JP2007143076A - Codec switching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it impossible that a codec which has developed trouble or the like to become unable to transmit is judged as most suitable for transmission. <P>SOLUTION: The codec switching device 10 includes a plurality of codecs a1 to an and a controller 13. The controller 13 searches its own codec information s1 containing a transmission band of the plurality of the codecs a1 to an and other codec information s2 containing a transmission band of a plurality of codecs b1 to bn of a transmission party as well as network information s3 containing a size of a free bandwidth of a network 30. Based on the searched results, a codec utilized at the time of transmission is selected from among the plurality of codecs a1 to an. On this occasion, a codec with the most large-sized transmission bandwidth is selected from among free bandwidths of the network 30. These operations are implemented also during transmission. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a codec switching device that determines a network band that is optimal for transmission and selects a codec that can transmit in that band.

  When video and audio are encoded and transmitted, a delay may occur depending on network conditions such as congestion. A technique for solving such a problem is known (for example, see Patent Document 1).

  As shown in FIG. 5, the input unit 101 to which speech to be encoded is input, a plurality (n) of encoding units c1 to cn corresponding to a plurality of different encoding methods, and the state of the network 100 And a switching unit 103 that switches between a plurality of encoding units c1 to cn based on the measurement result. With this configuration, the network state measurement unit 102 investigates the state of the network 100 such as congestion, so that the band that can be transmitted without delay is grasped, and transmission can be performed in the band from among the plurality of encoding units c1 to cn. In this technique, transmission is performed by switching to the encoding units c1 to cn.

In the prior art shown in FIG. 5, the state of the network 100 such as congestion is investigated, and the encoding units c1 to cn are selected based on the state of the network 100. For example, when investigating the network 100, if the band x1 can be transmitted without a failure such as congestion, it is switched to the encoding unit c1 that performs transmission using the band x1. In addition, since the state of the network 100 is regularly monitored, it is possible to switch to the encoding unit c2 that can transmit in the optimum band x2 even during transmission.
JP 2002-290436 A

  However, since the technique of Patent Document 1 is configured to investigate only the state of the network, even if the encoding unit is broken, transmission is performed using the encoding unit even when transmission is not possible. Could be judged to be optimal.

  For example, when it is determined that it is optimal to transmit using the band x1 as a result of the network investigation, the encoding unit c1 corresponding to transmission in the band x1 is in a state where transmission is not possible due to a failure or the like. However, there is a possibility that the encoding unit c1 is selected.

  Furthermore, since the codec of the transmission partner has not been investigated, it is not known whether the transmission band and the encoding method of the transmission partner are compatible with the codec of the transmission partner, and countermeasures have been desired.

  The present invention has been made in view of the above. The purpose of the present invention is not only to investigate the state of the network but also to investigate the state of the codec of the own device, causing a failure or the like so that transmission becomes impossible. Another object of the present invention is to provide a codec switching device that prevents a codec from being determined to be optimal for transmission.

  It is another object of the present invention to provide a codec switching device that makes it possible to determine whether or not transmission with a codec selected by a partner is possible by transmitting and receiving information obtained by examining a codec with a transmission partner.

  In order to achieve the above object, a codec switching apparatus according to the first aspect of the present invention includes a plurality of codecs that encode information and decode encoded information, and are suitable for transmission of the encoded information. A codec switching device that determines a band and selects a codec capable of transmitting the encoded information in the band from the plurality of codecs, and checks a network information including a size of a free band of the network A codec checking means for checking codec information including transmission bands of the plurality of codecs; and a codec for selecting a codec to be used during transmission from the plurality of codecs based on the network information and the codec information. And a selection unit.

  According to a second aspect of the present invention, in the first aspect of the invention, the codec checking means obtains the own codec information including a transmission band and a coding method of the own codec controlled in the plurality of codecs. Means for checking in advance before transmission of encoded information; means for holding own codec information available from the checked result; means for transmitting the own codec information to a transmission partner; Means for receiving other codec information including the transmission band of the other codec and the encoding method from the transmission partner, and the own codec and the other codec can transmit to each other based on the own codec information and the other codec information. And a means for judging whether or not.

  According to a third aspect of the present invention, in the second aspect of the present invention, the codec selection means is a self-codec having the largest transmission band in a free band of the network among the self-codecs that can be transmitted with the other codec. It has the means to select.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the network investigation means and the codec investigation means are configured to be operable even during transmission of the encoded information. It is characterized by.

