JP3060442B2 - Data multiplexing device and multiplexed data separating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to reproduce a variable rate de-<br/> over data of a plurality of the plurality of channels variable rate data from the data multiplexer and the multiplexed data to time division multiplexing the original channel To a multiplexed data separation device.

[0002]

2. Description of the Related Art Conventionally, in order to time-division multiplex a plurality of variable-rate time-series data (for example, compressed digital moving image (or audio) data) and record them on a recording medium, a plurality of variable-rate time-series Data is grouped together (the grouped data is hereinafter referred to as a pack), a header is added to the head of the pack, and a code indicating time is written in the header to create multiplexed data. Then, the play separating the original data from the multiplexed data has been adjusted the transfer rate of record media have groups Dzu the time written in the pack header.

[0003]

In the above-described conventional data multiplexing method, a plurality of data generated within a fixed time are put together and used as a multiplexing unit, so that the data length of the multiplexing unit is reduced. When recording the multiplexed data on the storage medium, there is a problem that it cannot be matched with the recording unit of the storage medium.

[0004] The present invention has been made in view of such a situation, and an object of the present invention is to provide a data multiplexing apparatus capable of matching a multiplexing unit with a physical recording unit of a storage medium.

Another object of the present invention is to provide a method for multiplexing a plurality of variable-rate data without causing any trouble even if data is pre-read when time-division multiplexing is performed in a multiplexing unit having a fixed data length. An object of the present invention is to provide a separation device.

[0006]

Means for Solving the Problems A data multiplexing apparatus according to claim 1, a variable included in the data of a plurality of channels
The rate data is divided or
Combine and time-division by multiplexing unit with longer fixed data length
Control means for multiplexing, the control means comprising:
At the beginning of the fixed-length multiplexed data
Time information of multiple variable rate data included in weighted data
Time information indicating the earliest time is recorded.
Control .

A multiplexed data demultiplexing apparatus according to a second aspect of the present invention provides a multiplexed data demultiplexing apparatus in which the variable rate
Multiple buffers provided for each data
And the time information recorded at the beginning of the multiplexed data.
Holding means, time information held by the holding means,
Comparison means for comparing with the current time and multiple multiplexed data
Separation means for separating and inputting to the buffer of the
Fa is the variable rate data of at least the multiplexing unit.
It has a long fixed data length and the separation means
The time information and the current time held in the holding means are determined by the step.
If it is determined that the time matches, the time
The multiplexed data is separated .

[0008]

According to the data multiplexing apparatus of the first aspect, the variable rate data included in the data of a plurality of channels is provided.
Data is divided or combined according to the data length variation,
Time division multiplexed with longer fixed data length multiplexing unit
Of fixed-length multiplexed data obtained by time-division multiplexing.
At the beginning, multiple variable rates included in the multiplexed data
Time information indicating the earliest time in the data time information
Is recorded, the multiplexing unit can be made to match the physical recording unit of the storage medium, so that the recording management overhead of the storage medium can be reduced.

In the multiplexed data separating apparatus according to the second aspect, the variable data included in the data of the original plurality of channels is used.
Multiple buffers are provided for each rate data
Time information recorded at the beginning of the multiplexed data
The stored time information is compared with the current time.
Multiplexed data is separated into multiple buffers and input.
The buffer has a variable rate of at least the multiplexing unit.
Has a fixed data length capacity longer than the data, and
Judge that the stored time information and current time match
Multiplexed data corresponding to the time information is
Therefore, for example, even if multiplexed data is stored in a storage medium and the multiplexed data demultiplexer is configured to read out the multiplexed data from the storage medium, the demultiplexer can output the multiplexed data from the storage medium. Can be continued to be read at the maximum transfer rate, for example, without any trouble.

[0010]

FIG. 1 shows a configuration of an embodiment of a data multiplexing apparatus and a multiplexed data demultiplexing apparatus according to the present invention. For example, variable-rate time-series data D1, D2,... Dn composed of compressed digital moving image (or audio) data are respectively stored in code buffers M1, M2,
... Stored in Mn. Variable rate time series data is
The signal itself contains a synchronization signal, that is, information about a data read interval after passing through a separation device described later. The output terminals of the code buffers M1, M2,... Mn are input terminals E1, E2,.
-Connected to En. The output terminal F of the switching circuit 2 is connected to the input terminal of the header adding circuit 3. The output of the header adding circuit 3 is supplied to a variable rate data storage medium DSM composed of, for example, an optical disk. The variable rate data storage medium DSM is a storage medium that can always read data at an arbitrary rate equal to or lower than the maximum transfer rate in accordance with a request from the reading side. In the embodiment shown in FIG. 1, the multiplexed data separating apparatus always reads data from the storage medium DSM at the highest transfer rate.

