JP2024004606A - Content receiving device, content relay device, and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce loss of a packet containing a content.

SOLUTION: A content receiving device includes: a receiving unit that receives a stream containing a content; a processing unit that processes the stream received by the receiving unit; and a control unit that controls a communication band of the receiving unit for receiving the stream. When the receiving unit detects that a first stream according to TCP (Transmission Control Protocol) and a second stream according to UDP (User Datagram Protocol) are received in parallel, the control unit performs suppression control to suppress the communication band for receiving the first stream.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to a content receiving device, a content relay device, and a communication control method.

2. Description of the Related Art Conventionally, techniques have been proposed for controlling the communication band of communication according to TCP (Transmission Control Protocol).

For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2006-173961) discloses the following TCP congestion control device. That is, the TCP congestion control device measures the bandwidth of the communication network during communication, and determines the congestion window size using the window size that allows maximum use of the network bandwidth (hereinafter referred to as measurement window size) obtained from the measured value. one method uses the measurement window size to set the TCP congestion window size and slow start threshold after data loss revealed by duplicate ACKs, and the other method uses the measurement window size to set the TCP congestion window size and slow start threshold after data loss is confirmed by data segment acknowledgment after retransmission timeout. Accelerates TCP communication in broadband and high-latency wireless networks by detecting ACK segment loss and delay to prevent erroneous data retransmission, and by not reducing the congestion window size to prevent a drop in transmission rate. do.

Japanese Patent Application Publication No. 2006-173961

A technology is desired that can reduce the loss of packets containing content beyond the technology described in Patent Document 1.

The present disclosure has been made to solve the above-mentioned problems, and the purpose is to provide a content receiving device, a content relay device, and a communication control method that can reduce loss of packets containing content. be.

A content receiving device of the present disclosure includes a receiving unit that receives a stream including content, a processing unit that processes the stream received by the receiving unit, and a communication band of the receiving unit for receiving the stream. When the control unit detects that the receiving unit is receiving the first stream according to TCP and the second stream according to UDP (User Datagram Protocol) in parallel, Suppression control is performed to suppress the communication band for receiving the first stream.

One aspect of the present disclosure can be realized not only as a content receiving device including such a characteristic processing unit, but also as a semiconductor integrated circuit that realizes part or all of the content receiving device, It can be realized as a system including a device.

Further, one aspect of the present disclosure can be realized not only as a content relay device including such a characteristic processing unit, but also as a semiconductor integrated circuit that realizes part or all of the content relay device, It can be realized as a system including a content relay device.

According to the present disclosure, loss of packets containing content can be reduced.

FIG. 1 is a diagram showing the configuration of a content distribution system according to a first embodiment of the present disclosure. FIG. 2 is a diagram showing the configuration of the STB according to the first embodiment of the present disclosure. FIG. 3 is a diagram illustrating an example of the bit rate of IP packets received by the STB according to the first embodiment of the present disclosure. FIG. 4 is a functional block diagram showing the configuration of the STB according to the first embodiment of the present disclosure. FIG. 5 is a diagram showing IP packets stored in the ring buffer in the STB according to the first embodiment of the present disclosure. FIG. 6 is a flowchart defining an example of an operation procedure when the STB according to the embodiment of the present disclosure suppresses the communication band for receiving the stream S1. FIG. 7 is a diagram illustrating an example of a communication sequence in the content distribution system according to the first embodiment of the present disclosure. FIG. 8 is a diagram showing the configuration of a content distribution system according to the second embodiment of the present disclosure. FIG. 9 is a diagram showing the configuration of a repeater according to the second embodiment of the present disclosure. FIG. 10 is a functional block diagram showing the configuration of a repeater according to the second embodiment of the present disclosure.

First, the contents of the embodiments of the present disclosure will be listed and explained.

(1) A content receiving device according to an embodiment of the present disclosure includes a receiving unit that receives a stream including content, a processing unit that processes the stream received by the receiving unit, and a processing unit that processes the stream received by the receiving unit. a control unit that controls a communication band of the reception unit, and the control unit detects that the reception unit is receiving the first stream according to TCP and the second stream according to UDP in parallel. In this case, suppression control is performed to suppress the communication band for receiving the first stream.

In this way, when the first stream according to TCP and the second stream according to UDP are being received in parallel, the configuration that suppresses the communication band for receiving the first stream allows, for example, the first stream It is possible to suppress overflow of the buffer for storing the packets constituting the stream and the packets constituting the second stream. Therefore, loss of packets containing content can be reduced.

(2) In (1) above, the control unit may reduce the window size in communication according to TCP as the suppression control.

With such a configuration, it is possible to reduce the amount of data transmitted at one time from the transmission source of the first stream, and therefore it is possible to reduce the communication rate of the first stream.

(3) In (1) or (2) above, the control unit may delay transmission of ACK by the reception unit to packets forming the first stream as the suppression control.

With such a configuration, the transmission timing of the first stream by the transmission source of the first stream can be delayed, so the communication rate of the first stream can be reduced.

(4) In any one of (1) to (3) above, the control unit may detect that the receiving unit is receiving the first stream and the second stream in parallel. If the second stream is a multicast stream, the suppression control may be performed.

With such a configuration, it is possible to reduce the loss of application packets that constitute the second stream and are not retransmitted.

