JPS6268350A - Voice packet communication system - Google Patents

Abstract

PURPOSE:To set properly and simply a minimum recovery queue time suppressing an abolition rate to a prescribed value or below by transmitting a voice packet only added with header information, calculating the abolition rate of each packet at each prescribed time and controlling the recovery queue time of a received packet variably. CONSTITUTION:A voice/silence discrimination section 16 discriminates whether a voice packet generated by a packet composing section 14 from an input voice is a voice packet or a silence packet and a packet transmission control section 15 sends only the voice packet according to the result of discrimination. A packet reception section 2 stores the reception packet by a transmission control section 21 to a buffer memory 22 once, and it is extracted by a packet decomposing section 23 after a prescribed waiting time elapses and the result is decoded by a decoder 24 and the voice is outputted from a D/A converter 25 via a voice output section 26. Then a packet abolition rate discrimination section 27 inputs header information and calculates the abolition rate of the transmission packet at each prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a voice packet overconfidence system that can efficiently communicate voice from a telephone terminal or the like via a packet communication network.

[Technical background of the invention and its problems]

Recently, attempts have been made to efficiently communicate voices from telephone terminals and the like through packet communication networks and to have conversations in real time.

However, Bucket 1 to the communication line network were originally developed for data transmission, and are configured for the purpose of reliably transmitting the data even if a transmission delay occurs. Therefore, when the packet communication network is used to transmit voices from telephone terminals and have a conversation in real time, if all the voices are to be transmitted faithfully, the conversation will be unnatural due to the large transmission delay.

Conventionally, attempts have been made to transmit audio packets with priority over information packets such as computer data, or to ensure real-time performance at the expense of audio quality.

However, even if such measures are taken, it is undeniable that the time required for packet transmission (transmission delay time) will vary depending on the traffic status of the transmission path and the operating status of each packet processing unit. .

Therefore, a buffer memory is provided in the packet receiving section to sequentially store received packets, and the received packets are sequentially read out from this buffer memory after a predetermined waiting time. This reproduction scheduling control using the buffer 7 memory effectively absorbs variations in the transmission delay time of individual received packets. In other words, even if multiple packets sent sequentially from the transmitter are received randomly with variations in transmission delay time, they will be stored in the buffer memory and then played back in order after the above-mentioned waiting time. It is possible to reproduce packet information that absorbs variations in the arrival time of each packet.

However, if the above waiting time is set to a large value, it is possible to absorb even received packets with large transmission delay time fluctuations, but on the other hand, the time required to reproduce the packets increases, and the telephone voice is not transmitted through packet communication. A problem arises when there is a delay in response when having a conversation. In other words, real-time conversation is hindered.

If the waiting time is short compared to the noise, packets that arrive after the waiting time will be discarded, which will reduce the amount of information that can be received and reproduced, and in the case of voice communication, the sound quality will deteriorate significantly. I end up.

For this reason, optimal setting of the above-mentioned meeting time has become an important issue.

[Purpose of the invention]

The present invention has been developed in consideration of the above circumstances, and its purpose is to suppress the packet discard rate to a predetermined value or less, reduce the playback waiting time, and ensure real-time performance of audio. The purpose of the present invention is to provide a voice packet overconfidence system that enables communication.

(Summary of the Invention) The present invention separates generated voice packets into voiced packets and unvoiced packets, transmits only the separated voiced packets, and provides a cumulative value indicating, for example, the number of generated voice packets. and a sequence number that is sequentially given only to voiced packets, and transmits the voiced packets by adding header information to the voiced packets. On the other hand, in the packet receiving section, for example, the header information that is added to the received packets at predetermined time intervals is transmitted. The packet discard rate is determined from the header information, and the playback waiting time of the received packet is variably controlled in accordance with the packet discard rate, for example, during the silent period.

〔Effect of the invention〕

Thus, according to the present invention, only voiced packets are transmitted with header information added, and the packet receiving section calculates the discard rate of bucket 1- at predetermined intervals, for example, from the header information added to the received packets. Variable waiting time for replaying received packets based on the packet discard rate υJl11
Therefore, the minimum playback waiting time that can suppress the packet discard rate to a predetermined value or less can be easily and appropriately set.

Moreover, as described above, since no silent packets are transmitted, the silent period can be effectively utilized to perform variable control of the playback waiting time. Furthermore, it is possible to flexibly deal with traffic fluctuations on communication lines and set an optimal playback waiting time.

Therefore, it is possible to effectively perform voice communication without sacrificing real-time performance by reducing the voice packet playback waiting time while keeping the packet discard rate low and ensuring voice quality.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of a packet transmitting section 1 and a packet receiving section 2 of a packet communication terminal to which the embodiment method is applied.

