JP2003029787A - Data transmitting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the delay of transmitting/receiving time by decreasing the amount of data to be transmitted per packet by expressing time information with little data amount when transmitting the data while making the time information contained in a packet. SOLUTION: When transmitting the packet of a plurality of audio sample data having the time sequential array of a variable first cycle (T), for every second cycle (SF) asynchronous to and longer than the first cycle (T), a plurality of data (x) supplied within one second cycle are prepared as one packet. In that case, one piece of data in a group is specified for each group of data composed of a prescribed constant (M) of >='2' and data are transmitted/ received while adding the time information showing the time position of one specified piece of data to the packet to which these data belong. On the side of receiving, the time position, namely, the first cycle (T) for each of data is reproduced on the basis of the time information in the received packet and the data are reproduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system for transmitting a plurality of audio sample data such as digital audio data having a time-series arrangement of a predetermined period via a network, and more particularly to a receiving side. The present invention relates to a data transmission method in which a data format is configured and transmitted on the transmission side in such a manner that the accurate time relationship can be reproduced.

[0002]

2. Description of the Related Art Data transmission systems via a network are roughly classified into a synchronous system and an asynchronous system. In the synchronous method, the transmitting side and the receiving side operate in synchronization, so
It is suitable for audio data transmission that requires accurate reproduction of the temporal position of information on the receiving side. However, since a configuration for synchronizing the transmission and reception, such as by providing a separate synchronization signal line, is required, and the communication band is statically secured by synchronizing the transmission and reception, it is a communication method. However, it lacked versatility. That is, even if the synchronous communication is not necessary, there is a problem that an unnecessary band is kept secured and other information cannot be transmitted.

On the other hand, in the asynchronous method, the above-mentioned drawbacks can be avoided by dynamically securing the communication band, but in order to reduce the communication overhead, a certain amount of information is required. If the asynchronous packet is not issued after collecting the above, the data communication efficiency will decrease. However, when transmitting a packet in which a certain amount of information is collected, the information on the original time position of the data is lost. Therefore, in the data transmission method using packets, it is considered to transmit the time information indicating the temporal position of the data together with the data.
In other words, each piece of data is added with time information called "time stamp" indicating its time position, and these pieces of information are included in one packet for transmission.

[0004]

However, if one packet is formed by adding time information indicating the time position of each data, the amount of data will increase.
Not a good idea. The present invention has been made in view of the above points, and is a form in which a plurality of audio sample data, such as digital audio data, having a time-series arrangement with a constant cycle can reproduce the time relationship on the receiving side. Therefore, when transmitting from the transmitting side via the network, asynchronous packets are adopted so that the advantages can be enjoyed, and the time information to be transmitted included in the packet is expressed by the smallest possible data amount per packet. The present invention aims to provide a data transmission method capable of reducing the amount of transmission data of the above.
Further, the present invention intends to provide a data transmission method in which the time delay between transmission and reception is minimized. Further, it is another object of the present invention to provide a data transmission system that can simplify the reproduction calculation processing of the time information on the receiving side as much as possible when the time information is expressed by a small amount of data.

[0005]

A data transmission system according to the present invention comprises: (a) supplying a plurality of audio sample data having a time-series arrangement of a first period at a transmitting side, and The first period is variable,
1 for every predetermined number of audio sample data of 2 or more
Specifying one audio sample data and adding time information indicating a time position of the specified audio sample data; and adding to a predetermined number of the audio sample data and any one of the audio sample data. The time information as one packet,
Sending to a network at a predetermined timing of a second cycle that is asynchronous to the first cycle, and (b) receiving the packet via the network at the receiving side; Temporarily storing the audio sample data contained in the received packet, and sequentially reproducing and reading the temporarily stored audio sample data, the temporary storing based on the time information contained in the received packet. And updating the sampling period of the audio sample data and controlling the reading so that the reproduction is performed in the period corresponding to the first period.

According to this, audio sample data that can arbitrarily take various sampling periods (that is, audio sample data having a variable first period array)
When transmitting, the audio sample data packet is transmitted at a predetermined timing of a predetermined second cycle that is asynchronous with the first cycle. At that time, without adding the time information to all the audio sample data, one audio sample data is specified for every predetermined number of the audio sample data of 2 or more, and the specified audio sample data is specified. The time information is added to. Then, one packet is composed of a predetermined number of audio sample data,
Further, the time information added to any of the audio sample data is included in the one packet, and the packet is transmitted via the network. On the reception side, the audio sample data included in the packet received via the network is temporarily stored, and the sequentially read out of the temporarily stored audio sample data is
By updating and controlling the sampling period of the temporarily stored audio sample data based on the time information included in the received packet, reproduction is performed at a period corresponding to the original predetermined period. Therefore,
Asynchronous packets can be adopted and the advantages can be enjoyed, and since only one time information is included in one packet, the time information is expressed by the smallest possible data amount to reduce the transmission data amount per packet. Can be made.

According to another aspect of the data transmission system according to the present invention, (a) at the transmitting side, a step of supplying a plurality of audio sample data having a time-series arrangement of a first cycle, And the first cycle is variable, one audio sample data is specified for each of the supplied plurality of audio sample data, and time information indicating a time position of the specified audio sample data is added. Any of the audio sample data and the audio sample data supplied within one cycle of the second cycle every predetermined second cycle longer than the first cycle and asynchronous with the first cycle. And sending the time information added to the network to the network as one packet, (b) at the receiving side, the network A step of receiving the packet via a network, a step of temporarily storing the audio sample data included in the received packet, and a step of sequentially reproducing and reading the temporarily stored audio sample data, Updating the sampling period of the temporarily stored audio sample data based on the time information included in the received packet and controlling the reading so that the reproduction is performed at a period corresponding to the first period. And is provided.

