JPH11234253A - Data converter - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To easily transmit and receive data between devices having different input / output data clocks. SOLUTION: The apparatus has a plurality of input / output ports 12a to 12d for inputting / outputting data, respectively, and converts data input from an arbitrary input / output port into data controlled by a clock corresponding to a transmission destination. In the output data converter, the time for converting the clock for controlling the input data into time information based on the clock of the output data, and converting the time information of the input data into time information based on the clock of the output data Information conversion means 16 is provided. Further, a plurality of input / output conversion means for outputting input data to the internal bus and replacing time information contained in data taken from the internal bus with time information converted by the time information conversion means and transmitting the time information from the input / output port. 13a to 13d are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data converter for converting data controlled by one clock into data controlled by another clock when transmitting data.

[0002]

2. Description of the Related Art For example, when continuous data is divided into a plurality of unit data each having a predetermined unit length and each unit data is transmitted in synchronization with a predetermined transmission clock, the receiving apparatus also synchronizes with the transmission clock. Each unit data is received at the receiving clock. As described above, it is generally necessary to match the transmission clock with the reception clock.

In this case, the data length of the unit data is naturally limited because it is necessary to incorporate the unit data within one transmission clock cycle. Therefore, when the period of the transmission clock changes, the data length of the unit data often changes.

[0004] Specifically, if the period of the transmission clock is changed to a shorter period, it is necessary to divide the data that had been transmitted at one transmission clock period before the change into a plurality of data and transmit the data at different periods. Since each unit data is incorporated into an individual data frame and transmitted, if the data length to be transmitted at one time changes, the format of the data frame also needs to be changed. Of course, even if the data length of the unit data is short and the period of the transmission clock is changed, there is a case where the unit data length does not need to be changed and the format of the data frame does not need to be changed.

In order to efficiently transmit moving image data, generally, moving image data is image-compressed and transmitted. As a method of transmitting a compressed image, the compressed image is embedded in an MPEG2 data format and transmitted. MP like this
In the data format of EG2, the compressed image of the MPEG2 data is decompressed, and the time information as the time information for specifying the display timing of each still image in the original moving image data composed of a plurality of still images arranged in chronological order. A time stamp is set.

The time stamp is, for example, MPEG2
In many cases, for example, a count value of a moving image to be transmitted in a transmission clock when transmitting data is set, for example, from a start point. Therefore, when the transmission clock for transmitting the MPEG2 data is changed, it is necessary to change each time stamp value included in the MPEG2 data.

As described above, by previously matching the transmission clock with the reception clock, each data can be transmitted and received smoothly. However, when data is transmitted from one transmission device to a plurality of types of reception devices having different reception clocks, the transmission clock and the reception clock may not match.

For example, a transmission clock for transmitting MPEG2 data to each home from a transmission side device via a cable, such as a transmission side device disposed in a transmission station of a CATV system and a reception side device in each home; By making the receiving clock of MPEG2 data different in the receiving device of each home,
It is conceivable to increase the data transmission efficiency.

In this case, a data conversion device (abpter) for converting a data clock into a reception clock is interposed in the vicinity of the reception device in each home, so that the data transmission clock matches the reception clock as the reception device. I try to make it.

[0010] As described above, a data converter for converting data transmission-controlled by a transmission clock into data controlled by a reception clock different from the transmission clock is configured, for example, as shown in FIG.

For example, data a controlled by a transmission clock from a CATV station as an external device is input to a data input circuit 2 in the data converter 1. The data input circuit 2 sends the input data a to the time information conversion circuit 3 and the data output circuit 4. The reception clock output from the receiving device at home is input to the time information conversion circuit 3.

The time information conversion circuit 3 extracts a time stamp, which is included in the data a input from the data input circuit 2 and is created using the transmission clock, and converts this time stamp to a time stamp corresponding to the reception clock. Convert to For example, when the cycle (frequency) of the reception clock has a cycle that is three times the cycle of the transmission clock, the extracted time stamp is converted to 1/3. The time information conversion circuit 3 outputs the converted time stamp TS to the data output circuit 4.
Send to

The data output circuit 4 rewrites the time stamp included in the data a input from the data input circuit 2 to the time stamp TS input from the time information conversion circuit 3. Then, the data output circuit 4 transmits the data a ₁ is rewritten to the time stamp TS corresponding to the receive clock to the home of the receiving device as an external device.

