WO2018008618A1

WO2018008618A1 - Audio communication system, transmission device, reception device, transmission method, reception method, and recording medium

Info

Publication number: WO2018008618A1
Application number: PCT/JP2017/024431
Authority: WO
Inventors: 裕基中山
Original assignee: シントレーディング株式会社
Priority date: 2016-07-08
Filing date: 2017-07-04
Publication date: 2018-01-11
Also published as: JP2018007192A

Abstract

[Problem] To eliminate or reduce disturbance in audio caused in a reception device, and also to shorten a delay in audio output. [Solution] A transmission device is provided with: an audio data accepting unit which accepts audio data; a packet transmission unit which successively transmits two or more packets constituting the audio data; a retransmission request reception unit which receives from a reception device a retransmission request including a packet identifier; and a packet retransmission unit which transmits, by unicast, a packet corresponding to the packet identifier included in the retransmission request to the reception device that has transmitted the retransmission request. The reception device is provided with a packet storage unit; a packet reception unit which receives a packet from the transmission device and stores the packet in the packet storage unit; a packet acquisition unit which acquires from the packet storage unit a packet to be output next; an audio output unit which, upon acquisition by the packet acquisition unit of the packet to be output next, outputs the packet to be output next; and a retransmission request transmission unit which, if the packet reception unit does not receive the packet to be output next by a first deadline, transmits a retransmission request.

Description

Audio communication system, transmission apparatus, reception apparatus, transmission method, reception method, and recording medium

The present invention relates to an audio communication system that transmits and receives audio data.

As an audio communication system that transmits and receives audio data in real time, for example, there is an Internet radio that uses wireless communication such as Wi-Fi (registered trademark) to distribute audio live to many receiving devices (for example, non-patented). Reference 1).

However, in the prior art, depending on the bandwidth of the communication path from the transmitting device to each receiving device, traffic, etc., there is a problem that packet loss frequently occurs in some receiving devices and the sound output from the receiving devices is disturbed. there were.

The voice communication system according to the first aspect of the present invention is a voice communication system including a transmission device that transmits voice data and two or more reception devices that receive and output the voice data, and the transmission device accepts the voice data. An audio data receiving unit; a packet transmitting unit that sequentially transmits two or more packets corresponding to a packet identifier that identifies two or more packets constituting the audio data; and a reception device that receives a retransmission request having the packet identifier A retransmission request receiving unit that receives the packet identifier, and a packet retransmission unit that transmits the packet corresponding to the packet identifier included in the retransmission request to the receiving device that has transmitted the retransmission request by unicast. The receiving device stores the packet A packet storage unit that receives the packet from the transmitting device and stores the packet in the packet storage unit, A packet acquisition unit that acquires a packet to be output next using a packet identifier corresponding to the packet, and a packet acquisition unit that acquires a packet to be output next, Voice communication comprising: a voice output unit that outputs a packet to be output; and a retransmission request transmission unit that transmits a retransmission request to a transmission device when the packet reception unit does not receive the next packet to be output by the first time limit System.

With this configuration, it is possible to suppress the occurrence of packet loss in the receiving device, and to reduce or reduce the audio output delay in the receiving device while eliminating or reducing the audio disturbance that occurs in the receiving device.

Further, in the voice communication system according to the second aspect of the present invention, in contrast to the first aspect, the receiving device determines whether or not the packet receiving unit has received the next packet to be output before the first time limit. A determination unit configured to determine using the corresponding packet identifier, and the retransmission request transmission unit, when the determination unit determines that the packet reception unit has not received the next packet to be output by the first time limit. A voice communication system for transmitting a retransmission request to a transmission apparatus.

With such a configuration, it is possible to reduce the delay of audio output while suppressing the occurrence of packet loss in the receiving apparatus and eliminating or reducing the audio disturbance.

Further, in the voice communication system according to the third aspect of the present invention, in contrast to the first or second aspect, the retransmission request transmission unit is configured such that the packet reception unit does not receive the next output packet by the Nth time limit. , N (N is a natural number equal to or greater than 2), a voice communication system that transmits a retransmission request to a transmitter.

With this configuration, even if the first retransmission request is transmitted and the next packet to be output is not received, the receiving apparatus recovers the lost packet that is a lost packet by transmitting the second and subsequent retransmission requests. The rate can be expected to improve.

Further, in the voice communication system according to the fourth aspect of the present invention, the receiving device acquires communication related information that is information related to communication between the transmitting device and the receiving device in any one of the first to third inventions. Communication-related information acquisition unit, the capacity of the packet storage unit, the number N of times that the retransmission request transmission unit can transmit a retransmission request, and the N deadlines from the first deadline to the Nth deadline corresponding to the number N The communication system further includes a communication parameter changing unit that changes communication parameters, which are one or more types of information, according to communication-related information.

With this configuration, the receiving apparatus can acquire communication related information and dynamically change communication parameters according to the communication related information.

The voice communication system according to the fifth aspect of the present invention is different from the fourth aspect in that the communication-related information includes the number of terminals that is the number of receiving devices that receive a packet, or the packet that the packet receiving unit outputs next. This is a voice communication system including either information of error rate information regarding the inability to receive or normal rate information regarding that the packet receiving unit has been able to receive the next output packet.

With this configuration, the receiving device can acquire communication-related information and dynamically change communication parameters according to the number of terminals, error rate, or normal rate included in the communication-related information.

Further, in the voice communication system according to the sixth aspect of the present invention, in contrast to any one of the first to fifth aspects, the transmitting device acquires terminal number information related to the number of receiving devices that receive packets. And a method determining unit that determines whether to adopt multicast or broadcast or unicast as a method for transmitting a packet according to the number-of-terminals information. This is a voice communication system that transmits a packet based on the method determined by the unit.

With such a configuration, the transmission device can transmit a packet by a method corresponding to the number of terminals among multicast or broadcast and unicast.

For example, when the number of terminals is equal to or less than the threshold or less than the threshold, both the compression to the bandwidth and the disturbance of voice are reduced by transmitting the packet by unicast with a large bandwidth but a small loss. In addition, when the number of terminals is greater than or equal to the threshold or more than the threshold, packets are transmitted by multicast or broadcast with a small bandwidth but a large loss, and retransmission when packet loss occurs is performed by unicast. Both compression and voice disturbance are reduced.

Further, in the voice communication system according to the seventh aspect of the present invention, in contrast to any one of the first to sixth aspects, the transmitting device is a checksum packet that is a packet for constituting a packet that the receiving device cannot receive. Is further generated using two or more packets transmitted by the packet transmission unit, the packet transmission unit transmits three or more packets including the checksum packet, and the packet reception unit includes: When three or more packets including the checksum packet are received, and the packet acquisition unit cannot acquire the next packet to be output, the receiving apparatus outputs the next packet using the two or more packets including the checksum packet. The voice communication system further includes a packet generation unit that generates a packet.

With this configuration, when a packet loss occurs in the receiving apparatus and the next output packet cannot be received even if the retransmission request is transmitted one or more times, two or more packets including the checksum packet received by the receiving apparatus Can be used to restore lost packets. As a result, for example, the transmission / reception efficiency is increased as compared with the case where the retransmission request is continuously transmitted.

Further, in the voice communication system of the eighth invention, in contrast to any one of the first to seventh inventions, the voice data receiving unit is a voice receiving unit that receives analog voice, digitally converts the voice, AD conversion means for acquiring data, the voice output unit includes DA conversion means for converting the analog signal of the packet and acquiring voice, and voice output means for outputting the voice, and the receiving device receives the packet. A first speed information acquisition unit that acquires first speed information about a speed at which the unit receives a packet; a second speed information acquisition unit that acquires second speed information about a processing speed of the receiving device; This is information obtained from the two-speed information, and a shift complement process that is a process for complementing the clock frequency error based on the shift information regarding the clock frequency error between the transmitting device and the receiving device. A voice communication system, further comprising a complementary processing unit that performs.

With this configuration, it is possible to reduce the disturbance of the output sound caused by the clock frequency error that occurs between the transmitting device and each receiving device.

According to the present invention, it is possible to suppress the occurrence of packet loss in the receiving device, and to reduce or reduce the voice output delay in the receiving device while eliminating or reducing the audio disturbance generated in the receiving device.

Block diagram of a voice communication system in an embodiment Block diagram of the transmitter Block diagram of the receiver Flow chart for explaining the operation of the transmitter Flow chart for explaining the operation of the receiving apparatus External view of the computer system Internal configuration diagram of the computer system

Hereinafter, embodiments of a voice communication system and the like will be described with reference to the drawings. In addition, since the component which attached | subjected the same code | symbol in embodiment performs the same operation | movement, description may be abbreviate | omitted again.

In this embodiment, when a receiving apparatus cannot receive a packet to be output next, a transmitting apparatus that transmits a packet corresponding to the packet identifier included in the retransmission request to the receiving apparatus that transmitted the retransmission request by unicast. A voice communication system will be described.

Also, in the present embodiment, a voice communication system capable of customizing communication parameters such as the buffering amount and the timing of one or more retransmission requests will be described.

FIG. 1 is a block diagram of the voice communication system in the present embodiment. This voice communication system includes a transmission device 1 and two or more reception devices 2. The transmission device 1 and each of the two or more reception devices 2 are communicably connected via a network such as a LAN or the Internet, a wired or wireless communication line, and the like. The transmission device 1 transmits audio data. Each of the two or more receiving devices 2 receives and outputs the audio data.

FIG. 2 is a block diagram of the transmission device 1. The transmission device 1 includes a storage unit 11, a reception unit 12, a processing unit 13, a reception unit 14, a transmission unit 15, and an output unit 16. The storage unit 11 includes a terminal identifier storage unit 111, a terminal number information storage unit 112, an audio data storage unit 113, and a transmission time information storage unit 114. The reception unit 12 includes an audio data reception unit 121. The voice data reception unit 121 includes a voice reception unit 1211 and an AD conversion unit 1212. The processing unit 13 includes a terminal number information acquisition unit 131, a method determination unit 132, and a checksum packet generation unit 133. The receiving unit 14 includes a retransmission request receiving unit 141. The transmission unit 15 includes a packet transmission unit 151 and a packet retransmission unit 152.

