CN108632644B - Preview display method and device - Google Patents

Abstract

An embodiment of the present invention provides a method for displaying a preview image, including the client acquiring an index file of a video program from a server, where the index file contains description information of the preview image; and the client acquiring the preview image according to the description information of the preview image Figure; the client displays the preview image according to the user operation instruction. The method includes the description information of the preview image in the index file of the video program, so that the client can directly obtain the preview image according to the index file when playing the video according to the index file. Combining the realization of the preview image with the playback protocol ensures the consistency of the user experience, and can also reduce the complexity of developing the preview image realization protocol independently by the video service provider, and can realize the rapid online service of the video service.

Description

Display method and device of preview image

technical field

The present invention relates to the field of video, and in particular, to a method and device for displaying preview images.

Background technique

With the development of the Internet, video resources are becoming more and more abundant. In video playback, it is a common user experience to drag the video progress by dragging the playback progress bar. In the process of dragging the video progress, many video service manufacturers currently provide a preview image effect, which can accurately see the preview image of the video at the corresponding playback progress bar position (videopreview), helping users quickly locate what they want to watch. Content.

However, at present, the preview image implementation protocol and video playback protocol provided by each video service provider are independent of each other. In addition, the preview image information provided by each video service provider is not uniform, and the implementations vary greatly, which is not conducive to the consistency of user experience.

SUMMARY OF THE INVENTION

In view of this, it is necessary to provide a preview image implementation method combined with the playback protocol to ensure the consistency of user experience.

In a first aspect, a method for displaying a preview image is provided, including:

The client obtains the index file of the video program from the server, the index file includes the description information of the preview image, and the index file is the media presentation description MPD file in the DASH protocol;

The client obtains the preview image from the server according to the preview image description information;

The client terminal displays the preview image according to the user operation instruction, for example, when the user drags the playback progress bar, displays the preview image at the corresponding position. The method includes the description information of the preview image in the index file of the video program, so that the client can directly obtain the preview image according to the index file when playing the video according to the index file. Combining the implementation of the preview image with the playback protocol ensures the consistency of user experience, and can also reduce the complexity of separately developing the preview image implementation protocol for the video service provider, enabling rapid online video services.

Optionally, the preview image description information includes:

The address information of the preview image and the time information corresponding to the preview image, the address information may be the location information stored in the preview image, and the time information corresponding to the preview image may include the corresponding time of the first preview image of the video and the time interval between the preview images. In this way, when the client displays the preview image, it can determine which preview image needs to be displayed according to the time information of the preview image and the position of the playback progress bar, so as to obtain the corresponding preview image for display, and ensure that the displayed preview image and the video are consistent with each other. consistency.

Optionally, the client can download the preview image from the server in advance and store it locally according to the address information of the preview image. When the user drags the playback progress bar, the client can obtain the preview image at the corresponding time locally, so that the speed of displaying the preview image can be increased. Faster and more real-time.

Optionally, when the user drags the playback progress bar, the client determines the address information of the corresponding preview image according to the position of the playback progress bar and the time information corresponding to the preview image, and determines the address information of the corresponding preview image according to the determined preview image. The address information downloads the preview image from the server. This optional method can reduce the storage pressure of the client and save storage space.

In the second aspect, a method for displaying preview images is provided, which is applied on the server side, including:

The server sends the index file of the video program to the client, the index file is a media presentation description MPD file of the DASH protocol, and the index file includes the description information of the preview image;

Receive client preview image download request;

In response to the download request of the client, the preview image is sent to the client.

Optionally, the preview image description information includes:

The address information of the preview image and the time information corresponding to the preview image.

Optionally, the method further includes:

The server generates a preview image and preview image description information according to the preview image generation rule.

Optionally, the preview image generation rules include:

Preview image interval time information and preview image resolution information.

Optionally, the server may generate the preview image by directly intercepting video frames from the video file according to the interval time information and resolution information of the preview image.

In a third aspect, a client device is provided, including:

a receiver, for obtaining the index file of the video program from the server, the index file is the MPD file of the DASH protocol, and the index file includes the description information of the preview image;

The processor is configured to obtain a preview image from the server according to the preview image description information, and display the preview image according to a user operation instruction.

Optionally, the preview image description information includes:

The address information of the preview image and the time information corresponding to the preview image.

Optionally, the processor is specifically used for:

When the user drags the playback progress bar, a corresponding preview image is displayed according to the position of the playback progress bar.

Optionally, the processor is further configured to: before the user drags the playback progress bar, download the preview image from the server according to the address information of the preview image.