However, this data conversion device 1
Only applicable to data a transmitted in the direction of arrow A in the figure. That is, for example, in addition to transmitting moving image data from a CATV station to each home, in a two-way TV system that transmits various image data from a personal computer in each home to the CATV station, as shown in FIG. In addition to the data conversion device 1 for transmitting data a from one external device 5a shown in the direction of arrow A to the other external device 5b, data b is transmitted from the other external device 5b shown in the direction of arrow B to the one external device 5a. Is required to be provided in parallel with the data converter 1b for transmitting the data.

That is, the data converter 1b has a data input circuit 2a having the same configuration as that of the other data converter 1a.
It comprises a time information conversion circuit 3a and a data output circuit 4a.

[0016]

However, a data converter in which the same data converters 1 and 1b shown in FIG. 8 are connected in parallel in opposite directions to realize bidirectional data transmission is still solved. There were the following issues to be addressed.

That is, since data transmission is not performed bidirectionally and simultaneously via one signal line, the data converters 1 and 1b are not operated at the same time, and one of them is in a standby state. Therefore, each circuit 2, 2
The actual operation rates of a, 3, 3a, 4, 4b are low, and the data conversion device is inefficient. Further, there is a problem that the entire data conversion device becomes large, the circuit becomes complicated, and the manufacturing cost increases.

The present invention has been made in view of the above circumstances, and it is possible to arbitrarily convert a clock for controlling input data according to a transmission destination of the data, and to convert input data into a transmission data. It is an object of the present invention to provide a data conversion device that can send data to an arbitrary input / output port that has been adjusted in advance and that can automatically convert a data format to a format corresponding to a clock of a transmission destination as needed.

[0019]

In order to solve the above-mentioned problems, a data conversion device according to the present invention has a plurality of input / output ports for inputting / outputting data, respectively. , And converts the data into data controlled by a clock corresponding to the transmission destination and outputs the data to the transmission destination.

Further, the clock for controlling the input data is converted into time information based on the clock of the output data, and the time information included in the input data is converted into the time information based on the clock of the output data. Time information converting means for converting the input data to the internal bus, and replacing the time information contained in the data fetched from the internal bus with the time information converted by the time information converting means. A plurality of input / output conversion means for outputting from the input / output port to the transmission destination.

In the data converter configured as described above, the clock of the input data (transmission clock)
The time information included in the input data is converted into time information based on the clock (reception clock) of the transmission destination of the data.

The data input from the input / output port is transferred to the input / output conversion means of the destination input / output port via the input / output conversion means and the internal bus. The time information included in the data transferred to the input / output conversion means of the input / output port of the transmission destination is rewritten to the time information converted by the time information conversion means. The data whose time information has been rewritten is output from the transmission destination input / output port to the transmission destination under the control of a clock (reception clock) corresponding to the input / output port.

Another aspect of the present invention is directed to a data conversion device according to the above-described invention, wherein each input / output conversion means is provided with a data format which is obtained from an internal bus when the format of the data is different from a format of data output to a transmission destination. Format changing means for changing the format of the data to the format of the data to be output, time information generating means for generating time information to be written into the data after the format change from the time information converted by the time information converting means, and generation of the time information Time information writing means for writing the written time information into the format-converted data, and data sending means for outputting the data in which the time information is written to a transmission destination are added.

In the data converter configured as described above, for example, when the period of the transmission clock on the transmission side is significantly different from the period of the reception clock on the reception side, the data length of the unit data transmitted in one clock period Need to be changed. In such a case, the format is converted by the input / output conversion means of the data conversion device. The time information included in the converted data also needs to be newly generated according to the format conversion. However, the generation of new time information accompanying this format conversion is included in the old data by the time information conversion unit. Is generated from the time information converted from the time information.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a data conversion device according to an embodiment of the present invention.

A plurality of external devices 11a, 11b, 11c, 11d can be connected to the data converter 10. In the embodiment apparatus shown in FIG. 1, four external devices 11a to 11d are shown, but the number of installed external devices is not particularly limited to four. These external devices 11a to 11
d is, for example, a CATV station, a TV device installed in each home, or an information terminal such as a personal computer installed in each home. Therefore, the frequency (period) of the transmission clock or the reception clock when each of the external devices 11a to 11d transmits and receives various data is set to an optimum value for each external device.

