corresponding to the presentation time per EU. Number of ECC blocks constituting PRU NPRU, ECC is

[0043]

(Equation 2)

Is defined as The audio data to be recorded in the PRU is recorded at the same data rate and the same sampling frequency as the audio of the VU in the EU including the PRU.

FIG. 8 shows the structure of the PRU immediately after recording the original data. One PRU Header Block (PH-BLK) is recorded at the beginning, and the remaining area is filled with Padding Block (P-BLK). That is, immediately after the recording of the original data, no audio data is recorded.

FIG. 9 shows the configuration of the PRU after audio dubbing is performed on the PRU. PRU Header Block (PH-BLK) at the beginning
Is recorded, and thereafter, the audio data synchronized with the EU is recorded as a column of A-BLK, and the remaining area is filled with P-BLK. At this time, the number of A-BLKs in the PRU is the same as the total number of A-BLKs included in each VU in the same EU.
Furthermore, the PTS value of each A-BLK in the PRU is
The post-recording audio data is recorded in the same order and with the same value as the PTS of the A-BLK included in each of the VUs. That is, in the post-recording PRU, there is an A-BLK column corresponding to the A-BLK column included in each VU. Such a row of A-BLKs in a PRU corresponding to a VU is referred to as an SAU (sub audio unit). Needless to say, the SAU includes an integer number of AAUs like the VU.

FIG. 10 shows the structure of PH-PKT. packet-star
The t-code-prefix, stream-id, and PES-packet-length are the same as in the VU header packet. Length of PRU
Describes the number of blocks constituting a PRU including this PH-PKT. Number of VU indicates the number of VUs constituting the EU including the PH-BLK. Start RLBN of Data for VU
Indicates the number of blocks from the beginning of the AU PRU.

As described above, by setting the PRU as a set of units (SAUs) including an integer number of blocks, that is, an integer number of AAUs composed of sectors, the PRU is read into the buffer memory 108, and then the It becomes easy to partially rewrite post-record data in SAU units. Because the A included in each SAU
AU is stored in a packet independent of AAU in other SAUs, so if rewriting in SAU units, other SAUs
This is because AU is not affected. If such a configuration is not taken, a different SAU
There is an AAU included in the PRU, and when dubbing a PRU that has already been dubbed in the middle, it is necessary to take the procedure of unpacking the packet, searching for the beginning of the AAU, rewriting the data, and repacketizing it. Not
Processing becomes complicated.

Further, since information indicating the start position of each SAU is inserted in the stream, when rewriting a PRU in SAU units, it is immediately known from which position to start rewriting.

Further, by making the data in the PRU have the same structure as the audio data in the VU, for example, the audio data in the PRU can be partially copied into the VU.
Data exchange between U and VU becomes easy.

The arrangement of PRUs in the EU will be described. PRU
Is placed on the ECC boundary within the first 15 sectors of the EU in which it is contained, ie, the first ECC boundary in the EU. For example, if an EU starts with an ECC block boundary,
As shown in (a), a PRU is placed immediately after the head of the EU.
Also, if the beginning of the EU is not an ECC block boundary,
As shown in (b), it is located at the ECC block boundary within 15 logical blocks immediately after the EU boundary, that is, at the first ECC block boundary in the EU. In this case, the first VU in the EU is PRU
Will be divided by

As described above, by making the size of the PRU an integral multiple of the ECC block size and arranging the PRU at the ECC block boundary, the data to be rewritten on the recording medium during dubbing is only the PRU. This is advantageous in that the area for performing the operation is minimized.

In the above embodiment, the reason why the PRU is near the head of the EU is that, when a certain EU is reproduced, synchronous reproduction of the VU and the PRU becomes possible when the entire PRU and one VU are read. is there. If the PRU is near the end of the EU, the program cannot be reproduced until most of the EU data has been read, and a buffer memory for storing almost the entire EU is required.

FIG. 12 shows the structure of the EUS Management file. The EUS Management file stores information for managing all EUS files recorded on the disc. Hereinafter, only the items essential for the description of the present embodiment will be described. Field Number of EUSI
Represents the number of EUS files managed by this file. A field EUSI (EUS Information) is information on each EUS file, and has a number of EUSIs. EU
The SI is further configured as shown in Figure 13. Start PT in the figure
“End PT” is the one in which the most significant bits of the start PTS and end PTS in the EUS file managed by this EUSI are omitted. Hereinafter, a format in which the most significant bit of the PTS is omitted will be referred to as a PT format. Post R
ecording Unit Size indicates the size of the PRU in the EUS file managed by this EUSI.