Optionally, the processor is further configured to: when the user drags the playback progress bar, according to the position of the playback progress bar and the time information corresponding to the preview image, determine the address information of the corresponding preview image, according to the The address information of the determined preview image is used to download the preview image from the server.

In a fourth aspect, a server is provided, including:

The transmitter is used to send the index file of the video program to the client, the index file is the MPD file of the DASH protocol, and the index file includes the description information of the preview image;

The receiver is used to receive the client preview image download request;

The transmitter is further configured to send the preview image to the client in response to the download request of the client.

Optionally, the server also includes:

The processor is used to generate a preview image and preview image description information according to the preview image generation rule.

Optionally, the preview image generation rules include:

Preview image interval time information and preview image resolution information.

Optionally, the processor may generate the preview image by directly intercepting video frames from the video file according to the interval time information and resolution information of the preview image.

In a fifth aspect, a computer program product is provided, including executable program code, wherein the program code includes instructions that, when executed by the processor, cause the server or client to execute the above-mentioned instructions The preview image display method described in the aspect.

In a sixth aspect, an embodiment of the present application provides a computer storage medium for storing computer software instructions used by the above-mentioned server and client, which includes a program designed to execute the above-mentioned aspects.

Description of drawings

1 is a system architecture diagram for implementing adaptive HTTP streaming according to an embodiment of the present application;

FIG. 2 is a structural block diagram of a network device for implementing an embodiment of the present application;

3 is an interactive flowchart of a preview image display method according to an embodiment of the present application;

FIG. 4 is an interaction flowchart of a preview image display method according to another embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present invention will be described below with reference to the accompanying drawings in the embodiments of the present invention.

FIG. 1 shows a typical system architecture for implementing adaptive HTTP streaming according to an embodiment of the present application. As shown in FIG. 1 , the system 100 may include n HTTP servers 110 , where n may be any integer number, clients 120 and networks 130 . HTTP server 110 and client 120 may be coupled to each other through network 130 and other network components such as HTTP caching (not shown).

HTTP server 110 may be any hardware computer server for sending and receiving data over HTTP. The HTTP server 110 may include a server DASH module (DM) 111 for sending and receiving data over HTTP and according to the DASH standard. The HTTP server may form a Content Delivery Network (CDN) 140, which may refer to a distributed server system deployed in multiple data centers through multiple backbone networks for distributing content. CDN 140 may include any number of HTTP servers 110, such that n may be any integer number. Typically, a CDN can include thousands or hundreds of servers.

Client 120 may be any hardware device for sending and receiving data over HTTP. For example, client 120 may be a laptop computer, tablet computer, desktop computer, mobile phone, or other device. The client 120 may include a client DASH module (DM) 121 , an application 122 and a graphical user interface (GUI) 123 .

The client DM121 can be used to send and receive data via HTTP and according to the DASH standard. The client DM 121 may further include a DASH access engine (DAE) 1211 and a media export (ME) 1212 . The DAE 1211 may be the main component for receiving raw data from the HTTP server 110 and structuring this data into a viewing format. For example, the DAE 1211 may format data in a Moving Picture Experts Group (MPEG) container format together with timing data, and then output the formatted data to the ME 1212. ME 1212 may be responsible for initialization, playback, and other functions associated with content and outputting the content to applications 122.

Application 122 may be a web browser or other application with an interface for downloading and displaying content. Application 122 may be coupled to GUI 123 so that a user associated with client 120 may view various functions of application 122 . Application 122 may include a search function so that a user can search for content. For example, if application 122 is a media player, application 122 may include a search bar so that a user may enter a string to search for a movie. The application 122 can present a list of search hits from which the user can select the desired movie. After selection, the application 122 may send an instruction to download the movie to the client DM 121 . DM 121 can download movies and process movies for output to application 122 . Application 122 may provide instructions to GUI 123 for GUI 123 to present the movie to the user for viewing. Application 122 may further provide instructions to GUI 123 for GUI 123 to display a progress bar that displays the time progress of the movie.

Network 130 may be any network used to provide communication between HTTP server 110 and client 120 . For example, network 130 could be the Internet, a mobile phone network, or other network. Network 130 may allow communication along wired or wireless channels.

FIG. 2 is a schematic diagram of a network device 200 for implementing an embodiment of the present invention. Device 200 may include a plurality of ingress ports 210 and/or receiver units (Rx) 220 for receiving data; a logic unit or processor 230 for processing signals; and a plurality of egress ports 240 and/or transmitter units (Tx) ) 250 for sending data to other components; and memory 260. Apparatus 200 may be adapted to implement any of the disclosed features, methods and apparatus. For example, device 200 may be adapted to implement HTTP server 110 , and client 120 .