(5) In any one of (1) to (4) above, when the receiving unit is receiving an adaptive stream as the first stream, the control unit may control the communication rate according to the communication rate of the first stream. Then, the amount of suppression in the suppression control may be adjusted.

With such a configuration, it is possible to more appropriately set the amount of suppression of the communication band according to the communication rate of the first stream, which may vary.

(6) In any one of (1) to (5) above, the processing unit may detect a packet loss in the second stream received by the receiving unit, and the control unit may detect a packet loss in the second stream received by the receiving unit. The amount of suppression in the suppression control may be adjusted according to the detection result of the packet loss by the unit.

With such a configuration, it is possible to more appropriately set the communication band suppression amount according to the number of packet losses that actually occur.

(7) In (6) above, when the processing unit detects a packet loss in the second stream, the processing unit may perform packet restoration processing, and the control unit may perform the restoration processing by the processing unit. The amount of suppression in the suppression control may be adjusted depending on the success rate.

With such a configuration, while restoring packets in the second stream, it is possible to more appropriately set the communication band suppression amount according to the success rate of the restoration process.

(8) A content relay device according to an embodiment of the present disclosure includes a receiving unit that receives a stream including content, a relay unit that performs relay processing of the stream received by the receiving unit, and a relay unit that receives the stream. and a control unit for controlling a communication band of the receiving unit, the control unit configured to receive the first stream according to TCP and the second stream according to UDP in parallel. If detected, suppression control is performed to suppress the communication band for receiving the first stream.

In this way, when the first stream according to TCP and the second stream according to UDP are being received in parallel, the configuration that suppresses the communication band for receiving the first stream allows, for example, the first stream It is possible to suppress overflow of the buffer for storing the packets constituting the stream and the packets constituting the second stream. Therefore, loss of packets containing content can be reduced.

(9) A communication control method according to an embodiment of the present disclosure is a communication control method in a content receiving device, which includes a step of receiving a stream including content, a step of processing the received stream, and a step of processing the stream. and controlling a communication band for receiving, and in the step of controlling the communication band, if the first stream according to TCP and the second stream according to UDP are being received in parallel, Suppression control is performed to suppress the communication band for receiving the first stream.

In this way, in a state where the first stream according to TCP and the second stream according to UDP are being received in parallel, for example, the first stream can be It is possible to suppress overflow of the buffer for storing the packets constituting the stream and the packets constituting the second stream. Therefore, loss of packets containing content can be reduced.

Embodiments of the present disclosure will be described below with reference to the drawings. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated. Furthermore, at least some of the embodiments described below may be combined arbitrarily.

<First embodiment>
[Configuration and basic operation]
FIG. 1 is a diagram showing the configuration of a content distribution system according to a first embodiment of the present disclosure. Referring to FIG. 1, a content distribution system 401 includes an STB (Set Top Box) 101, an HTTP (HyperText Transfer Protocol) server 301, and an IP broadcast distribution device 302. STB 101 is an example of a content receiving device. Note that the content distribution system 401 may be configured to include a plurality of HTTP servers 301 or may be configured to include a plurality of IP broadcast distribution devices 302.

The STB 101 is installed at a user's home 111. The HTTP server 301 is provided at a business office 311 of an OTT (Over The Top) business. The IP broadcast distribution device 302 is installed in a cable television station building 312.

The HTTP server 301 distributes VOD content, which is VOD (Video On Demand) content. More specifically, the HTTP server 301 transmits the stream S1 including VOD content to the STB 101 via the network 351. Stream S1 is an example of a first stream. VOD content includes audio information, video information, subtitle information, and the like.

Stream S1 is composed of a plurality of IP packets P1 containing information on which VOD content is divided into a plurality of pieces. IP packet P1 includes a TCP packet.

The IP broadcast distribution device 302 distributes broadcast content such as terrestrial digital broadcast, BS (Broadcast Satellite) broadcast, CS (Communication Satellite) broadcast, and independent broadcast. More specifically, the IP broadcast distribution device 302 transmits a stream S2 including broadcast content to the STB 101 via the network 351. Stream S2 is an example of a second stream. Broadcast content includes audio information, video information, EPG (Electronic Program Guide) information, SI information (Service Information), subtitle information, and the like.

Stream S2 is composed of a plurality of IP packets P2 containing information on which broadcast content is divided into a plurality of pieces. IP packet P2 includes a UDP packet. Hereinafter, each of the IP packets P1 and P2 will also be referred to as an IP packet P.

STB 101 receives stream S1 transmitted by HTTP server 301 via network 351. Further, the STB 101 receives stream S2 transmitted by the IP broadcast distribution device 302 via the network 351. Note that the STB 101 may receive in parallel a plurality of streams S2 each including a plurality of broadcast contents.

FIG. 2 is a diagram showing the configuration of the STB according to the first embodiment of the present disclosure. Referring to FIG. 2, STB 101 includes network device 10, processor 20, and memory 30. Memory 30 is, for example, a nonvolatile memory.

The network device 10 receives the IP packet P1 that constitutes the stream S1 from the HTTP server 301 via the network 351. The network device 10 stores the received IP packet P1 in a buffer in the memory 30.

Further, the network device 10 receives IP packets P2 constituting the stream S2 from the IP broadcast distribution apparatus 302 via the network 351. Network device 10 stores the received IP packet P2 in a buffer in memory 30.

