CN106658067A - Cache setting method and apparatus - Google Patents

Abstract

The invention discloses a method and device for setting cache. The method includes: acquiring the operating parameters when the user watches the video; identifying the user's operating habits based on the operating parameters; and setting the capacity of the cache based on the operating habits. The embodiment of the present invention recognizes the user's operating habits and sets the size of the cache capacity according to the user's operating habits, which can not only meet the user's needs, but also save terminal resources and user traffic, and ensure the normal use of network resources.

Description

Method and device for setting cache

technical field

The invention relates to the field of computers, in particular to a method and device for setting cache.

Background technique

With the rapid development of Internet technology, people have become accustomed to obtain more information through the Internet. At the same time, the wide popularization of digital video technology and smart terminals enables users to obtain online videos for viewing through smart terminals.

Currently, more and more users watch videos online through various websites. For this kind of online video viewing, video cache is usually set in the streaming media processing and playback software of the terminal, and the video after the current playback point is pre-downloaded so that the user can keep watching smoothly.

In addition, the cache will be deleted uniformly when the user closes the terminal application or after a certain time lag, so that the data before the current playback point can still be cached in the terminal for the user to play back. The video after the current playback point is usually not loaded infinitely, but will be downloaded according to the preset data volume of the terminal. On the one hand, it ensures that users can watch smoothly and supports appropriate fast-forwarding. On the other hand, it avoids excessive caching to increase unnecessary user traffic or Increase the resource overhead of terminals and traffic.

In the current common cache setting method, the overall size of the cache area is fixed, and the way of acquiring and filling the cached streaming media is also fixed. In the cache area with a fixed overall size, video playback can be performed by searching back and forth. However, if the backward buffer area is set too small, when the user's fast-forward search range exceeds the buffer range, the user needs to wait for re-reading; if the backward buffer area is set too large, a large amount of terminal resources will be occupied. At the same time, it may also lead to a large amount of pre-downloaded content that users do not need, wasting traffic resources. Similarly, if the forward buffer area is set too large, it will occupy a large amount of memory resources of the terminal; if the forward buffer area is set too small (delete after viewing), it may affect the user to watch the previously played content.

In the existing caching method, the size of the buffer area is fixed, and if the forward or backward buffer setting is unreasonable, it will seriously affect the viewing experience of the user.

Contents of the invention

In view of one or more of the above problems, embodiments of the present invention provide a method and device for setting a cache.

In the first aspect, a method for setting cache is provided, including the following steps:

Obtain the operating parameters when the user watches the video;

Identify the user's operating habits based on the operating parameters;

Based on operating habits, set the size of the cache.

In the second aspect, a device for setting cache is provided, including:

An acquisition module, configured to acquire operating parameters when the user watches the video;

An identification module, configured to identify the user's operating habits based on the operating parameters;

The first setting module is configured to set the capacity of the cache based on operating habits.

In the embodiment of the present invention, by acquiring the operating parameters of the user when watching a video, identifying the user's operating habits based on the operating parameters, and setting the size of the cache capacity according to the user's operating habits, it can not only meet the user's needs, but also save terminal resources and user costs. Data flow, and guarantee the normal use of network resources. In addition, by flexibly setting the size of the cache capacity, you can dynamically allocate and adjust the cache resources on the server side and the terminal side, thereby reducing the burden on the terminal and server side, and making full use of existing network and terminal resources to achieve a better user experience.

Description of drawings

The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, wherein the same or similar reference numerals represent the same or similar features.

FIG. 1 is a schematic flow chart of a method for setting a cache according to an embodiment of the present invention;

FIG. 2 is a schematic flowchart of a method for setting cache according to another embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a device for setting cache according to an embodiment of the present invention.

FIG. 4 is a schematic structural diagram of an apparatus for setting cache according to another embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

FIG. 1 is a schematic flowchart of a method for setting a cache according to an embodiment of the present invention.

As shown in Figure 1, the method for setting the cache may include the following steps: S110, obtain the operating parameters when the user watches the video; S120, identify the user's operating habits based on the operating parameters; S130, set the capacity of the cache based on the operating habits .