FIG. 3 is a block diagram of the receiving device 2. The reception device 2 includes a terminal storage unit 21, a terminal reception unit 22, a terminal processing unit 23, a terminal reception unit 24, a terminal transmission unit 25, and a terminal output unit 26. The terminal storage unit 21 includes a packet storage unit 211, a time limit information storage unit 212, an output time information storage unit 213, and an erasure list storage unit 214. The terminal processing unit 23 includes a packet acquisition unit 231, a determination unit 232, a communication related information acquisition unit 233, a communication parameter change unit 234, a packet generation unit 235, a first speed information acquisition unit 236, a second speed information acquisition unit 237, and A complement processing unit 238 is provided. The terminal receiving unit 24 includes a packet receiving unit 241. The terminal transmission unit 25 includes a retransmission request transmission unit 251. The terminal output unit 26 includes an audio output unit 261. The audio output unit 261 includes a DA conversion unit 2611 and an audio output unit 2612.

The storage unit 11 constituting the transmission device 1 can store various types of information. The various information includes, for example, a terminal identifier described later, terminal number information described later, audio data described later, transmission time information described later, and the like.

The terminal identifier storage unit 111 stores two or more terminal identifiers that identify two or more receiving apparatuses 2 constituting the voice communication system. Each of the two or more terminal identifiers is, for example, a MAC address or an IP address, but may be anything. The two or more receiving apparatuses 2 constituting the voice communication system may be static or may change dynamically according to the detachment of the existing receiving apparatus 2 or the participation of a new receiving apparatus 2. In the latter case, the processing unit 13 adds a new terminal identifier to the terminal identifier storage unit 111 according to the separation of the existing receiving device 2 or the participation of a new receiving device 2, or the existing terminal identifier is added to the terminal identifier. By deleting from the storage unit 111 or the like, the terminal identifier storage unit 111 stores two or more terminal identifiers that identify the two or more receiving devices 2 that currently constitute the voice communication system.

The terminal number information storage unit 112 stores terminal number information. The number-of-terminals information is information indicating the number of receiving apparatuses 2 constituting the voice communication system (hereinafter, sometimes referred to as “number of terminals”). The terminal number information acquisition unit 131 described later acquires the current number of terminals using the number of terminal identifiers stored in the terminal identifier storage unit 111 and updates the terminal number information. As a result, the terminal number information storage unit 112 stores terminal number information indicating the current number of terminals.

The audio data storage unit 113 stores audio data at least temporarily. The audio data is audio data obtained by digitally converting analog audio, and is audio data transmitted to each of the two or more receiving devices 2. Usually, the audio data is composed of one or more packets, and the audio data storage unit 113 stores one or more packets in pairs with a packet identifier for identifying the packet. The packet identifier may be anything such as an identification number or a time stamp. In the following, identification numbers “1”, “2”,..., “K”,... Are used as examples of packet identifiers, and one packet constituting audio data may be described as “packet k” or the like. . However, the data structure of audio data does not matter.

The transmission time information storage unit 114 stores transmission time information. The transmission time information is information indicating the transmission time of one or more packets constituting the audio data. The transmission time information is, for example, a set of pairs of packet identifiers and transmission times. However, the data structure of transmission time information does not matter. Further, the transmission time information is not essential, and the transmission time information storage unit 114 may be omitted.

The reception unit 12 receives various types of information. The various information includes, for example, the above-described terminal identifier, the above-described audio data, the above-described transmission time information, and the like. Acceptance means, for example, acceptance of information input via an input device such as a keyboard, mouse, microphone, etc., reception of information transmitted via a network or communication line, recording medium such as an optical disk, magnetic disk, or semiconductor memory This is a concept including reception of information read out from.

The voice data receiving unit 121 receives voice data. The audio data receiving unit 121 normally receives analog audio and digitally converts the received audio. However, the audio data receiving unit 121 may receive audio data output from an external device such as a digital recorder, for example, and it does not matter where and how audio data is received. The audio data reception unit 121 normally stores the received audio data in the audio data storage unit 113. However, the audio data may be accumulated in a storage unit included in an external device such as a cloud server, for example, and the accumulation destination is not limited.

The voice receiving means 1211 normally receives analog voice via a voice input device such as a microphone. However, the voice receiving unit 1211 may receive a voice signal output from an external device such as an analog recorder, for example, and it does not matter where and how analog voice is received.

The AD conversion means 1212 digitally converts the analog voice received by the voice receiving means 1211 and acquires voice data. Digital conversion is a process of converting analog sound into digital sound data by sampling the sound in a cycle according to a clock output from an oscillation element or the like included in the AD conversion circuit. The oscillation element included in the AD conversion circuit is, for example, a crystal oscillation element, a ceramic resonator, or the like, but the type is not limited.

The processing unit 13 executes various processes. For example, the various types of processing are processing for acquiring terminal number information, determining a method for transmitting a packet, and generating a checksum packet to be described later. Further, the processing unit 13 temporarily stores the received audio data packet in the audio data storage unit 113. Further, the processing unit 13 may delete a packet (for example, a packet that is not subject to a retransmission request) for which a predetermined time has elapsed from the transmission from the audio data storage unit 113. Further, the processing unit 13 acquires the transmission time of each packet constituting the audio data stored in the audio data storage unit 113, and performs processing of accumulating the transmission time information in the transmission time information storage unit 114. The transmission time information will be described later. Further, the processing unit 13 acquires the transmission time from a clock (not shown), for example. However, it does not matter how the processing unit 13 acquires the transmission time.

The terminal number information acquisition unit 131 acquires terminal number information regarding the number of receiving apparatuses 2 that receive packets. The number of receiving apparatuses 2 that receive a packet is normally the number of receiving apparatuses 2 (the number of terminals described above) constituting the voice communication system. In this case, the terminal number information acquisition unit 131 uses the two or more terminal identifiers stored in the terminal identifier storage unit 111 to acquire terminal number information indicating the number of terminals.

However, among the two or more receiving apparatuses 2 constituting the voice communication system, the receiving apparatus 2 that continuously stops receiving packets for a certain period of time or longer than a certain period is included. The terminal number information acquisition unit 131 may acquire terminal number information indicating a number (actual terminal number) obtained by subtracting the number of receiving devices 2 (the number of dormant terminals) from the number of terminals. . For example, while the processing unit 13 adds a flag to a terminal identifier corresponding to a terminal determined to be a dormant terminal among two or more terminal identifiers stored in the terminal identifier storage unit 111, the terminal number information The acquisition unit 131 counts the number of two or more terminal identifiers stored in the terminal identifier storage unit 111, counts the number of terminal identifiers to which a flag is added, and calculates the number of terminals obtained from the former count. By subtracting the number of dormant terminals obtained by the latter counting, terminal number information indicating the number of active terminals can be acquired. Note that the number-of-terminals information indicating the number of working terminals can also be obtained by counting the number of terminal identifiers to which no flag is added.

The method determination unit 132 determines whether to adopt multicast or unicast as a method of transmitting a packet, according to the terminal number information acquired by the terminal number information acquisition unit 131. Multicast refers to data communication performed in a one-to-many manner by specifying an application identifier. Unicast refers to data communication performed on a one-to-one basis by designating a single terminal identifier. In general, multicast is less reliable for reasons such as light load on the network and packet loss is likely to occur, while unicast is more reliable for reasons such as packet loss is less likely to occur and load on the network. Is heavy. Therefore, for example, the method determining unit 132 may employ multicast when the number of terminals indicated by the terminal number information is greater than or equal to the threshold or greater than the threshold, and may employ unicast when less than or less than the threshold.

However, the method determination unit 132 may determine whether to adopt broadcast or unicast as a method for transmitting a packet, according to the terminal number information acquired by the terminal number information acquisition unit 131. . Broadcast refers to data communication that is performed in a one-to-one unspecified number without specifying a terminal identifier. Broadcast, like multicast, has a light load on the network, but has low reliability. In this case, for example, the method determining unit 132 may employ broadcast when the number of terminals indicated by the terminal number information is greater than or equal to the threshold or greater than the threshold, and may employ unicast when less than or less than the threshold.
Note that, within a single network such as a LAN or Fi-Fi (registered trademark) network, for example, there is no difference in the rate of occurrence of packet loss, the efficiency of voice communication, etc. between multicast and broadcast. It can be handled as a method of characteristics. Therefore, for example, unicast may be collectively referred to as “one-to-one communication” multicast and broadcast may be referred to as “one-to-many communication”.

The checksum packet generation unit 133 generates a checksum packet for configuring a packet that could not be received by the reception device 2 using two or more packets transmitted by the packet transmission unit 151. For example, the checksum packet generation unit 133 may generate two or more checksum packets corresponding to two or more packets constituting the audio data. In this case, for example, one packet (hereinafter sometimes simply referred to as “packet”) constituting the audio data and a checksum packet corresponding thereto are, for example, a common identification number “k”, A pair of an identifier (for example, “m”) indicating that it is a packet, and the latter is a combination of a common identification number “k” and an identifier (for example, “r”) indicating that it is a checksum packet May be identified. However, the data structure of the checksum packet does not matter.

For example, the packet identifiers of two or more packets transmitted by the packet transmission unit 151 are “m001”, “m002”,..., “M091”, “m092”, ..., “m100”, “m101”,. Assuming that the number of packets used for generating the checksum packet is 10, the checksum packet generation unit 133 converts the checksum packet “r100” corresponding to a certain packet “m100” into the past 10 packets including the packet. It may be generated using “m091”, “m092”,..., “M100”. Similarly, the checksum packet “r101” corresponding to the next packet “m101” may be generated using the past ten packets “m092”, “m093”,..., “M101” including the packet. In this case, the checksum packet “r001” is generated using the packet “m001”, the checksum packet “r002” is generated using the two packets “m001” and “m002”,... The checksum packet “r009” may be generated using nine packets “m001” to “m009”. However, any number of packets may be used for generating one checksum packet, and the method for generating the checksum packet is not limited.

The receiving unit 14 receives various types of information. The various information is, for example, a retransmission request.

The retransmission request receiving unit 141 receives a retransmission request from the receiving device 2. A retransmission request is an instruction for requesting retransmission of a packet. The retransmission request has a packet identifier.

The transmission unit 15 transmits various information. The various information includes, for example, a packet and a checksum packet.