Each of the external devices 11a to 11d is connected to each of the input / output ports 12a,
12b, 12c, and 12d. Each of the input / output ports 12a, 12b, 12c, 12d has an input / output conversion circuit 13 as individual input / output conversion means.
a, 13b, 13c and 13d are connected. Each of the input / output conversion circuits 13a, 13b, 13c, and 13d has a first internal bus 14a and a second internal bus 14 respectively.
b.

A first switch 15a and a second switch 15b are interposed between the first internal bus 14a and the second internal bus 14b. The switches 15a and 15b are closed to connect the first internal bus 14a and the second internal bus 14b.

A time information conversion circuit 16 as time information conversion means is connected to the first internal bus 14a and the second internal bus 14b. External clocks c ₁ and c ₂ are input to the time information conversion circuit 16 from the outside via input terminals 17a and 17b, respectively. In the time information conversion circuit 16, counters 19a and 19b for counting the external clocks c ₁ and c ₂ are formed. Further, a clock bus 18 for supplying new reference time information to each of the input / output conversion circuits 13a to 13d is connected to the time information conversion circuit 16.

The data formats of the data d and e input / output from the external devices 11a to 11d to the data converter 10 via the input / output ports 12a to 12d take various formats, for example, as shown in FIG. It is possible to get.

In the data having the leading data format 20a, one unit data 21 and one packet ID 22 are incorporated in the data. In the data having the second data format 20b, one unit data 21, one time stamp 23, and one packet ID 22 are incorporated in the data. Furthermore, the third data format 20
In the data having c, one unit data 21, two time stamps 23 and 24, and one packet ID 22 are incorporated in the data.

Each of the data formats 20a to 20c has the same overall format length La, and can transmit and receive each data with the same clock having a cycle Ta corresponding to the format length La.

Each of the following data formats 20d-
The unit data 21, time stamp 23,
24 and the packet ID 22 are the same as the data formats 20a to 20c described above, but the data length of each unit data 21 is different.
Therefore, the format length Lb of the data formats 20d to 20f is set to, for example, three times the value of the format length La of the data formats 20a to 20c (Lb = 3La).

The cycle T corresponding to the format length Lb
Each data can be transmitted and received by the same clock having b.
The data formats 20b, 20c, 20e, 2
0f is, for example, a format of MPEG2 data for transmitting a compressed image, and the time stamp 23 indicates an elapsed time from a start time of the corresponding moving image by a clock count value. The time stamp 24 is time information for a transmission path delay. This time stamp 2
4 is also indicated by the count value of the clock.

It is now assumed that data having a data format 20f controlled by a clock (transmission clock) having a period Tb is converted into data controlled by a clock (reception clock) having a period Ta. In this case, since the format length Lb of the data format 20f does not fall within the changed clock cycle Ta, as shown in FIG. 3, this data format 20f is converted into another data format 20c having three format lengths La. Need to be divided into data having

For this purpose, the unit data 21 of the data format 20f is defined as D1, D2. D3 into three equal parts, each unit data D1, D2. D3 is incorporated into a separate data format 20c. In this case, it is necessary to set individual IDa, IDb, and IDc for the packet ID 22 as well.

The time stamp T1, which indicates the time elapsed from the start time, also includes the unit data D1, D2. D3
Must be converted into individual time stamps T1a, T1b, and T1c indicating the display timings, and set. Specifically, each time stamp T1a, T1b, T
1c is a value obtained by converting the elapsed time from the start time of the moving image to each count value when counting with the clock after the change. The values T1a, T1b, T1c can be easily obtained by calculation from the original time stamp T1 and the rate of change of the clock cycle.

Further, the time stamp T2 indicating the time information for the transmission line delay also needs to be converted into individual time stamps T2a, T2b and T2c and set. Then, if the three divided data are sequentially output in synchronization with the changed clock, the data controlled by the input clock of the cycle Tb is converted into the data controlled by the clock of the cycle Ta and output. can do.

Next, the overall operation of the data converter 10 will be described. For example, any one of the above data formats 20a to 20f input from one external device 11a
Is input to the input / output conversion circuit 13a via the input / output port 12a. Input / output conversion circuit 13
a is the first internal bus 14
The data is transferred to the input / output conversion circuit 13c of the input / output port 12c to which the destination external device 11c is connected via a. The data d output from the input / output conversion circuit 13a to the first internal bus 14a is input to the time information conversion circuit 16.