In some embodiments, the operating parameters may include at least one of the following: number of searches, search direction, and search frequency.

In some embodiments, the operating habit may also include: a habit of fast forwarding and/or a habit of rewinding.

In the embodiment of the present invention, by acquiring the operating parameters of the user when watching a video, identifying the user's operating habits based on the operating parameters, and setting the size of the cache capacity according to the user's operating habits, it can not only meet the user's needs, but also save terminal resources and user costs. Data flow, and guarantee the normal use of network resources. In addition, by flexibly setting the size of the cache capacity, you can dynamically allocate and adjust the cache resources on the server side and the terminal side, thereby reducing the burden on the terminal and server side, and making full use of existing network and terminal resources to achieve a better user experience.

In some embodiments, based on operating habits, the step of setting the size of the buffer (ie S130 ) may include: increasing the size of the forward buffer when the number or frequency of fast forwarding reaches a preset threshold.

In some embodiments, based on operating habits, the step of setting the size of the buffer (ie S130 ) may further include: increasing the size of the backward buffer when the number or frequency of rewind operations reaches a preset threshold.

In some embodiments, after the step of identifying the user's operating habits based on the operating parameters (ie S120), the following step is further included: binding the user's operating habits with the user's account.

In some embodiments, the strategy for setting or adjusting the cache capacity according to the user's operating habits can be implemented as follows:

Obtain the seek operation information of the progress bar when the user watches similar videos, including seek direction (fast forward/rewind), seek times or seek frequency. The more frequent the operation, the larger the corresponding size and ratio. Analyze and record the user's seek habits and characteristics. Increase the size of the forward seek buffer when users frequently perform forward seek operations. Increase the size of the backward buffer when users frequently perform backward seeks.

1) When a user basically does not adjust the progress bar when watching a video, the default caching strategy is adopted;

The default cache setting parameters are the user's initial value obtained through the server or the initial value preset by the video APP, including the overall size of the buffer area, the size of the forward/backward buffer area, and the speed threshold of the code stream obtained by the cache, etc. The initial value acquired by the server may be that the server provides different templates according to different regions and user groups.

2) When it is detected that a certain user has frequent fast-forward operations when watching a video, for example, the number of fast-forward times reaches more than 5 times within 30 minutes of video playback time, then increase the size of the user's backward cache, or when it is a cache When the total amount of ring cache video is fixed, increase the proportion of the backward cache. Similarly, if the user frequently looks back at the previous content, increase the size of the forward cache or the cache ratio.

3) Considering that the default cache settings may already be able to satisfy the user's fast forward or fast rewind operation, the terminal can further detect whether the user needs to wait for the cache to load after fast forwarding or fast rewinding based on the frequency of the user's fast forward and fast rewind operations For example, when the user only performs a small fast-forward (the requested playback time lags behind the current playback time by about 10 seconds), the existing caching strategy can support the user's direct viewing without freezing, but if the user performs a large When fast forwarding (the requested playback time is about 10 minutes behind the current playback time), the terminal will be able to perceive that the user needs to wait for the cache to reload, that is, the existing caching strategy cannot meet the user's playback habits. By analyzing and recording the frequency that users need to wait for the cache to load after fast forwarding/rewinding, the size or proportion of the forward or backward cache is adjusted.

When the user frequently performs backward seek operations, the terminal will increase the cache acquisition speed within the threshold based on the initial value to fill the backward film source faster and facilitate viewing. And when the user performs many forward seek operations, the terminal cache acquisition speed can be appropriately reduced or kept unchanged.

Fig. 2 is a flowchart of a method for setting a cache according to another embodiment of the present invention.

As shown in Figure 2, the method for setting the cache may include the following steps: S110, obtain the operating parameters when the user watches the video; S120, identify the user's operating habits based on the operating parameters; S140, based on the operating habits, combined with the user's current selection to watch One or more of the video source type, video source format, and playback conditions set the size of the cache.

In some embodiments, based on operating habits, the step of setting the size of the buffer (i.e. S140) in one or more of the source type, source format, and playback conditions of the video currently selected by the user to watch may include: When the source type is on-demand, set the total cache capacity to a fixed value.

