JPH0429442A - Multimedia multiplex transmission equipment - Google Patents

Abstract

PURPOSE:To remarkably improve multiplexing efficiency by selecting a CODEC with low compressibility when traffic at a transmission line is less than a value set in advance, and switching the CODEC to the one with high compressibility when it arrives at the value set in advance. CONSTITUTION:The traffic of a transmission packet is measured at a traffic monitoring circuit 22, and the arrival of traffic to 99% of the effective maximum amount of transmission on the transmission line 23 is informed to a switch 16 and the CODECs 17, 18, and the next audio signal of one line is switched from the CODEC 17 for 16kb/s to the CODEC 18 for 8kb/s. After that, when the traffic is further increased, the audio signal is switched from 16kb/s compression to 8kb/s compression at every line. When the traffic is decreased and it becomes less than 98.5, a speech path is returned from 8kb/s compression to 16kb/s gradually within a range not exceeding 99.0%.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multimedia multiplex transmission device most suitable for asynchronous transmission mode (ATM), and particularly to a multimedia multiplex transmission device for realizing efficient multiplex transmission of audio. Regarding.

2. Description of the Related Art Conventionally, this type of multimedia multiplex transmission equipment has two methods: a time division multiplexing method and a packet multiplexing method.
A method has been adopted in which compressed or uncompressed audio signals from 32 kb/s to 32 kb/s are transmitted only when there is sound.

FIG. 2 shows the configuration of a conventional multimedia multiplex transmission device using packet multiplexing. In FIG. 2, 1 is an analog telephone, and CODE is transmitted through an analog circuit 2.
C (a general term for devices including an audio encoding/decoding circuit and an audio compression/expansion circuit; the same applies hereinafter).

4 is a digital interface, which is connected to the CODEC 3 through a digital interface circuit 5. This CODEC 3 is connected to a silence detection circuit 6 and a silence section regeneration circuit 9, the silence detection circuit 6 is connected to a transmission line 10 via a packet multiplex transmission circuit 7, and the silence section regeneration circuit 9 is connected to a packet reception circuit 8. It is connected to the transmission line 1o via the.

Next, the operation of the conventional example will be explained. In FIG. 2, in the case of transmission, the voice from analog telephone 1 passes through analog circuit 2 and is A/D converted by CODEC 3, and the digitized voice signal has a bit rate of 54 kb.
It is compressed to S or 32 kb/s or 16 kb/s. Similarly, the digital interface 4 and the digital interface circuit 5 receive an already digitized 64k b/s audio signal, and the CODEC 3
is compressed to 32kb/s or 16kb/s.

The sound compressed by the CODEC 3 is subjected to a sound/non-sound detection circuit 6 to determine whether it is a sound or not. Here, if there is a sound, it is sent to the packet multiplex transmission circuit 7 as audio information,
If there is no sound, it will not be sent to the packet multiplex transmission circuit 7. Then, in the packet multiplex transmission circuit 7, when a specified amount of information is reached or a certain period of time has elapsed, the audio information is assembled into a packet with a header such as a destination address, a trailer, etc., and sent to the transmission path 10.

In the case of reception, the packet arriving at the transmission path 10 is received by the packet receiving circuit 8, where the header, trailer, etc. are removed, and only the audio information is sent to the silent section regenerating circuit 9. If a packet does not arrive within a certain period of time, the silent section regeneration circuit 9 performs an operation to insert white noise etc. into the interval, corrects it to continuous audio, and then outputs COD.
32 k b/s or 16 k b/s in EC3
The audio is expanded to 64 kb/s, D/A converted, and sent from the analog circuit 2 to the analog telephone 1, or from the digital interface circuit 5 to the digital interface 4, where the audio is reproduced.

In this way, even in the conventional multimedia multiplex transmission device using packet multiplexing, the multiplexing efficiency can be improved by not transmitting silent sections of audio.

Problems to be Solved by the Invention However, in the conventional multimedia multiplex transmission device, since the voice silent period cannot be uniformly defined, there is a problem that information is discarded during peak traffic, and the call quality is not guaranteed.

The present invention solves these conventional problems,
It is an object of the present invention to provide an excellent multimedia multiplex transmission device that can guarantee call quality even during peak traffic and improve multiplexing efficiency.

In order to achieve the above object, the present invention provides a plurality of CODECs with different compression ratios, a switch means for selecting these CODECs, and a switch means for monitoring the traffic state of packets on a transmission path. A CODEC with a low compression rate is selected when the traffic on the transmission path is smaller than a preset value as measured by the traffic monitoring means, and when the traffic becomes large and reaches the preset value. In this case, the codec is switched to a CODEC with a higher compression ratio.

Effects The present invention has the following effects due to the above-described configuration. In other words, when the transmission path usage rate measured by the traffic monitoring means reaches a preset value, the communication path is switched to a CODEC with a high compression rate, and the next input voice is compressed with a high compression rate and transmitted. be done. In other words, by increasing the compression rate only when traffic increases, the amount of information to be transmitted is reduced, thereby minimizing the deterioration of voice quality when traffic increases, and also reducing the amount of information transmitted through already established communication channels. This has the effect of eliminating the inconvenience of forcibly disconnecting the data and further increasing the multiplexing efficiency.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, reference numeral 11 is an analog telephone set, which is connected to a 54 kb/s CODEC 13 through an analog circuit 12. 14 is a digital interface, which is connected to a digital interface circuit 15. 16 is C for these 64kb/s, OD E C13
and a switch connected to the digital interface circuit 15 for switching input and output. 17 is 16k which compresses digitized audio to 15kb/s
The b/s CODEC 18 is an 8 kb/s CODEC that compresses digitized audio to 8 kb/s, and these are selected by the switch 16. 19 is a silence detection circuit, which is connected to CODECs 17 and 18; 20 is a silent section regeneration circuit, and CODEC1
? and 18. 21 is a packet multiplex transmission circuit, which is connected to the silence detection circuit 19. 2
A traffic monitoring circuit 2 is connected between the packet multiplex transmission circuit 21 and the transmission line 23, measures the traffic state on the transmission line 23, and notifies the switch 16 and each CODEC 17 and 18 of this. 24 is a packet receiving circuit connected between the silent section regeneration circuit 20 and the transmission line 23.