The packet transmission unit 151 sequentially transmits two or more packets constituting the audio data received by the audio data reception unit 121. The packet transmitter 151 normally transmits a packet including a packet identifier. Further, the packet transmission unit 151 may transmit a packet associated with the packet identifier. The packet transmission unit 151 normally transmits two or more packets to two or more receiving devices identified by the two or more terminal identifiers stored in the terminal identifier storage unit 111 by multicast. However, packet transmission may be performed by broadcast or unicast. Desirably, the packet transmission unit 151 transmits a packet based on a method determined by the method determination unit 132 among multicast or broadcast and unicast.

The packet transmission unit 151 may also transmit the checksum packet generated by the checksum packet generation unit 133. The packet transmission unit 151 normally transmits three or more packets including a checksum packet. For example, the packet transmission unit 151 may alternately transmit a packet and a checksum packet. In that case, the packet transmission unit 151 may transmit the checksum packet immediately after the corresponding packet, or may transmit the checksum packet with a certain number of delays from the corresponding packet. That is, the packet transmitter 151 transmits the packets “m091”, “m092”,..., “M100”, “m101”,... And checksum packets “r091”, “r092”,. “R101”,... May be transmitted without delay, for example, “m091”, “r091”, “m092”, “r092”,... Delayed transmission may be performed such as “m096”, “r091”, “m097”, “r092”,. Thus, by delaying the transmission timing of the checksum packet with respect to the packet by two or more packets, there is an increased possibility that it can be restored even when a plurality of packets are continuously lost.

The packet retransmission unit 152 transmits a packet corresponding to the packet identifier included in the retransmission request received by the retransmission request reception unit 141 to the reception apparatus 2 that has transmitted the retransmission request by unicast. Since the retransmission request usually has a terminal identifier that identifies the receiving device 2 that has transmitted the retransmission request, or is transmitted in pairs with the terminal identifier, the packet retransmission unit 152 transmits the packet to the terminal. Retransmit to the receiving device 2 identified by the identifier. Note that the packet retransmission unit 152 is a packet that is normally temporarily stored in the audio data storage unit 113, acquires a packet corresponding to the packet identifier included in the retransmission request, and retransmits the packet to the receiving device 2.

The output unit 16 can output various types of information. Output includes display on a display, printing on a printer, sound output from a speaker, transmission to an external device, storage in a recording medium, delivery of processing results to other processing devices or other programs, etc. It is a concept that includes. The various information is, for example, the terminal number information described above. However, in the transmission apparatus 1, the output of information is not essential, and the output unit 16 can be omitted.

The terminal storage unit 21 constituting the receiving device 2 can store various types of information. The various types of information include, for example, the aforementioned packet, deadline information described later, output time information described later, and a loss list described later.

In the packet storage unit 211, a packet received by the packet receiving unit 241 is stored in a pair with a packet identifier for identifying the packet. The packet stored in a pair with the packet identifier may be stored as a packet having the packet identifier. The packet storage unit 211 normally stores a packet temporarily. Note that the packet storage unit 211 is, for example, a queue.

The term information storage unit 212 stores N pieces of term information corresponding to N terms (N is a natural number of 2 or more: the same applies hereinafter) from the first term to the Nth term. The term information is usually information indicating the term in which the packet receiving unit 241 receives a packet.
However, the time limit information may be information indicating a time limit for accumulating the packet received by the packet receiving unit 241 in the packet storage unit 211. A deadline is usually a relative deadline for a specific time. The relative time limit for the specific time may be, for example, a time “t−T” that is a time T before the time t at which the packet is output. However, the time limit may be an absolute time limit, for example, a time such as ○ hour, minute, second, and the time limit expression format is not limited.

The first time limit is, for example, information indicating a time limit for the packet receiving unit 241 to receive a packet to be output next. However, the first time limit may be, for example, information indicating a time limit for the packet reception unit 241 to accumulate the next output packet in the packet storage unit 211, and the expression format is not limited. The packet to be output next is usually a packet corresponding to the packet identifier next to the packet identifier of the packet output immediately before.

For example, when the packet receiving unit 241 does not receive a packet to be output next before the first time limit, the retransmission request transmitting unit 251 has a packet identifier that identifies the packet. This is information indicating a time limit for the packet receiving unit 241 to receive the packet in response to transmitting the request. The second deadline is information indicating a deadline from when the first retransmission request is transmitted until the reception of a packet corresponding to the retransmission request is waited. However, the second deadline is, for example, a packet identifier that allows the retransmission request transmission unit 251 to identify the packet when the packet reception unit 241 does not accumulate the packet to be output next in the packet storage unit 211 by the first deadline. May be information indicating a time limit for the packet receiving unit 241 to store the packet in the packet storage unit 211 in response to transmitting the first retransmission request having the In addition, expression formats, such as a 1st time limit and a 2nd time limit, are not ask | required.

The Nth time limit is usually information related to a period from when the N-1th retransmission request is transmitted until the Nth retransmission request is transmitted. The Nth time limit is information indicating a time limit for receiving the packet by the packet receiving unit 241 in response to transmitting the Nth retransmission request, for example. However, the Nth deadline is, for example, in response to the N−1th retransmission request, when the packet receiving unit 241 does not accumulate the packet in the packet storage unit 211 by the N−1th deadline. It may be information indicating a time limit for the packet reception unit 241 to accumulate the packet in the packet storage unit 211 in response to transmitting a retransmission request.

The N pieces of deadline information are, for example, first deadline information indicating a first deadline {t (k) -T (1)}, and second deadline indicating a second deadline {t (k) -T (2)}. The Nth deadline information indicating the deadline information,..., And the Nth deadline {t (k) −T (N)} may be used. However, the data structure of each N pieces of time limit information does not matter. The first time limit may be the same as the second time limit, the Nth time limit, or the like. In such a case, only the first time limit may be stored in the time limit information storage unit 212.

The output time information storage unit 213 stores output time information. The output time information is information indicating the time when the audio output unit 261 outputs a packet. The output time information is composed of a set of pairs of packet identifiers (1, 2,..., K,...) And output times (t (1), t (2),..., T (k),...), For example. Is done. The output time t (k) is, for example, a time limit for outputting the packet k, and may be a threshold used when the audio output unit 261 determines whether or not a timeout has occurred. However, the data structure of the output time information does not matter.

The disappearance list storage unit 214 stores the disappearance list. The erasure list is a list for registering packet identifiers of lost packets in pairs with the number of times a retransmission request having the packet identifier is transmitted. The lost packet is a packet that has not been received by the packet receiving unit 241 by the time limit indicated by the time limit information. The erasure list is information having at least one set of a packet identifier and the number of times a retransmission request is transmitted, for example. The disappearance list may not be managed. In such a case, for example, when the next packet after the output packet has not been received for a predetermined time or longer from the output of the previous packet, the process proceeds to a process of acquiring the next packet.

The terminal reception unit 22 receives various types of information. The various information is, for example, the time limit information described above. However, the time limit information or the like may be received by the receiving unit 14, for example, and the terminal receiving unit 22 may be omitted.

The terminal processing unit 23 executes various processes. The various processes include, for example, the packet acquisition unit 231, the determination unit 232, the communication related information acquisition unit 233, the communication parameter change unit 234, the packet generation unit 235, the first speed information acquisition unit 236, and the second speed information acquisition unit 237. , Processing performed by the complement processing unit 238 and the like. Also, the terminal processing unit 23 determines the output time of each of two or more packets stored in the packet storage unit 211, and performs a process of storing the output time information in the output time information storage unit 213. The output time information will be described later.

The packet acquisition unit 231 is a packet stored in the packet storage unit 211, and acquires a packet to be output next using a packet identifier corresponding to the packet. The packet acquisition unit 231 stores, for example, a packet corresponding to the identifier next to the packet identifier of the packet output immediately before (if the packet identifier is a numerical value, the number obtained by adding 1 to the packet identifier of the immediately preceding packet). It searches from the part 211 and acquires. For example, the packet acquisition unit 231 uses the output time information stored in the output time information storage unit 213 and the current time to output the next one of the two or more packets stored in the packet storage unit 211. The packet to be performed may be specified. The current time can be acquired from an external device such as an MPU built-in clock or an NPT server, for example. Moreover, the algorithm which the packet acquisition part 231 searches for the next packet from the packet storage part 211 is not ask | required.

The determining unit 232 normally determines whether or not the packet receiving unit 241 has received the next packet to be output by the first time limit, using the packet identifier corresponding to the packet. The determination as to whether or not the packet receiving unit 241 has received the next packet to be output by the first time limit is the determination of whether or not the packet acquisition unit 231 has acquired the next output packet by the first time limit. You may think that it is equivalent. Whether the packet receiving unit 241 has received the next packet to be output by the first time limit is determined by whether the audio output unit 261 has output the next output packet by the first time limit. You may think that it is equivalent. The determination unit 232 may also determine whether the packet reception unit 241 has received the next packet to be output before the Nth time limit. The determination unit 232 determines whether or not the packet receiving unit 241 has accumulated the next output packet in the packet storage unit 211 from the first time limit to the Nth time limit, using the packet identifier corresponding to the packet. May be.

The communication related information acquisition unit 233 acquires communication related information. The communication related information is information related to communication between the transmission device 1 and the reception device 2. The communication-related information is, for example, the number of terminals that is the number of receiving apparatuses 2 that receive packets, error rate information regarding that the packet receiving unit 241 cannot receive the next packet to be output, or the packet receiving unit 241 outputs next May include any information of normal rate information regarding the fact that the received packet could be received.

The communication related information acquisition unit 233 can acquire the number of terminals by receiving, for example, the terminal number information acquired by the terminal number information acquisition unit 131 from the transmission device 1.

In addition, the communication related information acquisition unit 233 displays the error rate information or the normal rate information, for example, the number of packets stored in the packet storage unit 211 (or the number of packet identifiers paired with the packet) and the loss. It may be acquired using the number of packet identifiers registered in the loss list stored in the list storage unit 214. For example, when the number of packets stored in the packet storage unit 211 is 1000 and 10 packet identifiers are registered in the loss list, the error rate is 10/1000 (= 1%), and the normal rate is 990 / It is calculated as 1000 (= 99%). However, the content of communication-related information, the acquisition destination, the acquisition method, etc. are not limited.