In some embodiments, based on the operating habits, the step of setting the capacity of the buffer (i.e. S140) in combination with one or more of the source type of the video currently selected by the user to watch, the format of the source, and the playback situation (i.e. S140) may also include: When the source type is live broadcast, set the total cache capacity as a variable value.

In some embodiments, the step of setting the total capacity of the cache as a variable value may include: arbitrarily increasing the size of the forward cache in the cache.

In some embodiments, the method for setting the cache may, for example, be jointly completed by the cache identification module, the cache execution module, and the ring cache on the terminal side.

In some embodiments, the cache identification module on the terminal side is the core, which is responsible for identifying, analyzing and recording relevant playback data on the terminal side. formats and content sources, preferred seek operations, such as the number, direction and frequency of seeks), combined with the current network conditions on the user side (for example, under different user habits, the actual code stream acquisition speed of different content sources, network delay and jitter conditions, etc.), giving parameter recommendations for cache adjustment.

In some embodiments, the implementation of setting or adjusting the caching strategy for the type of film source may be as follows:

Determine the type of video source played when the user uses the application, that is, on-demand or live broadcast, and set the total amount of buffered video on demand as a fixed value, that is, process the on-demand video through a ring buffer; set the total amount of buffered live video as variable The value, that is, the forward cache can be increased infinitely, which is convenient for users to look back at any time. The backward cache can be set to a larger fixed value or loaded as much as possible, or the total cache of live video can also be set to a variable value, but it should be greater than the total cache of on-demand videos, and the forward cache should be increased accordingly size.

Considering that it is unlikely for users to watch the video on demand completely, the use of ring buffer can save the memory resources of the terminal; and for live video, considering that the user may not have time to review the previous clips during the live broadcast, so we will not delete them for the time being. Forward caching, so that after the live broadcast ends, users can catch up on the previously missed clips, and the backward caching of the live broadcast is not limited (that is, load as much as possible), so as to ensure the real-time performance of the live broadcast.

When the bit rate of most of the video sources played by the user is too high, the terminal will increase the cache acquisition speed within the threshold based on the initial value to fill up the video sources faster and facilitate viewing. And when most of the bitrates of the video sources played by the user are relatively small, the terminal cache acquisition speed can be appropriately reduced or kept unchanged, and it can be increased according to the situation when the user is playing a high bitrate video source.

In some embodiments, the implementation of adjusting the caching strategy for the format of the film source may be specifically as follows:

Because the data volume of various formats of film sources is different, it is necessary to dynamically adjust the size of the video cache based on the film source format in order to ensure the user's fast forward/rewind operation time. For example, when the video source is in H.264 format, a 100M cache can satisfy offline browsing for 80 seconds, but when the video source is in H.265 format, a 100M cache can satisfy offline browsing for 160 seconds. If there is a difference, a certain percentage of the cache size needs to be converted according to the photo source format.

When most of the video sources played by the user have a low compression rate, the terminal will increase the cache acquisition speed within the threshold based on the initial value to fill the backward video sources faster and facilitate viewing. And when most of the movie sources played by the user have a high compression rate, the terminal cache acquisition speed can be appropriately reduced or kept unchanged.

In some embodiments, the manner of adjusting the caching policy according to the network conditions may be specifically as follows:

When there are many network freezes and delays in the video source played by the user, the cache execution module is notified to appropriately increase the overall size of the cache area and the cache acquisition speed, so as to obtain a larger backward read during the network fluctuation process. Possibilities, and when the playback source is very smooth and there are very few freezes, the cache size and cache acquisition speed can be appropriately reduced to reduce terminal overhead and server-side overhead.

The cache execution module can fill the content in the cache according to the set parameters, and is responsible for feeding back relevant execution data. For ring buffers, when the contents of the entire buffer are not full, it is first filled backwards. When the entire cache area is full, the oldest cached content will be replaced by the latest cached content, but the replaced content will not exceed the progress point of video playback.

