CN105991469B - Dynamic time window and caching mechanism under a kind of heterogeneous network transmission - Google Patents

Abstract

The invention provides the dynamic time window under a kind of heterogeneous network transmission and caching mechanism, methods described is directed to the signaling in existing MMT, increase Available_Time the and Asset_Size attributes of media content in the signaling or elsewhere, enable the size of time that client terminal knows that respective media content obtains and media content；Simultaneously, client terminal can determine that network bandwidth under contemporary broadband network and content leniently take the network delay of client to by corresponding method in IP network, by the delay for obtaining time and broad-band channel of broadband source contents, client terminal can calculate the buffer window size required for the time interval for sending request buffered in advance and terminal.The present invention solves the problems, such as broadcast with content in the heterogeneous terminals formed in broadband because broadband congestion can not be synchronous, while also reduces the overhead that client is brought due to caching.

Description

A Dynamic Time Window and Caching Mechanism under Heterogeneous Network Transmission

technical field

The present invention relates to a dynamic time request window and cache mechanism of a client terminal under heterogeneous network transmission, specifically, to a method for determining the time interval during which a terminal requests to send media content and the size of a cache window.

Background technique

With the change of the times, people are no longer satisfied with only relying on traditional TVs to obtain information and entertainment, and more terminal devices appear in front of us, such as PCs connected to the Internet, almost everyone has a mobile phone, and the increasingly popular These new products, such as mobile tablet PCs, are slowly eroding the traditional TV business market. With the development of mobile communication and broadband wireless technology, as well as the maturity of multimedia services, convergence has become the development trend of the information and communication industry. It enables users to easily access the network and enjoy richer media content and diversified services.

At the same time, the presentation of media content will not only be simple video, audio, and subtitles, but the media types will become more and more diverse. Media sources are not limited to specific content providers. More and more producers are involved, including many individual users who are also content providers and producers. These contents from different providers have various association relationships, and in order to meet the individual needs of different users, these associated contents often need to be presented synchronously. In this environment, heterogeneous network convergence is an inevitable trend in the development of next-generation networks, which fully demonstrates that future communication is no longer a specific access technology, but multiple access technologies coexist and work together.

In a heterogeneous network environment composed of broadcast and broadband, the media content presented by the terminal can be transmitted from the broadcast and broadband channels at the same time. For the presentation of the heterogeneous network terminal, there is a multi-source content distribution mechanism based on presence information (CI, Composition Information). CI uses technologies such as HTML5 and XML to provide time and space information of media data, so that multimedia data can be presented in a variety of ways on the terminal.

The terminal can request relevant content from the server according to the information in the signaling, but when the server receives the request, the relevant content may or may not be ready. If the relevant content is not ready, the terminal's request will fail, and then request again until the relevant content is obtained. This is a great burden on the terminal and also increases the burden on the network.

Since the current broadband network needs to forward content on multiple nodes, there are problems such as large network delay or even network congestion. Therefore, it is necessary to cache the content in advance at the receiving end to deal with the problem that the terminal content cannot be played or the media content cannot be played synchronously.

The introduction of caching has brought new problems. How much content the terminal needs to cache in advance and when to start caching will affect the configuration of the client device and the performance of the system. Therefore, the size of the client cache window and the time to pull the cache become an urgent problem to be solved.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a method for adaptively adjusting the size of the request time window and buffer window in a heterogeneous network terminal, thereby solving the problem of content loss due to broadband congestion in heterogeneous terminals composed of broadcast and broadband. The problem of being unable to synchronize, but also reduces the additional overhead caused by the client due to caching.

The present invention is realized by adopting the following technical solutions:

The present invention provides a method for adaptively adjusting the size of the request time window and cache window at a heterogeneous network terminal, the method increases the Available Time and Asset_Size of media content in signaling (such as MPT, CI, MPU) or other places attribute, so that the client terminal knows the time when the corresponding media content can be obtained; at the same time, the client terminal determines the network bandwidth under the current broadband network and the one-way network delay of the content from the broadband to the client through the corresponding method in the broadband network, and the content is transmitted through the broadband source content. The available time and the delay of the broadband channel, the client terminal calculates the cache window size required to ensure the synchronization of the current broadcast and the broadband content and the time to send the request.

