JP5598335B2 - Data receiving apparatus, data transmitting apparatus, data receiving method, and data transmitting method - Google Patents

Description

  The present invention relates to a data transfer system and a transfer method for transferring data via a network.

  In recent years, with the spread of the Internet and network cameras, transmission of video and audio data via a network has been widely performed. The interface standard of network camera products is standardized by ONVIF (Open Network Video Interface Forum). In ONVIF, interfaces necessary for setting / acquiring camera information, streaming, security, and the like are defined, and camera control via a network is possible. In data transfer via a network, a usable bandwidth may be limited depending on network conditions, and problems such as data transfer delay occur. Therefore, a method of compressing the data to be transferred and reducing the data amount is taken.

  For example, in the image data transfer method described in Patent Document 1, moving image data is compression-encoded into MPEG format compressed data, sequentially stored in a buffer, and the stored compressed data is transmitted to a receiving device via a network. It is disclosed that when compressed data stored in a buffer exceeds a predetermined amount, the compressed data stored in the buffer is deleted in GOP (Group of Picture) units or picture units. .

JP 2003-219337 A

  Japanese Patent Application Laid-Open No. 2004-228561 describes a data thinning process when a bandwidth necessary for data transmission cannot be ensured. However, according to this method, when MPEG-based compressed data is deleted in GOP units, the number of frames of the image is reduced on the receiving side, resulting in an image with dropped frames. In addition, when deleting in units of pictures, there is a risk that image quality will deteriorate when data is decoded.

  Accordingly, an object of the present invention is to provide a data transfer system and a transfer method capable of transferring video data without degrading the image quality even when the network bandwidth cannot be secured.

In order to solve the above problems, for example, the configuration described in the claims is adopted.

  According to the present invention, it is possible to provide a data transfer system and a transfer method capable of transferring video data without degrading image quality even when the network bandwidth cannot be secured.

1 is a configuration diagram showing a data transfer system according to a first embodiment of the present invention. The figure which shows the case where data transfer is performed without camera control for comparison. FIG. 3 is a diagram illustrating data transfer control according to the first embodiment. 3 is a flowchart illustrating a data transfer process according to the first embodiment. FIG. 10 is a diagram illustrating data transfer control according to the second embodiment. 10 is a flowchart illustrating a flow of data transfer processing according to the second embodiment. The block diagram which shows the data transfer system which concerns on 3rd Example of this invention.

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

  FIG. 1 is a block diagram showing a data transfer system according to a first embodiment of the present invention. Here, as an example of the data transfer system, a case where video data from a plurality of video transfer cameras (data transfer devices) is transferred to a video reception device (data reception device) via a network is shown.

  A plurality of video transfer cameras 1a, 1b, and 1c (hereinafter simply referred to as cameras) include an imaging unit 2, an encoder (data compression unit) 3, a data control unit 4, a memory 5, and a network I / F 6. Is provided. The video reception device 8 includes a network I / F 9, a decoder (data decoding unit) 10, an output unit 11, a camera control unit 12, and a band usage rate calculation unit 13. Video data from each of the cameras 1 a to 1 c is input to a hub (HUB) 7, and is transferred from the HUB 7 to the video receiving device 8 through one transmission path.

  The operation of each part will be described. In each of the cameras 1a to 1c, the video data captured by the imaging unit 2 is converted into compressed data by the encoder 3. In this embodiment, the data is converted into MPEG format compressed data, and the compressed data is stored in the memory 5. Data stored in the memory 5 is transferred to the network via the network I / F 6. At that time, the data control unit 4 receives a camera control signal from the video reception device 8 via the network I / F 6 and controls data to be transferred onto the network.

  The video receiver 8 receives the video data transferred from the HUB 7 via the network I / F 9 and decodes it by the decoder 10. The decoded video data is output from the output unit 11 to an external device (for example, a monitor) (not shown). The bandwidth usage rate calculation unit 13 monitors the total amount of data transferred from the cameras 1a to 1c to the video receiving device 8, and calculates the bandwidth usage rate of the transmission path. Specifically, the total bit rate of data transferred from each camera at the next timing is predicted, and the ratio to the allowable bit rate of the transmission path is calculated. In accordance with the calculated bandwidth usage rate, the camera control unit 12 transmits a camera control signal for instructing data to be transferred at the next timing to each camera via the network I / F 9. With this camera control signal, video data can be transferred within the allowable range of the transmission path.