According to this, like the above, without adding the time information to all the audio sample data, one audio sample data is set for every predetermined number of audio sample data of 2 or more. Identify,
Time information is added to the specified audio sample data. Then, for each predetermined second cycle that is longer than the first cycle and asynchronous to this, one packet is composed of the audio sample data supplied within one cycle of the second cycle, and The time information added to any of the sample data is included in the one packet, and the packet is transmitted through the network. On the receiving side, the audio sample data included in the packet received via the network is temporarily stored, and the sequentially read out of the temporarily stored audio sample data is temporarily stored based on the time information included in the received packet. By updating and controlling the sampling cycle of the audio sample data, the reproduction is performed at the cycle corresponding to the original first cycle. Therefore, also in this case, it is possible to use the asynchronous packet to enjoy its advantages, and since only one time information is included in one packet, the time information can be expressed by the smallest possible data amount. It is possible to reduce the amount of data transmitted. Since the packet transmission is performed every predetermined second cycle, it is not necessary to wait until a predetermined number of data are accumulated, and it is possible to provide a data transmission method in which the time delay between transmission and reception is minimized. The meaning of the asynchronous packet described here is that the packet transmission cycle is
This means that the original sample data to be transmitted is set independently of the sampling period. For sending and receiving the packet itself,
Since it is performed in a fixed cycle, it is a synchronous communication.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. First, in order to facilitate understanding, some specific examples of the data transmission method according to the embodiment are illustrated in FIG.
FIG. 1A illustrates an example of a data transmission method according to the first aspect, and FIGS. 1B and 1C illustrate two different examples of the data transmission method according to the second aspect. It is shown in FIG. 1 (a), (b),
An example of a time-series arrangement of a plurality of audio sample data having a time-series arrangement of a predetermined cycle (first cycle) T supplied on the transmission side is shown in each of the first rows of (c). The numbers 0, 1, 2, 3, ... Are ordinal numbers indicating the time series order of each data. The numbers (1, 13, 17, 2) shown above the specific audio sample data in the first row
1, 29, 33, etc.) exemplify a time stamp, that is, time information added to the audio sample data. SF indicates one cycle of a service section of packet transmission, and the cycle T of data to be transmitted is appropriately variable, whereas in an asynchronous packet, one cycle of the service section SF is fixed to a predetermined value. . Therefore, SF and T
The time relationship of is not limited to the one shown in the figure, and it is possible to take any time relationship. Generally, the cycles of both are in a non-integer multiple relationship (of course, there may be an integer multiple relationship. Absent). The second row of each of FIGS. 1A, 1B, and 1C shows the state of a packet transmitted via the network, and the number included in the time slot frame is included in the packet. It is an ordinal number that identifies the audio sample data, and the numbers (1, 13, 1) written below it.
7, 21, 29, 33, etc.) indicate the time stamp included in the packet, that is, the time information. Figure 1 (a),
The third row of (b) and (c) shows the reproduction state of the audio sample data on the receiving side.

Explaining the example of FIG. 1A according to the first aspect, one packet is composed of a predetermined number N (N = 4 in the example of the figure) of audio sample data at the time of transmission, and one packet of data is included. The head audio sample data of the packet is specified for each of the same number of data as the number N (= 4), and a time stamp indicating the time position of the specified head audio sample data is added. For example, the first packet has ordinal numbers 0, 1, 2,
It is composed of four audio sample data No. 3, and a time stamp "1" indicating the time position of the ordinal 0 data at the head thereof is added. In this case, since two cycle periods of the service section SF are required to supply four data on the transmission side, after the lapse of two service sections SF from the time when the first data (ordinal number 0) is supplied, The first packet is sent. Therefore, the rise time delay of packet transmission is two cycle periods of the service section SF. Two
The second packet consists of four data of ordinal numbers 4, 5, 6, and 7, and a time stamp “17” indicating the time position of the ordinal number 4 data at the head thereof is added. In this case, the second packet is transmitted in the service section SF (shown as SF5) next to the service section SF (shown as SF4) in which the last ordinal 7 data included in the second packet is supplied. Since the packet is transmitted, the second packet is transmitted after two service sections from the time of transmitting the first packet.

On the receiving side, the original predetermined period T on the transmitting side can be estimated based on the change or function of the time stamps contained in each packet that is sequentially given. There may be various methods for estimating the original period T based on the time stamp, but the most typical method is to perform the following calculation from the difference between the time stamps included in two consecutive packets. That is, the time stamp value of the packet transmitted this time is set to TS (i), and the time stamp value of the packet transmitted before that is T (i).
If S (i-1) is set, N pieces of data exist between them. Therefore, the original period T can be estimated by performing the calculation of the following equation. T = {TS (i) -TS (i-1)} / N (Equation 1) On the receiving side, the data contained in the received packet is sequentially reproduced at a cycle corresponding to the original cycle T thus estimated. Read. Thus, the data reproduction in the original cycle T can be ensured. In the case of FIG. 1A, since it is necessary to wait until two packets are transmitted for the above estimation calculation, the data reproduction is started on the reception side at the first data (ordinal number) on the transmission side. 0) is supplied, the service section SF has passed 5 cycles, that is, the sixth service section SF6 in FIG.

As described above, as in the transmission method according to the first aspect, the number of data per packet is set to a predetermined fixed number N.
Then, the rising delay of packet transmission and the delay of data reproduction start on the receiving side become problems. The transmission method according to the second aspect can improve this point and avoid such a delay problem as much as possible. The transmission method according to the second aspect illustrated in FIGS. 1B and 1C is different from the transmission method according to the first aspect in that the transmission method according to the second aspect accumulates a predetermined number of data. The point is that the packet transmission is regularly performed every predetermined second cycle without waiting until the packet transmission until the number of data constituting one packet is variable. is there. That is, one packet is composed of the data supplied within one cycle of the second cycle every predetermined second cycle longer than the first cycle T which is the original cycle of the data to be transmitted. , The second
Packet transmission will be performed every cycle of
In general, the relationship between the first and second cycles is non-integer multiple (of course, it may happen to be an integer multiple relationship). Therefore, within each one cycle of the second cycle, Therefore, the number of data included in the variable fluctuates (within a range of ± 1). In the examples of FIGS. 1B and 1C, one service section S is set as the second cycle for packet transmission.
It is shown that the operation is performed in every F cycle.