Address LUT (Look Up Table)
Is a table for searching an address where data corresponding to the time code is recorded from the time code described in the PT format. Figure 14 shows the configuration of the Address LUT. The field PBTime of EU represents the presentation time per EU in units of 1 / 90,000 [second], and has the same scale as the PT format. PB T
In the case of ime of VU, the presentation time per VU is similarly reduced to 1/90000 [second]
It is expressed in units. Number of PRU Informatio
n is the number of PRU Information in the Address LUT, and also represents the number of PRUs in the EUS. Number of VU Informa
In the same manner, “tion” indicates the number of VU information in the address LUT and the number of VUs in the EUS.

FIG. 15 shows the contents of PRU Information. RLBN of PRU in the figure indicates the address of the PRU managed by the PRU Information. FIG. 16 shows the contents of VU Information. RLBN of VU in the figure is the VU Information
Represents the address of the VU managed by.

Using the Address LUT, a certain time code P
The procedure for obtaining the address of the PRU corresponding to T is described below. First, the relative PT is calculated by subtracting the StartPT in EUSI from PT.
PRU that divides the relative PT by the PB Time of EU and truncates the decimal part to manage the PRU corresponding to that PT
Information index is found. Next, the address given by the RLBN of PRU in the PRU Information corresponding to the index is the address of the PRU corresponding to the target PT. Similarly, for the address of the VU corresponding to the time PT, the value obtained by subtracting the Start PT from the PT is divided by the PB Time of VU, and the VU of the index corresponding to the value obtained by truncating the decimal part
It can be obtained by referring to RLBN of VU in Information. The reason why the head address of the VU or PRU can be obtained by such simple processing is that the presentation time per EU and VU is kept constant.

The procedure for recording, reproducing, and post-recording in the above-described disk format will be described below. In the following description, video is recorded in NTSC, the VU is composed of one GOP consisting of 30 fields, and the maximum video bit rate is
8 [Mbps]. The disc transfer rate Rs is 12 [Mbps], the maximum jump time Tk to the post-recording area is 0.3 [second], and the maximum rotation waiting time Tv is 0.2 [second]. The audio bit rate and the number of audio channels are set to 0.12
5 [Mbps / channel] and 2 [channels] are used commonly for original and post-recording. At this time,
The presentation time Tpv per VU is about 0.5 seconds. The range of the number of VUs per EU Nvu where dubbing is possible is 7 ≦ Nvu ≦ 20. In the present embodiment, Nvu = 8, that is, the presentation time per EU is about 4 seconds.

The flow of processing of the CPU 102 when recording an original program will be described with reference to FIG. It is assumed that the EUS Management file and the file system management information have already been read from the disk into the RAM 103. The CPU 102 activates the encoder 106, and then checks based on the file system management information whether a continuous area sufficient for recording 1 EU worth of data exists on the disk (step 1). if,
If not, stop recording.

If there is a sufficient area, the VU to be recorded is
Reset the variable i representing the number of the VU in the EU to 0, and store the free area start address in the variable addr (step
2). Next, it waits for a notification from the multiplexer 107 that 1 VU worth of data has been buffered in the buffer memory 108 (step 3). When the notification comes from the multiplexer 107,
When the variable i is 0, it is determined whether or not the variable addr is on an ECC block boundary (step 9).
The VU data is recorded on the disk (step 10). Then, PH
Construct a PRU in RAM 103 with -PKT and P-PKT and record it on the disk (step 11). Next, buffer memory 10
Record the first VU data in 8 on the disc (step
6). When the recording is completed, the variable i is incremented (step 7). If the variable i is smaller than the variable Nvu representing the number of VUs in the EU, the process jumps to step 4 (step 8). The above processing is performed in EU units until a stop command is received from the operation unit 101 or a sufficient continuous area is not left in the disk.

