WO2016190462A1

WO2016190462A1 - Buffer management method for lossless video packet transmission on basis of ieee1722 network

Info

Publication number: WO2016190462A1
Application number: PCT/KR2015/005281
Authority: WO
Inventors: 송병철; 전원기; 박경원
Original assignee: 전자부품연구원
Priority date: 2015-05-27
Filing date: 2015-05-27
Publication date: 2016-12-01
Also published as: KR20160141013A; KR101845131B1

Abstract

Provided is a buffer management method for lossless video packet transmission on the basis of an IEEE1722 network. A buffer management method according to an embodiment of the present invention comprises: monitoring a BAP of a buffer by a listener system; and transmitting, by the listener system, a request for locating the BAP in a specific range to a talker system. Accordingly, the present invention adds a new buffer management block function to the listener system and allows the talker system to control a transmission rate, so that video can be displayed without video data overflow or signal interruption by adjusting the rate at which a stream is received by a reception application program.

Description

Buffer Management Method for Lossless Transmission of IEEE1722 Network-based Video Packets

The present invention relates to network-based video transmission, and more particularly, to a buffer management method for lossless transmission of IEEE1722 network-based video packet.

In a conventional audio video bridging (AVB) network that transmits IEEE1722 data, the video talker system synchronizes the time between the video talker system and the video listener system through 802.1AS, and the video listener system side of the video talker system at regular intervals. Send video data towards the system.

The video talker system is a system for transmitting video data in an AVB network, hereinafter abbreviated to a talker system. The video listener system is a system for receiving video data in an AVB network.

In most talker and listener system applications, data can be reproduced without loss of data, even with changes in data volume and speed due to changes in transmission conditions. Each system can have a transmit buffer and a receive buffer. The size of the buffer varies from system to system.

The transmission speed of the data transmitted from the listener system with the reception buffer is almost constant for each connected state in the AVB network. Transmitted latency can be faster or slower.

In situations such as typical MPEG2-TS data transmission of video, if the transmission latency is changed, the image or audio is displayed broken by the receiving listener system.

In the IP network structure, which was not related to the real-time data transmission, a buffer or a file transfer rather than a stream transmission was used.

In the AVB network that transmits time synchronization in real time, the maximum frame size and the maximum number of frames per interval transmitted by the transmitting side are determined by the parameters of the Stream Reservation Protocol (SRP) frame when the IEEE1722 data rate is connected.

A request for a lossless transmission of video packets to a listener system of the IEEE1722 network is requested.

The present invention has been made to solve the above problems, an object of the present invention, in the network for transmitting video data through IEEE1722 based on the IEEE AVB, without additional modification to the existing functions of the switching of the switch and the bridge In addition, the present invention provides a method for adjusting the transmission speed of a talker system by a listener system so that real-time video data transmitted between the talker system and the listener system can be transmitted without loss.

According to one embodiment of the present invention, a buffer management method includes: monitoring, by a listener system, a BAP of a buffer; And requesting, by the listener system, the talker system so that the BAP is located in a specific range.

In addition, in the requesting step, if the BAP is less than or equal to BN, the talker system may request a transmission speed increase.

In addition, in the requesting step, when the BAP is larger than NP, the talker system may request to reduce the transmission speed.

And, the requesting step, if the BAP is larger than the TP, request the talker system to reduce the transmission rate by one more step, the TP may be greater than the NP.

In addition, the buffer management method according to an embodiment of the present invention, the listener system, receiving the Maximum Frame Size (MFS) and Maximum # Frames Per Interval (MFPI) from the talker system; And setting, by the listener system, the specific range based on the MFS and the MFPI.

The requesting step may transmit a transmission rate, a time to apply the transmission rate, or the number of frames to the talker system.

In addition, the requesting step may be performed when the talker system responds with a system having a TVCP function.

On the other hand, in accordance with another embodiment of the present invention, a listener system, a buffer for storing video data received from the talker system; And a BMB for monitoring the BAP of the buffer and requesting the talker system to place the BAP in a specific range.

As described above, according to embodiments of the present invention, a new buffer management block function is added to the listener system, the talker system adjusts the transmission speed, and the video data is controlled by adjusting the speed of the stream received by the receiving application. It is possible to display images stably without overflowing or disconnection of signal.