The packet transmitting section 1 basically digitizes the audio input from the audio input section 11 via the A/D converter 12, converts it into a predetermined code sequence at the encoder 13, and sends it to the packet assembling section. After assembling the audio packets into audio packets in a predetermined format in step 14, the packet transmission υ control section 15 transmits the packets to the transmission path 3.

The characteristic configuration of the packet transmitting unit 1 to which this method is applied is that first, the voiced/unvoiced determining unit 16 determines from the input audio whether the audio packet generated by the packet assembling unit 14 is a voiced packet or an unvoiced packet. The point is to determine whether there is. According to the determination result of the determination section 16, the packet transmission control section 15 transmits only the voiced packet. In other words, silent packets are not transmitted.

The packet assembling unit 14 also includes a cumulative number counter 1.
7 gives a cumulative value corresponding to the number of generated packets, and a sequence number counter 18 gives a sequence number output in response to the generation of a voiced packet.

The cumulative number counter 17 is incremented each time the packet assembler 14 generates a voice packet, and generates a packet cumulative value indicating the number of generated packets. Further, the sequence number counter 18 is connected to the packet assembling unit 14.
When the generated voice packet is a voiced packet, it is detected and outputs a sequence number indicating the number of voiced packets generated.

The packet assembling unit 14 uses such a sequence number N
and the cumulative value C are added to the voice data D', for example, as shown in FIG. 2, to assemble a voiced packet. That is, header information consisting of the sequence number and cumulative value is added to the voiced packet, and only voiced packets in this format are sent from the packet transmission control section 15 to the transmission line 3.

Now, the packet transmitted from the packet transmitter 1 to the transmission path 3 is received by the packet receiver 2 after being subjected to various delays depending on the traffic condition of the transmission path 3.

The packet receiving unit 2 basically stores the received packets received by the transmission control unit 21 in the -H buffer memory 22, and
After a predetermined waiting time has elapsed, the received packet is read. The audio data in the received packet read from the buffer memory 22 is extracted by the packet disassembly unit 23, decoded by the decoder 24, and then sent from the D/A converter 25 to the audio output unit 26. It is now output.

The packet discard rate determining unit 27 inputs the header information (sequence number and cumulative value) in the received packet that has been disassembled by the packet disassembly unit 23, and calculates the discard rate of the transmitted packet at every predetermined time. are doing. This packet is discarded when the transmission delay is large, such as when the next packet to be played is not received even after the waiting time for playing the received packet stored in the buffer 7 memory 22 has elapsed. It is something that occurs.

Packet discard rate P determined by this packet discard rate determination unit 27
For example, at a certain point in time (the time of the previous packet discard rate measurement)
The serial number of the received packet obtained in is Nt-1, and the serial number of the received packet at the time of calculating the packet discard rate this time after a predetermined period of time has elapsed from the time of calculating the previous packet discard rate is N[. When the number of received packets reproduced in a given time is S, it is calculated as P-1-8/(Nt-Nt-1).

The timing control unit 28 determines, for example, the packet discard rate P according to the packet discard rate P calculated by the determination unit 27 in this manner.
is smaller than (0,01) or not, the read timing (
The playback waiting time) is variably controlled in stages.

The variable control of the playback waiting time based on the packet discard rate is performed by utilizing the silent period that occurs during the period in which the unvoiced packet is originally transmitted, since the unvoiced packet is not transmitted.

By controlling this playback waiting time,
If the packet discard rate is high, the waiting time
By increasing the rank by one rank, the number of discarded packets is reduced, and the quality of the transmitted voice is ensured. Further, when the bucket 1-discard rate is low, there is plenty of waiting time, so the waiting time is shortened by one rank to ensure real-time performance within the range where the quality of the communication voice does not deteriorate.

Note that the minimum waiting time as a range of variable control is set so as not to be less than the shortest packet delay time, and the maximum waiting time is set as a time that does not make the conversation extremely unnatural. .

Within this time range, variable control is performed step by step. As a result, the minimum playback waiting time that can suppress the packet discard rate below a predetermined value and ensure the quality of communication audio is adaptively set, and its real-time performance is ensured.

3 and 4 show control of playback waiting time, where (T> is voiced packet VLV 2.V
3 transmission timing, (R) is its reception timing, (
0) indicates the playback timing.

That is, the packet receiving section 2 basically operates as shown in FIG. Now, as shown in FIG. 3, it is assumed that a voice packet V1 generated at time t1 is received at time t2 and is reproduced from time t3 after a predetermined waiting time dt has elapsed. In this case, since the next audio packet v2 is received before the reproduction of the audio packet v1 ends,
This audio packet v2 is reproduced following the audio packet V1.