In this way, in the STB 101, the reception processing of the IP packets P1 and P2 is performed using common reception resources, that is, the buffers in the network device 10 and the memory 30.

Processor 20 processes IP packets P1, P2 stored in memory 30 by network device 10.

More specifically, for example, when the processor 20 receives an operation to record broadcast content from the user, it performs a process of acquiring the IP packet P2 from the memory 30 and storing the acquired IP packet P2 in the HDD 151.

Further, for example, when the processor 20 receives an operation for viewing broadcast content from the user, the processor 20 acquires the IP packet P2 from the memory 30, and reproduces the broadcast content using the information included in the acquired IP packet P2. The video information, audio information, etc. obtained are transmitted to the display device 161.

Further, for example, when the processor 20 receives an operation for viewing VOD content from the user, the processor 20 acquires the IP packet P1 from the memory 30, and reproduces the VOD content using the information included in the acquired IP packet P1. The video information, audio information, etc. obtained are transmitted to the display device 161.

In this way, in the STB 101, the common processing resource, ie, the processor 20, processes the IP packets P1 and P2 received by the network device 10.

[assignment]
In recent years, OTT services have become popular, and the number of OTT users and VOD content is expected to further increase. Furthermore, in recent years, the bit rates of stream S1 transmitted by HTTP server 301 and stream S2 transmitted by IP broadcast distribution apparatus 302 have become higher.

FIG. 3 is a diagram illustrating an example of the bit rate of IP packets received by the STB according to the first embodiment of the present disclosure. In FIG. 3, the horizontal axis shows time and the vertical axis shows bit rate. The solid line in FIG. 3 indicates the bit rate of the IP packet P1 received from the HTTP server 301 by the network device 10 in the STB 101. The broken line in FIG. 3 indicates the bit rate of the IP packet P2 received by the network device 10 in the STB 101 from the IP broadcast distribution apparatus 302.

Referring to FIG. 3, the bit rate of IP packets P2 received by network device 10 from IP broadcast distribution apparatus 302 via network 351 changes little over time and is almost constant.

On the other hand, the bit rate of the IP packet P1 received by the network device 10 from the HTTP server 301 via the network 351 may increase irregularly. More specifically, the stream S1 is an adaptive stream that follows an adaptive streaming method such as MPEG-DASH (Moving Pictures Expert Group-Dynamic Adaptive Streaming over HTTP) and HLS (HTTP Live Streaming). If the stream is a stream, it is received by the network device 10. The bit rate of IP packet P1 varies.

By the way, the STB 101 may receive streams S1 and S2 in parallel. More specifically, for example, when recording broadcast content and playing VOD content in parallel according to a user's operation, STB 101 receives streams S1 and S2 in parallel, and stores IP packet P2 in HDD 151. Processing for reproducing the VOD content is performed using the information contained in the IP packet P1.

When the STB 101 receives streams S1 and S2 in parallel, the buffer in the memory 30 overflows depending on the processing load on the processor 20 and the communication rate of the IP packets P1 and P2 received by the network device 10, and the IP Loss of packets P1 and P2 may occur.

Furthermore, when recording a plurality of broadcast contents and playing VOD contents in parallel according to a user's operation, the STB 101 receives stream S1 and a plurality of streams S2 each containing the plurality of broadcast contents in parallel. do. In this case, the processing load on the processor 20 and the communication rate of the IP packets P1, P2 increase, and loss of the IP packets P1, P2 is likely to occur.

The amount of data sent by the HTTP server 301 is variably controlled according to the processing speed of the STB 101 and the congestion state in the network 351 according to TCP, while the IP broadcast distribution device 302 using UDP has to send out broadcast content in real time. Therefore, control according to the network status is not performed.

When a loss of the IP packet P1 occurs, the STB 101 can receive the IP packet P1 having the same content as the lost packet, which is retransmitted by the HTTP server 301 according to TCP.

On the other hand, when the IP packet P2 is lost, the STB 101 restores the lost packet using FEC (Forward Error Correction). However, if the number of lost packets of the IP packet P2 per unit time exceeds a predetermined value, restoration of some or all of the lost packets may fail. If the STB 101 fails to restore lost packets, the video and audio will be distorted when the user views the corresponding content.

Therefore, the STB 101 according to the first embodiment of the present disclosure solves the above problem with the following configuration.

(STB configuration)
FIG. 4 is a functional block diagram showing the configuration of the STB according to the first embodiment of the present disclosure. Referring to FIG. 4, the STB 101 includes a communication section 11, a VOD packet acquisition section 21, a broadcast packet acquisition section 22, processing sections 23 and 24, a control section 25, a HW buffer 31, and a ring buffer 32. , a TCP socket buffer 33, and a UDP socket buffer 34. The communication unit 11 is an example of a receiving unit.

The communication unit 11 is realized by the network device 10. The VOD packet acquisition section 21, the broadcast packet acquisition section 22, the processing sections 23 and 24, and the control section 25 are realized by the processor 20. A HW buffer 31, a ring buffer 32, a TCP socket buffer 33, and a UDP socket buffer 34 are included in the memory 30.