Explaining the example of FIG. 1B, for each service section, the data supplied in that section is included in one packet and transmitted to the network in the next service section. The number x of data included in one packet is variable, and is three or two in the illustrated example. Figure 1 (b)
In the above example, the head data of the packet is specified for each data of the same number as the data number x (variable) of one packet, and the time stamp indicating the time position of the specified head data is added. There is. Therefore, the time stamp is 2
The above-described predetermined number of data is added, and the predetermined number is a variable number that is interlocked with the variable number x of packet-constituting data. For example, the first packet is composed of three data of ordinal numbers 0, 1 and 2, and a time stamp “1” indicating the time position of the data of the ordinal number 0 at the head thereof is added. In this case, the first packet is transmitted after the elapse of one service section SF from the time when the first data (ordinal number 0) is supplied, that is, in the second service section SF2. Therefore, the rise time delay of packet transmission is only one service section SF. The second packet consists of two data of ordinal numbers 3 and 4, and the time stamp "1" indicating the time position of the data of the ordinal number 3 at the head thereof.
3 ”is added. In this case, since the second packet is transmitted in the service section (SF3) next to the service section (SF2) to which the last ordinal 4 data included in the second packet is supplied, the first packet is transmitted. The second packet is transmitted one service section after the packet is transmitted.

In this case as well, on the receiving side, the original predetermined period T on the transmitting side can be estimated based on the change or function of the time stamps included in each packet that is sequentially given. As described above, there are various methods of estimating the original period T based on the time stamp, but the most typical method is to perform the following calculation from the difference between the time stamps included in two packets that are adjacent to each other. Therefore, the arithmetic expression for this case is shown below. T = {TS (i) -TS (i-1)} / x (Equation 2) Here, TS (i) and TS (i-1) are the same as those described above for the packet transmitted this time. The time stamp value and the time stamp value of the packet transmitted last time. x
Is the number of data included in the packet transmitted last time and is a variable number as described above. On the receiving side, the data contained in the received packet is sequentially reproduced and read at a cycle corresponding to the original cycle T thus estimated. Thus, the data reproduction in the original cycle T can be ensured. In the case of FIG. 1B, since the second packet is transmitted during the third service section SF3 counted from the time when the first data (ordinal number 0) is supplied at the transmitting side, the data is received at the receiving side. The reproduction starts after the first data (ordinal number 0) is supplied on the transmitting side, after three cycles of the service section SF, that is, at the fourth service section SF4. Thus, FIG. 1 (b)
In the case of 1, the rising of packet transmission and the start of data reproduction on the receiving side are earlier than in the case of FIG. 1A, and it can be understood that the problem of delay is improved. On the other hand, considering the reproduction process of the time information on the receiving side, the configuration is such that division is performed by a variable number x as shown in the above equation 2, and division is performed by a fixed number N as in the above equation 1. Since the divisor x has to be changed each time as compared with the configuration for performing the above, there is a problem that the configuration of the arithmetic processing becomes complicated.

The example shown in FIG. 1 (c) is obtained by further improving the example shown in FIG. 1 (b) so that the arithmetic processing on the receiving side can be simplified. Explaining the example of FIG. 1C, for each service section SF, the data supplied in that section is included in one packet and transmitted to the network in the next service section. Similar to (b), the number x of data included in one packet is variable, and in the example of the figure,
It is three or two. In the example of (c), the method of adding the time information is different from that of (b). That is, FIG.
In the example of (c), one data is specified for each data consisting of two or more predetermined constants M, and a time stamp indicating the time position of the specified data, that is, time information is added. In the illustrated example, M is 4, and for every four data groups, a time stamp indicating the time position of the head data of the group is added. Therefore, the time stamp is added to each of a predetermined number of data of 2 or more, but unlike the example of (b), the predetermined number is not related to the variable number x of 1 packet structure data. , A constant M (“4” in the figure). In the example of FIG. 1C, the first packet has an ordinal number 0, 1, 2
A time stamp "1" indicating the time position of the ordinal 0 data, which is the head of the first M = 4 data group, is added. In this case, the first packet is transmitted one service section SF after the first data (ordinal number 0) is supplied. Therefore, the rise time delay of packet transmission is only one service section SF, as in FIG. The second packet consists of two data of ordinal numbers 3 and 4, which contains the ordinal number 4 data which is the head of the next M = 4 data group. A time stamp “17” indicating the time position of is added. Also in this case, the second packet is transmitted in the service section (SF3) next to the service section (SF2) to which the last ordinal 4 data included in the second packet is supplied. The second packet is transmitted one service period SF after the packet transmission.

While the number of data in one packet is variable, the number M of data in one group to which one time stamp is added is a constant. Therefore, some packets may have a time stamp, that is, time information. Something does not come out. The fourth service section S in FIG. 1 (c)
A packet including the data of the ordinal numbers 5 and 6 transmitted in F4 corresponds to this, and in such a packet, instead of the data indicating the valid time stamp value, the predetermined data “indicating no time stamp” is displayed. voi
d "is transmitted. Of course, it is not always necessary to transmit this kind of data" void ", and the absence of a time stamp in the packet does not carry a time stamp, that is, time information. It may be recognized that FIG.
Also in the case of (c), the receiving side can estimate the original predetermined period T on the transmitting side based on the change or the function of the time stamp included in each packet sequentially given. As described above, there are various methods for estimating the original period T based on the time stamp, but the most typical method is to perform the following calculation from the difference between the time stamps included in two packets that are adjacent to each other. Therefore, the arithmetic expression for this case is shown below. T = {TS (i) -TS (i-1 ')} / M (Equation 3) Here, TS (i) is the time stamp value of the packet transmitted this time, similarly to the above. TS (i-1 ') is
It is a valid timestamp value that was sent before that. Therefore, when the packet transmitted this time includes the above "void" instead of the time stamp, this calculation is not performed. When the time stamp value of the packet transmitted last time has a valid value other than “void”, TS (i−1 ′) is the time stamp value TS (i of the packet transmitted last time. -1), but if the previously transmitted packet includes the above "void" instead of the time stamp, TS (i-1 ') is the time stamp of the packet transmitted two times before. It corresponds to the value TS (i-2).
As described above, M is a constant indicating the number of data in the data group to which one time stamp is added.