The execution result and related parameters can also be reported to the server by the cache execution module, especially the above-mentioned user operation habits, because this adjustment is strongly related to the user, and in order to maintain the high probability and rationality of parameter adjustment, several other adjustment strategies It is also related to the comprehensive result of the user's recent viewing content and the dynamic adjustment of network conditions. The server obtains and saves the user's operating habits of each account, so that when the user logs in next time, the stored user's operating habits can be sent to the current login terminal, so that the current terminal can update the cached parameters on the terminal according to the user's habits and network conditions. Adjustment.

The following takes the user watching a video as an example to describe the implementation of the cache setting method in detail. The method includes the following steps:

Step 1, the user logs in and obtains the user account information;

Step 2, obtain the user cache settings;

If the user’s habit parameters are not saved on the server side, then the user cache is set to the default cache setting for this type of user in the area at this time, and go to step 3; if the server side has the user’s operating habit parameters, such as the habit of frequently reviewing , send the habit to the application of the user's current terminal, and go to step 4;

Step 3: The user watches the on-demand video and performs frequent backward seek operations at the same time. At this time, the network condition is excellent. At this time, the size of the buffer area of the user terminal can be appropriately reduced, and the proportion of the backward seek buffer area can be appropriately increased. At the same time, the server is notified Appropriately reduce the acquisition speed of the cache code stream within the range.

Step 4, the user plays the HLS type live stream, because the user is used to watching back frequently, so the forward buffer is increased (or the amount of forward buffer is not limited); and because of the obvious lag and delay, the cache identification module notifies the cache to execute The module further increases the size of the buffer area and properly adjusts the proportion of the forward buffer area, so that users can obtain more forward buffers when the code rate changes greatly, and optimize the user's playback experience.

In this embodiment, the execution results of the specific total cache size, forward cache size, backward cache size, and terminal acquisition cache speed are combined with the judgment results of the above cases 1, 2, 3, and 4. For example, The total cache size is divided into 7 files from 1 to 10, gradually increasing. The forward cache size is from 2 to 10, and the backward cache size is from 0 to 8. The cache acquisition speed is divided into 5 levels from a to e, and gradually increases. Then the adjustment result of a certain item is the comprehensive result obtained from the factor of case 1 * the coefficient of case 1 + the factor of case 2 * the coefficient of case 2 + the factor of case 3 * the coefficient of case 3 + the factor of case 4 * the coefficient of case 4 .

For example, the size of the forward buffer, when multiple situations occur at the same time, such as situation 1 and situation 2 occur at the same time, in situation 1, the user likes to look forward frequently, and the operation factor is 2, and the coefficient is 2 by default; in situation 2, the bit rate of the user watching live broadcast The cases accounted for more than 90%, the operating factor is 2, and the coefficient is 4 by default; case 3 and case 4 meet the default conditions, then the impact value of increasing the forward cache is 12, and the basic conversion value is appropriately adjusted to increase the forward cache the size of. At the same time, the video source played by the user has frequently been stuck recently. The operation factor is 2, and the coefficient is 2 by default. Then, on this basis, the impact value of increasing the size of the buffer area is 4. Then the execution module will comprehensively increase the overall buffer area. , and increase the size and proportion of the backward buffer according to the influence value. The calculation methods of specific operation factors, coefficients, and influence values, as well as the relationship between parameter settings and execution results, can be pre-set and subsequently adjusted according to specific user usage and effects.

Thus, through the above-mentioned embodiment, the relevant playback data on the terminal side can be identified, analyzed and recorded, and according to the user's usage habits (including the type of film source he likes, the video format and content source including on-demand, live broadcast and film source, the seek he likes to perform) (search) operations, such as the number, direction and frequency of seeks), combined with the current network conditions on the user side (for example, under different user habits, the actual code stream acquisition speed of different content sources, network delay and jitter, etc.), Gives parameter recommendations for cache tuning.

In the foregoing embodiments, video stream buffering settings may be determined according to each user's operating habits. It is also possible to bind the user's operating habits with the user's account, so that each terminal can identify the user's operating habits in time to adjust the cache. Adjust the cache overhead of the terminal to achieve the purpose of maximizing resource utilization.