In parallel with the above processing of the CPU 102, the multiplexer 107 adds a PTS or the like to the data sent from the audio and video encoders 106, packetizes the data, and stores them in the buffer memory 108. If V-PKT for 1 GOP and A-PKT synchronized with it are stored in buffer memory 108, CP
Notify U102 that data for the VU has been buffered.

A description will be given of the flow of processing in the case where an instruction to start post-recording is given by the user during reproduction of the original program recorded according to the above procedure. It is assumed that the EUS Management file and the file system management information have already been read from the disk into the RAM 103. CPU1
02 activates the decoder 112 and issues a command to the disk drive 109 to read the specified EUS file from the beginning based on the file system management information. The disk drive 109 is connected to the demultiplexer 1 via the ECC decoder 112.
Send the read data to 11 and demultiplexer 111
Accumulates data in the buffer memory 108. The decoder 112 requests data necessary for video and audio reproduction from the demultiplexer 111, and
Sends the data stored in the buffer memory 108 to the appropriate decoder 112 based on the stream-id in the packet header in response to the request. The decoder 112 is a demultiplexer 111
From the PTS corresponding to the data, the system clock 105 is initialized when sufficient data is received and video and audio can be output.
Synchronize output based on 05 value.

The demultiplexer 111 calculates the total number of the PRU corresponding to the data currently being reproduced and the PRU corresponding to the EU to be reproduced next, when the user has given a post-recording instruction.
The two PRUs are always held in the buffer memory 108. Further, a table (PRU management table) for managing those PRUs is created in the RAM 103.

FIG. 18 shows the structure of the PRU management table. PR
The U management table has two tables, SAU start PTS (SAU-PTS
[j] [i]) and the SAU start address (RLBN [j] [i]). SAU-PTS [j] [i] is a two-dimensional array, in which the first index indicates the number of the PRU in the buffer memory 108, and the second index indicates the number of the SAU in the PRU.
With the two indices, the first PTS of the SAU can be obtained. RLBN [j] [i] has a similar structure, and it is possible to obtain the relative address of the SAU with the PRU number and the SAU number in the PRU as an index and the head of the PRU as a reference. By using these two tables, it is possible to know which SAU in the buffer memory 108 should record data corresponding to a certain PTS.

A description will be given of a process in the case where an instruction to perform post-recording is given from the user through the operation unit 101 during the above-described reproduction process. First, the CPU 102 activates the audio encoder 106. Demultiplexer 111
Obtains a time stamp (after-recording start PTS) at the time when the after-recording is started from the system clock 105, and obtains the SAU described above.
-Search the PTS [j] [i] for the index having the largest PTS that does not exceed the dubbing start PTS. The demultiplexer 111 notifies the multiplexer 107 of the PRU number n and the SAU number m obtained as a result of the search together with the after-recording start PTS. The multiplexer 107 stores the AAU sent from the encoder 106 from the position of RLBN [n] [m] of the nth PRU in the buffer memory 108. Depending on the difference between the start PTS of the SAU to start recording and the post-recording start PTS, the multiplexer 107 transmits the AAU sent from the audio encoder 106 before packetization.
Before, adjust the timing by inserting a silent AAU equivalent to the difference.

The value of the system clock 105 at the time when the post-recording is instructed by the user, that is, the post-recording start PTS is 22
The case of 8228 is explained as an example. First, SAU-PTS
Maximum SAU start PT not exceeding the dubbing start PTS in [i] [j]
Search for a set of SAU number and PRU number with S. In the case of FIG. 18, PRU number = 0 and SAU number = 5. Next, look at the value of RLBN [0] [5] corresponding to that number. As a result, the address 41 of SAU # 5 is obtained. Therefore, P in the buffer memory 108
After-recording data is recorded from SAU # 5 present in the 41st block from the head of RU # 0.

Assuming that the index of the PRU storing the post-record data is n, when the data is stored up to the end of the PRU, the values of RLBN [n] [i] from i = 0 to 7 are replaced with the current values. PR
It is stored in the field Start RLBN of Data for VU of the PH-PKT in U in order, and C indicates that the data has been stored until the end of the PRU.
Notify PU102. At this time, SAU-PTS [n] [0], that is, the first PTS of the EU including the PRU is also notified. On the other hand, the CPU 102
While receiving the notification from the multiplexer 107 while playing back the original program, on the disk 113 on which the post-record audio data is to be recorded by referring to the Address LUT based on the EU leading PTS obtained at that time. Of the PRU, and instructs the disk drive 109 to record the n-th PRU in the buffer memory 108 at the address. After that, the PRU in the buffer memory
Are stored alternately.