The communication parameter changing unit 234 changes one or more communication parameters according to the communication related information. The communication parameters include, for example, the capacity of the packet storage unit 211, the number N of times that the retransmission request transmission unit 251 can transmit a retransmission request, and N time limits from the first time limit to the Nth time limit corresponding to the number N. One or more types of information. For example, when the communication-related information includes the number of terminals, the communication parameter changing unit 234 increases or decreases the capacity of the packet storage unit 211 (capacity of memory capable of buffering packets) according to the number of terminals, or increases the number N of times. Or it may be reduced, or the N deadlines may be shortened or lengthened. More specifically, the communication parameter changing unit 234 increases the capacity of the packet storage unit 211 in preparation for an increase in error rate or a decrease in normal rate due to an increase in traffic when the number of terminals is greater than or equal to the threshold. It is also possible to increase the number of times N or shorten the N deadlines. In addition, when the number of terminals is less than or less than the threshold, the communication parameter change unit 234 decreases the capacity of the packet storage unit 211 in anticipation of a decrease in the error rate or an increase in the normal rate due to a decrease in traffic. N may be reduced or N deadlines may be lengthened.

When the communication related information includes error rate information or normal rate information, the communication parameter changing unit 234 increases or decreases the capacity of the packet storage unit 211 or increases the number N of times according to the error rate information or normal rate information. Or it may be reduced, or the N deadlines may be shortened or lengthened. More specifically, the communication parameter changing unit 234 increases the capacity of the packet storage unit 211, increases the number of times N, or shortens the N deadlines when the error rate is greater than or equal to the threshold. You may do it. Further, the communication parameter changing unit 234 may reduce the capacity of the packet storage unit 211, decrease the number of times N, or increase the N deadlines when the error rate is less than or less than the threshold. good.

When the packet acquisition unit 231 cannot acquire the next packet to be output, the packet generation unit 235 uses the two or more packets including the checksum packet that are received by the packet reception unit 241 to output next. Packet to generate. For example, a packet and a checksum packet are transmitted as “m091”, “r091”, “m092”, “r092”,..., “M100”, “r100”,. "Is lost, the packet generator 235 may generate the lost packet“ m100 ”using the nine packets“ m091 ”to“ m099 ”and“ r100 ”received by the packet receiver 241. it can. “M...” Is a packet output from the receiving device 2. “R...” Is a checksum packet.

The first speed information acquisition unit 236 acquires first speed information. The first speed information is information related to the speed at which the packet receiving unit 241 receives a packet. The first speed information may be referred to as a first reception rate. The first speed information is information such as 1000 packets / second, for example. The speed indicated by the first speed information is a speed according to the clock of the transmission apparatus 1. As described above, the clock of the transmission apparatus 1 is a clock used when the AD conversion unit 1212 of the transmission apparatus 1 digitally converts sound.

The second speed information acquisition unit 237 acquires second speed information. The second speed information is information regarding the processing speed of the receiving device 2. The information related to the processing speed of the receiving device 2 is, for example, the speed at which the DA conversion unit 2611 performs analog conversion of the packet. However, the second speed information is information fed back from the DA conversion unit 2611, and may be information indicating the progress status of the analog conversion process (for example, a delay with respect to a predetermined processing speed, etc.). It doesn't matter. The speed indicated by the second speed information is preferably the same as the speed indicated by the first speed information, but the two speeds are different from each other in the clock difference between the transmitting device 1 and the receiving device 2 (for example, the respective conversions). For example, “1000 packets / second” vs. “1000.1 packets / second”, that is, 10000: 1001, etc., may occur due to the oscillation frequency mismatch of the oscillation elements of the circuit. Such a deviation generally increases with the passage of time.

The complement processing unit 238 performs a shift complement process, which is a process of complementing the clock frequency error, based on the shift information. The deviation information is information acquired from the first speed information and the second speed information, and refers to information regarding an error in the clock frequency between the transmission device 1 and the reception device 2. The deviation information may be information indicating a ratio of two speeds corresponding to the first speed information and the second speed information, for example. The shift complement process is a process for setting the ratio of two speeds corresponding to the first speed information and the second speed information to 1 or approaching 1. For example, if the ratio of the two speeds corresponding to the first speed information and the second speed information is a: b, the clock cycle on the receiving device 2 side is lengthened by “| b−a | / b” (a An expansion / contraction process that is a process of <b) or shortening (a> b) may be used. Such expansion / contraction processing is, for example, resampling / stretching for expanding / contracting the time interval of existing audio data, but may include interpolation processing for interpolating between existing audio data with estimated values. However, the method of misalignment complementing processing does not matter. The deviation information may be information indicating a difference between two speeds corresponding to the first speed information and the second speed information, for example. By such offset compensation processing, it is possible to reduce the disturbance of the output sound (for example, sound interruption, sound skipping, etc.) caused by the clock frequency error occurring between the transmission device 1 and the reception device 2.

The terminal receiving unit 24 can receive various types of information. The various information is, for example, the packet described above.

The packet receiving unit 241 receives a packet from the transmission device 1 and accumulates it in the packet storage unit 211. The packet receiving unit 241 normally receives two or more packets, and accumulates the received two or more packets in pairs with a packet identifier that identifies the packet. Note that accumulating in pairs includes that a packet has a packet identifier. The packet receiving unit 241 may receive three or more packets including the checksum packet described above.

The terminal transmission unit 25 can transmit various types of information. The various information is, for example, the above-described retransmission request.

The retransmission request transmission unit 251 transmits a retransmission request having a packet identifier for identifying the packet to the transmission device 1 when the packet reception unit 241 does not acquire the next output packet by the first time limit. The retransmission request usually further includes a terminal identifier for identifying the receiving device 2. However, the retransmission request transmission unit 251 may transmit a retransmission request having only a packet identifier to a pair with a terminal identifier that identifies the receiving device 2. The retransmission request transmission unit 251 normally transmits a retransmission request to the transmission apparatus 1 by unicast. This is to reduce the possibility that the retransmission request itself is lost.

The retransmission request transmission unit 251 transmits a retransmission request to the transmission device 1 when the determination unit 232 determines that the packet reception unit 241 has not received the next packet to be output by the first time limit.

The retransmission request transmission unit 251 transmits the Nth retransmission request to the transmission device 1 when the packet reception unit 241 does not receive the next packet to be output by the Nth time limit.

As the retransmission request transmission unit 251 transmits a retransmission request having a packet identifier for identifying a packet that has not been received by the packet reception unit 241 by the first deadline indicated by the first deadline information, A pair with the initial value “1” of the number of times of transmission of a retransmission request having a packet identifier (hereinafter sometimes simply referred to as “number of times”) is registered in the erasure list.

The retransmission request transmission unit 251 transmits an N-th retransmission request having a packet identifier for identifying a packet that has not been received by the packet reception unit 241 by the Nth deadline indicated by the Nth deadline information to the transmission device 1. Accordingly, the number of times paired with the packet identifier registered in the loss list is updated to N.

The terminal output unit 26 can output various types of information. The various information is, for example, the packet described above.

When the packet acquisition unit 231 acquires the next output packet, the audio output unit 261 outputs the next output packet as a sound. When the packet acquisition unit 231 does not acquire the next packet to be output, the voice output unit 261 outputs, for example, a packet generated by the packet generation unit 235 and corresponding to the packet to be output next. Also good. If the packet acquisition unit 231 does not acquire the next packet (for example, packet k), the audio output unit 261 determines whether or not a timeout has occurred using the output time (for example, output time t (k)) included in the deadline information, for example. When the packet generator 235 determines that a timeout has occurred, the packet generator 235 may generate a packet corresponding to the next packet to be output.

The DA conversion unit 2611 performs analog conversion on the packet acquired by the packet acquisition unit 231 to generate an analog audio signal. Analog conversion is a process in which digital audio data is read in a cycle according to a clock output from an oscillation element or the like included in a DA conversion circuit, an analog waveform is generated, and converted into an analog audio signal.

The audio output unit 2612 outputs the audio signal generated by the DA conversion unit 2611 through an output device such as a speaker.

Storage unit 11, terminal identifier storage unit 111, terminal number information storage unit 112, voice data storage unit 113, transmission time information storage unit 114, terminal storage unit 21, packet storage unit 211, time limit information storage unit 212, output time information storage The unit 213 and the disappearance list storage unit 214 are preferably non-volatile recording media, but can also be realized by volatile recording media.

It does not matter how information such as terminal identifiers is stored in the storage unit 11 or the like. For example, information may be stored in the storage unit 11 or the like via a recording medium, information transmitted via a communication line or the like may be stored in the storage unit 11 or the like, Alternatively, information input via the input device may be stored in the storage unit 11 or the like.

The accepting unit 12 and the terminal accepting unit 22 can be realized by a device driver of an input device or by an input device and its device driver. The input device may be anything such as a microphone, a keyboard, a mouse, or a touch panel. The voice data reception unit 121 and the voice reception unit 1211 can be realized by a device driver of a voice input device such as a microphone, or by a voice input device and its device driver. The AD conversion unit 1212 can be realized by, for example, an AD conversion circuit.

Processing unit 13, terminal number information acquisition unit 131, method determination unit 132, checksum packet generation unit 133, terminal processing unit 23, packet acquisition unit 231, determination unit 232, communication related information acquisition unit 233, communication parameter change unit 234, The packet generation unit 235, the first rate information acquisition unit 236, the second rate information acquisition unit 237, and the complement processing unit 238 can usually be realized by an MPU, a memory, or the like. The processing procedure of the processing unit 13 or the like is usually realized by software, and the software is recorded on a recording medium such as a ROM. However, it may be realized by hardware (dedicated circuit).

The receiving unit 14, the retransmission request receiving unit 141, the terminal receiving unit 24, and the packet receiving unit 241 are usually realized by wireless or wired communication means, but may be realized by means for receiving broadcasts.

The transmission unit 15, the packet transmission unit 151, the packet retransmission unit 152, the terminal transmission unit 25, and the retransmission request transmission unit 251 are normally realized by wireless or wired communication means, but may be realized by broadcasting means.

The output unit 16 and the terminal output unit 26 may or may not include an output device such as a display or a speaker. The output unit 16 and the like can be realized by output device driver software, or by an output device and its driver software. The audio output unit 261 and the audio output unit 2612 may or may not include an audio output device such as a speaker. The DA conversion unit 2611 can be realized by, for example, a DA conversion circuit.

Next, the operation of the voice communication system will be described with reference to the flowcharts of FIGS. FIG. 4 is a flowchart for explaining the operation of the transmission apparatus 1.

(Step S401) The processing unit 13 executes initial processing. The initial process includes, for example, a process of setting an initial value in system information indicating a system for transmitting a packet. The initial value is normally “multicast”, but may be “unicast”. The initial value may be the value of the method information at the end of the previous operation. The initial value may be stored in the storage unit 11 or may be held by the method determination unit 132, and the location thereof is not limited.