Note that whether or not the audio packets V1 and v2 are consecutive is determined based on the cumulative value of the header information.

Thereafter, when the next voice packet v3 is received and it is found from the cumulative value that there is an unsent packet between the voice packet V2 and the voice packet V2, the cumulative value is After a silent period corresponding to the difference, the audio packet (3) is reproduced.

In this way, received packets are reproduced in the same timing relationship as on the transmitting side, and variations in transmission delay are absorbed.

As a result, the transmission of voice packets progresses, and for example, as shown in FIG. 4, voice packets V G, V 7 . The audio packets V 8 are transmitted in order, and the packet receiving unit 2 receives the voice packets V
Assume that the packet discard rate P is determined at the reception time point of 6.

And the packet discard rate P calculated at this point is 0.0
If it is determined that the reproduction waiting time dt has a margin of 1% or less, control is performed to shorten the waiting time dt. However, in this case, even if you try to control the playback timing of the next audio packet v7 by shortening the waiting time immediately after audio packet ■6 is played, the audio packet ■7 is consecutive to the audio packet v6. Therefore, variable control cannot be performed.

Therefore, the timing control unit 28 uses an audio packet that is not consecutive to the audio packet being played back (in this example, an audio packet V).
8) The waiting time dt is variable controlled using the no-g period formed during the detection.

As a result, for example, the voice packet V8 is received at the reception time t7.
Time t8 is reproduced after the shortened waiting time dt. In this way, variable control of the playback waiting time dt is performed using the N sound period, and the minimum waiting time dt that can suppress the packet discard rate to a predetermined value or less is set.

Note that this control may result in one packet not being secured during the silent period 1ll1, but since this is a period in which no audio data substantially exists, the effect on the reproduced audio is small.

As described above, according to the present system, while ensuring the quality of communication audio, it is possible to adaptively set the reproduction waiting time of received packets to the minimum and reproduce them in real time. Therefore,
To enable effective conversation by minimizing playback delay of communication audio. In addition, great practical effects such as being able to effectively deal with fluctuations in the traffic state of the transmission path can be achieved.

Note that the present invention is not limited to the embodiments described above. For example, each time a predetermined number of packets are received, the packet discard rate may be determined and the playback waiting time may be variable υ controlled. Further, variable control of the waiting time may be performed during the voiced packet period by allowing some deterioration in the quality of the communication S voice. Furthermore, the method for calculating the packet discard rate can be modified in various ways depending on the format of the header information. Further, the threshold value for the packet discard rate for variable control of the waiting time may be set according to the communication specification. Although the transmission path 3 has been described as a packet communication network, it is also applicable to a private network as long as it uses a packet procedure. Also, voiced/unvoiced judgment is possible even after encoding, and A/D
It may be before conversion. In short, the present invention can be modified in various ways without departing from the gist thereof.

[Brief explanation of drawings]

The figures are for explaining one embodiment of the present invention, in which Fig. 1 is a schematic configuration diagram of a packet transmitting section and a packet receiving section, Fig. 2 is a diagram showing an example of the format of an audio packet, and Figs. Each figure is a timing diagram showing reproduction υ control of received packets. 1...Packet transmitter, 2...Bucket receiver, 3
...Transmission path, 14...Packet assembly section, 15...
- Packet transmission control unit, 16... voiced/unvoiced determination unit,
17... Cumulative number counter, 18... Sequence number counter, 22... Buffer memory, 23... Packet decomposition section, 27... Packet discard rate determination section, 28.
...Timing control section. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4

Claims (5)

[Claims] (1) In audio packet communication in which an audio signal is digitized and then packetized and transmitted, the packet transmitting unit separates the generated audio packets into voiced packets and unvoiced packets, and only the separated voiced packets are classified. Header information is added to the voiced packet and transmitted, and the packet receiving unit calculates the discard rate of the transmitted packet from the header information added to the received packet, and determines the playback waiting time of the received packet according to this packet discard rate. A voice packet overconfidence method characterized by variable control. (2) Variable control of the waiting time for playback of received packets is as follows:
The audio packet communication method according to claim 1, which is performed during a silent period. (3) Variable control of the waiting time for playback of received packets is as follows:
The voice packet communication system according to claim 1, wherein the voice packet communication system is variable in steps and controlled so as not to exceed a predetermined range. (4) The voice packet communication system according to claim 1, wherein the packet discard rate is calculated based on the number of received packets and their header information at each predetermined time. (5) The header information consists of a cumulative value indicating the number of voice packets generated and a sequence number sequentially given only to voiced packets.
Voice packet communication method described in section.