FIG. 19 shows the procedure for creating the PRU management table. The basic idea is that the number of A-BLKs contained in each VU is
Calculated from Start RLBN of Video in H-PKT, and the number is SA
Utilizing the same number of A-BLKs included in U, construct SAU start address table, and at the same time, the first A-PK in VU
The purpose is to extract the PTS of T and construct the SAU head PTS table. First, VH-flg which is a flag indicating immediately after VH-PKT is reset, and j which is an index indicating the PRU number in the buffer memory 108 is set to 1 (step 1). The packet arriving at the demultiplexer 111 is a VH-PK
If T (step 2), jump to step 3, otherwise jump to step 7.

If the packet is a VH-PKT, the Firs in the VH-PKT
Check if the VU of EU field is 1 (step 3),
If it is 1, j is incremented in order to change the area for storing data thereafter from the current PRU to the other PRU. At the same time, set 1 to RLBN [j] [0]. further,
Set the value of the Start RLBN of Video field in the current VH-PKT to the temporary variable tmp, and set i to 0 (step
Four). If the FirstVU ofEU field is 0, RLBN [j]
Set the temporary variable tmp in [i], and further set the current VH-PK in tmp
Add 1 minus the value of the Start RLBN of Video field in T (step 6). Subtract 1 here.
Start RL, which is the value obtained by adding the number 1 of VH-BLK to the number of A-BLK
This means subtracting VH-BLK from the BN of Video in order to find the number of A-BLKs in the VU needed here. In each case the First VU of EU field,
VH-flg is set to 1 and i is incremented (step 5).

In step 7, it is checked whether the packet arriving at the demultiplexer 111 is A-PKT. If it is A-PKT, the process jumps to step 8, and if it is not A-PKT, it jumps to step 2. In step 8, the variable VH-flg is checked, and VH-flg
If g is 1, set PTS in the packet header of the packet to S.
AU-PTS [j] [i] is set, and VH-flg is reset to 0 (step 9). By performing the above processing for each block, a PRU management table for PRUs in the EU can be created when all the EUs are read.

The temporal change of the head position in the disk and the amount of original data occupying in the buffer memory 108 during the after-recording will be described with reference to FIG. Here, the program is arranged in a continuous area of s11-s18- on the disk, s11-s13, s13-s15, s15-s17 respectively correspond to EU, s11-s12, s13-s14, s15-s16 , S17
Suppose that ~ s18 each correspond to a PRU.

At time t1, it is assumed that all the areas up to s13 have been read into the buffer memory 108, and the video of the areas s11 to s13 has been presented and the post-recording audio has been input while watching the video. It is assumed that the input post-record audio is stored in one PRU (PRU # 0) in the buffer memory.

At times t1 to t3, the disk drive 109 reads the areas s13 to s15. Time t2 corresponds to the time when the VUs in the areas s12 to s13 read up to time t1 are used up for video playback.

The time t3 corresponds to the time at which the encoding of the post-record audio input while watching the presentation of the VUs in the areas s12 to s13 ends. At this point, data is recorded up to the end of PRU # 0, and multiplexer 107
The PTS is notified to the CPU 102, and the storage destination of the post-record audio is switched to the other PRU (PRU # 1).

Here, at time t3, reading from the disk and post-recording audio encoding are simultaneously completed, but it is needless to say that they need not be simultaneously performed.

The CPU 102 obtains an address to record the contents of PRU # 0 from the top PTS sent from the multiplexer 107, that is, an address of the areas s11 to s12.
The contents of 0 are recorded on the disk 113.

At time t5, the next area s15 to s17 is read. This timing only needs to be after the end of writing at t4, and the buffer memory 108 does not overflow and the data does not disappear (underflow) in the buffer memory 108 (from t4 to t6).
You can start reading with. Hereinafter, the same processing is repeated.