Next, the data transfer control in this embodiment will be specifically described.
FIG. 2 is a diagram illustrating a case where data transfer is performed without camera control for comparison. Here, for simplicity, data transfer from two cameras 1a and 1b is shown. The horizontal axis represents time, and schematically shows the transfer timing of data transferred from each camera and the transfer data amount. The data to be transferred here includes three types of pictures, MPEG picture, I picture (intra-frame encoded picture), P picture (inter-frame forward predictive encoded picture) and B picture (bidirectional predictive encoded picture). Consists of. Comparing the data amount (bps) of each picture, the I picture is generally the largest, followed by the P picture and the B picture. The bandwidth usage rate is defined as the ratio of the transfer data amount (bps) to the transfer allowable amount.

  In this example, the pictures are transferred from the cameras 1a and 1b in the order of I → B → B → P pictures at the same timing. Data from each camera is multiplexed by the HUB 7 and transferred to the video receiver 8 through one transmission path. Accordingly, the band usage rate between the HUB 7 and the video receiver 8 is highest when the I picture is transferred from the cameras 1a and 1b, and conversely, when the B picture is transferred from the cameras 1a and 1b. Is the lowest. Thus, the bandwidth usage rate changes according to the time according to the transfer timing from each camera. At the timing when I pictures are simultaneously transferred from multiple cameras, the total amount of transfer data may exceed the transfer allowable amount (bandwidth usage rate exceeds 100%), and each video data may be transferred normally. There is a risk that the playback operation on the video receiving side may fail or image quality of the displayed video may be degraded.

  FIG. 3 is a diagram showing data transfer control in this embodiment. In this embodiment, a camera control signal is sent to each camera based on the bandwidth usage rate, and control is performed to shift the data transfer timing from each camera. Similar to FIG. 2, each picture is transferred from the two cameras 1a and 1b in the order of I → B → B → P picture. However, the total amount of data to be transferred is controlled so as not to exceed the allowable transfer amount by shifting the transfer timing from both cameras 1a and 1b by the camera control signal. In this example, the transfer of the I picture from the camera 1b is delayed at the timing when the camera 1a transfers the I picture having a large amount of data. Then, the transfer of the I picture from the camera 1b is started at the next timing when the B picture with a small amount of data is transferred from the camera 1a. According to this, since I pictures are not simultaneously transferred from a plurality of cameras, the band usage rate is always 100% or less, and each video data can be transferred normally.

FIG. 4 is a flowchart showing the flow of data transfer processing in this embodiment.
Each camera 1a to 1c temporarily stores video data to be transferred in the memory 5 (SP11). The bandwidth usage rate calculation unit 13 of the video reception device 8 predicts the data amount of data transferred next from each camera, and calculates the bandwidth usage rate of the network (SP12). Specifically, the type (I, P, B) of the picture transferred from each camera at the next timing is predicted, and the total amount of data is calculated from the combination. The camera control unit 12 determines whether the calculated bandwidth usage rate exceeds the allowable level (100%) (SP13).

  If the band usage rate exceeds the allowable level in the determination of SP13, the camera control unit 12 sends a camera control signal to delay the data transfer timing to the camera attempting to transfer an I picture with a large amount of data. Transmit (SP14). In this case, a camera for delaying the transfer timing is determined in advance by setting a priority order of data transfer for each camera. Alternatively, the camera for delaying the transfer timing may be determined by circulating between a plurality of cameras. The camera that has received this camera control signal waits for data transfer until the next timing under the control of the data control unit 4.

  If the band usage rate does not exceed the allowable level in the determination of SP13, a camera control signal is transmitted to each camera so as to transfer the next data (SP15). As a result, the camera whose transfer timing is delayed can transfer the data waiting at the next timing. Then, it is determined whether there is untransferred data (SP16), and if there is remaining data, the process returns to SP12 and repeats SP12 to SP16.

  The amount of data stored in the memory 5 in the SP 11 may be any amount. For example, data may be stored in a memory in GOP units. In this case, when the transfer of 1 GOP is completed, the next 1 GOP is stored in the memory, and the process is executed again from SP 12. By repeating this, it becomes possible to transfer the video sequentially. Further, as long as the data amount can be stored in the memory 5, an arbitrary data amount may be stored in the memory 5 at a time to perform data transfer. It is preferable to store data in the memory as needed. This is because a transfer interruption period occurs in data transfer when the next transfer data is stored in the memory 5 after waiting for completion of transfer of the data stored in the memory 5.