1 is an IEEE1722 based video transmission network configuration

2 is a diagram illustrating a structure of a buffer operated by a listener system receiving video data from a talker system;

3 is a flowchart provided to explain a buffer management process by a BMB;

4 is a diagram provided to explain a TVCP registration process between a listener system and a talker system;

5 illustrates a TVCP packet structure;

6 shows a TVCP structure, and

7 is a block diagram of a listener system.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

1 is a diagram illustrating a video transmission network to which the present invention is applicable. The video transmission network shown is an AVB related IEEE1722 based video transmission network. A video transmission network to which the present invention is applicable is constructed by connecting devices through switches, as shown in FIG. 1.

Display listeners are listener systems that have applications that receive and display video data on the screen. The Video Server Talker is a talker system capable of transmitting a video stream held in accordance with user requirements.

'V-1' and 'V-2' are video camera systems with AVB interface. Manager is a system that performs connection and control between each device using IEEE1722 protocol.

In a service in which a video server talker and a display listener-3 and 4 are connected through the network environment shown in FIG. 1 to transmit a video file, an MPEG-TS stream, and the like, a data transmission connection is established between the talker system and the listener system through a manager. Use it.

When connecting, the talker system transmits Talker Advertisement packet. The packet contains traffic related information, including MFS (Maximum Frame Size) and MFPI (Maximum # Frames Per Interval).

When connected, the talker system transmits data according to the configured frame size (FS) and # frames per interval (FPI). At this time, Interval selects one of '125usec' and '250usec'.

FIG. 2 is a diagram illustrating a structure of a buffer operated by a listener system that receives video data from a talker system. The illustrated buffer is managed by a BMB (Buffer Management Block).

Terms shown in Figure 2 are as follows.

BM: Buffer Max Value (means the maximum capacity / space of the buffer)

TP: Threshold Point (usually set to 80% of BM, can be changed)

NP: Notification Point (normally set to 60% of BM, can be changed)

BAP: Buffer Active Point (storage state of video data in buffer)

BN: Buffer miN value (usually set to 20% of BM, can be changed)

As shown in FIG. 2, the buffer is divided into a primary buffer area and a secondary buffer area based on the TP. Hereinafter, a buffer management process by the BMB will be described in detail with reference to FIG. 3.

The BMB manages the buffer so that the BAP stays between NP and BN. To this end, first, the BMB sets TP, NP, and BN based on the talker system, the FS, FPI, Interval, and the BM set in the buffer (S210).

Accordingly, the listener system receives the video from the talker system and stores the video in the buffer, and the BMB monitors the BAP to check the buffer storage state (S220).

If the BAP is less than or equal to the BN (S230-N) in step S220, the BMB requests the video transmission speed to be increased to the talker system through the transport velocity control protocol (TVCP) (S240). The TVCP will be described in detail below.

If the BAP is less than BN, the buffer storage amount is small. This is to control the BAP to be larger than the BN by storing video quickly in the buffer. In the initial stage of reception, since the BAP is less than or equal to BN, in this case, step S240 is not applied.

On the other hand, if the BAP is greater than the NP as a result of monitoring in step S220 (S250-Y), the BMB requests the video transmission speed reduction to the talker system through the TVCP (S260). If the BAP is larger than NP, the buffer storage is large. This is to adjust the BAP to be smaller than NP by storing video slowly in the buffer.

Despite the decrease in the transmission rate in step S260, when the BAP is larger than the TP (S270-Y), the BMB operates in the TVCP Emergency Mode (S280). In TVCP Emergency Mode, the BMB requests the talker system to further reduce the video transmission speed via TVCP.

In addition, in TVCP Emergency Mode, the BMB may extend the buffer, for example only if TVCP Emergency Mode occurs frequently (occurs three times in the last minute).

Hereinafter, TVCP will be described in detail. TVCP is a protocol between the listener system and the talker system proposed in the embodiment of the present invention in order to adjust the transmission speed of the video data packet being transmitted.

In order to apply TVCP between the listener system and the talker system, the TVCP registration process is assumed. 4 is a diagram provided to explain a TVCP registration process between a listener system and a talker system.

As shown in FIG. 4, the listener system with the TVCP function pings the talker system to support TVCP for smooth video transmission (S310), and the talker system with the TVCP function pongs (S320). ), The talker system registers the listener system (S330).

Thus, the video transmission rate adjustment is made through the TVCP (S340), if the TVCP is impossible or unnecessary situation can be terminated (S350).