Next, the operation of the above embodiment will be explained.

First, the case where a packet is transmitted to the transmission path 23 will be explained. In FIG. 1, audio from an analog telephone 11 passes through an analog circuit 12 to a 64 kb S CODEC.
13 into a 54 kb/s digital audio signal. Also, the digital interface circuit 15 receives an audio signal already encoded at a bit rate of 64 kb/s through the digital interface 14 . These digitized audio signals are normally converted to 15kb/s by a 15kb/s CODEC 17 through a switch 16.
b/s. In this embodiment, the transmission line 23
In the normal state, that is, within the range where the traffic does not exceed the effective maximum transmission capacity, all communication paths are connected to the 16 kb/s CODEC 17 by the switch 16,
When the normal state is likely to be exceeded, several communication paths are connected to the 8 kb/s CODEC 18 depending on the amount of information. Note that the effective maximum transmission capacity means a throughput within a range where packet delay and discard can be practically tolerated, and its value differs depending on the system.

The audio signal compressed by the 15 kb/s CODEC 17 is determined by a silence detection circuit 19 as to whether there is a sound or not.
Only when there is a sound, it is sent out as transmission audio information, which is assembled into packets by the packet multiplex transmission circuit 21 with a header, trailer, etc., and sent to the transmission path 23 through the traffic monitoring circuit 22. In the traffic monitoring circuit 22, the traffic of the transmitted packets is measured, and when the traffic reaches 99% of the effective maximum transmission capacity of the transmission path 23, this is notified to the switch 16 and each CODEC 17, 18, and the next 8kb of audio signal for one line from 15kb/s CODEC17
Switch to CODEC18 for /s. If the traffic increases further thereafter, the audio signal is switched from 15 kb/s compression to 8 kb/s compression for each line. And when the traffic decreases to less than 98.5%,
Gradually speed up the communication path to 8 kb/s within a range not exceeding 99°0%.
From compression back to 15kb/s compression.

Next, a case will be described in which a packet is received from a transmission path. In FIG. 1, a packet received from a transmission path 23 is sent to a packet reception circuit 24, where headers, trailers, etc. are removed, and then passed through a silent section regeneration circuit 20.
CODEC1 for 15kb/s respectively based on the type of kb/s compression or 8k b/s compression? or 8kb/
This is input to the s CODEC 18 as audio information. If no packet is received within a certain period of time, the silent section regeneration circuit 20 generates white noise and inserts it into the silent section as audio information. As a result, audio continuity is regenerated, and the audio signal is routed by the switch 16 and sent to a predetermined analog telephone 11 or digital interface 14.

As described above, according to the embodiment, when audio is packetized and transmitted, silent information is not transmitted, and in addition to regenerating silent sections when receiving audio, traffic on the transmission path is By increasing the compression rate of some audio to reduce the amount of information only when Even when traffic increases, there is no need to forcibly disconnect already established call paths (this has the effect of guaranteeing call quality and increasing the number of telephones and digital interfaces that can be accommodated in this device). has.

Effects of the Invention As is clear from the embodiments described above, the present invention includes a plurality of CODECs with various compression ratios, a switch means for selecting these CODECs, and a switch means that operates by monitoring the traffic state of packets on a transmission path. A CODEC with a low compression ratio is selected when the traffic on the transmission path is smaller than a preset value as measured by the traffic monitoring means, and when the traffic increases and reaches the preset value. By switching to a CODEC with a high compression rate, the multiplexing efficiency can be greatly improved, and the communication quality can be guaranteed even when traffic increases.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a multimedia multiplex transmission apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a conventional multimedia multiplex transmission apparatus. 11... Analog telephone, 12... Analog circuit,
13...54kb] S CODEC, 14...Digital interface, 15...Digital interface circuit, 16...Switch, 17...16kb
ノ5pACODEC, CODE for 18...8kb/s
C, 19... Silence detection circuit, 20... Silent section regeneration circuit, 21... Packet multiplex transmission circuit, 22... Traffic monitoring circuit, 23... Transmission line, 24... Packet reception circuit.

Claims (1)

[Claims] a plurality of CODECs that encode or decode audio into digital signals with different compression rates; and the plurality of CODEs.
a switch means for selecting the selected CODE;
Silence detection means that determines whether the digital audio signal output from C is silent or active, and sends only the audio signal as transmission audio information; and packet multiplex transmission means that assembles the transmission audio information into packets and transmits them to a transmission path. a traffic monitoring means for measuring the traffic state of transmitted packets on the transmission path; a packet reception means for disassembling packets received from the transmission path and extracting received audio information; and silent section regeneration means for regenerating a silent section when a silent section occurs, and when the traffic on the transmission path is smaller than a preset value as measured by the traffic monitoring means, the switch A CODEC with a low compression rate is selected depending on the method, and when the traffic increases and reaches a preset value, a CODEC with a high compression rate is selected.
A multimedia multiplex transmission device that switches to EC.