Hereinafter, the buffer size of the HW buffer 31 is "B1", the buffer size of the ring buffer 32 is "B2", the buffer size of the TCP socket buffer 33 is "B3", and the buffer size of the UDP socket buffer 34 is "B4". shall be. Further, the free capacity of the HW buffer 31 is set as "E1", the free capacity of the ring buffer 32 is set as "E2", the free capacity of the TCP socket buffer 33 is set as "E3", and the free capacity of the UDP socket buffer 34 is set as "E4". shall be. Note that the STB 101 may have a configuration including five or more buffers.

The communication unit 11 receives the stream S1 according to TCP. More specifically, the communication unit 11 receives the IP packet P1 constituting the stream S1 from the HTTP server 301 via the network 351, and stores the received IP packet P1 in the HW buffer 31.

The communication unit 11 also receives the stream S2 according to UDP. More specifically, the communication unit 11 receives the IP packet P2 constituting the stream S2 from the IP broadcast distribution device 302 via the network 351, and stores the received IP packet P2 in the HW buffer 31.

The communication unit 11 acquires the IP packet P from the HW buffer 31 and stores it in the ring buffer 32 at a timing according to a predetermined read cycle R1.

The VOD packet acquisition unit 21 acquires the IP packet P1 from among the IP packets P stored in the ring buffer 32 and stores it in the TCP socket buffer 33. More specifically, the VOD packet acquisition unit 21 acquires the IP packet P1 from the ring buffer 32 and stores it in the TCP socket buffer 33 at a timing according to a predetermined read cycle R2.

The broadcast packet acquisition unit 22 acquires the IP packet P2 from among the IP packets P stored in the ring buffer 32 and stores it in the UDP socket buffer 34. More specifically, the broadcast packet acquisition unit 22 acquires the IP packet P2 from the ring buffer 32 and stores it in the UDP socket buffer 34 at a timing according to the read cycle R2.

The processing unit 23 processes the stream S1 received by the communication unit 11. More specifically, the processing unit 23 acquires the IP packet P1 from the TCP socket buffer 33 at a timing according to the predetermined read cycle R3, and processes the acquired IP packet P1. Specifically, the processing unit 23 decodes the IP packet P1 and decodes the VOD content included in the decoded IP packet P1. The processing unit 23 performs a process of playing back the decoded VOD content, and transmits the obtained video information, audio information, etc. to the display device 161.

Furthermore, the processing unit 24 processes the stream S2 received by the communication unit 11. More specifically, the processing unit 24 acquires the IP packet P2 from the UDP socket buffer 34 at a timing according to a predetermined read cycle R4, and processes the acquired IP packet P2. Specifically, the processing unit 24 decodes the IP packet P2 and stores the decoded IP packet P2 in the HDD 151. Alternatively, the processing unit 24 decodes the broadcast content included in the decoded IP packet P2, performs processing to reproduce the decoded broadcast content, and transmits the obtained video information, audio information, etc. to the display device 161.

The control unit 25 controls the communication band of the communication unit 11 for receiving the stream S1. When the control unit 25 detects that the communication unit 11 is receiving streams S1 and S2 in parallel, it performs suppression control to suppress the communication band for receiving stream S1.

FIG. 5 is a diagram showing IP packets stored in the ring buffer in the STB according to the first embodiment of the present disclosure. Referring to FIG. 5, when receiving streams S1 and S2 in parallel, communication unit 11 receives IP packets P1 and P2 serially. The IP packets P1 and P2 are stored in the ring buffer 32 in the order in which they were received by the communication unit 11.

The control unit 25 monitors the ring buffer 32, and if it is determined that the communication unit 11 is receiving streams S1 and S2 in parallel based on the monitoring result, it suppresses the communication band for receiving stream S1. performs inhibitory control. For example, the communication band [bps] for receiving stream S1 is the value obtained by dividing 8 times the window size WS [byte] in communication according to TCP by the RTT (Round Trip Time) between the HTTP server 301 and STB 101. Represented by

More specifically, the control unit 25 refers to the ring buffer 32 and determines whether the communication unit 11 receives the streams S1 and S2 in parallel, that is, at the same time, if the IP packets P1 and P2 are stored in the ring buffer 32. It is determined that On the other hand, if only one of the IP packets P1 and P2 is stored in the ring buffer 32, the control unit 25 determines that the communication unit 11 is not receiving streams S1 and S2 in parallel. .

For example, when the control unit 25 detects that the communication unit 11 is receiving streams S1 and S2 in parallel and the stream S2 is a multicast stream, the control unit 25 performs suppression control.

More specifically, if a multicast address is stored as the destination IP address in the header of the IP packet P2 in the ring buffer 32, the control unit 25 determines that the stream S2 is a multicast stream. On the other hand, if the multicast address is not stored in the header of the IP packet P2, the control unit 25 determines that the stream S2 is not a multicast stream.

When the control unit 25 determines that the communication unit 11 is receiving streams S1 and S2 in parallel and determines that stream S2 is a multicast stream, it performs suppression control.

On the other hand, if the control unit 25 determines that the communication unit 11 is not receiving streams S1 and S2 in parallel, or if it determines that stream S2 is not a multicast stream, it does not perform suppression control.

For example, the control unit 25 determines that the communication unit 11 is receiving streams S1 and S2 in parallel and performs suppression control, and then the communication unit 11 receives at least one of the streams S1 and S2. If the system stops, the inhibitory control is canceled.