On the receiving side, the data contained in the received packet is sequentially reproduced and read at a cycle corresponding to the original (original) cycle T thus estimated. Thus, the data reproduction in the original cycle T can be ensured. Also in the case of FIG. 1C, since the second packet is transmitted during the third service section SF3 counted from the time when the first data (ordinal number 0) is supplied on the transmitting side, the second packet is transmitted on the receiving side. Data reproduction starts at the time of the fourth service section SF4 after three cycles of the service section SF have passed since the first data (ordinal number 0) was supplied on the transmitting side. Therefore, also in the case of FIG. 1C, the rise of packet transmission and the start of data reproduction on the receiving side are earlier than in the case of FIG. 1A, and the problem of delay is improved. It can be understood. Furthermore, FIG.
In the case of (c), considering the reproduction processing of the time information on the receiving side, the configuration is such that division is performed by a fixed number M, as shown in the above-mentioned equation 3, and it is possible to perform as in the above-mentioned equation 2. There is an advantage that the configuration of arithmetic processing is simpler than the configuration in which division is performed by the variable x. Here, the fixed number M is 4 or 8.
If a power of 2 is used, it is advantageous because the digital division of Expression 3 can be performed by a simple data shift process. Therefore, according to the example of FIG. 1 (c), in the case of expressing time information with a small amount of data, a data transmission method using an asynchronous packet that can simplify the reproduction calculation processing of time information on the receiving side as much as possible. It has the advantage that it can be provided.

As mentioned above, FIG. 1 in the second aspect.
It can be understood that the most preferable data transmission method can be provided according to the example of (c). Therefore, the present invention can be implemented from the viewpoint of performing asynchronous packet transmission in such a most preferable format on the transmission side. That is, from the viewpoint of such a transmission method, the data transmission method according to the present invention comprises the steps of supplying a plurality of data having a time-series arrangement of the first cycle and two or more predetermined constants. Specifying one data in each group of the data, and adding time information indicating the time position of the specified data; and a predetermined second cycle longer than the first cycle. For each time, the plurality of data supplied in one cycle of the second cycle is regarded as one packet, and if the data in the packet includes the data to which the time information is added, the time information is And including the packet and transmitting it via the network. This action and effect are as described above according to the example of FIG. Of course, also in the examples of FIGS. 1A and 1B, the invention can be understood from the viewpoint of only the transmission method.

Next, as a most preferred embodiment, a detailed example of the embodiment according to the example of FIG. 1C in the second aspect will be described. FIG. 2 is a schematic block diagram showing the overall configuration of an embodiment of the data transmission system according to the present invention. On the transmission side 10, the data generation unit 11 sequentially generates and outputs a plurality of data having a time-series arrangement of a predetermined sampling period T, and
For example, the sequential sample data of the digital audio signal is output. For example, the data generating unit 11 may include an audio reproducing device such as a CD (Compact Disc) player, or may include a musical tone synthesizing device that synthesizes musical tone sample data in real time. . The sampling cycle T of the audio sample data output from the data generator 11 may be appropriately changed according to the data source.

The audio sample data output from the data generation unit 11 is processed in the data buffer 1 in chronological order.
Temporarily stored in 2. As the data buffer 12, an asynchronous input / output buffer register is used. The timer 13 creates time stamp data, that is, time information, and may include a running counter for counting a predetermined clock. Network processing unit 1
4 is the data buffer 12 for each predetermined transmission interrupt cycle.
1 based on audio sample data temporarily stored in
Processing of aligning a plurality of audio sample data forming packets in the transmission buffer TBF into one group, specifying one audio sample data for every predetermined number M of audio sample data, and specifying the time of the specified audio sample data. A process of adding time stamp data indicating a position, a plurality x of audio sample data arranged in the transmission buffer TBF, and the time stamp data added to any of the audio sample data as one packet , And processing of transmitting to the receiving side 20 via the network 30. The transmission interrupt cycle corresponds to the service section SF of the packet,
It is set to be longer than the sampling period T of the audio sample data, and a plurality of x audio sample data can be included in one packet. However, for the reason described above, the number x of audio sample data in one packet is variable.

On the receiving side 20, the network processing unit 24
In (1), the packet transmitted via the network 30 is received, and a plurality of x's of audio sample data included in the received packet are temporarily stored in the data buffer 22 in chronological order. For the data buffer 22, an input / output asynchronous buffer register such as a FIFO having a plurality of storage stages may be used. Clock generator 2
3 reproduces the original sampling period T of the audio sample data supplied from the data generation unit 11 of the transmission side 10, based on the time stamp data included in the received packet. For example, the original sampling cycle T is estimated and calculated by performing the calculation as in the above-described equation 3, and a clock signal corresponding to the calculated cycle T is generated. The data use unit 21 sequentially reproduces and reads out the audio sample data temporarily stored in the data buffer 22 in accordance with the reproduced sampling period T given from the clock generation unit 23, and uses this as appropriate. In what form the reproduced and read audio sample data is used may be appropriately selected. For example,
It may be directly DA-converted and then sounded from a speaker or the like, or may be processed by effects or the like and then sounded from the speaker or processed audio sample data may be sent to the outside. May be

On the transmitting side 10 and the receiving side 20, by executing a software program under the control of a microcomputer or the like, the processing in each of the above parts is controlled. An example of the processing flow for that is shown below.
FIG. 3 schematically shows an example of “transmission preparation processing” performed on the transmission side 10. This “transmission preparation process” is mainly a process that the network processing unit 14 takes charge of, and does not include the process of the data generation unit 11 and the input process to the data buffer 12. For example, this "transmission preparation process"
Is executed in the course of the main routine at the sender 10. First, in step S1, the storage contents of the data buffer 12 are scanned, and new data is stored in the data buffer 1.
Check to see if it was entered in 2. If new data has been input to the data buffer 12, YES is obtained and the process proceeds to the next step S2. If NO, return.

In step S2, the ordinal number register ORDR
The content of is divided by a predetermined number M to check whether the remainder is 0. The ordinal number register ORDR stores data indicating the ordinal number of the data detected to have been input to the data buffer 12 in the previous step S1.
The ordinal number is set to 0 by an initialization process (not shown), and thereafter, each time new data is input to the data buffer 12, it is incremented by the process of step S5 described later. As described above, the predetermined number M is a constant indicating the number of data in one data group to which one time stamp should be added, and if it is a power of 2 such as 4 or 8,
It is preferable because the division can be simplified. Ordinal number register ORD
The content of R is divided by a predetermined number M, and the remainder is 0, that is, the determination in step S2 is YES means that the current data corresponding to the content of the ordinal number register ORDR (in the data buffer 12 The new data just input) is the data to which the time stamp should be added.