The clock (transmission clock) of the input data d is sent to the data converter 10 as _one external clock c ₁ . Further, it sends it to the data converting device 10 transmits the destination external device 11c of the data d ₁ is input to the clock (reception clock) as the other of the external clock c _2. Each external clock c input to the data converter 10
₁ and c ₂ are input to the time information conversion circuit 16. In this case, is defined as a reference clock an external clock c ₂ indicating the transmission destination of the external device 11c of the data d ₁ is input to the clock (receiving clock).

The time information conversion circuit 16 performs a time information conversion process in accordance with the flowchart shown in FIG. When data d for one packet having a specified data format among the data formats 20a to 20f output from the input / output conversion circuit 13a on the transmission side to the first internal bus 14a is input (S1), this data is input. The data format of the data d is checked, and if the time information B1 such as the time stamps 23 and 24 is included (S2), the time information B1 is extracted (S3). Then converted into the other external clock reference indicated by the count value of c ₂ time information t of the reference clock time information B1 indicated by the count value of the external clock c ₁ corresponding to the transmission clock (B1) (S
4). Then, the counter 19a with external clock c ₁
(S5), and from this count value E1, reference time information t indicating the elapsed time on the transmitting side.
(E1) is created (S6).

[0042] Similarly, extracts the count value E2 obtained by the counter 19b with the external clock c ₂ (S7),
From the count value E2, reference time information t (E2) indicating the elapsed time of the receiving side (transmission destination) is created (S8). Then, the created reference time information t (B1), t (E1),
t (E2) is transmitted to the clock bus 18.

Since the time information conversion processing for one data d has been completed, the process returns to S1 and waits for the next data d to be input. Thus, the time information conversion circuit 16
Is one data d from the input / output conversion circuit 13a on the transmission side.
Every time is input, each reference time information t (B1), t (E1), t (E2) for the corresponding data d is created and sent to the clock bus 18.

Each of the input / output conversion circuits 13a to 13d
Is the input data d, according to the flowchart shown in FIG.
Perform the process for e. When data d and e are input from the external devices 11a to 11d via the input / output ports 12a to 12d to which they are connected (Q1), the input data d and e are directly received on the receiving side via the internal buses 14a and 14b. The data is transferred to the input / output conversion circuits 13a to 13d connected to the (transmission destination) input / output ports 12a to 12d (Q
2).

When data d and e are transferred from the input / output conversion circuits 13a to 13d connected to the input / output ports 12a to 12d on the transmission side via the internal buses 14a and 14b (Q3), the data format is changed. It is determined according to the above-described algorithm whether or not the change of (i) is necessary (Q4).
If not necessary, it is determined whether or not the data d and e include time information (Q5). If the time information is not included, the reference time information t input from the clock bus 18
(E1) and t (E2) are compared and compared to the reference time information t (E2) on the receiving side which is closest to the reference time information t (E1) on the input side via its own input / output ports 12a to 12d. These data d and e are transmitted to the external devices 11a to 11d as data d ₁ and e ₁ controlled by a reception clock (reference clock).
(Q7).

If the data d and e include the time information B1 in Q5, the time information B1 is rewritten to the reference time information t (B1) input from the clock bus 18 (Q6). . Thereafter, the process proceeds to Q7, and the time information d ₁ and e ₁ whose data has been rewritten are transmitted to the external devices 11a to 11d in synchronization with the reception clock (reference clock).

If the data format needs to be changed in Q4, the data format of the input data d and e is changed to a data format that matches the reception clock (Q8). Then, the reference time information t (B1), t (E1), and t (E2) are read from the clock bus 18 (Q9). Time information based on the reception clock (reference clock) to be written in the changed data (data format) is newly generated by the above-described method (Q10). Next, the generated time information is written at a predetermined position of the changed data (data format) (Q11). Then Q
Advances to 7, the time information is transmitted in synchronization to the external device 11a~11d data d _1, e ₁ of rewriting already a and formatted changed to the reception clock (reference clock).

The data conversion device 10 thus configured
In, the time information conversion circuit 16 converts each of the external clocks c ₁ and c ₂ corresponding to the transmission clock on the transmission side or the reception clock on the reception side from the reference clock information t (E1) using the reception clock as a reference clock. , T (E2), and from the time information B1 included in the data a, e, reference time information t (B1) using the reception clock as a reference clock.
Is calculated and sent to the clock bus 18.