(Change of window size WS)
The control unit 25 reduces the window size WS in communication according to TCP as suppression control.

More specifically, the control unit 25 determines a window size WS smaller than the current window size WS.

Specifically, the control unit 25 specifies the value of x that gives the smallest value of buffer size Bx/reading cycle Rx. Here, x is an integer from 1 to 4. The control unit 25 determines whether a value V1 obtained by dividing the current window size WS by the VOD content transmission rate in the HTTP server 301 and the network 351 is smaller than the read cycle Rx. When the value V1 is smaller than the read cycle Rx, the control unit 25 determines a window size WS that satisfies the following equation (1).
Bx-Brat×Rx>WS... (1)

Here, Brat is the bit rate of stream S1.

The control unit 25 outputs a suppression instruction A1 indicating the determined window size WS to the communication unit 11.

When receiving the suppression instruction A1 from the control unit 25, the communication unit 11 notifies the HTTP server 301 of the window size WS indicated by the received suppression instruction A1. More specifically, the communication unit 11 includes an ACK packet including the window size WS indicated by the suppression instruction A1 in an IP packet and transmits it to the HTTP server 301 via the network 351.

(ACK delay)
As suppression control, the control unit 25 delays transmission of ACK by the communication unit 11 to the IP packet P1 that constitutes the stream S1.

More specifically, the control unit 25 determines the delay time DT of the ACK packet according to TCP and to be transmitted to the HTTP server 301.

Specifically, the control unit 25 specifies the value of x for which the free capacity Ex is the smallest value. When the free capacity Ex is smaller than a threshold value TH1 obtained by adding a predetermined margin value to the product of the bit rate Brat of the stream S1 and the read cycle Rx, the control unit 25 determines the read cycle Rx as the delay time DT.

The control unit 25 outputs a suppression instruction A2 indicating the determined delay time DT to the communication unit 11.

When the communication unit 11 receives the suppression instruction A2 from the control unit 25, the communication unit 11 transmits the ACK packet to the HTTP server 301 after holding the delay time DT indicated by the received suppression instruction A2.

(Other example 1 of inhibitory control)
For example, the communication unit 11 acquires one of a plurality of representations with different bit rates prepared in the HTTP server 301 according to MPEG-DASH, for example, according to the communication band of the network 351 and the specifications of the STB 101. Stream S1 containing the selected Representation is received. The communication unit 11 can dynamically change the representation to be acquired.

When the communication unit 11 receives the adaptive stream as the stream S1, the control unit 25 adjusts the amount of suppression in the suppression control according to the communication rate of the stream S1.

More specifically, the communication unit 11 holds an MPD (Meida Presentation Description) file that indicates the acquired representation and other selectable representations.

The control unit 25 refers to the MPD file held by the communication unit 11 and checks the representation currently acquired by the communication unit 11 and the bit rate of the representation.

For example, if there is a Representation with a lower bit rate than the bit rate of the Representation currently acquired by the communication unit 11 as another selectable Representation indicated by the MPD, the control unit 25 suppresses the Representation. In the control, the amount of decrease in the window size WS is set to a larger value.

On the other hand, if there is no Representation with a bit rate lower than the bit rate of the Representation currently acquired by the communication unit 11 as another selectable Representation indicated by the MPD, the control unit 25 suppresses the Representation. In the control, the amount of decrease in the window size WS is set to a smaller value.

Alternatively, if there is a Representation with a bit rate lower than the bit rate of the Representation currently acquired by the communication unit 11 as another selectable Representation indicated by the MPD, the control unit 25 suppresses the Representation. In the control, the delay time DT is determined to be a larger value.

On the other hand, if there is no Representation with a bit rate lower than the bit rate of the Representation currently acquired by the communication unit 11 as another selectable Representation indicated by the MPD, the control unit 25 suppresses the Representation. In the control, the delay time DT is determined to be a smaller value.

(Other example 2 of inhibitory control)
The processing unit 24 detects packet loss in the stream S2 received by the communication unit 11. When the processing unit 24 detects a packet loss in the stream S2, it performs a restoration process on the IP packet P2. The processing unit 24 regularly or irregularly notifies the control unit 25 of the packet loss detection result and the result of the restoration process of the IP packet P2.

The control unit 25 adjusts the amount of suppression in the suppression control according to the packet loss detection result by the processing unit 24 . For example, the control unit 25 adjusts the amount of suppression in suppression control according to the success rate of the restoration process by the processing unit 24.

More specifically, if the processing unit 24 has failed to restore the IP packet P2 and the minimum value E3min of the free capacity E3 during a predetermined period is smaller than the current window size WS, the control unit 25 A difference D1 between the value E3min and the current window size WS is calculated. The control unit 25 determines the value obtained by subtracting the difference D1 from the current window size WS as the new window size WS.

On the other hand, if the processing unit 24 has failed to restore the IP packet P2 and the minimum value E3min of the free capacity E3 during the predetermined length period is greater than or equal to the current window size WS, the control unit 25 controls the window size WS. No changes made.