Compared with the prior art, the present invention has the following beneficial effects:

By adopting the technical scheme of the present invention, aiming at the signaling in the existing MMT, by adding new attributes in the signaling or other places, the problem of difficult synchronization of media content caused by network congestion in broadband is solved, thereby solving the problem of Synchronization problems caused by network congestion.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Figure 1 is a schematic diagram of a model of a heterogeneous network;

Fig. 2 is a flow chart of calculating the dynamic time window for sending a request by the client and the buffer window size allocated by the terminal.

detailed description

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Nowadays, diversified terminal presentation methods based on heterogeneous networks have become a development trend. While watching high-quality broadcast video programs, people's demands for diversified online media services are also getting higher and higher. In a heterogeneous system composed of broadcast and broadband networks, the CI controls the time and space layout of the broadcast and broadband content played by the client to achieve synchronization of media content. Generally speaking, the media content coming from the broadcast channel has a small and fixed delay, so it has no effect on synchronization; while the media content coming from broadband, such as audio and video, subtitles, multimedia applications, etc., are easily affected by the current IP network. Large and jittering delays have caused problems for content synchronization; at the same time, content from broadband has the problem of valid access period, that is, it can be accessed from a certain point in time and is valid until a certain point in time. Therefore, the present invention provides the effective time information of the content, and designs a mechanism for requesting the transmission of the information in advance at the terminal, and allocating a cache window for the corresponding content.

In order to solve the problem, first add a new attribute to each part of the content in the original signaling or other places: Available_Time, which is used to indicate the time when the content to be transmitted in the broadband is ready and can start transmission at the content provider, and End access time. Its assignment follows the following rules:

1) The time is unknown

If the server cannot determine the time when the content to be transmitted is ready, the Available_Time will be assigned a value of "unknown"; at the same time, in order to consider the compatibility of the system, if the Available_Time attribute is not added to the signaling sent by the server, the terminal will interpret the Available_Time as unknown.

2) Accessible anytime

If the media content on the server side can be accessed and sent at any time, the Available_Time is assigned a value of "anytime".

3) After a certain time starts, it is always valid

If the content on the server side is valid after a specific time, the Available_Time is assigned the specific UTC time, namely "UTC1".

4) Valid within a specific time zone

If the content on the server side is available within a specific time interval, the Available_Time is assigned the time interval, that is, "UTC1--UTC2", and UTC is in brackets.

The analysis of Available_Time is done in the terminal

Similarly, the Asset_Size attribute can be added to each part of content in signaling or other places as required to indicate the size of the part of content.

The newly added attributes, Available_Time and Asset_Size, can be added in different places according to the specific location in the system. Such as CI, MPT, MPU, etc. Here are some examples of these locations.

Examples of adding Available_Time and Asset_Size attributes in CI, MPT and MPU are given below:

1) Add new properties in CI

If the mediaSrc attribute is in the MediaSync element, put the newly added attribute in this element as well, as follows:

If the mediaSrc attribute is in the sourceList sub-element of the MediaSync element, the newly added attribute is placed in the corresponding sourceList, as follows:

2) Add new attributes in MPT

Asset_Size can be added to each asset in the MPT table to describe its size.

If the content has multiple source addresses, an Available_Time is allocated to the content in each source address; if the content has only one source address, only one Available_Time is allocated to the source content of the address. There may be multiple specific implementation manners, and two examples are given below.

A. Add Available_Time_Type and MMT_Available_Time_info() to MPT. Taking four cases as examples, we can allocate two bits of Available_Time_Type. If there are more classifications of available time, we can consider allocating more bits. MMT_Available_Time_info() describes the available time or available time interval information of the media content. MPTs are as follows:

MP table Syntax

MMT_Available_Time_info Syntax

Available_Time_Type: These two bits indicate the type of available time, described as follows:

Value of Available_Time_Type

B. Only MMT_Available_Time_info() is added to the MPT. MMT_Available_Time_info() indicates the available time or available time interval information of the media content. MPTs are as follows:

MP table Syntax

MMT_Available_Time_info Syntax

The usage of available_begin and available_end is as follows

3) Add new attributes in MPU

In MPU, because the size of a single MPU is described, mpu_size is taken here

The design idea of the caching mechanism for dynamically allocating the size of the cache window is as follows: the existing attributes in the CI file already include the normal start time of the object—begin, and at the same time, it can be obtained through the corresponding method in the IP network, such as sending ICMP segments. Current one-way broadband network delay—t ₁ and broadband network bandwidth—Bandwidth. After adding the attributes Available_Time and Asset_Size of the available time of broadband content in signaling or other places: set a threshold Threshold, if the delay t ₁ is less than this threshold, the delay is negligible, and the system does not need to provide media for broadband transmission Content allocation additional buffer; if t ₁ is greater than this threshold, the time interval for requesting to send media content in broadband in advance can be determined through the method in the specific solution, and a buffer window can be allocated for the terminal. If the network delay is very large, and the Available_Time provided by the content provider does not meet the condition of pre-caching and keeping synchronization, the auxiliary content transmitted by the broadband channel is directly discarded.