  It goes without saying that the control method of the present embodiment is possible both when the transfer of video data is started and during the transfer is continuing. In the above description, the type of data to be transferred is described as being divided into I, P, and B pictures. However, the present invention is not limited to this, and the same is achieved by appropriately classifying the types of data according to the amount of data (bps). Can be controlled. In the above example, when the band usage rate exceeds the allowable level, the transfer of the I picture having the maximum data amount is delayed. However, if the excess amount of the band usage rate with respect to the allowable level is small, the P picture is not the I picture. Transfer of pictures and B pictures may be delayed. The picture selection at that time may be appropriately determined by the camera control unit 12 in the video reception device 8 according to the band usage rate. Thereby, the transmission capability of the network can be used more efficiently (with a bandwidth usage rate close to 100%).

  As described above, according to this embodiment, in video transfer from a plurality of cameras, by controlling the data transfer timing of each camera to be shifted, video data is not lost or deteriorated within the allowable bandwidth of the network. Data transfer can be performed. As a result, the video receiving side can reproduce and display a video with no image quality deterioration.

  In the first embodiment, the method of transferring video data within the allowable bandwidth of the network by shifting the video transfer timing of each camera has been described. In contrast, the second embodiment describes a method of transferring video data within the allowable bandwidth of the network by changing the transfer order in units of pictures in the transfer data of each camera. The data transfer system according to the present embodiment has the same configuration as that of the first embodiment (FIG. 1), and a description thereof will be omitted.

  FIG. 5 is a diagram showing data transfer control in this embodiment. In this embodiment, a camera control signal is sent to each camera based on the bandwidth usage rate, and the data transfer order from each camera is controlled. As in the first embodiment, the data transfer order in the case of transferring an I picture, a B picture, a B picture, and a P picture as MPEG video from two cameras 1a and 1b is shown. The camera 1a transfers each picture in the order of I → B → B → P picture. On the other hand, the camera 1b transfers each picture in the order of B → I → B → P picture. Originally, the camera 1b transfers each picture in the order of I-> B-> B-> P-picture in the same manner as the camera 1a, and replaces the first (I) and second (B) transfer pictures. This is an example. By replacing the transfer pictures in this way, it is possible to avoid overlapping I pictures having a large amount of data in the first transfer picture transferred from the cameras 1a and 1b. The first transfer picture is a combination of an I picture with a large amount of data and a B picture with a small amount of data, and these are transferred at the same timing. As a result, the total amount of data transferred at each transfer timing can be prevented from exceeding the allowable amount.

  In the transfer control of the present embodiment, the transfer is performed by changing the order in units of pictures. This is because the B picture refers to the previous and subsequent pictures, and the P picture refers to the previous picture to generate the video. If the referenced picture is replaced with another picture, the B picture and the P picture are correct. The video cannot be generated. Therefore, in order to understand the original picture order, transfer is performed by describing a number indicating the picture order before replacement in the header of each picture. On the video receiving side, the original picture order can be known by referring to this number, and the video can be generated by referring to the correct picture. Note that the picture order may be managed in GOP units. In that case, the picture order may be described in the GOP sequence header.

FIG. 6 is a flowchart showing the flow of data transfer processing in this embodiment.
Each camera 1a-1c stores the transfer data in the memory 5 (SP21). The bandwidth usage rate calculation unit 13 of the video receiver 8 predicts the data amount of the next data transferred from each camera, and calculates the bandwidth usage rate of the network (SP22). The camera control unit 12 determines whether or not the calculated bandwidth usage rate exceeds the allowable level (100%) (SP23).

  If the bandwidth usage rate exceeds the allowable level in the determination of SP23, the camera control unit 12 replaces the B picture data with a small data amount with the camera that is to transfer the I picture with the large data amount. A camera control signal is transmitted so as to be transferred (SP24). Also in this case, a camera for exchanging data is determined in advance by setting a priority order of data transfer for each camera. Alternatively, the camera for exchanging data may be determined by circulating between a plurality of cameras. Upon receiving this camera control signal, the camera transfers the data (B picture) with a small data amount by changing the data transfer order under the control of the data control unit 4. At this time, the I picture replaced with the B picture is ordered so as to be transferred at the original transfer timing of the B picture.

  On the other hand, if the band usage rate does not exceed the permissible level in the determination of SP23, a camera control signal is transmitted to each camera so as to transfer the data as it is (SP25). Thereby, the camera which replaced data can transfer the replaced data. Then, it is determined whether or not there is untransferred data (SP26). If there is remaining data, the process returns to SP22 and repeats SP22 to SP26.