  According to the first aspect of the present invention, the codec that has become unable to transmit due to a failure or the like by investigating not only the network status but also the codec status of its own device is optimal for transmission. It becomes possible not to be judged.

  According to the second aspect of the present invention, in addition to the above, by further transmitting / receiving information obtained by investigating the codec to / from the transmission partner, it is possible to determine whether transmission is possible with the codec selected by the partner.

  According to the third aspect of the invention, in addition to the above, it is possible to select an optimal codec that can be transmitted with higher quality.

  According to the invention of claim 4, in addition to the above, even during transmission, it is possible to perform normal transmission by the codec in use due to occurrence of congestion or the like by periodically checking the state of the network. By switching to a codec that uses a transmittable band, transmission is possible without interruption. Also, during the transmission, investigate the occurrence of the failure by investigating the state of the codec, and if the codec being transmitted cannot be transmitted normally due to the failure, etc., switch to a codec that can transmit The transmission can be continued.

  The best mode for carrying out the codec switching device according to the present invention will be described below with reference to the drawings. In the present invention, “band” refers to the maximum transmission rate. That is, a codec having a bandwidth of 30 Mbps means a codec having a maximum transmission rate of 30 Mbps.

  FIG. 1 shows an overall configuration of a codec switching apparatus according to the present embodiment. As shown in the figure, a first codec switching device 10 and a second codec switching device 20 are provided, and both the devices 10 and 20 are communicably connected via a network 30.

  The first codec switching device 10 encodes information input by the input unit 11 and information input by the input unit 11 such as audio and video, and encodes the encoded signal transmitted through the network 30. A plurality of (n) codecs a1 to an that decode the original information and an output unit 12 that outputs the decoded information are provided.

  In addition, the codec switching device 10 investigates and holds the codec information of the own device, the codec information of the transmission partner, and the free bandwidth of the network 30, and is optimally selected from the plurality of codecs a1 to an based on these information. And a switching unit 14 that switches to the encoded signal of the selected codec and outputs it to the network 30 based on a control signal from the control unit 13.

  For example, the control unit 13 includes a CPU that operates under program control and a controller that includes a memory that stores the control program. The control unit 13 includes information on all codecs being controlled, that is, own codec information (own codec information) s1, and information on all codecs controlled by the transmission partner, that is, codecs of the transmission partner. Information (partner codec information) s2 is investigated, and both codec information s1 and a2 obtained by the investigation are stored as a table in, for example, a memory (not shown). In addition, the control unit 13 investigates the network 30, measures the size of the free band, and stores the measurement result as network information s3 in, for example, a memory (not shown). Furthermore, the control unit 13 selects codecs a1 to an that are optimal for transmission using the free bandwidth of the network 30 based on the information a1 to a3.

  The plurality of codecs a <b> 1 to an encode the information input from the input unit 11 and transmit the information through the network 30 in each band. Further, the encoded information is received through the network 30, decoded and output to the output unit 12.

  On the other hand, the second codec switching device 20 also includes an input unit 21, a plurality (n) of codecs b1 to bn, an output unit 22, a control unit 23, and a switching unit 24 in terms of function. Since the functions of these units 21 to 24 are the same as those of the above-described units 11 to 24, their details are omitted.

  Next, the overall operation of this embodiment will be described with reference to FIG. Here, a case will be described in which the first codec switching device 10 is a transmission source and the second codec switching device 20 is a transmission partner. The control program corresponding to the flowchart shown in FIG. 2 is stored in advance in a memory in the control unit, and the command is executed by the CPU in the control unit during operation.

  In FIG. 2, the control unit 13 checks in advance the own codec information s1, such as the transmission band and the encoding method, for all the codecs being controlled, and holds the information s1 in the memory (step S101).

  Next, before encoding and transmitting the input information, the control unit 13 sends the switching unit 14 the own codec information s1 related to all codecs held by the control unit 13 to the control unit 23 of the transmission partner. Send through. At the same time, the control unit 13 receives partner codec information s2 related to all codecs held by the transmission partner control unit 23 via the switching unit 14 (step S102). After the reception, the control unit 13 compares the own codec information s1 investigated in step S101 with the partner codec information s2 received in step S102, and holds the result in the memory (step S103).

  Next, the control unit 13 investigates the state of the network 30, measures the size of the free bandwidth, and stores it in the memory as network information s3 (step S104).