The control unit 4 receives the output of the multiplexing system clock 5 and switches the switching circuit 2 at a predetermined period.
, And En are sequentially connected to the output terminal F, and the code buffers M1, M2,.
n to variable rate time-series data D1, D2,... Dn
Are sequentially extracted and grouped in time series (this grouped data is hereinafter referred to as a packet), and the header adding circuit 3 is controlled to add a packet header to the head of each packet (see FIG. 2). . The control device 4, to create a more fixed length packs that cut out variable length packet sequence that is regularly generated as described above fixed data length is multiplexed basis. The control device 4 controls the header adding circuit 3 to add a pack header including time information to the head of each pack (see FIG. 2).

When the total amount of data of the packet sequence to be packed is less than the fixed data length, which is a unit of multiplexing, the control device 4 waits for the next pack generation time without packing, and waits for the total amount of data. When the data exceeds the fixed data length as a multiplexing unit, that is, one pack, a pack is generated. At this time, data of a plurality of times is included in one pack, but the control device 4 controls the header adding circuit 3 so that the earliest time of the plurality of times is recorded in the pack header. Therefore, part of the data
It will be sent ahead of schedule. In addition, it is possible that the packet header is on the boundary of the pack. In this case,
The control device 4 divides the packet header into two packs, or performs an operation of combining the same time data in one pack into one pack to avoid dividing the header. The time-division multiplexed data packed as described above is supplied to the variable-rate data storage medium DSM.

The header separation circuit 6 of the multiplexed data separation device
, Separates the pack header from the data read from the storage medium DSM , supplies the separated pack header to the pack time information holding circuit 7 , and sets the variable rate time-series data D1, D2,.
Dn is supplied to the input terminal G of the switching circuit 8. Output terminals H1, H2,... Hn of the switching circuit 8
Are connected to the input terminals of the code buffers S1, S2,... Sn, respectively. An input terminal G and an output terminal H1 of the switching circuit 8 are controlled under the control of a control device (not shown).
.. Hn are sequentially connected in a predetermined cycle,
The variable rate time series data D1, D2,... Dn are supplied to the code buffers S1, S2,.

The pack time information holding circuit 7 holds the time information contained in the pack header and supplies it to one input of the comparator 10. Comparator 10 receives the output of separator system clock 9 at the other input. Comparator 10
Is the time indicated by the output of the pack time information holding circuit 7 and the minute
When the time indicated by the remote device system clock 9 matches, a read request for the storage medium DSM is output.

As described above, when data of a plurality of times are included in one pack, the control device 4 of the data multiplexing apparatus records the earliest time of the plurality of times in the pack header. Therefore, in order to reproduce the multiplexed data in the pack to the original data, the multiplexed data separation device side needs to store the storage medium D when the time recorded in the pack header has been reached.
When the pack is read from the SM, since the data to be read at a later time is also included in the pack ahead of time, the data cannot be read from the device after the multiplex data separation device. Storage medium D
A situation may occur in which reading from the SM at the highest transfer rate cannot be continued. In order to avoid such a situation, the capacity of the code buffers S1, S2,... Sn is set to a fixed data length that is multiplexed data, that is, one pack. This is because the advanced data described above does not exceed at most one pack.

[0016] In the data demultiplexer of FIG. 1, min
The first time of the release system clock 9 is set to the time indicated by the header of the first pack. Therefore, the comparator 10 outputs a read request for the storage medium DSM. In response to this, the variable rate time-series data D1, D2,... D included in the first pack from the storage medium DSM
After the n has passed through the header separation circuit 6, the switching circuit 8 causes the code buffers S1, S2,.
Sn. On the other hand, the header separation circuit 6 outputs the pack header of the next pack after the first pack to the pack time information holding circuit 7. Pack time information holding circuit 7
Holds the time information included in the pack header. Separation
When the time indicated by the device system clock 9 matches the time held by the pack time information holding circuit 7,
The comparator 10 outputs a read request for the storage medium DSM. Accordingly, the variable-rate time-series data D included in the next pack after the first pack is stored in the storage medium DSM.
., Dn pass through the header separation circuit 6 and are then distributed by the switching circuit 8 to the code buffers S1, S2,. In this way, the variable rate time-series data D1, D2,... Dn divided into a plurality of packs are stored in the code buffers S1, S2,. , D2,... Dn.

Next, the operation of the embodiment of FIG. 1 configured as described above will be described with reference to FIG. In FIG. 3, the number of channels to be time-division multiplexed is 2 for simplicity.
That is, the variable rate time-series data in FIG. 1 is two data D1 and D2. In this case, the number of code buffers on the multiplexer side is M1 and M1, and the number of code buffers on the demultiplexer side is S1 and S2. First, the control device 4 of the data multiplexing apparatus creates the first pack having a fixed data length including not only the packet sequence A but also a part B1 of the packet sequence B conventionally included in the next pack, Send it to the storage medium DSM. Next, the control unit 4, the remainder B 2 of packet sequence B, conventionally creates a second fixed-data-length packs, including a portion C1 of the packet sequence C that has been included in the third pack , To the storage medium DSM. Next, the control device 4 determines the remainder C of the packet sequence C.
3, a third packet having a fixed data length including the entire packet sequence D conventionally included in the fourth pack and the part E1 of the packet sequence E conventionally included in the fifth pack. Is created and sent to the storage medium DSM. In the next pack creation cycle, control device 4 does not create a pack. Next, the control device 4 determines the rest E2 of the packet sequence E,
A fourth pack having a fixed data length is created including the entire packet sequence F conventionally included in the sixth pack and the part G1 of the packet sequence G conventionally included in the seventh pack, Send it to the storage medium DSM. In this way, packs having a fixed data length are sequentially created, sent to the storage medium DSM, and recorded.