Therefore, if step S2 is YES,
In step S3, the current value of the timer 13 (this indicates the time when one sample data from the data generation unit 11 arrives / inputs in the data buffer 12) is stored in the transmission side time stamp register TSt, Then go to step S4. In this way, one piece of data to which a time stamp is to be added is specified by the processing of step S2, and the time stamp data, that is, time information, to be added to the specified data is determined / generated by the processing of step S3 and registered in the register TSt. On the other hand, if step S2 is NO, the process jumps to step S4 and the time stamp data is not registered.

In step S4, the new data (that is, the ordinal number register ORDR) input to the data buffer 12 is input.
(Current data corresponding to the contents of) is taken out from the buffer 12 and stored in a predetermined transmission buffer TBF. In the next step S5, the content of the ordinal number register ORDR is incremented by 1. Then, the process returns to the main routine. Then, the "transmission preparation process" of FIG. 3 is performed again in the process of the main routine. In this way, the "transmission preparation process" of FIG. 3 is repeated. In the process of repeating the “transmission preparation process”, some data that are sequentially supplied are sequentially stored in the transmission buffer TBF. Some (generally a plurality of x) data stored in the transmission buffer TBF is transmitted as one packet by the "transmission interrupt process" described below.

FIG. 4 schematically shows an example of the "transmission interrupt process" performed on the transmission side 10, and is executed as an interrupt process for the process of FIG. This "transmission interrupt process"
Are executed at regular interrupt intervals according to a predetermined transmission interrupt cycle. This transmission interrupt cycle corresponds to, for example, one service section SF of the packet and is generally longer than the sampling cycle T of the data to be transmitted. When a transmission interrupt occurs, first, in step S6, the time stamp information registered in the transmission side time stamp register TSt is changed to the time stamp information "TIME STA".
MP "is set for transmission, and the transmission buffer T
The number x of data stored in the BF is counted and set as the sample number x “SAMPLE x” and set, and the sample number x is determined from the contents of the ordinal number register ORDR.
Value obtained by subtracting "SAMPLE x" (ORDR- "SAM
PLE x ”) is the packet top sample ordinal number“ SAMP
The transmission is set as "LE ORDER". This packet top sample ordinal number "SAMPLE ORDER" is
The sample ordinal number of the data whose time series order is the first among the plurality of data included in one packet to be transmitted is shown. Since the current content of the ordinal number register ORDR indicates the sample ordinal number next to the last data item in the time series order among the plurality of data items included in one packet to be transmitted, the sample number "SAMPLE" of the data items included in the packet will be changed. Subtracting "x" will indicate the sample ordinal number of the leading data in the packet.

In the next step S7, a plurality of x data stored in the transmission buffer TBF and each information set for transmission in the previous step S6, that is, time stamp information "TIME STAMP", sample number x "SAM"
PLE x ”, packet ordinal sample ordinal“ SAMPL
E ORDER "is made as one packet and the packet is transmitted via the network 30.
Since the actual concrete communication work with the receiving side 20 via the network 30 is performed via the communication interface, the packet is sent to the communication interface (not shown) in this step S7. It consists of It is assumed that the buffer TBF is cleared after the data stored in the transmission buffer TBF is sent out. In the next step S8, empty data "void" is set in the transmission side time stamp register TSt, and then the process returns. If the next packet has a valid time stamp, the contents of the register TSt are updated with the valid time stamp value by passing through the process of step S3 of FIG. On the other hand, if the next packet does not have a valid time stamp, it does not go through the process of step S3 of FIG.
Holds the empty data "void" without being updated, and the next "transmission interrupt process" is reached. In such a case, in step S6 of FIG. 4, the empty data "voi" is set as the time stamp information "TIME STAMP".
d "will be set for transmission.

For example, assuming that M = 4, FIG.
The operation examples of FIGS. 3 and 4 will be described with reference to the first and second stages of FIG. First, when ordinal 0 data is fetched into the data buffer 12, the register ORDR
Since the content of is 0, step S2 becomes YES,
In step S3, the current value of the timer 13 (it is initially set to "1" in FIG. 1 for convenience, but it is not limited to this is stored in the transmitter time stamp register TSt). This ordinal 0 data is stored in the transmission buffer TBF (S4), and the value of the ordinal register ORDR is incremented to 1 (S5). Next, when the data of the ordinal number 1 is fetched into the data buffer 12, since the content of the register ORDR is 1, the step S2 becomes NO, the step S3 is skipped, and the steps S4 and S5 are executed. Is stored in the transmission buffer TBF, and the value of the ordinal number register ORDR is increased to 2. The same applies when the data of the ordinal number 2 is fetched into the data buffer 12, and the step S3 is jumped to the step S3.
4 and S5 are performed, and the data of this ordinal number 2 is sent to the transmission buffer
It is stored in BF and the value of the ordinal number register ORDR is incremented to be 3.

In this way, three data of ordinal numbers 0, 1, 2 are supplied during the first service section SF1, and these data are stored in the transmission buffer TBF. At the end of the service section SF1 (or at the beginning of the next service section SF2), the "transmission interruption process" of FIG. 4 is performed. By the processing of step S6, the time stamp information "TIM
"1" of the register TSt is transmitted and set as "E STAMP", "3" is transmitted and set as the sample number x "SAMPLE x", and "0" (3-3 =) as the packet head sample ordinal number "SAMPLE ORDER".
0) is set for transmission. Then, based on the processing of step S7, these pieces of information and the three data of the ordinal numbers 0, 1 and 2 in the transmission buffer TBF are transmitted as one packet at an appropriate time in the second service section SF2. Become.

In the second service section SF2,
Two data of ordinal numbers 3 and 4 are supplied. When the data of the ordinal number 3 is supplied, step S2 is NO, and the data of the ordinal number 3 is stored in the transmission buffer TBF (S
4), the value of the ordinal number register ORDR is incremented to 4 (S5). Next, when the data of the ordinal number 4 is supplied, step S2 becomes YES, the process proceeds to step S3, and the current value of the timer 13 (“17” in FIG. 1) is stored in the transmission side time stamp register TSt. Also, this ordinal number 4
Is stored in the transmission buffer TBF (S4), and the value of the ordinal number register ORDR is increased to 5 (S4).
5). When the "transmission interruption process" of FIG. 4 is performed after the end of the second service section SF2, the time stamp information "TIME STAMP" is obtained by the process of step S6.
"17" of the register TSt is set to be transmitted and the sample number x "SAMPLE x" is set to be "2" to be transmitted, and the packet head sample ordinal number "SAMPLE"
"3" (5-2 = 3) is transmitted and set as "ORDER". Then, based on the process of step S7, these pieces of information and the two data of the ordinal numbers 3 and 4 in the transmission buffer TBF are transmitted as one packet at an appropriate time in the third service section SF3. Also,
In step S8, the empty data "voi" is stored in the register TSt.
d "is set.