The logic unit 230 , which may be referred to as a central processing unit (CPU), may communicate with the ingress port 210 , the receiver unit 220 , the egress port 240 , the transmitter unit 250 and the memory 260 . Logic unit 230 may be implemented as one or more CPU chips, cores (eg, multi-core processors), field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), and/or digital signal processors (DSPs), and/or Or can be part of one or more ASICs.

Memory 260 may consist of one or more magnetic disks, tape drives, optical disk drives, or solid-state drives; may be used for non-volatile storage of data and as an overflow data storage device; may be used to store programs when such programs are selected for execution; and Can be used to store instructions and data read during program execution. Memory 260 may be volatile and/or non-volatile and may be read only memory (ROM), random access memory (RAM), triple content addressable memory (TCAM), static random access memory (SRAM) , other suitable memory types, or any combination thereof. Memory 260 may include DM270, which may be adapted to implement server DM111 or client DM121. Although memory 260 is shown as including DM 270, logic unit 230 or any combination of logic unit 230 and memory 260 may include DM 270.

Based on the foregoing typical system architecture and network devices for HTTP streaming, FIG. 3 is a flow interaction diagram of a method for displaying preview images according to an embodiment of the present application.

Client 110 may use an HTTP GET request or similar message to download a media presentation description (MPD) from HTTP server 120 or an HTTP cache (not shown). The MPD may be an Extensible Markup Language (XML) document. The MPD includes metadata of the format used for encoding the media content, such as bit rate, codec, screen resolution, and language. In this embodiment, the MPD also includes description information of the preview image.

In this embodiment, when the video content is injected, the server can read the preview image generation rules of the corresponding video, such as the interval time of the preview images, the resolution of the preview images, etc., to generate the preview image and the description information of the preview image, and the preview image description Information can be implemented in several ways:

In the first implementation, all preview images can be compressed into one file and carried in the form of a compressed package. The attribute parameters of the preview images are defined in MPD Representation, which are described as follows:

Elements in the Representation tag are introduced:

id: Preview image group ID.

width: The width of the preview image, in pixels.

height: The height of the preview image, unit: pixel.

startTime: The first preview image corresponds to the time point in the video.

interval: interval between adjacent preview images, unit: seconds.

number: The total number of preview images generated by this video.

BaseURL: The URL of the group of preview images packaged into a zip file for download.

In the second embodiment, the preview image is described by a list, and the attribute parameters of the preview image are defined in MPDRepresentation, and the description is as follows:

Elements in the Representation tag are introduced:

id: The ID of the preview image (group).

width: The width of the preview image, in pixels.

height: The height of the preview image, unit: pixel.

startTime: The first preview image corresponds to the time point in the video.

interval: interval between adjacent preview images, unit: seconds

number: The total number of preview images generated by this video.

SegmentURL: tag supports multiple values

Media: The URL of the specific preview image file for the terminal to download.

In the third embodiment, the preview image is described by a template, and the attribute parameters of the preview image are defined in MPDRepresentation, and the description is as follows:

Elements in the Representation tag are introduced:

PreviewTemplate: Rules for the download address (URL) of the preview image.

PreviewTimeline: Describes the rules for the preview image corresponding to the video content.

startTime: The first preview image corresponds to the time point in the video.

interval: The interval between adjacent preview images, unit: seconds.

number: The total number of preview images generated by this video.

id: Preview image (group) ID.

width: The width of the preview image, in pixels.

height: The height of the preview image, unit: pixel.

As shown in FIG. 3 , the preview image display method of this embodiment includes the following steps:

In step 310 , the client 120 may send a request for MPD to the HTTP server 110 .

At step 320 , the HTTP server 110 may send the MPD to the client 120 . The client 120 can receive the MPD through the DASH access engine DAE1211, where the MPD includes description information of the preview image. Specifically, the description information of the preview image may include address information and time information of the preview image, and may also include resolution information of the preview image.

Step 330, the client 120 parses out the description information of the preview image from the MPD file, and obtains the address information, time information and resolution information of the preview image, wherein the time information of the preview image at least includes: the time corresponding to the first frame preview image, The interval between adjacent preview images, and the total number of frames in the preview images.

In step 340, the client 120 requests a preview image from the HTTP server according to the description information of the preview image.

Specifically, the client 120 can select an appropriate preview image resolution according to terminal parameters such as screen size, and request a corresponding preview image xml document from the server to download the corresponding preview image according to the address of the preview image in the document.