As described above, since the data length of the pack created by the multiplexer of FIG. 1 is fixed, the storage medium D
SM can be matched with the physical recording unit of the SM, and the recording management overhead can be reduced.
When it is desired to play back randomly from the SM, the waiting time can be reduced, and search and intermittent playback can be realized at high speed.

In the lower half of FIG. 3, a change in the storage amount of the code buffer S1 on the separation device side is indicated by oblique lines. As described above, data to be read at a later time is also written ahead of time in the code buffer S1, but since the storage capacity of the code buffer S1 is a fixed data length which is a multiplexing unit, that is, one pack, there is no problem. There is no.

In the above embodiment, the storage capacity of the code buffers S1, S2,... Sn on the side of the demultiplexer is set to a fixed data length as a multiplexing unit, that is, one pack, but may be larger. However, it is preferable to use one pack for one pack in terms of miniaturization and cost reduction of the apparatus.

In the above embodiment, an optical disk is used as a storage medium. However, a magneto-optical disk, a magnetic hard disk, a digital audio tape or the like can be used.

[0022]

As is apparent from the above description, according to the data multiplexing apparatus of the first aspect, a plurality of channels are provided.
The variable rate data included in the data
Divided or combined according to the motion, longer fixed data length
Time-division multiplexing in the multiplexing unit of
Multiplexed data at the beginning of the fixed-length multiplexed data
Of the time information of the plurality of variable rate data included in
Time information indicating the earliest time is recorded
In addition to reducing the recording management overhead,
When it is desired to reproduce the data randomly from the recording medium, the waiting time can be reduced, and search and intermittent reproduction can be realized at high speed.

According to the multiplexed data demultiplexing device of the second aspect, the variable data contained in the original data of the plurality of channels is variable.
Multiple buffers are provided for each
The time information recorded at the beginning of the multiplexed data is
Compares the held time information with the current time, and
When the time information stored in the column matches the current time
If determined, the multiplexed data corresponding to the time information is copied.
Separate numbers are input to the number of buffers.
Fixed data longer than variable rate data
Since the data multiplexing device has a long capacity, the data multiplexing device side pre-reads the variable rate data in order to create a multiplexing unit of a fixed data length, and the pre-read data may be read from devices after the multiplexing data separation device. Demultiplexed data is recorded at the beginning of the
This is performed based on the time information obtained, and the buffer can store data having a fixed data length, which is a unit of multiplexing, so that no problem occurs.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a data multiplexing device and a multiplexed data demultiplexing device of the present invention.

FIG. 2 is an explanatory diagram showing an example of a pack created by the data multiplexing device of FIG. 1;

FIG. 3 is an explanatory diagram showing an operation example of the embodiment of FIG. 1;

[Explanation of symbols]

 4 control device DSM variable rate data storage medium S1, S2,... Sn code buffer

Continuation of front page (56) References JP-A-2-104180 (JP, A) JP-A-1-146479 (JP, A) JP-A-3-250935 (JP, A) Edited by Hiroshi Yasuda, “Multimedia Code International Standard for Chemicalization ", Maruzen (1991-6-30), p. 221-232 Supervised by Hiroshi Fujiwara, "Latest MPEG Textbook", ASCII (1994-8-1), p.231-252 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04J 3/00-3 / 26

Claims (2)

(57) [Claims] A plurality of channels having time information.
A data multiplexing apparatus for time-division multiplexing the data , wherein the variable rate data included in the data of the plurality of channels is divided or combined in accordance with a change in data length,
Control means for performing time-division multiplexing in a multiplexing unit having a longer fixed data length , wherein the control means comprises a fixed-length multiplex obtained by time division multiplexing.
Included in the multiplexed data at the beginning of the multiplexed data
Of the time information of the plurality of variable rate data,
So that the time information indicating the earlier time is recorded
Data multiplexing apparatus which is characterized in that. 2. The data of a plurality of channels having time information.
Time-division multiplexed in fixed-length multiplexing units.
The original data of multiple channels from the multiplexed data
A multiplexed data separation apparatus for reproducing, wherein the variable rate included in the data of the original plurality of channels is provided.
Multiple buffers provided for each data
And the time information recorded at the beginning of the multiplexed data.
Holding means, the time information held by the holding means,
Comparing means for comparing the time and time, and separating and inputting the multiplexed data to the plurality of buffers.
To a separation unit, said Baffua is of at least the multiplexing unit has a capacity of said variable rate data longer than the fixed data length, said separating means by said comparing means, said holding means
When the held time information matches the current time
If it is determined, the multiplexed data corresponding to the time information
Data demultiplexer, characterized in that the separation of over data.