In the third service section SF3,
Two data of ordinal numbers 5 and 6 are supplied. When the data of the ordinal number 5 is supplied, the step S2 is NO, and the data of the ordinal number 5 is stored in the transmission buffer TBF (S
4), the value of the ordinal number register ORDR is incremented to 6 (S5). When the data of the ordinal number 6 is supplied next, step S2 is NO, the data of the ordinal number 6 is stored in the transmission buffer TBF, and the value of the ordinal number register ORDR is simply incremented to 7. After all, in the third service section SF, the empty data "void" is kept in the register TSt without passing through step S3. Therefore, in the next "transmission interrupt process", empty data "void" is set as the time stamp information "TIMESTAMP", and the number of samples x
"2" is sent and set as "SAMPLE x",
Packet top sample ordinal "SAMPLE ORDE
As R "," 5 "(7-2 = 5) is set for transmission. Then, these information and the transmission buffer TBF
Two data of ordinal numbers 5 and 6 in the above will be transmitted as one packet. Thereafter, the same operation is performed, and FIG.
Packets having the contents shown in the second row are transmitted according to the time-series data shown in the first row.

FIG. 5 schematically shows an example of "reception processing" performed on the receiving side 20. This "reception processing"
Mainly includes the network processing unit 24 and the clock generation unit 2.
3 shows processing performed by the third party. This "reception process" is executed every time the receiving side 20 receives one packet information given from the network 30. First, in step S11, 1 received via the network 30
Of each information included in the packet, the packet head sample ordinal number “SAMPLE ORDER” is stored in the register j, and the sample number x “SAMPLE x” is stored in the register X.
To store. Also, update clock register up
Set a false value FALSE to dateCLOCK. This update clock register updateCLOC
When the true value TRUE is set in K, the update of the clock frequency is instructed, and when the false value FALSE is set, the update of the clock frequency is not instructed. next,
In step S12, the variable register i is set to the initial value 0. In the next step S13, one data DATA (i) of the order designated by the variable register i among the plurality of x data contained in one packet received via the network 30 is transferred to the data buffer 22.

At the next step S14, the contents of the register j (that is, the packet head sample ordinal "SAMPLE"
The value obtained by adding the current value of the variable register i to ORDER ") is divided by the predetermined number M to check whether the remainder is 0. That is, the data written to the data buffer 22 in the previous step S13 (this ordinal number). Is “j + i”) corresponds to the specific data to which the time stamp is added. When the data written in the data buffer 22 in the previous step S13 corresponds to the specific data, the ordinal number j + i of the data is divisible by the predetermined number M, and the remainder becomes 0.
Judged as ES. In that case, steps S15 to S1
After going through the route of 8, go to step S19. NO
In the case of, the route of steps S15 to S18 is jumped to step S19. In step S15, the contents of the receiving side time stamp register TSr are empty data “v”.
It is checked whether or not it is “Oid”. The contents of the register TSr are empty data “v
Oid "is set as an initial setting, and after that, by performing the next step S16, the received 1
Time stamp information "TIMES" included in the packet
TAMP "is loaded into the register TSr.
This step S16 is the first time stamp information "T
This is a process for loading "IMESTAMP" into the register TSr. Thereafter, step S15 is determined to be NO, and the process is performed exclusively through the routes of steps S17 and S18.

In step S17, the calculation corresponding to the equation 3 is performed to calculate / estimate the original sampling period T. That is, from the time stamp information “TIME SAMP” (corresponding to TS (i) in the above expression 3) included in the packet received this time, the contents of the time stamp register TSr on the receiving side (the time included in the packet received last time or the time before last). The stamp information, which corresponds to TS (i-1 ') in the above equation 3, is subtracted and a constant M indicating the number of data in the data group to which one time stamp is added
Divide by (for example, 4). The quotient is registered as data that estimates the original sampling period T. In the next step S18, the time stamp information "TIME STAMP" included in the packet received this time.
Is loaded into the reception side time stamp register TSr, the contents of the register TSr are updated, and the true value TRU is set in the update clock register updateCLOCK.
Set E.

In step S19, the value of the variable register i is incremented by 1. In the next step S20, it is checked whether or not the value of the incremented variable register i is equal to the number x of data in the packet stored in the register X. If NO, the process returns to step S13, and with respect to the value of the incremented variable register i, the steps S13 to S
The process of 18 is repeated. If step S20 is YES, the process proceeds to step S21, and on the condition that the content of the update clock register updateCLOCK is a true value TRUE, the sampling clock frequency at the receiving side 20 is set in accordance with the original sampling period T calculated at step S17. According to this cycle T, the clock synchronization processing for setting is performed. That is, the sampling clock frequency on the receiving side 20 is set or updated according to the calculation result T in step S17. After that, the process returns and the "reception process" is completed. Since only one piece of time stamp information is included in one packet, it is not necessary to repeat the processing of steps S13 to S20 after passing through the routes of steps S17 and S18 once. Therefore, after step S18, the flow may be changed so as to jump to step S21.

Next, assuming that M = 4, the operation example of FIG. 5 will be described with reference to the second and third stages of FIG. 1C. In the second service section SF2, ordinal number 0,
When the information of the first packet including the data of 1 and 2 is received, j = 0 and X = 3 are set in step S11. In this case, when j = 0 and i = 0, step S14
Is YES. Since "void" is initially set in TSr, the next step S15 is YES, and the time stamp information "TIME STAMP" = "1" included in the packet received this time is
It is set in the register TSr. Eventually, step S1
After repeating the processes of 3 to S20, the process goes to step S21. In this case, the update clock register upd
Since the content of ateCLOCK remains set to the false value FALSE, the sampling clock frequency is not set on the receiving side 20. Therefore, the reproduction / reading of the data stored in the data buffer 22 is not started yet.