The input / output conversion circuits 13a to 13d
Is the reference time information t (B) obtained from the clock bus 18.
1) Using t (E1) and t (E2), the input data a and e are converted into data d ₁ and e ₁ controlled by a reference clock, that is, a reception clock, and transmitted to the reception side (transmission side). doing.

In this case, in the time information conversion circuit 16, any _one of the input external clocks c ₁ and c ₂ may be used as the reference clock corresponding to the reception clock, so that data can be transmitted in any direction. For example, it can be easily applied to the above-described interactive TV system.

Each of the input / output conversion circuits 13a to 13d can easily change the data formats 20a to 20f of the input data d and e in accordance with the characteristics such as the period of the reception clock to be changed. Further, data formats 20a-2
If you change the 0f, data format 20a~ of after change time information included in the data d _1, e ₁ after change
20f, and can be changed to a value corresponding to the reference clock, that is, the reception clock.

The input / output conversion circuits 13a, 13b are controlled by appropriately opening and closing the switches 15a, 15b.
Data transmission and reception can be performed between b and the input / output conversion circuits 13c and 13d.

FIG. 6 is a schematic diagram showing a network adapter 10a to which the data converter 10 of the embodiment is applied. This network adapter 10a is connected to a plurality of input / output devices (not shown) connected to the network adapter 10a.
Each data to be input to a is converted into a data format or a reception (transmission) clock that can be handled by the personal computer 25 and transferred to the personal computer 25.

The personal computer 25 performs necessary processing on the input data, converts the processed data again into a data format or a reception (transmission) clock that can be input to the input / output device by the network adapter 10a, and Transfer to I / O device. Then, the input / output device outputs the corresponding data.

[0055]

As described above, the data converter according to the present invention employs a time information conversion method capable of converting time information between a transmission side clock and a reception side clock in an arbitrary direction.

Therefore, the clock for controlling the input data can be arbitrarily converted in accordance with the transmission destination of the data, and the input data can be transmitted to any input / output port in accordance with the transmission destination of the data. The data format can be automatically converted to a format corresponding to the converted clock if necessary.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a data format of general data.

FIG. 3 is a diagram showing data format conversion.

FIG. 4 is a flowchart showing the operation of a time information conversion circuit in the data conversion device.

FIG. 5 is a flowchart showing the operation of each input / output conversion circuit in the data conversion device.

FIG. 6 is a diagram illustrating a method of using a network adapter to which the data conversion device is applied.

FIG. 7 is a block diagram showing a schematic configuration of a conventional one-way only data converter.

FIG. 8 is a block diagram showing a schematic configuration of a conventional bidirectional data converter.

[Explanation of symbols]

 Reference Signs List 10 data conversion devices 11a, 11b, 11c, 11d external devices 12a, 12b, 12c, 12d input / output ports 13a, 13b, 13c, 13d input / output conversion circuits 14a, 14b internal buses 15a, 15b switches 16 ... Time information conversion circuit 18 ... Clock bus 19a, 19b ... Counter 20a-20f ... Data format 21 ... Unit data 22 ... Packet ID 23,24 ... Time stamp

Claims (2)

[Claims] A plurality of input / output ports for inputting / outputting data, converting data input from the input / output ports into data controlled by a clock corresponding to a transmission destination of the data, and A data conversion device for outputting to a transmission destination, wherein the clock for controlling the input data is converted into time information based on the clock of the output data, and the time information included in the input data is converted. To
A time information conversion unit for converting the output data into time information based on a clock; outputting the input data to an internal bus, and converting the time information included in the data taken from the internal bus into the time information. A data conversion device, comprising: a plurality of input / output conversion means for outputting the time information converted by the conversion means to a transmission destination from an input / output port. 2. The method according to claim 1, wherein when the format of the data fetched from the internal bus is different from the format of the data output to the transmission destination, the input / output conversion unit converts the format of the fetched data into the format of the output data. Format changing means for changing, and time information generating means for generating time information to be written into the data after the format change from the time information converted by the time information converting means,
Time information writing means for writing the generated time information to the format-converted data; and data transmission means for outputting the data in which the time information is written to the transmission destination. Data conversion device.