(Step S402) The voice data receiving unit 121 determines whether the voice receiving unit 1211 has received voice. If the voice receiving unit 1211 receives a voice, the process proceeds to step S403. If not received, the process proceeds to step S404.

(Step S403) The AD conversion unit 1212 digitally converts the voice received by the voice reception unit 1211 to obtain voice data. The audio data reception unit 121 accumulates the acquired audio data in the audio data storage unit 113. As a result, in the audio data storage unit 113, two or more packets constituting the audio data received by the audio data reception unit 121 are stored in pairs with packet identifiers for identifying each packet. Then, it returns to step S402.

(Step S404) The processing unit 13 sets an initial value “1” to the variable i.

(Step S405) The processing unit 13 determines whether or not the i-th packet exists in the audio data storage unit 113. If there is an i-th packet in the voice data storage unit 113, the process proceeds to step S406, and if not, the process returns to step S402.

(Step S406) The packet transmission unit 151 transmits the i-th packet to two or more receiving devices identified by two or more terminal identifiers stored in the terminal identifier storage unit 111 in a scheme indicated by the scheme information. . The packet transmission unit 151 is the i-th packet stored in the audio data storage unit 113, and a flag indicating transmission may be added to the transmitted packet corresponding to the transmitted packet.

(Step S407) The processing unit 13 determines whether to generate a checksum packet. For example, the processing unit 13 may determine that a checksum packet is always generated when generating checksum packets for all of two or more packets constituting audio data, or a predetermined number (for example, two, ten, etc.). However, it may be determined that the data is generated at a rate of once every predetermined number of times. If a checksum packet is to be generated, the process proceeds to step S408; otherwise, the process proceeds to step 410.

(Step S408) The checksum packet generation unit 133 generates a checksum packet corresponding to the packet using two or more transmitted packets including the packet. Since the checksum packet generation procedure has been described above, it will not be repeated.

(Step S409) The packet transmission unit 151 also transmits the checksum packet generated by the checksum packet generation unit 133 to the two or more receiving apparatuses using the method indicated by the method information. Thereafter, the process proceeds to step S410.

(Step S410) The processing unit 13 increments the variable i. Thereafter, the process returns to step S405.

(Step S411) The processing unit 13 determines whether or not the retransmission request receiving unit 141 has received a retransmission request. If the retransmission request receiving unit 141 receives a retransmission request, the process proceeds to step S412. If not received, the process proceeds to step S413.

(Step S412) The packet retransmission unit 152 transmits the packet corresponding to the packet identifier included in the retransmission request received by the retransmission request reception unit 141 to the reception device 2 that has transmitted the retransmission request by unicast. Then, it returns to step S402.

(Step S413) The processing unit 13 determines whether it is time to acquire the terminal number information. Specifically, for example, the processing unit 13 counts the clock, and determines that it is the timing to acquire the terminal number information when the first number indicating the counting result reaches the first predetermined number. The process of resetting the number of times may be repeatedly executed. If it is time to acquire the terminal number information, the process proceeds to step S414. If it is not time to acquire the terminal number information, the process returns to step S402.

(Step S414) The terminal number information acquisition unit 131 uses the two or more terminal identifiers stored in the terminal identifier storage unit 111 to acquire terminal number information indicating the number of terminals.

(Step S415) The method determining unit 132 determines whether to adopt multicast or unicast as a method of transmitting a packet according to the terminal number information acquired by the terminal number information acquiring unit 131. Specifically, the method determining unit 132 may employ multicast when the number of terminals indicated by the terminal number information is greater than or equal to a threshold or greater than the threshold, and may employ unicast when less than or less than the threshold.

(Step S416) The method determining unit 132 sets the determined method in the method information. Then, it returns to step S402.

Note that the processing according to the flowchart of FIG. 4 starts, for example, in response to power-on of the transmission device 1 and ends in response to power-off of the transmission device 1 or interruption of an end process. However, the trigger for starting or ending the process does not matter.

Although omitted in FIG. 4, the processing unit 13 monitors the addition of a new receiving device 2 and the presence or absence of the existing receiving device 2, and if there is a new receiving device 2, While the terminal identifier for identifying the receiving device 2 is accumulated in the terminal identifier storage unit 111, if there is a detachment of the existing receiving device 2, the terminal identifier for identifying the receiving device 2 is deleted from the terminal identifier storage unit 111. Do.

In the description of the flowchart of FIG. 4, “multicast” may be read as “broadcast”.

FIG. 5 is a flowchart for explaining the operation of the receiving device 2.

(Step S501) The packet receiver 241 determines whether or not a packet has been received. If a packet has been received, the process proceeds to step S502. If no packet has been received, the process proceeds to step S503.

(Step S502) The packet receiving unit 241 stores the received packet in the packet storage unit 211 in a pair with a packet identifier for identifying the packet. Accordingly, the terminal processing unit 23 determines the output time of each of two or more packets stored in the packet storage unit 211, and accumulates the output time information in the output time information storage unit 213. Thereafter, the process returns to step S501.

(Step S503) The audio output unit 261 determines whether or not the packet to be output next is in the packet storage unit 211. If the packet to be output next is in the packet storage unit 261, the process proceeds to step S504, and if not, the process proceeds to step S505.

(Step S504) The packet acquisition unit 231 acquires the packet from the packet storage unit 211. Thereafter, the process proceeds to step S507.

(Step S505) The audio output unit 261 determines whether or not a timeout has occurred. For example, the audio output unit 261 may determine that a timeout has occurred when the elapsed time from the previous packet output exceeds or exceeds the threshold. If it is determined that the time is out, the process proceeds to step S506. If it is determined that the time is not out, the process proceeds to step S508.

(Step S506) The packet generation unit 235 is a packet received by the packet reception unit 241, and generates a packet to be output next using two or more packets including a checksum packet. Since the procedure for generating the next packet to be output has been described above, it will not be repeated. Thereafter, the process proceeds to step S507.

(Step S507) The DA conversion unit 2611 performs analog conversion on the packet acquired by the packet acquisition unit 231 or the packet generated by the packet generation unit 235 to generate an audio signal. The audio output unit 2612 outputs the audio signal generated by the DA conversion unit 2611 via an output device such as a speaker. Thereafter, the process returns to step S501.

(Step S508) The terminal processing unit 23 determines whether it is time to transmit a retransmission request. Specifically, for example, the terminal processing unit 23 counts the clock, determines that it is the timing to output the packet when the second number indicating the counting result reaches the second predetermined number, and determines the second number of times. The process of resetting may be repeated. If it is time to transmit a retransmission request, the process proceeds to step S509. If it is not time to transmit a retransmission request, the process proceeds to step S514.

(Step S509) The retransmission request transmission unit 251 executes a retransmission request transmission process that is a process of transmitting a retransmission request for the next packet. Specifically, the retransmission request transmission unit 251 transmits a retransmission request having a packet identifier for identifying the next packet to the transmission device 1 in a pair with a terminal identifier for identifying the reception device 2. In the case of the first retransmission request, the retransmission request transmission unit 251 registers the pair of the packet identifier and the number of times i (initial value “1”) in the erasure list stored in the erasure list storage unit 214. In the case of the second retransmission request, a process of incrementing the number of times i may be executed. Thereafter, the process returns to step S501.

(Step S510) The terminal processing unit 23 determines whether it is time to acquire speed information. Specifically, for example, the terminal processing unit 23 counts the clock, and determines that it is the timing to acquire the speed information when the third number indicating the counting result reaches the third predetermined number. The process of resetting the number of times may be repeatedly executed. If it is time to acquire speed information, the process proceeds to step S511. If it is not time to acquire speed information, the process proceeds to step S514.

(Step S511) The first speed information acquisition unit 236 acquires first speed information. Since the first speed information has been described above, it will not be repeated.

(Step S512) The second speed information acquisition unit 237 acquires the second speed information. Since the second speed information has been described above, it will not be repeated.

(Step S513) The complement processing unit 238 acquires the shift information using the acquired first and second speed information, and performs the shift complement process based on the acquired shift information. Since the shift information and the shift complement processing have been described above, they will not be repeated. Thereby, the error of the clock frequency between the transmission device 1 and the reception device 2 is complemented by the sound expansion / contraction process or the like, and the disturbance of the output sound due to the error is eliminated or reduced. Thereafter, the process returns to step S501.

(Step S514) The terminal processing unit 23 determines whether it is time to acquire communication-related information. Specifically, for example, the terminal processing unit 23 counts the clock, determines that it is the timing to acquire the communication related information when the fourth number indicating the counting result reaches the fourth predetermined number, The process of resetting the four times may be repeatedly executed. If it is time to acquire communication-related information, the process proceeds to step S515. If it is not time to acquire communication-related information, the process returns to step S501.

(Step S515) The communication related information acquisition unit 233 acquires communication related information including any one of the number of terminals, error rate information, and normal rate information, for example. Note that the procedure for acquiring communication related information has been described above and will not be repeated.

(Step S516) The communication parameter changing unit 234 determines the capacity of the packet storage unit 211, the number N of times that the retransmission request transmission unit 251 can transmit a retransmission request, and N from the first time limit to the Nth time limit corresponding to the number N. The communication parameter, which is one or more types of information within the period, is changed according to the communication related information acquired by the communication related information acquisition unit 233. Since the communication parameter changing procedure has been described above, it will not be repeated. Thereafter, the process returns to step S501.

Note that the processing according to the flowchart of FIG. 5 starts, for example, in response to power-on of the receiving device 2 and ends in response to power-off of the receiving device 2 or an interruption in termination processing. However, the trigger for starting or ending this process does not matter.
Further, in the flowchart of FIG. 5, when it is determined that there is no next packet to be output, a retransmission request is transmitted in a period until a timeout occurs, and when the timeout occurs, two or more packets including a checksum are used. For example, if it is determined that there is no next packet to be output, it is determined whether or not two or more packets including a checksum necessary for completion are prepared. If not, a retransmission request may be transmitted. Even if a time-out occurs, if there is no packet to be output next and complementation by two or more packets including a checksum cannot be performed, the output of the next output packet is abandoned and smoothing processing is performed. Good. The smoothing process is a process for reducing gap noise, which is noise generated in a gap between a packet output immediately before the next output packet and a packet output immediately after the next output packet. The smoothing process is, for example, a process of fading out the voice of the packet output immediately before to the silence and then fading in from the silence to the voice level of the packet output immediately after. Any process may be used as long as the process is reduced.