In addition, the control unit 25 determines whether the processing unit 24 has successfully restored the IP packet P2 a predetermined number of times or more, or the processing unit 24 has not performed the restoration process, and the maximum value E3MAX of the free capacity E3 during a period of a predetermined length is If the maximum value E1MAX of the free capacity E1 during a period of a predetermined length is larger than the current window size WS, a value obtained by adding a predetermined value to the current window size WS is determined as the new window size WS.

On the other hand, the control unit 25 determines whether the processing unit 24 has not succeeded in restoring the IP packet P2 a predetermined number of times or more, the maximum value E3MAX is smaller than the current window size WS, or the maximum value E1MAX is smaller than the current window size WS. If it is smaller than , the window size WS is not changed.

[Flow of operation]
FIG. 6 is a flowchart defining an example of an operation procedure when the STB according to the embodiment of the present disclosure suppresses the communication band for receiving the stream S1.

Referring to FIG. 6, in STB 101, control unit 25 waits for communication unit 11 to receive streams S1 and S2 in parallel (NO in step S11), and waits for communication unit 11 to receive streams S1 and S2 in parallel. If the stream S2 received by the communication unit 11 is a multicast stream (YES in step S12), suppression control is performed to suppress the communication band for receiving the stream S1 (YES in step S11). Step S13).

Next, the control unit 25 waits until the communication unit 11 stops receiving at least one of the stream S1 and the stream S2 (NO in step S14), and waits until the communication unit 11 stops receiving at least one of the stream S1 and the stream S2. If one of the receptions has stopped (YES in step S14), the suppression control is canceled (step S15).

Next, the control unit 25 waits for the communication unit 11 to receive the streams S1 and S2 in parallel again (NO in step S11).

FIG. 7 is a diagram illustrating an example of a communication sequence in the content distribution system according to the first embodiment of the present disclosure.

Referring to FIG. 7, first, HTTP server 301 transmits stream S1 to STB 101 (step S21).

Next, the STB 101 receives the stream S1 from the HTTP server 301 via the network 351, includes an ACK packet for the received stream S1 in an IP packet, and transmits the IP packet to the HTTP server 301 (step S22).

Next, the IP broadcast distribution device 302 starts transmitting the stream S2 to the STB 101 (step S23).

Next, since the STB 101 receives streams S1 and S2 in parallel, it performs suppression control to suppress the communication band for receiving stream S1. For example, the STB 101 determines a window size WS smaller than the current window size WS, and transmits an ACK packet including the determined window size WS to the HTTP server 301 in an IP packet (step S24).

Next, the HTTP server 301 receives the ACK packet from the STB 101 via the network 351, and transmits the stream S1 of the amount of data indicated by the window size WS included in the received ACK packet to the STB 101 (step S25).

Note that although the content distribution system 401 according to the first embodiment of the present disclosure has a configuration including the IP broadcast distribution device 302, the present disclosure is not limited to this. The content distribution system 401 may have a configuration that does not include the IP broadcast distribution device 302. In this case, the communication unit 11 in the STB 101 receives, for example, a stream S3 including VoIP (Voice over Internet Protocol) audio content instead of the stream S2. Stream S3 includes audio information. When the control unit 25 detects that the communication unit 11 is receiving streams S1 and S3 in parallel, it performs suppression control to suppress the communication band for receiving stream S1.

Furthermore, in the STB 101 according to the first embodiment of the present disclosure, the control unit 25 determines that the communication unit 11 is not receiving streams S1 and S2 in parallel, or that stream S2 is multicast. Although the configuration is such that suppression control is not performed when it is determined that the stream is not a stream, the present invention is not limited to this. When the control unit 25 determines that the communication unit 11 is receiving streams S1 and S2 in parallel, the control unit 25 may perform suppression control regardless of whether stream S2 is a multicast stream. good.

Further, in the STB 101 according to the first embodiment of the present disclosure, the control unit 25 is configured to reduce the window size WS and delay the transmission of ACK to the IP packet P1 as suppression control. However, it is not limited to this. The control unit 25 may have a configuration in which it does not reduce the window size WS or delay the transmission of ACK to the IP packet P1.

Further, in the STB 101 according to the first embodiment of the present disclosure, the control unit 25 is configured to adjust the amount of suppression in the suppression control according to the bit rate of the stream S1, but the present disclosure is not limited to this. isn't it. The control unit 25 may be configured to adjust the amount of suppression in suppression control depending on the frame rate of stream S1 and the like. Further, the control unit 25 may be configured to perform suppression control of a predetermined suppression amount regardless of the communication rate of the stream S1.

Further, in the STB 101 according to the first embodiment of the present disclosure, the control unit 25 is configured to adjust the amount of suppression in the suppression control according to the packet loss detection result by the processing unit 24. It is not limited to. The control unit 25 may be configured to perform suppression control by a predetermined amount of suppression regardless of the packet loss detection result by the processing unit 24.

Further, in the STB 101 according to the first embodiment of the present disclosure, the control unit 25 is configured to adjust the suppression amount in suppression control according to the success rate of the restoration process by the processing unit 24. It is not limited to. The control unit 25 may be configured to perform suppression control of a predetermined suppression amount regardless of the success rate of the restoration process by the processing unit 24.

Next, other embodiments of the present disclosure will be described using the drawings. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

<Second embodiment>
This embodiment relates to a content distribution system 402 in which the relay machine 201 performs suppression control, compared to the content distribution system 401 according to the first embodiment. The content distribution system 401 is the same as the content distribution system 401 according to the first embodiment except for the contents described below.