  Also in the present embodiment, the type of data to be transferred is not limited to the division of I, P, and B pictures, and can be similarly controlled by appropriately dividing into a plurality of types depending on the amount of data (bps). In the above example, when the band usage rate exceeds the allowable level, the I picture having the maximum data amount is replaced with the B picture having the minimum amount. However, if the excess amount with respect to the allowable level is small, Alternatively, it may be replaced with a P picture. The picture selection at that time may be appropriately determined by the camera control unit 12 in the video reception device 8 according to the band usage rate. Thereby, the transmission capability of the network can be used more efficiently (with a bandwidth usage rate close to 100%).

  As described above, according to the present embodiment, in the data transfer of a plurality of cameras, the transfer order is changed in units of pictures, so that the data transfer can be performed within the allowable bandwidth of the network without loss or deterioration of the video data. it can. Thereby, on the video receiving side, it is possible to reproduce and display a video with no image quality deterioration. In particular, in this embodiment, the transfer data from each camera is not interrupted, so that the data can be transferred more efficiently.

  FIG. 7 is a block diagram showing a data transfer system according to the third embodiment of the present invention. In this embodiment, the bandwidth usage rate is monitored on the camera side, and data transfer from each camera is controlled.

  Compared with the configuration of the first embodiment (FIG. 1), the camera 1a of the plurality of video transfer cameras 1a, 1b, and 1c includes a band usage rate calculation unit 14, and the video reception device 8 includes a band usage rate calculation unit. This is a configuration not provided. The camera 1a provided with the band usage rate calculation unit 14 is referred to as “parent camera”, and the other cameras 1b and 1c not provided are referred to as “child cameras”. The cameras 1a, 1b, and 1c communicate with each other via a network and share data information transferred from each camera. In particular, in the parent camera 1a, the band usage rate calculation unit 14 monitors the total data amount from all the cameras including data transferred from the child cameras 1b and 1c at the next timing, and calculates the bandwidth usage rate. Then, a camera control signal for instructing data to be transferred at the next timing is transmitted to the child cameras 1b and 1c via the network I / F 6 in accordance with the calculated bandwidth usage rate. In some cases, an instruction is given to the parent camera 1a itself. When the cameras 1a, 1b, and 1c receive the camera control signal, the data control unit 4 controls the data transferred to the network.

  The data transfer control performed in this embodiment can be any of the control of the transfer timing from each camera as described in the first embodiment and the control of the transfer order of data from each camera as described in the second embodiment. It is. Also according to the present embodiment, data transfer can be performed without loss or deterioration of video data within the allowable bandwidth of the network. Thereby, on the video receiving side, it is possible to reproduce and display a video with no image quality deterioration.

  The data transfer system of each embodiment described above can be applied to a monitoring system, for example. In that case, the video transfer cameras 1a, 1b, and 1c are connected to a network using a monitoring camera and the video receiving device 8 is connected to a network to control the monitoring camera. When controlling transfer data, it is desirable that the surveillance recorder and the surveillance camera are provided by the same manufacturer. This is because it is necessary to match the interface standard in communication between the surveillance recorder and the surveillance camera. On the other hand, if the monitoring recorder and the monitoring camera are devices that are compatible with ONVIF, the interface standards are the same. Therefore, this embodiment can be applied even to combinations of different manufacturers.

  The present invention is not limited to the embodiments described above, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

1a, 1b, 1c ... video transfer camera (data transfer device),
2 ... Imaging unit,
3. Encoder,
4 ... Data control unit,
5 ... Memory,
6 ... Network I / F,
7 ... Hub (HUB),
8: Video receiver (data receiver),
9 ... Network I / F,
10: Decoder,
11 ... output part,
12 ... Camera control unit,
13, 14... Band usage rate calculation unit.

Claims (8)