In the flowchart of FIG. 5, the following steps S509a to S509e may be executed instead of the above step S509.

(Step S509a) The determination unit 232 acquires the current time from the MPU built-in clock. Alternatively, the determination unit 232 may acquire the packet identifier of the packet output immediately before by the audio output unit 261.

(Step S509b) The determination unit 232 uses the acquired current time and the output time information stored in the output time information storage unit 213 to output the output time after the first time T (1) from the current time. A packet identifier for identifying a packet is acquired from the packet storage unit 211. Alternatively, the determination unit 232 acquires, from the audio output unit 261, for example, a packet identifier obtained by adding a natural number (for example, “N−1” or a natural number equal to or less than that) to the packet identifier of the packet output immediately before by the audio output unit 261. May be.

(Step S509c) The determination unit 232 determines whether or not a packet whose output time is a first time T (1) after the current time has been received. For example, when the packet identifier for identifying the packet whose output time is after the first time T (1) from the current time can be acquired, the determination unit 232 determines that the packet has been received, and the packet identifier May not be received, it may be determined that the packet has not been received. Alternatively, the determination unit 232 may determine whether a packet identified by the packet identifier acquired from the audio output unit 261 as described above has been received. If the packet identified by the packet identifier has not been received, the process proceeds to step S509d. If the packet has been received, the process proceeds to step S509e.

(Step S510d) The retransmission request transmission unit 251 executes a first retransmission request transmission process that is a process of transmitting a first retransmission request for the packet identified by the packet identifier. The first retransmission request transmission process will be described later.

(Step S510e) The retransmission request transmission unit 251 executes a second retransmission request transmission process, which is a process of transmitting the second to Nth retransmission requests for the packet identified by the packet identifier registered in the loss list. The first retransmission request transmission process will be described later. Thereafter, the process returns to step S501.

In the first retransmission request transmission process in step S510d, for example, the following steps S601 to S603 may be executed.

(Step S601) The retransmission request transmission unit 251 transmits a first retransmission request having a packet identifier for identifying the packet to the transmission device 1.

(Step S602) The retransmission request transmission unit 251 sets an initial value “1” for the number of times i paired with the packet identifier.

(Step S603) The retransmission request transmission unit 251 registers the pair of the packet identifier and the number of times i in the erasure list stored in the erasure list storage unit 214. Thereafter, the process returns to the upper process.

In the second retransmission request transmission process in step S510e, for example, the following steps S701 to S708 may be executed.

(Step S701) The retransmission request transmission unit 251 sets an initial value “1” in the variable j.

(Step S702) The retransmission request transmission unit 251 determines whether or not the j-th packet identifier is in the erasure list. If there is a j-th packet identifier in the loss list, the process proceeds to step S703, and if not, the process returns to the upper process.

(Step S703) The retransmission request transmission unit 251 determines whether the packet identified by the jth packet identifier has been received. Specifically, for example, if the packet identified by the jth packet identifier is stored in the packet storage unit 211, the retransmission request transmission unit 251 has received the packet identified by the jth packet identifier. If it is determined that it has not been stored, it may be determined that it has not been received. If the packet identified by the jth packet identifier has been received, the process proceeds to step S704, and if not received, the process proceeds to step S705.

(Step S704) The retransmission request transmission unit 251 deletes the pair of the jth packet identifier and the number of times i from the erasure list. Thereafter, the process proceeds to step S708.

(Step S705) The retransmission request transmission unit 251 determines whether the number of times i corresponding to the jth packet identifier is equal to or greater than the number of times N. If the number of times i corresponding to the j-th packet identifier is not equal to or greater than the number N (that is, the number i is less than the number N), the process proceeds to step S706. If the number i is equal to or greater than the number N, the process proceeds to step S708.

(Step S706) The retransmission request transmission unit 251 increments the number of times i corresponding to the j-th packet identifier.

(Step S707) The retransmission request transmission unit 251 transmits the i-th retransmission request having the j-th packet identifier to the transmission device 1. Thereafter, the process returns to step S703.

(Step S708) The retransmission request transmission unit 251 increments the variable j. Thereafter, the process returns to step S702.

According to the first retransmission request transmission process in step S501d and the second retransmission request transmission process in step S501e, the reception device 2 is a packet after a packet to be output next (for example, packet “k”), When there is no packet (for example, packet “k + 4”, etc.) that should be buffered at the time of outputting the next packet, a retransmission request for the lost packet is transmitted, and the transmission apparatus 1 receives the lost packet. By transmitting to the apparatus 2 by unicast, the possibility that the lost packet is successfully recovered before the output time of the lost packet arrives increases.

Hereinafter, specific operations of the voice communication system according to the present embodiment will be described. However, this operation example does not limit the present invention in any way, and needless to say, the operation example can be changed as appropriate.

Currently, the transmitter 1 is transmitting Wi-Fi (registered trademark), for example, voice data of a voice that is simultaneously interpreted at an international conference hall or a stadium. Each of the two or more receiving apparatuses 2 receives voice data and outputs a voice of simultaneous interpretation as voice.

The terminal identifier storage unit 111 of the transmission device 1 stores two or more terminal identifiers that identify the two or more (for example, several hundreds, thousands, etc.) of the reception devices 2. The number-of-terminals information storage unit 112 stores number-of-terminals information indicating the number of receiving apparatuses 2 (number of terminals) constituting the voice communication system. The storage unit 11 stores method information indicating “multicast”. In the audio data storage unit 113, two or more packets constituting the audio data received by the audio data receiving unit 121 so far are packet identifiers (for example, “1”, “2”,..., “ k ″,... are stored in pairs.

In the packet storage unit 211 of each of the two or more receiving apparatuses 2, packets received by the packet reception unit 241 so far are stored in pairs with packet identifiers that identify the packets. Note that the capacity of the packet storage unit 211 may be different for each terminal.

The deadline information storage unit 212 stores N pieces of deadline information corresponding to N deadlines from the first deadline to the Nth deadline. The N pieces of deadline information are first deadline information indicating the first deadline, second deadline information indicating the second deadline,..., And Nth deadline information indicating the Nth deadline. Note that the natural number N may be different for each terminal.

In the transmission apparatus 1, when the audio data receiving unit 121 receives audio data, two or more packets constituting the audio data are accumulated in the audio data storage unit 113 in pairs with a packet identifier for identifying the packet. .

The packet transmission unit 151 determines whether it is time to transmit a packet. If it is time to transmit a packet, the packet identifier 151 stores two or more packets stored in the voice data storage unit 113. Are sequentially transmitted to the two or more receiving devices identified by the two or more terminal identifiers stored in the network using the method indicated by the method information (currently multicast).

The checksum packet generation unit 133 generates a checksum packet corresponding to the packet transmitted by the packet transmission unit 151 using two or more transmitted packets including the packet. For example, when the packet transmitted by the packet transmission unit 151 is the packet “m100” and the number of packets used to generate one checksum packet is 10, the checksum packet generation unit 133 determines that the packet “m100” May be generated using the past 10 packets “m091”, “m092”,..., “M100” including the packet “m100”. After transmitting the packet “m100”, the packet transmission unit 151 also transmits the checksum packet “r100” generated by the checksum packet generation unit 133 in this manner to the two or more receiving devices in the method.

By repeating the above process, two or more packets constituting the audio data and two or more checksum packets corresponding to the two or more packets are alternately transmitted to the two or more receiving apparatuses 2 by multicast. Sent.

The processing unit 13 also determines whether or not the retransmission request receiving unit 141 has received a retransmission request. When the retransmission request receiving unit 141 receives the retransmission request, the packet retransmission unit 152 acquires a packet corresponding to the packet identifier included in the retransmission request from the voice data storage unit 113, and transmits the acquired packet to the retransmission request. Unicast to the receiving device 2 that has been transmitted.

The processing unit 13 also determines whether or not it is time to acquire the terminal number information. When it is time to acquire the terminal number information, the terminal number information acquisition unit 131 acquires terminal number information indicating the number of terminals using two or more terminal identifiers stored in the terminal identifier storage unit 111. The method determining unit 132 determines whether to adopt multicast or unicast as a method for transmitting packets according to the number-of-terminals information. For example, when the number of terminals indicated by the number-of-terminals information is greater than or equal to the threshold value or greater than the threshold value, it may be determined to employ multicast, and when less than or less than the threshold value, unicast may be employed. The method determining unit 132 sets the method determined in this way in the method information. Thus, for example, when the number of terminals falls below the threshold due to the withdrawal of an existing terminal, the packet transmission method is changed from multicast to unicast. Thereafter, when the number of terminals exceeds a threshold value due to the participation of a new terminal, the packet transmission method is changed from unicast to multicast.

In each of the two or more receiving apparatuses 2, when the packet receiving unit 241 receives a packet, the packet is stored in the packet storage unit 211 in a pair with a packet identifier for identifying the packet.

The packet acquisition unit 231 determines whether or not it is time to output a packet. If it is time to output a packet, the packet acquisition unit 231 acquires the next packet to be output from the packet storage unit 211. Specifically, the packet acquisition unit 231 stores the packet identifier of the packet output immediately before, and the identifier next to the stored identifier (for example, the number obtained by adding 1 to the packet identifier of the previous packet) ) Is retrieved from the packet storage unit 211 and acquired.

When the packet acquisition unit 231 does not acquire the next packet to be output, the voice output unit 261 starts timing and determines whether or not a timeout has occurred. If it is determined that a timeout has occurred, the packet generator 235 generates a packet to be output next using two or more packets that are packets received by the packet receiver 241 and include a checksum packet. For example, the packet storage unit 211 stores packets and checksum packets “m091”, “r091”, “m092”, “r092”,..., “M099”, “r099”, “r100”, “m101”, “r101”. ,... Are stored, and if the packet whose output time corresponds to the current time is the packet “m100” and this packet “m100” is lost, the packet generation unit 235 stores the packet in the packet storage unit 211. The lost packet “m100” is generated using the nine packets “m091” to “m099” and the checksum packet “r100”.

The voice output unit 261 outputs the packet acquired from the packet storage unit 211 or the packet generated by the packet generation unit 235 by voice. Specifically, the audio output unit 261 performs analog conversion on the packet, acquires audio, and outputs the audio from the speaker.