  Next, the control unit 13 uses the free bandwidth of the network 30 based on the network information s3 that is the result of investigating the state of the network 30 and the information on the comparison result between the codec information s1 and s2 held in step S103. It is determined whether there is a codec that can perform optimum transmission (step S105).

  As a result, when there is a codec that can be transmitted, the control unit 13 selects and transmits only the input information encoded by the codec by the switching unit 14 (step S106). At this time, the control unit 13 outputs a control signal for a codec switching command to the switching unit 14, and the switching unit 14 selects and outputs only the codec encoding information that can be transmitted based on the control signal. .

  Even during transmission, it is possible to switch to a codec that uses a band that can be transmitted even if normal transmission is not possible with the codec that is in use due to congestion, etc., by examining the network 30 periodically. Transmission is possible without interruption. Furthermore, during transmission, the codec status is investigated and the occurrence of a failure or the like is investigated. When the codec being transmitted cannot be transmitted normally due to a failure or the like, it is possible to continue transmission by switching to a codec capable of transmission.

  Next, a specific example of the above will be described.

  The control unit 13 checks in advance information such as a transmission band, an encoding method, and a manufacturer for all controlled codecs, and stores the information as its own codec information s1. The codec transmission band refers to the maximum transmission rate (bps) as described above. The encoding method of the codec includes conventionally well-known encoding methods such as audio and video, but the description thereof is omitted because it does not constitute the main part of the present invention.

  Further, the control unit 13 investigates whether or not the codec is operating normally, and retains the information as its own codec information s1. The connection between the control unit 13 and each of the codecs a1 to an includes an IP connection and a serial connection. However, the connection is not limited to this as long as the codec a1 to an can be controlled and investigated.

  As an example of FIG. 1, when the control unit 13 controls four codecs a1 to a4, the above contents are investigated for each of the codecs a1 to a4. As a result, as the own codec information s1, for example, as shown in FIG. 3, 1) the codec a1 is operating normally with the transmission band x1 and the encoding method y1, and 2) the codec a2 The transmission band is x2 and the encoding method is y2, and is operating normally. 3) The codec a3 is operating normally with the transmission band of x3 and the encoding method being y3. ) The codec a4 has a transmission band of x4 and an encoding method of y4. However, information indicating that the codec a4 is not operating normally can be obtained. The control unit 13 holds the own codec information s1 as a table in a memory, for example.

  Next, prior to encoding and transmitting the information input from the input unit 11, the control unit 13 transmits the own codec information s1 to the transmission partner control unit 23, while transmitting the transmission partner. The other party codec information s2 is also received from the control unit 23. For example, in the example of FIG. 1, it is assumed that the transmission partner control unit 23 controls the four codecs b1 to b4.

  As a result, as the counterpart codec information s2, for example, as shown in FIG. 4, 1) the codec b1 is operating normally with the transmission band x1 and the encoding method y1, and 2) the codec b2 The transmission band is x4 and the encoding method is y4 and is operating normally. 3) The codec b3 is not operating normally. 4) The codec b4 has the transmission band of x3 and the encoding method is y3. , Information that it is operating normally can be obtained. The control unit 13 holds the partner codec information s2 as a table in the memory.

  Next, the control unit 13 compares all the own codec information s1 being controlled with all the other codec information s2 controlled by the transmission partner control unit 23, and extracts and determines a codec that can be transmitted. To do.

  In the above case, the codec a1 of the own device and the codec b1 of the transmission partner are the same as the transmission band x1 and the encoding method y1, and both are operating normally, and the codec a3 of the own device and the codec b4 of the transmission partner transmit. It is the same as the band x3 and the encoding method y3, and both operate normally and match. The control unit 13 holds in the memory information on the codec that can be transmitted and extracted and determined in this way.

  Next, the control unit 13 investigates the transmission band of the network 30, measures a vacant band that can be transmitted, and stores the measurement result in the memory as network information s3.

  Next, the control unit 13 selects a codec to be transmitted using a vacant band based on the codec information extracted and determined as described above and the network information s3. At this time, if a failure such as congestion does not occur, a codec that can transmit with high quality is selected.

  For example, consider a case where a codec that can transmit at 30 Mbps and a codec that can transmit at 4 Mbps can be used by comparing the own codec information s1 and the counterpart codec information s2. In this case, the codec having a transmission band of 30 Mbps is selected because it is possible to perform transmission with higher quality by using a codec capable of transmission at 30 Mbps.