It should be noted that, in the case of no conflict, the features in the various embodiments can be combined with each other. The order of the operation steps in Figure 1 and Figure 2 can be flexibly adjusted. For the sake of brevity, this aspect will not be repeated here.

FIG. 3 is a schematic structural diagram of a device for setting cache according to an embodiment of the present invention.

As shown in FIG. 3 , the apparatus 300 for setting cache may include: an acquisition module 310 , an identification module 320 and a first setting module 330 . Among them, the obtaining module 310 can be used to obtain the operating parameters when the user watches the video; the identifying module 320 can be used to identify the user's operating habits based on the operating parameters; the first setting module 330 can be used to set the capacity of the cache based on the operating habits size.

It should be noted that the implementation of the functional units or functional modules shown in each embodiment may be hardware, software, firmware or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an application specific integrated circuit (ASIC), suitable firmware, a plug-in, a function card, or the like. When implemented in software, the elements of the invention are the programs or code segments employed to perform the required tasks. Programs or code segments can be stored in machine-readable media, or transmitted over transmission media or communication links by data signals carried in carrier waves. "Machine-readable medium" may include any medium that can store or transmit information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, and the like. Code segments may be downloaded via a computer network such as the Internet, an Intranet, or the like.

It can be understood that the apparatus 300 for setting a cache may be a terminal device, for example, a mobile phone, a tablet computer, a computer, and the like. Various functional units in the device for buffer setting of the terminal can be combined and applied in different degrees. The functional modules can be flexibly adjusted or combined flexibly. In addition, when configuring the above-mentioned functional units or functional modules, as long as specific functions can be realized, there is no limitation on the specific manufacturing method or model of the product, and there is no limitation on the connection position of each functional unit or functional module.

FIG. 4 is a schematic structural diagram of an apparatus for setting cache according to another embodiment of the present invention.

As shown in FIG. 4 , the apparatus 400 for setting cache may include: an acquisition module 310 , an identification module 320 , a first setting module 330 and a second setting module 340 . Among them, the obtaining module 310 can be used to obtain the operating parameters when the user watches the video; the identifying module 320 can be used to identify the user's operating habits based on the operating parameters; the first setting module 330 can be used to set the capacity of the cache based on the operating habits Size; the second setting module 340 can be used to set the capacity size of the cache based on one or more of the source type, source format, and playback conditions of the video currently selected by the user to watch based on operating habits.

Those of ordinary skill in the art can realize that each of the above-mentioned functional units or modules can be realized by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above-mentioned Function generally describes the composition and steps of each example. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

In some embodiments, the operational parameters include at least one of: number of searches, search direction, and search frequency.

In some embodiments, the operating habit includes: a habit of fast forwarding and/or a habit of fast rewinding.

In some embodiments, the first setting module 330 is further configured to: increase the size of the forward buffer when the number or frequency of fast forwarding reaches a preset threshold.

In some embodiments, the first setting module 330 is further configured to: increase the size of the backward buffer when the number or frequency of rewind operations reaches a preset threshold.

As an optional embodiment, a binding unit may be added on the basis of FIG. 2 or FIG. 3 . The binding unit can be used to bind the user's operating habits with the user's account.

In some embodiments, the second setting module 340 is further configured to: set the total capacity of the cache as a fixed value when the film source type is an on-demand type.

In some embodiments, the second setting module 340 is further configured to: set the total cache capacity as a variable value when the film source type is live broadcast.

In some embodiments, the second setting module 340 is further configured to: arbitrarily increase the size of the forward cache in the cache when the film source type is live broadcast.

In some embodiments, the apparatus for setting a cache may include: the above-mentioned cache identification module, cache execution module, and ring cache.

Therefore, the above-mentioned embodiment of the present invention proposes to adjust the cache strategy according to the user's operating habits, and the terminal obtains the seek operation information of the progress bar during the user's viewing of the video, including the seek direction, the number of seeks or the seek frequency (or to further detect whether to wait for the cache to load) . The more frequent the operation (the more frequent the wait), the larger the size and ratio of the corresponding direction buffer will be adjusted. In addition, the above-mentioned embodiments of the present invention also disclose specific solutions for adjusting the caching strategy according to the type of the film source, the format of the film source or network conditions. In addition, the terminal can adjust the cache settings according to the user's video viewing habits, which is more in line with the user's needs. On this basis, combined with other policy adjustment schemes, the cache setting can be made flexible, the existing network and terminal resources can be fully utilized, and the user experience can be improved.