The terminal processing unit 23 determines whether it is time to make a retransmission request, and when it is time to make a retransmission request,

The retransmission request transmission unit 251 executes retransmission request transmission processing. In the retransmission request transmission process, the retransmission request transmission unit 251 first transmits a first retransmission request having a packet identifier for identifying the next packet to be output to the transmission apparatus 1.

If the next packet to be output is not received by the first time limit after transmitting the first retransmission request, the retransmission request transmission unit 251 sends the second retransmission request for the next packet to be output next time. Is sent at the timing of requesting retransmission. If the next output packet is not received by the second time limit after the second retransmission request is transmitted, the retransmission request transmission unit 251 sends the third retransmission request for the next output packet one after another. Is sent at the timing of requesting retransmission. Such processing is repeated at most N times before time-out occurs.

When the next output packet is received before the time-out, the audio output unit 261 outputs the received packet as audio, and when not received, the audio output unit 261 corresponds to the next output packet. The packet generator 235 outputs the packet generated by using the checksum packet as described above.

The terminal processing unit 23 determines whether it is time to acquire communication-related information. When it is determined that it is time to acquire communication-related information, the communication-related information acquisition unit 233 acquires communication-related information including any of the number of terminals, error rate information, and normal rate information, for example. To do. The communication parameter changing unit 234 includes the capacity of the packet storage unit 211, the number N of times that the retransmission request transmission unit 251 can transmit a retransmission request, N time limits from the first time limit to the Nth time limit corresponding to the number N, The communication parameter that is one or more types of information is changed according to the communication related information acquired by the communication related information acquisition unit 233.

For example, when the communication-related information includes the number of terminals, the communication parameter changing unit 234 may increase the capacity, increase the number of times N, and advance the N deadlines if the number of terminals is greater than or equal to the threshold value. However, if the number of terminals is equal to or less than the threshold value or less than the threshold value, the number of times N may be decreased, the N deadlines may be delayed, and the capacity may be reduced.

When the related information includes error rate information, the communication parameter changing unit 234 increases the number of times N by increasing the capacity if the error rate indicated by the error rate information is equal to or higher than the threshold value or higher than the threshold value. If the error rate is equal to or lower than the threshold value or lower than the threshold value, the number N may be reduced, and the N deadlines may be delayed to reduce the capacity. Alternatively, when the communication-related information includes normal rate information, the communication parameter changing unit 234 increases the capacity, increases the number of times N, and increases N if the normal rate indicated by the normal rate information is equal to or lower than the threshold value The time limit may be advanced, or if the normal rate is equal to or higher than the threshold value or higher than the threshold value, the number N may be reduced, and the N time limits may be delayed to reduce the capacity.

The terminal processing unit 23 also determines whether or not it is time to acquire speed information. When it is determined that it is time to acquire speed information, the first speed information acquisition unit 236 acquires first speed information, and the second speed information acquisition unit 237 acquires second speed information. The complement processing unit 238 acquires the shift information using the acquired first and second two speed information, and performs the shift complement process based on the acquired shift information. For example, when the ratio of the two speeds corresponding to the first speed information and the second speed information is “1000 packets / second” vs. “1000.1 packets / second”, that is, 10000: 10001, the complementary processing unit 238 receives Complementary processing for delaying the clock cycle on the apparatus 2 side by 1/10000 may be performed. Thereby, the disturbance of the output sound due to the error in the clock frequency between the transmission device 1 and the reception device 2 is eliminated or reduced.

As described above, according to the present embodiment, when receiving audio data, transmitting apparatus 1 sequentially transmits two or more packets corresponding to a packet identifier that are two or more packets constituting the audio data and identifies the packet. When the retransmission request having the packet identifier is received from the receiving device 2, the packet corresponding to the packet identifier included in the retransmission request is transmitted by unicast to the receiving device 2 that has transmitted the retransmission request. When a packet is received from the apparatus 1, the packet is stored in the packet storage unit 211 and stored in the packet storage unit 211. The packet to be output next is acquired using the packet identifier corresponding to the packet, When the packet to be output is acquired, the next output packet is output, but the next output packet by the first deadline When not receiving, the voice communication system that transmits a retransmission request to the transmitter 1 suppresses the occurrence of packet loss in the receiver 2 and eliminates or reduces the audio disturbance generated in the receiver 2, while the receiver 2 Audio output delay can be reduced.

In the voice communication system, the receiving device 2 determines whether or not the next output packet is received by the first time limit by using the packet identifier corresponding to the packet, and by the first time limit. When it is determined that the packet to be output next has not been received, a retransmission request is transmitted to the transmission device, thereby suppressing the occurrence of packet loss at the reception device and eliminating or reducing the audio disturbance. Delay can be shortened.

In the above voice communication system, the receiving apparatus 2 transmits an N-th retransmission request to the transmitting apparatus when the next output packet is not received by the Nth time limit (N is a natural number of 2 or more). Thus, if the next output packet is not received even if the first retransmission request is transmitted, the receiving apparatus 2 can be expected to improve the lost packet recovery rate by transmitting the second and subsequent retransmission requests. .

In the voice communication system, the reception device 2 can acquire communication-related information that is information related to communication between the transmission device 1 and the reception device 2, and can transmit the capacity of the packet storage unit 211 and a retransmission request. By changing the communication parameter, which is one or more types of information among the N times from the number N, the first time limit to the Nth time limit corresponding to the number N, according to the communication related information, 2 Each of the above receiving devices 2 obtains communication related information (number of terminals, error rate, etc.) and dynamically changes communication parameters according to the communication related information, thereby responding to communication with the transmitting device 1. Thus, it is possible to eliminate or reduce the audio disturbance, and to reduce the amount of buffering and thus the delay.

In the voice communication system, the communication-related information is the number of terminals that is the number of receiving apparatuses 2 that receive a packet, the error rate information regarding that the receiving apparatus 2 cannot receive the next output packet, or the receiving apparatus 2 By including any one of the normal rate information regarding that the packet to be output next can be received, each of the two or more receiving devices 2 has the communication parameter including the number of terminals and the error rate included in the communication related information. Or, by changing dynamically according to the normal rate, depending on the frequency of packet loss that occurs in communication with the transmitting device, it is possible to eliminate or reduce voice disturbance, reduce the amount of buffering, and thus reduce the delay. It can be shortened.

In the voice communication system, the transmission device 1 acquires terminal number information regarding the number of reception devices 2 that receive packets, and adopts multicast or broadcast as a method of transmitting packets according to the terminal number information. Or unicast is adopted, and the transmission device 1 transmits the packet based on the determined method, so that the transmission device 1 can transmit the packet in a method according to the number of terminals among multicast, broadcast, and unicast. Thus, regardless of the number of terminals, pressure on the communication path band is reduced, and voice disturbance due to packet loss is reduced.

For example, when the number of terminals is less than or less than the threshold, the number of terminals that can reduce both compression on the band and voice disturbance by transmitting packets with unicast with a large amount of bandwidth but low loss is greater than or equal to the threshold. Alternatively, when the number is larger than the threshold, the packet is transmitted by multicast or broadcast with a small bandwidth but a large loss, and retransmission when packet loss occurs can be performed by unicast.

In the voice communication system, the transmission device 1 generates a checksum packet, which is a packet for configuring a packet that the reception device 2 could not receive, using two or more packets to be transmitted. When the receiving apparatus 2 receives three or more packets including a checksum packet and fails to obtain a packet to be output next, the receiving device 2 transmits two or more packets including the checksum packet. If a packet loss occurs in the receiving device 2 by generating a packet to be output next, and the packet to be output next cannot be received even if the retransmission request is transmitted one or more times, the receiving device 2 The lost packet can be reconstructed using two or more packets including the checksum packet received. As a result, for example, the transmission / reception efficiency is increased as compared with the case where the retransmission request is continuously transmitted.

Further, in the above voice communication system, the transmission device 1 includes a voice reception unit 1211 that receives analog voice, and an AD conversion unit 1212 that digitally converts the voice and obtains voice data. Are converted to analog signals to obtain voice, and DA output means 2611 for outputting voice, and voice output means 2612 for outputting voice. The receiving apparatus 2 acquires first speed information regarding the speed at which packets are received, and the receiving apparatus 2 Is obtained from the first speed information and the second speed information, and is based on the deviation information about the clock frequency error between the transmission device 1 and the reception device 2. The error in the clock frequency that occurs between the transmission device 1 and each reception device 2 is obtained by performing a shift compensation process that is a process for compensating for an error in the clock frequency. It is possible to reduce the disturbance of the output sound due to.

Furthermore, the processing in the present embodiment may be realized by software. Then, this software may be distributed by software download or the like. Further, this software may be recorded on a recording medium such as a DVD and distributed. This also applies to other embodiments in this specification.

In addition, the software which implement | achieves the transmitter 1 in this Embodiment is the following programs. That is, this program is a program executed by a computer of the transmission device 1 that transmits audio data to two or more reception devices 2, and the computer receives the audio data reception unit 121 that receives audio data and the audio data. The packet transmission unit 151 that sequentially transmits two or more packets corresponding to the packet identifier that identifies the packet and the packet identifier, which are output next by the first deadline A retransmission request receiving unit 141 that receives a retransmission request transmitted from the receiving device 2 when not receiving a packet, and a packet corresponding to a packet identifier included in the retransmission request to the receiving device 2 that has transmitted the retransmission request. This is a program for causing the packet retransmission unit 152 to transmit by unicast.

Further, the software that realizes the receiving apparatus 2 in the present embodiment is the following program. That is, this program is a program executed by the computer of the receiving device 2 that receives and outputs audio data from the transmitting device 1, and the recording medium accessible by the computer is a packet storage unit 211 that stores packets. A packet receiving unit 241 that receives a packet from the transmission device 1 and stores the packet in the packet storage unit 211, and a packet stored in the packet storage unit 211. A packet acquisition unit 231 that acquires a packet to be output next using a corresponding packet identifier, and an audio output that outputs the packet to be output next when the packet acquisition unit 231 acquires a packet to be output next 261 and the packet receiver 241 output next by the first time limit. If not receiving a packet, a program for functioning as a retransmission request transmitting unit 251 transmits a retransmission request to the transmitting apparatus 1.