According to the present embodiment, the time for writing the after-recording data is shorter than that of the prior art, so that the period between t4 and t5 in FIG. 20 can be shortened.
This means that video and audio are not interrupted even when the presentation time with respect to the disk reading time is short (when a large amount of information is allocated during a unit time or when the disk reading transfer rate is low). This has the effect.

In this embodiment, the field St in the PH-PKT
Although the art RLBN of Data for VU is recorded at the time of post-recording, it is a fixed value and may be recorded in advance at the time of original data recording. Further, it is conceivable to add a field for recording the head PTS of each SAU in the PH-PKT. In that case, by recording the value in the field in advance when recording the original data, it is possible to obtain the information necessary for constructing the PRU management table only by reading the PH-PKT during post-recording. Is unnecessary.

Further, in the present embodiment, the First VU of EU field in the VH-PKT is used as information indicating the head of the EU, but a packet indicating the boundary of the EU may be inserted at the head of the EU.

In the present embodiment, the presentation time of the SAU and the presentation time of the VU are the same, but this is not essential. In particular, if the presentation time of the SAU is shorter than the VU, for example, half or 1/4, the after-recording start / end time can be made more precise. For example, in this embodiment, if the post-recording is started in the middle of the EUS where the post-record data is recorded, in the worst case, the recorded post-record data near 1 SAU (= 1 VU) before and after the post-record section is overwritten silently. Would be. However, if the SAU is shorter in time than the VU, it is possible to reduce the range of overwriting with silence.

A procedure for reproducing from the middle of a program after-recorded by the above procedure will be described. Already
File system management information and EUS Mana from disk
It is assumed that the gement file has been read into the RAM103. CP from program and timing specified by user
U102 finds the corresponding EUS file and PTS (playback start PTS), and sends the values to demultiplexer 111 and decoder 112. Next, the start address of the VU (VU start address) and the start address of the PRU (PRU start address) including the corresponding data are calculated from the reproduction start PTS using the Address LUT.

At this time, if the difference between the addresses of the PRU and the VU is small as shown in FIG. 21A, the disk drive 109 is instructed to start reading from the smaller address of the addresses of the VU and the PRU. Put out. On the other hand, as shown in FIG. 21 (b), when the address of the VU is larger than the PRU by a certain degree or more, that is, when reproduction is performed from the latter VU in the EU, the CPU 102 first stores the Post Recording Unit Siz in the EUSI in the disk drive 109.
An instruction is issued to read data of the data size of the PRU indicated by e from the PRU start address, and then instruct reading from the VU start address. The reason for this is that, when starting playback from the VU at the rear of the EU, skipping the VU located before that will eliminate useless data reading and speed up the response to the user.

As described above, the PRU is skipped without skipping the VU.
And the case where VU and VU are read in EU units for decoding and reproduction, and the case where VU skips to the VU including the reproduction start point and then reads after reading PRU, , Choose a method that has a quick response.

For example, a specific example of calculation is as follows: the time for reading one VU is Rvu, the number of VUs constituting the EU is Nvu,
The position (number) from the beginning of the VU including the playback start point is Nrs, V
Assuming that the time required for skipping U is Tsk, if Rvu × Nvu> Tsk + Rvu × (Nvu−Nrs + 1), after reading the PRU, the VU including the playback start point
Skip to and read.

As another example, by comparing the time required to skip from the beginning of the VU to the VU including the reproduction start point with the time required to read the same section without skipping, either of them is determined. It is also possible to judge whether to use the method of (1). In this case, if Rvu × (Nrs−1)> Tsk, after reading the PRU, the VU including the playback start point
It is only necessary to skip until reading.

As another method, a criterion such as skipping may be used if the time required for skipping is within a predetermined time.

If the time code of the playback start point is Ts, the start position of the VU including the playback start point is calculated from Ts to EUS Informat.
The value obtained by subtracting the Start PT in the ion is P in the VU Information.
It can be obtained by referring to the RLBN of VU in the VU Information of the index corresponding to the value obtained by dividing by the B time of VU and truncating the decimal part. After reading the PRU using the start position of the VU including the playback start point obtained in this way, skip to the start position of the VU including the playback start point, and skip to the end of the VU constituting the EU. read out.