It should be noted that the devices in the above-mentioned embodiments can be used as the execution subject in the methods of the above-mentioned embodiments, and can realize the corresponding processes in each method. The contents in the above-mentioned embodiments can be used by referring to each other. The content will not be repeated.

The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be applied to the foregoing embodiments Modifications to the technical solutions described in the examples, or equivalent replacement of some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (20)

1. it is a kind of that the method for caching is set, it is characterised in that to comprise the following steps：

Obtain operating parameter during user's viewing video；

Based on the operating parameter, the operating habit of the user is recognized；

Based on the operating habit, the amount of capacity of caching is set.

2. method according to claim 1, it is characterised in that the method also includes：

Based on the operating habit, piece Source Type, piece source format and the broadcasting of the video of viewing are currently selected with reference to the user One or more in situation arrange the amount of capacity of caching.

3. method according to claim 1, it is characterised in that the operating parameter includes at least one in following item： Searching times, the direction of search and search rate.

4. method according to claim 1, it is characterised in that the operating habit includes：The custom of F.F. and/or rewind Custom.

5. method according to claim 4, it is characterised in that based on the operating habit, the amount of capacity of caching is set The step of include：

When the number of times or frequency of F.F. reach default threshold value, increase before to buffer area size.

6. method according to claim 4, it is characterised in that the amount of capacity of caching is arranged based on the operating parameter The step of include：

When the number of operations or frequency of rewind reach default threshold value, increase the size of backward buffer area.

7. method according to claim 1, it is characterised in that based on the operating parameter, recognize the operation of the user It is further comprising the steps of after the step of custom：

The operating habit of the user is bound with the account of the user.

8. method according to claim 2, it is characterised in that the method also includes：

When described Source Type is program request type, the total capacity of the caching is dimensioned into fixed value.

9. method according to claim 2, it is characterised in that the method also includes：

When described Source Type is live, the total capacity of the caching is dimensioned into change value.

10. method according to claim 9, it is characterised in that when described Source Type for it is live when, by the caching The step of total capacity is dimensioned to change value includes：

When described Source Type is live, arbitrarily increase the size of the forward direction caching in the caching.

11. a kind of devices that caching is set, it is characterised in that include：

Acquisition module, for obtaining operating parameter during user's viewing video；

Identification module, for based on the operating parameter, recognizing the operating habit of the user；

First setup module, for based on the operating habit, arranging the amount of capacity of caching.

12. devices according to claim 11, it is characterised in that also include：

Second setup module, for based on the operating habit, the film source class of the video of viewing currently being selected with reference to the user One or more in type, piece source format and broadcasting situation arrange the amount of capacity of caching.

13. devices according to claim 11, it is characterised in that the operating parameter includes at least in following item ：Searching times, the direction of search and search rate.

14. devices according to claim 11, it is characterised in that the operating habit includes：The custom of F.F. and/or fast The custom moved back.

15. devices according to claim 14, it is characterised in that the first setup module is additionally operable to：When F.F. number of times or When person's frequency reaches default threshold value, increase before to buffer area size.

16. devices according to claim 14, it is characterised in that the first setup module is additionally operable to：When the operation time of rewind When number or frequency reach default threshold value, increase the size of backward buffer area.

17. devices according to claim 11, it is characterised in that also include：

Binding unit, for the operating habit of the user to be bound with the account of the user.

18. devices according to claim 12, it is characterised in that second setup module is additionally operable to：When the film source When type is program request type, the total capacity of the caching is dimensioned into fixed value.

19. devices according to claim 12, it is characterised in that second setup module is additionally operable to：When the film source When type is live, the total capacity of the caching is dimensioned into change value.

20. devices according to claim 14, it is characterised in that second setup module is additionally operable to：When the film source When type is live, arbitrarily increase the size of the forward direction caching in the caching.