The specific scheme is as follows (the following steps can be selected and combined according to the actual situation):

1) Add the Available_Time and Asset_Size attributes of the corresponding content in the signaling or elsewhere;

2) The client terminal obtains the one-way delay t1 of the current broadband network and the bandwidth Bandwidth of the broadband network through a corresponding method in the IP network, such as by sending an ICMP message segment;

3) The client obtains the available time (Available_Time), normal playback time (begin) and the size of the corresponding content (Asset_Size) of the corresponding media content by analyzing the signaling (such as MPT, CI);

4) If t ₁ <Threshold, the delay is ignored; if t ₁ >Threshold, the time window for the terminal to send the request and the cache size allocated by the terminal are calculated by the following method:

① Calculate the time required by the service provider to transmit a content unit: Data_Transfer_Time, this time can be calculated from the size of a content unit and the bit rate in the current broadband environment;

② If Available_Time is "unknown" or there is no such attribute in CI, no processing will be performed; if Available_Time is "anytime", skip this step and proceed to ③; if Available_Time is a specific UTC time and a UTC time interval, then Take the earliest time for the following judgment:

Available_Time+t1+Data_Transfer_Time<begin (1)

If the condition (1) is not true, it means that the media content to be transmitted can be acquired too late, and cannot reach the terminal in time under the delay of the current network, so this part of the content is discarded; if the condition (1) is true, it means that the current network delay The out-of-sync problem caused by time can be solved by pre-caching for the next step of calculation;

③ Calculate the time interval for the terminal to request to send the media content in advance:

Earliest request time:

Earliest_Request_Time = Available_Time - t1 (2)

Request latest time:

Latest_Request_Time=begin-2t1-Data_Transfer_Time (3)

The actual requested time is between two points in time:

Earliest_Request_Time<Actual_Request_Time<Latest_Request_Time (4)

④ After the terminal selects a request time, the time when the terminal can start to accept data from the service provider is:

Receive_Time=Actual_Request_Time+2t1 (5)

The time for the terminal to receive data before the begin time point is:

Δt=begin-Receive_Time

(6)

⑤If the Asset_Size attribute is given in CI, the size of the cache window allocated by the terminal is:

Buffer_Size=min{Δt*bitrate, Asset_Size} (7)

If the Asset_Size attribute is not given in CI, the buffer window size allocated by the terminal is:

Buffer_Size=Δt*bitrate (8)

The calculation flow chart is shown in Figure 2. The variables used in the scheme and their meanings are summarized in the following table:

variable Meaning and use begin The time when the client normally plays specific content Available_Time The time when the content to be delivered is ready at the content provider and can begin delivery Asset_Size size of media content t1 One-way network latency in broadband channels Bandwidth Broadband network bandwidth Threshold Used to determine whether the current delay will affect the synchronization of the main and auxiliary videos Earliest_Request_Time Earliest time requested by the terminal Latest_Request_Time The latest time requested by the terminal Actual_Request_Time The time actually requested by the terminal Receive_Time The time when the terminal starts to accept data Buffer_Size The buffer window size allocated by the terminal

An example is given below:

It is known that the current state of the system when the client receives the corresponding signaling is as follows. Here, Threshold is set to 0.1s. Data_Transfer_Time is generally based on the current data size and bit rate. Here, 3s is used.

parameter value t1 10s Bandwidth 10Mbps Threshold 0.1s

The file information of an image and audio contained in this signaling is as follows:

The current network delay is 10s, which is much greater than the Threshold of 0.1s, indicating that the broadband delay of 10s is unacceptable, and it is necessary to request content delivery in advance.

For Image.1, its available time is all the time after 4:59:50 Beijing time, but its available time is too late to meet the condition (1), that is, the content can no longer be sent to the terminal when playing, so Content discarded.

For Audio.1, its available time is between 4:59:20 and 4:59:50 Beijing time, and its 4:59:20 meets the condition (1), so the request can be obtained from formulas (2) and (3) Sending time interval:

Earliest_Request_Time＝2015-01-31T4:59:10+08:00

Latest_Request_Time＝2015-01-31T4:59:37+08:00

If the actual request time is taken as:

Actual_Request_Time＝2015-01-31T4:59:30+08:00

If the current bit rate is 200Kb/s, the variable parameters are as follows

Earliest_Request_Time 2015-01-31T4:59:10+08:00 Latest_Request_Time 2015-01-31T4:59:37+08:00 Actual_Request_Time 2015-01-31T4:59:30+08:00 Receive_Time 2015-01-31T4:59:50+08:00 Δt 20s Δt*bitrate 4M Buffer_Size 2Mb

Among them, Buffer_Size takes the minimum value of Δt*bitrate and Asset_Size, which is 2Mb.