FIG. 6 is a diagram illustrating an example of the external appearance of a computer system 900 that executes the program according to the present embodiment to realize a voice communication system. The present embodiment can be realized by computer hardware and a computer program executed on the computer hardware. In FIG. 6, the computer system 900 includes a computer 901 including a disk drive 905, a keyboard 902, a mouse 903, and a display 904. Note that the entire system including the keyboard 902, the mouse 903, and the display 904 may be called a computer.

FIG. 7 is a diagram illustrating an example of the internal configuration of the computer system 900. In FIG. 7, in addition to the disk drive 905, a computer 901 is connected to an MPU 911, a ROM 912 for storing a program such as a bootup program, and the MPU 911, and temporarily stores an instruction of an application program. A RAM 913 that provides storage space, a storage 914 that stores application programs, system programs, and data, a bus 915 that interconnects MPU 911, ROM 912, and the like, and a network card 916 that provides connection to a network such as the Internet . The storage 914 is, for example, a hard disk, a solid state drive, a flash memory, or the like.

A program that causes the computer system 900 to execute the function of the voice communication system may be stored in a disk 921 such as a DVD or a CD-ROM, inserted into the disk drive 905, and transferred to the storage 914. Alternatively, the program may be transmitted to the computer 901 via a network such as the Internet and stored in the storage 914. The program is loaded into the RAM 913 when executed. The program may be loaded directly from the disk 921 or the network. Further, the program may be read into the computer system 900 via another removable recording medium (for example, a DVD or a memory card) instead of the disk 921.

The program may not necessarily include an operating system (OS) or a third-party program for executing the function of the voice communication system in 901 indicating the details of the computer. The program may include only a part of an instruction that calls an appropriate function or module in a controlled manner and obtains a desired result. How the computer system 900 operates is well known and will not be described in detail.

In the above program, in a transmission step for transmitting information, a reception step for receiving information, etc., processing performed by hardware, for example, processing performed by a modem or an interface card in the transmission step (only performed by hardware). Not included) is not included.

Further, the computer that executes the program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

In the above embodiment, it is needless to say that two or more communication means (such as the reception unit 14 and the transmission unit 15) existing in one apparatus may be physically realized by one medium.

In the above embodiment, each processing (each function) may be realized by centralized processing by a single device (system), or may be realized by distributed processing by a plurality of devices. May be.

The present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included in the scope of the present invention.

As described above, according to the audio communication system and the like according to the present invention, the delay of audio output at the receiving device while suppressing the occurrence of packet loss at the receiving device and eliminating or reducing the audio disturbance occurring at the receiving device. Is useful as a voice communication system.

Claims

An audio communication system comprising a transmitting device for transmitting audio data and two or more receiving devices for receiving and outputting audio data,
The transmitter is
An audio data receiving unit for receiving audio data;
A packet transmission unit that sequentially transmits two or more packets corresponding to a packet identifier that is a packet identifier that identifies two or more packets constituting the voice data;
A retransmission request receiving unit for receiving a retransmission request having a packet identifier from the receiving device;
A packet retransmission unit that transmits a packet corresponding to a packet identifier included in the retransmission request to a receiving apparatus that has transmitted the retransmission request by unicast;
The receiving device is:
A packet storage unit for storing packets;
A packet receiving unit that receives packets from the transmitting device and stores the packets in the packet storage unit;
A packet stored in the packet storage unit, using a packet identifier corresponding to the packet, a packet acquisition unit for acquiring a packet to be output next;
When the packet acquisition unit acquires a packet to be output next, an audio output unit that outputs the packet to be output next;
A voice communication system comprising: a retransmission request transmission unit configured to transmit a retransmission request to the transmission device when the packet reception unit does not receive a packet to be output next by a first time limit.
The receiving device is:
A determination unit that determines whether the packet reception unit has received a packet to be output next before the first time limit by using a packet identifier corresponding to the packet;
The retransmission request transmitter is
2. The voice communication system according to claim 1, wherein the determination unit transmits a retransmission request to the transmission device when it is determined that the packet reception unit has not received the next packet to be output before the first time limit.
The retransmission request transmitter is
2. The voice communication system according to claim 1, wherein when the packet receiving unit does not receive a packet to be output next before the N-th time limit, a N (N is a natural number of 2 or more) retransmission request is transmitted to the transmission device. .
The receiving device is:
A communication related information acquisition unit that acquires communication related information that is information related to communication between the transmission device and the reception device;
One or more types of the capacity of the packet storage unit, the number N of times that the retransmission request transmission unit can transmit a retransmission request, and N time limits from the first time limit to the Nth time limit corresponding to the number N The voice communication system according to claim 1, further comprising: a communication parameter changing unit that changes the communication parameter which is the information of the communication parameter according to the communication related information.
The communication related information is:
Number of terminals that are the number of receiving devices that receive packets, error rate information regarding that the packet receiving unit cannot receive the next output packet, or that the packet receiving unit has received the next output packet The voice communication system according to claim 4, comprising any of the normal rate information.
The transmitter is
A terminal number information acquisition unit that acquires terminal number information related to the number of receiving apparatuses that receive packets;
According to the number-of-terminals information, a method determining unit that determines whether to adopt multicast or broadcast or unicast as a method of transmitting a packet,
The packet transmitter is
The voice communication system according to claim 1, wherein the packet is transmitted based on a method determined by the method determining unit.
The transmitter is
A checksum packet generation unit that generates a checksum packet that is a packet that constitutes a packet that could not be received by the reception device using two or more packets that the packet transmission unit transmits;
The packet transmitter is
Sending three or more packets including the checksum packet;
The packet receiver
Receiving three or more packets including the checksum packet;
The receiving device is:
The packet generation unit further generates a packet to be output next using two or more packets including the checksum packet when the packet acquisition unit cannot acquire a packet to be output next. The described voice communication system.
The voice data receiving unit
Voice receiving means for receiving analog voice;
AD conversion means for digitally converting the sound and obtaining sound data,
The audio output unit
DA conversion means for analog-converting the packet and obtaining voice;
Voice output means for outputting the voice,
The receiving device is:
A first rate information acquisition unit for acquiring first rate information relating to a rate at which the packet receiving unit receives a packet;
A second speed information acquisition unit for acquiring second speed information regarding the processing speed of the receiving device;
A shift that is information acquired from the first speed information and the second speed information, and that is a process of complementing the clock frequency error based on the shift information regarding the clock frequency error between the transmitting device and the receiving device. The voice communication system according to claim 1, further comprising a complement processing unit that performs a complement process.
A transmitting device that transmits audio data to two or more receiving devices,
An audio data receiving unit for receiving audio data;
A packet transmission unit that sequentially transmits two or more packets corresponding to a packet identifier that is a packet identifier that identifies two or more packets constituting the voice data;
A retransmission request receiving unit that has a packet identifier and receives a retransmission request transmitted from the receiving device when a packet to be output next is not received by the first deadline;
A transmission apparatus comprising: a packet retransmission unit that unicasts a packet corresponding to a packet identifier included in the retransmission request to a reception apparatus that has transmitted the retransmission request.
A receiving device that receives and outputs audio data from the transmitting device according to claim 9,
A packet storage unit for storing packets;
A packet receiving unit that receives packets from the transmitting device and stores the packets in the packet storage unit;
A packet stored in the packet storage unit, using a packet identifier corresponding to the packet, a packet acquisition unit for acquiring a packet to be output next;
When the packet acquisition unit acquires a packet to be output next, an audio output unit that outputs the packet to be output next;
A receiving apparatus comprising: a retransmission request transmitting section that transmits a retransmission request to the transmitting apparatus when the packet receiving section does not receive a packet to be output next by a first time limit.
A transmission method performed by an audio data reception unit, a packet transmission unit, a retransmission request reception unit, and a packet retransmission unit included in a transmission device that transmits audio data to two or more reception devices,
A voice data receiving step in which the voice data receiving unit receives voice data;
A packet transmission step in which the packet transmission unit sequentially transmits two or more packets corresponding to a packet identifier that identifies two or more packets constituting the voice data;
A retransmission request receiving step for receiving, from the receiving device, a retransmission request transmitted when the retransmission request receiving unit has a packet identifier and does not receive a packet to be output next by a first time limit;
A packet retransmission step in which the packet retransmission unit transmits a packet corresponding to a packet identifier included in the retransmission request to a receiving apparatus that has transmitted the retransmission request by unicast.
A reception method performed by a packet reception unit, a packet acquisition unit, a voice output unit, and a retransmission request transmission unit included in a reception device that receives and outputs audio data from the transmission device according to claim 11,
The recording medium is
A packet storage unit for storing packets;
A packet receiving step in which the packet receiving unit receives a packet from the transmission device and accumulates the packet in the packet storage unit;
The packet acquisition unit is a packet stored in the packet storage unit, and a packet acquisition step of acquiring a packet to be output next using a packet identifier corresponding to the packet;
When the voice output unit acquires a packet to be output next by the packet acquisition unit, a voice output step of outputting the packet to be output next;
A retransmission method, comprising: a retransmission request transmission step in which the retransmission request transmission unit transmits a retransmission request to the transmission device when the packet reception unit does not receive the next packet to be output before the first time limit.
A recording medium that records a program executed by a computer of a transmitting device that transmits audio data to two or more receiving devices,
The computer,
An audio data receiving unit for receiving audio data;
A packet transmission unit that sequentially transmits two or more packets corresponding to a packet identifier that is a packet identifier that identifies two or more packets constituting the voice data;
A retransmission request receiving unit that has a packet identifier and receives a retransmission request transmitted from the receiving device when a packet to be output next is not received by the first deadline;
A recording medium recording a program for causing a receiving apparatus that has transmitted the retransmission request to function as a packet retransmission unit that transmits a packet corresponding to the packet identifier included in the retransmission request by unicast.
A recording medium recording a program executed by a computer of a receiving device that receives and outputs audio data from the transmitting device according to claim 13,
The computer-accessible recording medium is
A packet storage unit for storing packets;
The computer,
A packet receiving unit that receives packets from the transmitting device and stores the packets in the packet storage unit;
A packet stored in the packet storage unit, using a packet identifier corresponding to the packet, a packet acquisition unit for acquiring a packet to be output next;
When the packet acquisition unit acquires a packet to be output next, an audio output unit that outputs the packet to be output next;
A recording medium on which a program for causing a retransmission request to function as a retransmission request transmission unit that transmits a retransmission request to the transmission device when the packet reception unit does not receive a packet to be output next by a first time limit.