In step 350, the HTTP server sends the preview image to the client 120, and the client 120 caches the preview image in the local storage.

Step 360, when the user drags the playback progress bar, the client 120 displays a preview image corresponding to the progress.

Specifically, when the user drags the playback progress bar, the position and time at which the playback progress bar stops are determined, and a preview image corresponding to the time is obtained and displayed according to the time. It should be noted that the dragging of the playback progress bar can be realized by the user directly dragging the playback progress bar, or the user directly inputting time parameters to locate the position of the playback progress bar.

Optionally, when the video playback starts, the client 120 may download all the preview images from the server to the local storage in advance according to the address information of the preview images, and obtain the preview images at the corresponding time locally when the user drags the playback progress bar. For display, this method can display the preview image in real time when the user drags the playback progress bar, and the display experience is better.

In addition, the client 120 can also judge the stop position of the progress bar and the corresponding time when the user drags the progress bar, select a preview image corresponding to the time according to the time, and download the corresponding preview image from the server in real time according to the position information of the preview image. It is shown that this method can reduce the storage pressure of the client and save the storage space of the client.

As shown in FIG. 4 , it is an interaction flowchart of a preview image display method according to another embodiment of the present application.

In this embodiment, the preview image description information may be an independent XML file, and the MPD may only include a description of the XML file, such as the URL of the preview image XML file. After the client can parse the MPD, it can obtain the preview XML file from the server according to the URL of the preview XML file. The description of MPD on the XML file of the preview image may be as follows:

Parameter Description:

mimeType: identifies application/xml, not video audio, and the preview image belongs to the application class, which is carried by XML

value: It is clearly used for timeline preview, timelinepreview.

Representation id: When preview images with multiple resolutions are provided, distinguish multiple Representations by id.

width, the width of the preview image, in pixels

height, the height of the preview image, in pixels

BaseURL: URL of the preview image XML file, the client can obtain detailed description information of the preview image according to the URL.

Specifically, there are multiple ways to describe the preview image XML file. In this embodiment, the preview image XML file in the first implementation mode is a single image mode, and each preview image is a separate image, and the description is as follows:

<! --Preview preview_240.XML-->

<xml version="1.0"encoding="UTF-8">

<timemline>

<image time="000006" id="preview_240_$time$.jpg"/>

<image time="000012"id="preview_240_$time$.jpg"/>

<image time="005900"id="preview_240_$time$.jpg"/>

</timemline>

Parameter Description:

timemline: The content under this XML node is the scene for the timeline

image: indicates that the preview image object node is described

time: format hours, minutes, seconds HHMMSS

id="preview_240_$time$.jpg": URL of preview image file

In the second implementation, the preview image XML file is in the merged image mode, that is, multiple preview images are combined into one image:

<! --Preview preview_240.XML-->

<xml version="1.0"encoding="UTF-8">

<timemline>

<image startTime="000000" endTime="001000" interval="6"

id="preview_$startTime$_$endTime$.jpg"/>

<image startTime="001000" endTime="002000" interval="6"

id="preview_$startTime$_$endTime$.jpg"/>

…

<image startTime="012000" endTime="013000" interval="6"

id="preview_$startTime$_$endTime$.jpg"/>

</timemline>

Parameter Description:

timemline: The content under this XML node is the scene for the timeline

image: indicates that the preview image object node is described

startTime: the start time of the video, format: HHMMSS

endTime: the end time of the video, format: HHMMSS

interval: The interval for generating preview images in this video, unit: seconds

id="preview_$startTime$_$endTime$.jpg": URL of preview image file

The merged picture mode can reduce the number of pictures, and the client reads the merged pictures, which can reduce the number of files opened and closed, and improve the display speed.

In the present embodiment, the preview image display method includes the following steps:

In step 410 , the client 120 may send a request for the MPD to the HTTP server 110 .

At step 420 , the HTTP server 110 may send the MPD to the client 120 . The client 120 may receive the MPD through the DAE 1211, where the MPD includes preview image description information, specifically, the preview image description information includes: the URL of the preview image description file.

Specifically, the description information of the preview image can be described as follows:

The client 120 determines that the video supports the preview image feature according to the value="timelinepreview, wherein multiple Representations indicate that preview images with multiple resolutions can be obtained, and the terminal can select an appropriate resolution preview image xml according to its own screen size, In this example, the obtained 240-resolution preview image is taken as an example.

Step 430, the client 120 parses the URL of the preview image description file from the MPD file.