Therefore, in this example, Image.1 is discarded because the time point of Available_Time is given later, and Audio.1 can get the time that the terminal should request to send in advance and the size of the buffer window that should be prepared from the given Available_Time and Asset_Size in CI.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (2)

1. A method for adaptively adjusting the buffer window size at a heterogeneous network terminal, characterized in that, the method is aimed at the signaling in the existing MPEG media transmission MMT, and increases the Available_Time and Asset_Size of the media content in the signaling part attribute, so that the client terminal knows the time when the corresponding media content can be obtained; at the same time, the client terminal determines the network bandwidth under the current broadband network and the network delay of the content from the broadband to the client through the corresponding method in the IP network, and the availability of the broadband source content Obtaining the time and delay of the broadband channel, the client terminal calculates the time interval for sending the request to be buffered in advance and the size of the buffer window required by the terminal; The method adds new attributes in the original MPEG media transmission MMT signaling: Available_Time and Asset_Size, in order to illustrate the time when the content to be transmitted in the broadband is ready and can start transmission at the content provider and the size of the part of the content Size; Available_Time assignment follows the following rules: 1) The time is unknown If the server cannot determine the time when the content to be transmitted is ready, the Available_Time will be assigned a value of "unknown"; at the same time, in order to consider the compatibility of the system, if the Available_Time attribute is not added to the signaling sent by the server, the terminal will interpret the Available_Time as unknown; 2) Accessible anytime If the media content on the server side can be accessed and sent at any time, the Available_Time is assigned the value "anytime"; 3) After a certain time starts, it is always valid If the content on the server side is valid after a specific time, then the Available_Time is assigned the specific UTC time, namely "(UTC1)"; 4) Valid in a specific time zone If the content on the server side is available within a specific time interval, the Available_Time is assigned the time interval, namely "(UTC1)-(UTC2)"; The analysis of Available_Time is done in the terminal. 2. A method for determining the request time window and cache window size in heterogeneous terminals for the method of claim 1, characterized in that: the existing attributes in the presentation information CI file that the terminal can obtain include the normal start of the object The presented time—begin, and the current one-way broadband network delay—t ₁ and the bandwidth of the broadband network—Bitrate are obtained through corresponding methods in the IP network; attributes Available_Time and Asset_Size can be obtained by adding broadband content to the signaling After: set a threshold Threshold, if the delay _t1 is less than this threshold, then the delay is negligible, and the system does not need to allocate additional buffer for the media content transmitted by broadband; if _t1 is greater than this threshold, then pass the specific program The method determines the time interval for requesting to send media content in broadband in advance, and allocates a buffer window for the terminal; if the network delay is too large, and the Available_Time provided by the content provider does not meet the conditions for buffering in advance to maintain synchronization, the broadband channel is directly transmitted Auxiliary content discarded; The specific plan is as follows: 1) Add the Available_Time and Asset_Size attributes of the corresponding content to the signaling; 2) The client terminal obtains the one-way delay t1 of the current broadband network and the bandwidth Bitrate of the broadband network through a corresponding method in the IP network; 3) The client obtains the available time Available_Time of the corresponding media content, the normal playback time begin and the size Asset_Size of the corresponding content by analyzing the signaling; 4) If t ₁ <Threshold, the delay is ignored; if t ₁ >Threshold, the time window for the terminal to send the request and the cache size allocated by the terminal are calculated by the following method: ① Calculate the time required by the service provider to transmit a content unit: Data_Transfer_Time, this time is calculated by the size of a content unit and the bit rate in the current broadband environment; ② If Available_Time is "unknown" or there is no such attribute in the presentation information CI, no processing is performed; if Available_Time is "anytime", skip this step and enter ③; if Available_Time is a specific UTC time interval, take the earliest The time is judged as follows: Available_Time+t1+Data_Transfer_Time<begin(1) If the condition (1) is not true, it means that the media content to be transmitted can be acquired too late, and cannot reach the terminal in time under the delay of the current network, so this part of the content is discarded; if the condition (1) If established, it indicates that the asynchronous problem caused by the current network delay can be solved by pre-caching, and the next step of calculation is performed; ③ Calculate the time interval for the terminal to request to send the media content in advance: Earliest request time: Earliest_Request_Time = Available_Time - t1 (2) Request latest time: Latest_Request_Time=begin-2t1-Data_Transfer_Time (3) The actual requested time is between two points in time: Earliest_Request_Time<Actual_Request_Time<Latest_Request_Time (4) ④ After the terminal selects a request time, the time when the terminal can start to accept data from the service provider is: Receive_Time = Actual_Request_Time + 2t1 (5) The time for the terminal to receive data before the begin time point is: Δt=begin-Receive_Time (6) ⑤If the Asset_Size attribute is given in the presentation information CI, the size of the cache window allocated by the terminal is: Buffer_Size=min{Δt*bitrate, Asset_Size} (7) If the Asset_Size attribute is not given in the presentation information CI, the buffer window size allocated by the terminal is: Buffer_Size=Δt*bitrate (8).