In the third service section SF3, the ordinal number 3,
When the information of the second packet including the data of 4 is received, j = 3 and X = 2 are set in step S11. In this case, when j = 3 and i = 1, step S14
Is YES. The time stamp information “TIME STA” included in the previously received packet is stored in the register TSr.
Since MP ″ = “1” is set, it is determined as NO in the next step S15, and the process proceeds to step S17. In this case, the time stamp information “TIME STAMP” included in the packet received this time is “17”,
In the calculation of step S17, T = (17-1) / 4 = 4
Is obtained. In the next step S18, "TIME S
"17" of TAMP "is set in the register TSr, and the true value TRUE is set in updateCLOCK. Therefore, in the subsequent step S21, the sampling clock frequency on the receiving side 20 is set in accordance with the cycle T. As a result, the data stored in the data buffer 22 can be reproduced and read. Figure 1 (c)
Then, it is illustrated that the reproduction and reading of the data according to the cycle T are performed from the beginning of the next service section SF4. However, the present invention is not limited to this, and even when the service section SF3 is in the middle, as soon as the processing in step S21 is completed,
The reproduction and reading of the data stored in the data buffer 22 may be started.

In the fourth service section SF4, the ordinal number 5,
When the information of the third packet including the data of 6 is received, j = 5 and X = 2 are set in step S11. In this case, the value of the variable register i is initially set to 0 and then to 1. Therefore, in step S14,
The determination is made both in the case of j + i = 5 + 0 = 5 and in the case of j + i = 5 + 1 = 6. In either case, the determination result is NO, and the route of steps S17 and S18 is not passed. Therefore, the calculation of the original period T in step S17 is not performed, and the register TSr holds "17" of the time stamp information "TIME STAMP" included in the previously received packet. Therefore, the updating process of the sampling clock frequency in step S21 is not performed, and the clock frequency according to the previously calculated cycle T is maintained and the reproduction and reading of the data stored in the data buffer 22 is continued. in this way,
Time stamp information "TIMES" included in the packet
When TAMP "is empty data" void ", the updating process of the sampling clock frequency is not performed.

In the fifth service section SF5, the ordinal number 7,
When the information of the fourth packet including the data of 8 is received, j = 7 and X = 2 are set in step S11. Also in this case, the value of the variable register i is initially set to 0 and then set to 1. In step S14, j + i
= 7 + 1 = 8, YES is determined. Then, the procedure goes to step S17, and the time stamp information "TIME STAMP" included in the packet received this time is "33".
And "17" of the time stamp information included in the packet received two times before and stored in the register TSr.
Using and, the operation of T = (33−17) / 4 = 4 is performed. In the next step S18, "TIME STA
"33" of MP "is set in the register TSr, and
A true value TRUE is set in updateCLOCK.
Therefore, in the subsequent step S21, the sampling clock frequency on the receiving side 20 is updated in accordance with the cycle T. Thereafter, the same operation is performed, and in response to the reception of the packet having the contents shown in the second row of FIG. 1C, the time-series data is reproduced and read at the original cycle T shown in the third row. Be seen.

In the above example, since the numerical value of the time stamp information is simplified and shown, the period T obtained as a result of the calculation is a constant numerical value 4, but normally the resolution of each numerical value is set. Accordingly, the calculation result value T takes a more complicated value. On the receiving side 20, synchronization control is performed so as to constantly adjust the sampling clock frequency according to the calculation result value T. In this way, according to the time stamp information transmitted for each predetermined data group,
The sampling clock frequencies of the transmitting side 10 and the receiving side 20 are controlled so as to be constantly synchronized. The predetermined constant M in the above-described embodiment is a value that does not add a time stamp to two or more data in one packet generation cycle (that is, one service section SF), that is, within one packet generation cycle. It is desirable that the value is larger than the maximum value (“3” in the example of FIG. 1) of the number of supplied data, and the sampling period T on the receiving side is
In order to improve the reproduction resolution of, the minimum value among such values is desirable. Furthermore, it is preferable to set M to a power of 2 because the division operation can be simplified.

By the way, in order to synchronize the sampling clock frequencies on the transmitting side and the receiving side, in the simplest way,
At the beginning of data transmission, the transmitting side gives information for instructing the sampling clock frequency to the receiving side, and the receiving side sets the clock division ratio so as to oscillate the sampling clock frequency corresponding to the information. Should be good. However, due to individual differences in the crystal oscillator used as the oscillation source, a slight difference may occur in the actual sampling clock frequency on the transmitting side and the receiving side, which causes inconvenience in reproduction processing for a long time. There's a problem. That is, in the data reproduction / readout technique based on the clock oscillation output, the oscillation output of the crystal oscillator used as the oscillation source is divided to create a sampling clock with a desired cycle. The crystal oscillator to be used,
Due to individual differences between the crystal oscillator used for reading data on the receiving side, even if the same dividing ratio is set for transmission and reception, there may be a slight deviation between the actual sampling clock frequency on the transmitting side and the receiving side. . This subtle deviation is accumulated in a continuous audio reproduction process for a long time and the like, and finally causes a remarkable deviation in reproduction timing.

For example, in general, when transmitting / receiving information between different systems, a buffer is provided on the receiving side to absorb the timing deviation of data transfer. If there is a slight deviation, the receiving side buffer overflows (when the receiving side clock frequency becomes relatively slow) or underflows (when the receiving side clock frequency becomes relatively fast). I have something to do. In such a case, normal data transmission / reception cannot be performed, which is not preferable. On the other hand, in the method of controlling the sampling clock frequencies of the transmitting side and the receiving side to be constantly synchronized by adding the time information to the data to be transmitted as in the present invention, such a problem occurs. This is more preferable because it does not occur.

In the above embodiment, the receiving side 20 sets the sampling clock frequency for the reproduction / reading control of the data buffer 22 based on the cycle T calculated in step S17, but it is based on the time information. The mode of reproduction / readout control is not limited to this, and may be appropriately designed. For example, a process of adding unique time information to data to which time stamp information is not added may be performed, and reproduction / reading may be performed with reference to unique time information of each data. Further, prior to the data transmission, the data indicating the basic sampling period T is transmitted, and the receiving side 20 first starts the data reproduction / reading at the sampling period T corresponding to the transmitted data. Good. By doing so, the rising edge of data reproduction / reading on the receiving side 20 can be advanced by one service section as compared with the above embodiment. Also, some dummy data may be transmitted with an initial value of the time stamp prior to the original transmission of the data. In this case, the data reproduction / reading on the receiving side 20 is started by cutting the dummy data and starting from the actual data. For example, in the case of FIG. 1C, if the data of ordinal numbers 0, 1 and 2 is dummy data, the data of the ordinal number 3 (of the actual data) is read in the reproduction on the receiving side shown in the third row. Start reading from the beginning). Even in this case, the start of the actual reproduction / reading of data on the receiving side 20 can be advanced by one service section as compared with the above embodiment.