A network I / F that receives video data including an intra-frame coded picture and an inter-frame coded picture transmitted from a plurality of data transmission apparatuses via a network and transmits a control signal to the data transmission apparatus When,
A prediction unit that predicts a bit rate of video data received from the plurality of data transmission devices based on whether a picture transmitted in the future from the data transmission device is an intra-frame coded picture or an inter-frame coded picture; Prepared,
When the predicted bit rate exceeds the bandwidth capacity of the network, the network I / F
Transmitting at least one of the plurality of data transmission devices, either a control signal for controlling transmission to be transmitted by changing the order of pictures to be transmitted or a control signal for controlling transmission of a picture to be suspended;
A data receiving device. Data transmitting apparatus connected via a network to a data receiving apparatus that receives video data including an intra-frame encoded picture and an inter-frame encoded picture from another data transmitting apparatus connected via a network Because
Information of video data transmitted from the other data transmitting device to the data receiving device by transmitting video data including an intra-frame coded picture and an inter-frame coded picture to the data receiving device via the network receive, and Rene Ttowaku I / F to transmit a control signal to said other data transmission device,
Whether a picture to be transmitted in the future from the network I / F is an intra-frame coded picture or an inter-frame coded picture, and whether a picture to be transmitted in the future from the other data transmission apparatus is an intra-frame coded picture or an inter-frame code A prediction unit that predicts a total bit rate of video data transmitted to the data reception device including video data transmitted from the other data transmission device , based on whether the image is a converted picture;
The network I / F, when the total bit rate of the predicted video data transmitted to the data receiving device exceeds the predetermined allowable bandwidth of the network,
Either a control signal for controlling transmission to be transmitted by changing the order of pictures to be transmitted or a control signal for controlling transmission of a picture to be paused is transmitted to the other data transmission apparatus, or the network I A data transmitting apparatus, wherein the order of pictures transmitted by / F is changed, or transmission of pictures is temporarily stopped. A reception step of receiving video data including an intra-frame coded picture and an inter-frame coded picture transmitted from a plurality of data transmission devices via a network;
A prediction step of predicting a bit rate of video data received from the plurality of data transmission devices based on whether a picture transmitted in the future from the data transmission device is an intra-frame coded picture or an inter-frame coded picture;
If the predicted bit rate exceeds the bandwidth capacity of the network,
A transmission step of transmitting either a control signal for controlling transmission to change the order of pictures to be transmitted or a control signal for controlling transmission of a picture to be suspended, to at least one of the plurality of data transmission apparatuses. When,
A data receiving method characterized by comprising: Data transmitting apparatus connected via a network to a data receiving apparatus that receives video data including an intra-frame encoded picture and an inter-frame encoded picture from another data transmitting apparatus connected via a network The data transmission method in
A receiving step of receiving information of video data transmitted from the other data transmitting device to the data receiving device;
Whether a picture to be transmitted in the future from the data transmission apparatus is an intra-frame coded picture or an inter-frame coded picture, and whether a picture to be transmitted in the future from the other data transmission apparatus is an intra-frame coded picture or an inter-frame coding A prediction step of predicting a total bit rate of video data transmitted to the data receiving device including video data transmitted from the other data transmitting device based on a picture;
When the total bit rate of the predicted video data transmitted to the data receiving device exceeds a predetermined allowable bandwidth of the network,
Either a control signal for controlling transmission to be transmitted by changing the order of pictures to be transmitted or a control signal for controlling transmission of a picture to be paused is transmitted to the other data transmission device, or the network is A transmission step of transposing the picture to be transmitted via the transmission or temporarily stopping the transmission of the picture;
A transmission step of transmitting video data including an intra-frame coded picture and an inter-frame coded picture to the data receiving device via the network;
A data transmission method characterized by comprising: A control signal for controlling transmission to change the order of pictures to be transmitted,
When the next picture to be transmitted is an intra-frame coded picture, control is performed so that the inter-frame coded picture transmitted next to the intra-frame coded picture is transmitted before the intra-frame coded picture. The data receiving apparatus according to claim 1, wherein the data receiving apparatus is a control signal. A control signal for controlling transmission to change the order of pictures to be transmitted,
When the next picture to be transmitted is an intra-frame coded picture, control is performed so that the inter-frame coded picture transmitted next to the intra-frame coded picture is transmitted before the intra-frame coded picture. Control signal, and
The transmission of the network I / F by changing the order of pictures to be transmitted is as follows.
When the picture to be transmitted next is an intra-frame coded picture, the inter-frame coded picture transmitted next to the intra-frame coded picture is transmitted before the intra-frame coded picture. The data transmission device according to claim 2. A control signal for controlling transmission to change the order of pictures to be transmitted,
When the next picture to be transmitted is an intra-frame coded picture, control is performed so that the inter-frame coded picture transmitted next to the intra-frame coded picture is transmitted before the intra-frame coded picture. 4. The data receiving method according to claim 3, wherein the data receiving method is a control signal. A control signal for controlling transmission to change the order of pictures to be transmitted,
When the next picture to be transmitted is an intra-frame coded picture, control is performed so that the inter-frame coded picture transmitted next to the intra-frame coded picture is transmitted before the intra-frame coded picture. Control signal, and
The order of pictures transmitted through the network is changed and transmitted.
When the picture to be transmitted next is an intra-frame coded picture, the inter-frame coded picture transmitted next to the intra-frame coded picture is transmitted before the intra-frame coded picture. The data transmission method according to claim 4, wherein:

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