FIG. 8 is a diagram showing the configuration of a content distribution system according to the second embodiment of the present disclosure. Referring to FIG. 8, compared to content distribution system 401, content distribution system 402 includes STBs 102A and 102B instead of STB 101, and further includes relay machine 201. Hereinafter, each of STBs 102A and 102B will also be referred to as STB 102. The repeater 201 and STB 102 are provided at the user's home 111. STB 102 is connected to repeater 201. Relay machine 201 is, for example, a router. Note that the content distribution system 402 may have a configuration including three or more STBs 102.

Relay device 201 receives stream S1 transmitted by HTTP server 301 via network 351. Further, the relay device 201 receives the stream S2 transmitted by the IP broadcast distribution device 302 via the network 351.

FIG. 9 is a diagram showing the configuration of a repeater according to the second embodiment of the present disclosure. Referring to FIG. 9, relay machine 201 includes network devices 40 and 70, a processor 50, and memory 60. Memory 60 is, for example, a nonvolatile memory.

The network device 40 receives IP packets P1 constituting the stream S1 from the HTTP server 301 via the network 351. Network device 40 stores the received IP packet P1 in a buffer in memory 60.

Further, the network device 40 receives IP packets P2 constituting the stream S2 from the IP broadcast distribution apparatus 302 via the network 351. Network device 40 stores the received IP packet P2 in a buffer in memory 60.

In this way, in the relay device 201, the reception processing of the IP packets P1 and P2 is performed using common reception resources, that is, the buffers in the network device 40 and the memory 60.

Processor 50 processes IP packets P1, P2 stored in memory 60 by network device 40.

More specifically, for example, the processor 50 performs a relay process of acquiring the IP packet P1 from the memory 30 and transmitting the acquired IP packet P1 to the STB 102 via the network device 70 according to the destination IP address of the IP packet P1.

Further, for example, the processor 50 performs a relay process of acquiring the IP packet P2 from the memory 30 and transmitting the acquired IP packet P2 to the STB 102 via the network device 70 according to the destination IP address of the IP packet P2.

In this way, in the relay device 201, the relay processing of the IP packets P1 and P2 is performed by the common processing resource, that is, the processor 50.

[assignment]
By the way, the relay device 201 may receive streams S1 and S2 in parallel. More specifically, when performing relay processing of stream S1 to STB 102A and relay processing of stream S2 to STB 102B in parallel, relay device 201 receives streams S1 and S2 in parallel, and transmits IP packets to STB 102A. While performing relay processing of P1, relay processing of IP packet P2 to STB 102B is performed. Further, the relay device 201 may receive multiple streams S1 and multiple streams S2 in parallel depending on the number of STBs 102 connected to the relay device 201.

Therefore, in the relay device 201, similarly to the STB 101 according to the first embodiment, loss of IP packets P1 and P2 may occur.

Therefore, the repeater 201 according to the second embodiment of the present disclosure solves the above problem with the following configuration.

(Relay machine configuration)
FIG. 10 is a functional block diagram showing the configuration of a repeater according to the second embodiment of the present disclosure. Referring to FIG. 10, relay device 201 includes communication units 41 and 71, packet acquisition unit 51, processing unit 53, control unit 55, HW buffer 61, ring buffer 62, and socket buffer 63. Be prepared. The communication unit 41 is an example of a receiving unit. The processing unit 53 is an example of a relay unit.

The communication unit 41 is realized by the network device 40. The communication unit 71 is realized by the network device 70. The packet acquisition section 51, the processing section 53, and the control section 55 are realized by the processor 50. HW buffer 61, ring buffer 62, and socket buffer 63 are included in memory 60.

The communication unit 41 receives the stream S1 according to TCP. More specifically, the communication unit 41 receives the IP packet P1 constituting the stream S1 from the HTTP server 301 via the network 351, and stores the received IP packet P1 in the HW buffer 61. Furthermore, the communication unit 41 receives the stream S2 according to UDP. More specifically, the communication unit 41 receives the IP packet P2 constituting the stream S2 from the IP broadcast distribution device 302 via the network 351, and stores the received IP packet P2 in the HW buffer 61. The operation and processing of the communication unit 41 are similar to the operation and processing of the communication unit 11 in the STB 101.

The packet acquisition unit 51 acquires the IP packet P from the ring buffer 62 and stores it in the socket buffer 63 at a timing according to a predetermined read cycle R2.

The processing unit 53 performs relay processing on the streams S1 and S2 received by the communication unit 41. More specifically, the processing unit 53 acquires the IP packet P from the socket buffer 63 at a timing according to the predetermined read cycle R5, and transmits the acquired IP packet P to the STB 102 via the communication unit 71.

The STB 102A processes the IP packet P received from the relay device 201. More specifically, the STB 102A receives the IP packet P1 from the relay device 201, performs a process of reproducing the VOD content using the information included in the received IP packet P1, and reproduces the obtained video information, audio information, etc. is transmitted to a display device (not shown).

Furthermore, the STB 102B processes the IP packet P received from the relay device 201. More specifically, the STB 102B receives the IP packet P2 from the repeater 201, performs a process of reproducing the broadcast content using the information included in the received IP packet P2, and reproduces the obtained video information, audio information, etc. is transmitted to a display device (not shown).