The demultiplexer 111 accumulates data sent from the disk drive 109 via the ECC decoder 112 in the buffer memory 108, and sequentially receives data according to the decoder 112 when the decoder 112 requests data. send. The decoder 112 requests the demultiplexer 111,
The received data is decoded. Playback start PTS is G
If it is in the middle of the OP, the video decoder 112
, Decoding is performed from the beginning, and video is output from the timing of the reproduction start PTS. Similarly, the audio decoder 112 decodes the data received from the demultiplexer 111, and outputs audio from the timing of the reproduction start PTS. Since video decoding takes more time, the audio decoder 112 waits until the video decoder 112 can output the video of the reproduction start PTS, at which point the system clock 105 is set to the reproduction start PTS, and presentation is started. .

[0090]

According to the present invention, the original data and the corresponding post-record data are recorded in association with each other, and the area for recording the original data is divided into independently reproducible units for recording. When performing reproduction, it is not necessary to read the entire original data, and it is possible to start reproduction at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration according to an embodiment of the present invention.

FIG. 2 is a data layout in a disk according to an embodiment of the present invention.

FIG. 3 is a diagram showing an outline of an EUS file according to an embodiment of the present invention.

FIG. 4 is a diagram showing a structure of a packet.

FIG. 5 is a diagram illustrating a structure of an EU according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating a structure of a VU according to an embodiment of the present invention.

FIG. 7 shows a VU Header Pack according to an embodiment of the present invention.
It is a figure showing the structure of et.

FIG. 8: PR before dubbing in one embodiment of the present invention.
FIG. 3 is a diagram showing a structure of U.

FIG. 9 shows post-recording PR in one embodiment of the present invention.
FIG. 3 is a diagram showing a structure of U.

FIG. 10 shows a PRU Header P in one embodiment of the present invention.
It is a figure showing the structure of acket.

FIG. 11 is a diagram relating to the arrangement of PRUs in one embodiment of the present invention.

FIG. 12 shows an EUS Manageme according to an embodiment of the present invention.
FIG. 4 is a diagram showing the structure of an nt file.

FIG. 13 is a diagram showing a structure of EUSI in one embodiment of the present invention.

FIG. 14 shows an Address LUT according to an embodiment of the present invention.
FIG. 3 is a diagram showing the structure of FIG.

FIG. 15 shows an Address LUT according to an embodiment of the present invention.
It is a figure showing the structure of PRU Information in.

FIG. 16 shows a VU Informati according to an embodiment of the present invention.
It is a figure which shows the structure of on.

FIG. 17 is a flowchart of original data recording according to an embodiment of the present invention.

FIG. 18 is a diagram illustrating a structure of a PRU management table according to an embodiment of the present invention.

FIG. 19 is a flowchart of creating a PRU management table according to an embodiment of the present invention.

FIG. 20: Head movement and buffer memory during post-recording
108 is a schematic diagram of a change in the occupancy of data in 108. FIG.

FIG. 21 is a diagram illustrating an access method when reproduction is started from the middle of the EU according to an embodiment of the present invention.

FIG. 22 is a diagram showing a recording form on a disc according to the related art.

FIG. 23 is a schematic diagram showing the movement of the head during post-recording and the change in the occupancy of data in the buffer memory according to the conventional technique.

[Explanation of symbols]

 101 operation unit 102 CPU 103 RAM 104 ROM 105 system clock 106 encoder 107 multiplexer 108 buffer memory 109 disk drive 110 bus 111 demultiplexer 112 decoder 113 disk 114 ECC encoder / decoder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C052 AA02 AA03 AC08 AC10 CC11 CC12 DD04 DD06 DD10 5C053 FA14 FA23 GB01 GB11 GB37 GB38 HA29 HA40 JA02 JA07 KA24 5D044 AB05 AB07 DE03 DE17 DE57 EF07 FG18 FG21 GK11

Claims (8)