  In the above example, the codec a1 and the codec a3 can be used from the comparison between the own codec information s1 and the partner codec information s2. In this case, the transmission band x1 of the codec a1 is more than the transmission band x3 of the codec a3. If it is larger (x1> x3), the codec a1 is selected. If the opposite is true (x1 <x3), the codec a3 is selected.

  Furthermore, the control unit 13 investigates the state of the network 30 at the same time as investigating the codec being controlled during transmission. As a result, when a failure occurs in the transmitting codec or band, it is possible to transmit using another codec or band.

  For example, since transmission is possible in the transmission band x1, it is assumed that transmission is performed by the codec a1 having the transmission band x1. At this time, it is assumed that a failure occurs in the band x1 being transmitted or the codec a1. In that case, the transmission band is switched to the codec a3 of x3 (x1> x3), and transmission is continued using the transmission band x3.

  In addition, when the codec a4 of the transmission band x4 (x4> x1) cannot be used initially, but the codec a4 is restored after that, and the network 30 has a band equal to or larger than x4, the transmission in the transmission band x4 is performed. Since the quality is higher, the codec a4 of the transmission band x4 is used.

  Therefore, according to the present embodiment, the state of the codec controlled by the control unit is held, and the information is held by the control unit, so that it is not necessary to use the codec in which the failure has occurred.

  Further, in the present embodiment, the codec that matches the transmission method can be found by sending the retained codec information to the transmission counterpart control unit and receiving the counterpart codec information. Then, by examining the state of the network of the transmission band used by the matched codec, the network can be efficiently investigated. Furthermore, even during transmission, the codec and the network are investigated, and transmission is possible under the highest quality conditions, so that high quality transmission is always possible.

 In the present embodiment, as shown in FIG. 1, an example in which there is one input unit and one output unit is described, but there may be a plurality of input units and output units. When there are a plurality of input units and output units, a plurality of codecs may be selected and a plurality of communications may be performed by selecting one codec multiple times in step S105 illustrated in FIG. The switching operation is the same operation as when the number of input units and output units is one.

  Note that at least a part of the functions of the respective units in the apparatus described in the above embodiments may be realized by a computer by a program. This program may be read from a recording medium and loaded into a computer, or may be transmitted via a communication network and loaded into a computer.

  INDUSTRIAL APPLICABILITY The present invention can be applied to the use of a codec switching device that determines a network band that is optimal for transmission and selects a codec that can transmit in that band.

It is a block diagram which shows the whole structure of the codec switching apparatus which concerns on embodiment of this invention. It is a flowchart which shows the flow of the whole operation | movement of the codec switching apparatus shown in FIG. It is a figure explaining an example of own codec information. It is a figure explaining an example of the other party codec information. It is a block diagram which shows the whole structure of the system of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st codec switching apparatus 20 2nd codec switching apparatus 30 Network 11, 21 Input part 12, 22 Output part 13, 23 Control part 14, 24 Switching part a1-an, b1-bn Codec

Claims (4)

A plurality of codecs for encoding information and decoding the encoded information, determining an optimum network band for transmission of the encoded information, and determining the plurality of codecs capable of transmitting the encoded information in the band Codec switching device to select from among the codecs of
Network research means for investigating network information including the amount of free bandwidth of the network;
Codec investigation means for examining codec information including transmission bands of the plurality of codecs;
A codec switching device comprising: codec selection means for selecting a codec to be used at the time of transmission from among the plurality of codecs based on the network information and the codec information. The codec investigation means includes
Means for pre-inspecting the own codec information including the transmission band and encoding method of the own codec controlled in the plurality of codecs, before transmission of the encoded information;
Means for holding own codec information available from the surveyed results;
Means for transmitting the own codec information to a transmission partner;
Means for receiving other codec information including the transmission band and encoding method of the other codec held by the transmission partner from the transmission partner;
The codec switching according to claim 1, further comprising means for determining whether or not the own codec and the other codec can transmit to each other based on the own codec information and the other codec information. apparatus. The codec selection means includes
3. The codec switching apparatus according to claim 2, further comprising means for selecting a self-codec having the largest transmission band in the free band of the network among the self-codecs that can be transmitted with the other codec. The network investigation means and the codec investigation means are:
The codec switching device according to any one of claims 1 to 3, wherein the codec switching device is configured to be operable even during transmission of the encoded information.

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