The control unit 55 controls the communication band of the communication unit 41 for receiving the stream S1. When the control unit 55 detects that the communication unit 41 is receiving streams S1 and S2 in parallel, it performs suppression control to suppress the communication band for receiving stream S1. The operation and processing of the control unit 55 are similar to the operation and processing of the control unit 25 in the STB 101.

The above embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

Each process (each function) of the above-described embodiment is realized by a processing circuit (Circuitry) including one or more processors. In addition to the one or more processors, the processing circuit may include an integrated circuit or the like in which one or more memories, various analog circuits, and various digital circuits are combined. The one or more memories store programs (instructions) that cause the one or more processors to execute each of the above processes. The one or more processors may execute each of the above processes according to the program read from the one or more memories, or may execute each of the above processes according to a logic circuit designed in advance to execute each of the above processes. May be executed. The above processor includes a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), and an FPGA (Field Programmable Gate Array). ray), and ASIC (Application Specific Integrated Circuit), which are compatible with computer control. processor. Note that the plurality of physically separated processors may cooperate with each other to execute each of the above processes. For example, the processors installed in each of a plurality of physically separated computers cooperate with each other via networks such as a LAN (Local Area Network), a WAN (Wide Area Network), and the Internet to perform each of the above processes. May be executed. The program may be installed in the memory from an external server device or the like via the network, or may be installed on a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), or a semiconductor device. The information may be distributed in a state stored in a recording medium such as an essential memory, and may be installed into the memory from the recording medium.

The above description includes the features noted below.
[Additional note 1]
a receiving unit that receives a stream containing content;
a processing unit that processes the stream received by the receiving unit;
and a control unit that controls a communication band of the receiving unit for receiving the stream,
When the control unit detects that the reception unit is receiving the first stream according to TCP and the second stream according to UDP in parallel, the control unit controls the communication for receiving the first stream. Performs suppression control to suppress the bandwidth,
the first stream includes VOD content;
The content receiving device, wherein the second stream includes broadcast content.

[Additional note 2]
Equipped with a processing circuit,
The processing circuit includes:
receive a stream containing content,
processing the stream received by the receiving unit;
controlling a communication band of the receiving unit for receiving the stream;
A content receiving device that performs suppression control to suppress the communication band for receiving the first stream when receiving the first stream according to TCP and the second stream according to UDP in parallel.

10, 40, 70 Network device 11, 41, 71 Communication unit 20, 50 Processor 21, 51 VOD packet acquisition unit 22 Broadcast packet acquisition unit 23, 24, 53 Processing unit 25, 55 Control unit 30, 60 Memory 31, 61 HW Buffer 32, 62 Ring buffer 33 TCP socket buffer 34 UDP socket buffer 51 Packet acquisition section 63 Socket buffer 101, 102, 102A, 102B STB
111 User's home 151 HDD
161 Display device 201 Relay machine 301 HTTP server 311 Office 302 IP broadcast distribution device 312 Station building 351 Network 401,402 Content distribution system

Claims (9)

a receiving unit that receives a stream containing content;
a processing unit that processes the stream received by the receiving unit;
and a control unit that controls a communication band of the receiving unit for receiving the stream,
When the control unit detects that the reception unit is receiving the first stream according to TCP (Transmission Control Protocol) and the second stream according to UDP (User Datagram Protocol) in parallel, the control unit A content receiving device that performs suppression control to suppress the communication band for receiving one stream. The content receiving device according to claim 1, wherein the control unit reduces a window size in communication according to TCP as the suppression control. The content receiving device according to claim 1 or 2, wherein the control unit delays transmission of ACK by the receiving unit to packets forming the first stream as the suppression control. The control unit is configured to perform the suppression control when detecting that the reception unit is receiving the first stream and the second stream in parallel, and when the second stream is a multicast stream. The content receiving device according to claim 1 or 2, wherein the content receiving device performs the following. 2. The control unit according to claim 1, wherein when the receiving unit receives an adaptive stream as the first stream, the control unit adjusts the amount of suppression in the suppression control according to the communication rate of the first stream. The content receiving device according to claim 2. The processing unit detects packet loss in the second stream received by the reception unit,
The content receiving device according to claim 1 or 2, wherein the control unit adjusts the amount of suppression in the suppression control according to the detection result of the packet loss by the processing unit. When the processing unit detects a packet loss in the second stream, the processing unit performs a packet restoration process,
The content receiving device according to claim 6, wherein the control unit adjusts the amount of suppression in the suppression control according to the success rate of the restoration process by the processing unit. a receiving unit that receives a stream containing content;
a relay unit that performs relay processing of the stream received by the reception unit;
and a control unit that controls a communication band of the receiving unit for receiving the stream,
When the control unit detects that the reception unit is receiving the first stream according to TCP and the second stream according to UDP in parallel, the control unit controls the communication for receiving the first stream. A content relay device that performs suppression control to suppress bandwidth. A communication control method in a content receiving device, the method comprising:
receiving a stream containing the content;
processing the received stream;
controlling a communication band for receiving the stream,
In the step of controlling the communication band, when the first stream according to TCP and the second stream according to UDP are being received in parallel, the communication band for receiving the first stream is suppressed. A communication control method that performs suppression control.

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