[Claims] 1. A first unit comprising first data composed of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproduction method for a recording medium recorded as a set of units, wherein when a reproduction start position is designated, a position of the second unit including the reproduction start position on the recording medium is calculated; The first data is read from the position on the recording medium of the second unit including the determined reproduction start position together with the data of the second data, and the read first and second data are decoded. A data reproducing method comprising: performing synchronous reproduction from a reproduction start position. 2. A first unit comprising first data consisting of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproduction method for a recording medium recorded as a set of units, wherein when a reproduction start position is designated, a position of the second unit including the reproduction start position on the recording medium is calculated; Calculating a first read time for reading out only the first data after the position on the recording medium of the second unit including the determined reproduction start position together with the data of the second data; Is shorter than the predetermined time, the second data and the first unit after the position on the recording medium of the second unit including the obtained reproduction start position.
A data reproducing method comprising: reading out only the data of (i), decoding the read first and second data, and performing synchronous reproduction from the reproduction start position. 3. A first unit comprising first data composed of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproduction method for a recording medium recorded as a set of units, wherein when a reproduction start position is designated, a position of the second unit including the reproduction start position on the recording medium is calculated; A first read time for reading out only the first data after the position on the recording medium of the second unit including the determined reproduction start position together with the data of the second unit, and a first read time including the reproduction start position. And a second read time for reading out the entire unit in the recording order. If the first read time is shorter than the second read time, the second read time is included along with the second data. Only the first data after the position on the recording medium of the second unit is read, the read first and second data are decoded, and synchronous reproduction from the reproduction start position is performed. And a data reproducing method. 4. A first unit comprising first data composed of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproduction method for a recording medium recorded as a set of units, wherein when a reproduction start position is designated, a position of the second unit including the reproduction start position on the recording medium is calculated; From the head position of the first data and the first time required to skip from the head position of the first data to the second unit immediately before the second unit including the obtained reproduction start position. And a second time required to read up to the second unit immediately before the second unit including the reproduction start position obtained. If the first time is shorter than the second time, Along with the second data, only the first data after the position on the recording medium of the second unit including the obtained reproduction start position is read, and the read first and second data are read out. Decrypt and start playback A data reproduction method comprising performing synchronous reproduction from a device. 5. A first unit comprising first data composed of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproducing apparatus for reproducing a recording medium recorded as a set of units, comprising: means for designating a reproduction start position in data; and a position on the recording medium of a second unit including the reproduction start position. Means for calculating; means for reading out the first data from the second unit including the determined reproduction start position together with the second data; decoding the read-out first and second data Means for performing synchronous playback from the playback start position. 6. A first unit comprising first data composed of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproducing apparatus for reproducing a recording medium recorded as a set of units, comprising: means for designating a reproduction start position in data; and a position on a recording medium of a second unit including the reproduction start position. Calculating means for calculating, together with the second data, a first read time for reading only the first data after the position on the recording medium of the second unit including the determined reproduction start position. Means, and if the first read time is shorter than a predetermined time, the first data after the position on the recording medium of the second unit including the obtained reproduction start position together with the second data.
A data reproducing apparatus comprising: means for reading only the data; and means for decoding the read first and second data and performing synchronous reproduction from the reproduction start position. 7. A first unit comprising first data composed of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproducing device for reproducing a recording medium recorded as a set of units, comprising: a designation unit for designating a reproduction start position; and calculating a position on the recording medium of a second unit including the reproduction start position. Means, a first read time for reading out only the first data after the position on the recording medium of the second unit including the obtained reproduction start position together with the second data, Means for calculating a second read time for reading the entire first unit including the position in recording order; means for comparing the first read time with the second read time; and the first read time. If the time is shorter than the second read time, the first data after the position on the recording medium of the second unit including the determined reproduction start position is included together with the second data. Means for reading the data reproducing apparatus according to claim and means for performing synchronous reproduction from decoding the first and second data said read said reproduction start position. 8. A first unit comprising first data composed of video or audio and second data reproduced in synchronization with the first data, wherein the first data can be reproduced independently. The second unit
A data reproducing device for reproducing a recording medium recorded as a set of units, comprising: a designation unit for designating a reproduction start position; and calculating a position on the recording medium of a second unit including the reproduction start position. Means, a first time required to skip from a head position of the first data to a second unit immediately before the second unit including the determined reproduction start position, and Means for calculating a second time required to read from the head position to a second unit immediately before the second unit including the obtained reproduction start position; and the first time and the second time And a position on the recording medium of the second unit including the determined reproduction start position together with the second data when the first time is shorter than the second time. The first of the following Data reproducing apparatus according to claim comprising means for reading only over data, and means for performing synchronous reproduction from decoding the first and second data said read said reproduction start position.