If there is no TVCP function and the talker system does not respond (pong) or there is a TVCP function but the talker system cannot perform the TVCP function, the registration is not performed in step S330, and video transmission through TVCP is performed. Speed control is impossible.

The TVCP packet structure is illustrated in FIG. 5. As shown, the TVCP packet structure is implemented by modifying the basic format of the IEEE1722-AVTPDU. Specifically, the TVCP packet,

1) 'Control' is indicated on the top indicator of IEEE1722-AVTPDU.

2) The subtype field indicates a specific value indicating TVCP.

3) Put TVCP data after stream_id,

4) stream_id contains information for TVCP.

6 shows a detailed structure of TVCP information recorded in stream_id. As shown in FIG. 6, the first 1 byte of TVCP information includes a request / response such as a ping, a pong, a no, a stop, and the like.

Ping is stored not only when the listener system requests TVCP registration with the talker system, but also when the listener system requests transmission speed adjustment through TVCP.

Pong is recorded when the talker system responds to the listener system, No is recorded when the talker system is no longer able or unable to adjust the transmission speed via TVCP, and Stop is sent by the listener system via TVCP. It is recorded when you want to end the speed control.

The values indicating Ping, Pong, No, and Stop are as follows, but they can be changed by way of example.

Ping: 01010101

Pong: 11000011

No: 00111100

Stop: 11001100

Velocity is information indicating the transmission speed requested by the listener system to the talker system, and one of Emergency, Fast, and Slow is stored. Emergency is recorded when requesting faster transmission speed than Fast in TVCP Emergency Mode.

Duration is the time to maintain the transmission speed specified in Velocity, expressed in msec. # Frames is the number of frames to maintain the transmission speed specified in Velocity.

7 is a block diagram of a listener system. As shown in FIG. 7, the listener system includes a receiver 110, a buffer 120, a playback unit 130, an output unit 140, and a BMB 150.

The receiver 110 receives video data from the talker system based on the IEEE1722 network. The buffer 120 buffers the video data received through the receiver 110.

The playback unit 130 plays back the video data buffered in the buffer 120, and the output unit 140 displays or outputs the played video data to an external device.

The BMB 150 manages the buffer 120 through the TVCP by performing the procedures illustrated in FIGS. 3 and 4 described above.

Up to now, the preferred embodiment of the buffer management method for IEEE1722 network-based video packet lossless transmission and the system using the same has been described in detail.

In buffer management by BMB, it is possible to change to operate TP in two ways. For example, the upper limit TP and the lower limit TP are operated. The upper limit TP means the above-mentioned TP, and the lower limit TP is used as a criterion for requesting a transmission speed more quickly when the BAP is much smaller than the BN.

In addition, TP, NP, and BN set in step S210 of FIG. 3 may be reset during the video transmission process. At this time, the reset is performed with reference to the BAP monitoring result, and specifically, the frequency of BAP becoming less than BN, the frequency of BAP exceeding NP, and the frequency of BAP exceeding TP may be referred to.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

Claims

Monitoring, by the listener system, the storage state of the buffer; And

Requesting, by the listener system, the talker system to include the storage state of the buffer in a specific range.
The method according to claim 1,

The requesting step,

If the BAP (Buffer Active Point) indicating the storage state of the buffer is less than the buffer miN value (BN), requesting the talker system to increase the transmission speed, characterized in that the buffer management method.
The method according to claim 2,

The requesting step,

And if the BAP is larger than a notification point (NP), requesting the talker system to reduce a transmission speed.
The method according to claim 3,

The requesting step,

If the BAP is greater than the threshold point, request the talker system to reduce the transmission rate by one more step,

The TP is a buffer management method, characterized in that greater than the NP.
The method according to claim 1,

Setting, by the listener system, the talker system with a frame size (FS) and a # frames per interval (FPI); And

Setting, by the listener system, the specific range based on the FS and the FPI.
The method according to claim 1,

The requesting step,

And a transmission rate, a time to apply the transmission rate, or a number of frames to the talker system.
The method according to claim 1,

The requesting step,

And the talker system responds with a system having a transport velocity control protocol (TVCP) function.
A buffer in which video data received from the talker system is stored; And

And a buffer manager for monitoring the storage state of the buffer and requesting the talker system to include the storage state of the buffer in a specific range.