When the data transmission method as shown in FIG. 1 (b) is carried out, generally, the step S2 of FIG.
Omitting S3, in step S6 of FIG. 4, "TIME
Instead of "STAMP ← TSt", "TIME
STAMP ← current value of timer 13 ", and
Instead of the predetermined constant M in steps S14 and S17 of FIG. 5, a variable predetermined number x (value of register X) may be used. In the case of implementing the data transmission method as shown in FIG. 1A, the data per packet is generally replaced with the predetermined constant M in step S2 of FIG. 3 and steps S14 and S17 of FIG. Use a fixed number N that represents a number, and
At the start of the "transmission interrupt process" in FIG. 4, the transmission buffer TB
A step of checking whether the number of data x in F is N or more is provided. If NO, the interrupt processing is ended, and if YES, the interrupt processing is continued. Then, at the time of continuing, in step S6, "the number of samples x" S
A predetermined number N is set as AMPLE x ″ ”, and the preceding N pieces of data in the transmission buffer TBF are formed as one packet in step S7, and if there are remaining data, they are left in the transmission buffer TBF. I will leave it.

[0045]

As described above, according to the present invention, in the case of transmitting a plurality of audio sample data having a time-series arrangement of a constant period via a network,
Asynchronous packets can be used to enjoy their advantages, and the time information to be included in a packet can be expressed with the smallest possible amount of data to reduce the amount of transmitted data per packet. It has an excellent effect. Further, it is possible to provide a data transmission method in which the time delay between transmission and reception is minimized. Furthermore, when the time information is expressed with a small amount of data, the reproduction calculation processing of the time information on the receiving side can be simplified as much as possible.

[Brief description of drawings]

FIG. 1 is a timing chart illustrating some specific examples of a data transmission method according to the present invention.

FIG. 2 is a schematic block diagram showing the overall configuration of an embodiment of a data transmission system according to the present invention.

FIG. 3 is a flowchart schematically illustrating an example of “transmission preparation processing” performed on the transmission side in FIG.

FIG. 4 is a flowchart schematically illustrating an example of “transmission interrupt processing” performed on the transmission side in FIG.

5 is a flowchart schematically illustrating an example of "reception processing" performed on the reception side in FIG.

[Explanation of symbols] 10 sender 20 Receiver 30 network 11 Data generator 12,22 data buffer 13 timer 14, 24 Network processing unit 23 Clock generator 21 Data Usage Department

Claims (4)

[Claims] 1. A step of: (a) supplying a plurality of audio sample data having a time-series arrangement of a first period at a transmitting side, wherein the first period is variable, and is 2 or more. 1 for every predetermined number of audio sample data
Specifying one audio sample data and adding time information indicating a time position of the specified audio sample data, and adding the audio information to a predetermined number of the audio sample data and any one of the audio sample data. And transmitting the time information as one packet to the network at a predetermined timing of a predetermined second cycle asynchronous with the first cycle, (b) at the receiving side, via the network A step of receiving the packet, a step of temporarily storing the audio sample data included in the received packet, a step of sequentially reproducing and reading the temporarily stored audio sample data, the step including: Based on the time information By controlling the read and update the sampling period of the audio sample data, the data transmission method characterized by comprising the steps of: to play at a period corresponding to the first cycle is performed. 2. A step of: (a) supplying a plurality of audio sample data having a time-series arrangement of a first cycle at a transmitting side, wherein the first cycle is variable, and 1 for each of the plurality of audio sample data
Specifying one audio sample data and adding time information indicating the time position of the specified audio sample data; and for each predetermined second cycle longer than the first cycle and asynchronous with the first cycle, Sending the audio sample data supplied in one cycle of the second cycle and the time information added to any of the audio sample data to the network as one packet. (B) On the receiving side, receiving the packet via the network, temporarily storing the audio sample data included in the received packet, and sequentially reproducing and reading the temporarily stored audio sample data. The step of including the time included in the received packet Updating the sampling period of the temporarily stored audio sample data based on the information and controlling the reading so that the reproduction is performed in the period corresponding to the first period. Data transmission method. 3. A system for transmitting audio sample data between a transmission side device and a reception side device via a network, wherein: (a) the transmission side device is time-series in a first cycle. An apparatus for supplying a plurality of audio sample data having various arrangements, wherein the first period is variable, and 1 for every predetermined number of audio sample data of 2 or more.
A device for specifying one audio sample data and adding time information indicating a time position of the specified audio sample data; and a device for adding a predetermined number of the audio sample data and one of the audio sample data. And a device for transmitting the time information as one packet to the network at a predetermined timing of a predetermined second period that is asynchronous with the first period, (b) the receiving side device includes the network. A device for receiving the packet via the device, a device for temporarily storing the audio sample data included in the received packet, and a device for sequentially reproducing and reading the temporarily stored audio sample data, the received packet The temporarily stored audio based on the time information included in Update the sampling period of sample data by controlling the reading, and a thing that so reproduction is performed in a period corresponding to the first period. 4. A system for transmitting audio sample data between a transmitting side device and a receiving side device via a network, wherein: (a) the transmitting side device is time-series in a first cycle. A device for supplying a plurality of audio sample data having a different array, wherein the first period is variable, and 1 is set for each of the supplied plurality of audio sample data.
A device for specifying one audio sample data and adding time information indicating a time position of the specified audio sample data, and for each predetermined second cycle longer than the first cycle and asynchronous with the first cycle, The audio sample data supplied within one cycle of the second cycle and the time information added to any of the audio sample data as one packet, and a device for transmitting the packet to the network. (B) the receiving side apparatus receives the packet via the network, temporarily stores the audio sample data included in the received packet, and sequentially reproduces the temporarily stored audio sample data. A device for reading, based on the time information included in the received packet, By updating the sampling period of the temporarily stored audio sample data for controlling the read-out, and a thing that so reproduction is performed in a period corresponding to the first period.