Step 440, the client 120 requests the preview image description file from the server according to the URL of the preview image description file.

Specifically, the client 120 may request a description file of the preview image from the server according to the BaseURL of the selected preview image with a resolution of 240.

Step 450 , the HTTP server 110 returns the description file of the preview image to the client 120 .

Specifically, the preview image description file may be an XML document, and the specific content may be as follows:

<! --Preview XML-->

<xml version="1.0"encoding="UTF-8">

<timemline>

<image time="000006" id="preview_240_000006.jpg"/>

<image time="000012"id="preview_240_000012.jpg"/>

....

<image time="013000"id="preview_240_013000.jpg"/>

</timemline>

In step 460, the client 120 requests a preview image from the HTTP server according to the description file of the preview image.

In step 470, the HTTP server sends the preview image to the client 120, and the client 120 caches the preview image in the local storage.

Step 480: When the user drags the playback progress bar, the client 120 displays a preview image corresponding to the progress.

Specifically, when the user drags the playback progress bar, the position and time at which the playback progress bar stops are determined, and a preview image corresponding to the time is obtained and displayed according to the time.

Optionally, the client 120 may download all the preview images from the server to the local storage in advance according to the address information of the preview images when the video playback starts, and obtain the preview images of the corresponding time locally when the user drags the playback progress bar. For display, this method can display the preview image in real time when the user drags the playback progress bar, and the display experience is better.

In addition, the client 120 can also judge the stop position of the progress bar and the corresponding time when the user drags the progress bar, select a preview image corresponding to the time according to the time, and download the corresponding preview image from the server in real time according to the position information of the preview image. It is shown that this method can reduce the storage pressure of the client and save the storage space of the client.

It should be noted that the solutions of the embodiments of the present application can also be applied to other HTTP protocols such as HLS. If the HLS protocol is applied, the description information of the preview image can be included in the M3U8 file. For the specific implementation, refer to the above embodiments.

Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. Interchangeability, the above description has generally described the components and steps of each example in terms of function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of the present invention.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system, device and unit described above may refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may also be electrical, mechanical or other forms of connection.

The units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solutions in the embodiments of the present invention.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit. The above-mentioned integrated units may be implemented in the form of hardware, or may be implemented in the form of software functional units.

The integrated unit, if implemented in the form of a software functional unit and sold or used as an independent product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or a part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: U disk, removable hard disk, Read-Only Memory (ROM, Read-Only Memory), Random Access Memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of various equivalents within the technical scope disclosed by the present invention. Modifications or substitutions should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (19)

1. a display method of preview image, is characterized in that, comprises: The client obtains an index file of the video program from the server, where the index file is a media presentation description (MPD) file of the DASH protocol, and the index file includes description information of the preview image; obtaining, by the client, a preview image according to the preview image description information; The client displays the preview image according to the user operation instruction; The obtaining, by the client, the preview image according to the preview image description information includes: The client obtains the stop position of the progress bar and the corresponding time point, determines the position information of the preview image corresponding to the time point, and downloads the corresponding preview image from the server in real time according to the position information for display. 2. The method of claim 1, wherein the preview image description information comprises: The address information of the preview image and the time information corresponding to the preview image. 3. The method of claim 1, wherein the client displays the preview image according to a user operation instruction, comprising: When the user drags the playback progress bar, a corresponding preview image is displayed according to the position of the playback progress bar. 4. The method of claim 2, wherein the client displays the preview image according to a user operation instruction, comprising: When the user drags the playback progress bar, a corresponding preview image is displayed according to the position of the playback progress bar. 5. The method according to any one of claims 1-4, wherein the client obtains the preview image according to the preview image description information, comprising: Before the user drags the playback progress bar, the preview image is downloaded from the server according to the address information of the preview image and stored locally. 6. The method according to any one of claims 1-4, wherein the client obtains the preview image according to the preview image description information, comprising: When the user drags the playback progress bar, the address information of the corresponding preview image is determined according to the position of the playback progress bar and the time information corresponding to the preview image, and the preview image is downloaded from the server according to the determined address information of the preview image. picture. 7. A method for displaying preview images, comprising: The server sends the index file of the video program to the client, the index file is the MPD file of the DASH protocol, and the index file includes the description information of the preview image; The server receives a client preview image download request; The server sends the preview image to the client in response to the download request of the client; The server, in response to the download request of the client, sending the preview image to the client includes: The server sends to the client a preview image corresponding to the location information in the preview image download request, where the location information is determined by the client according to the stop position of the progress bar and the corresponding time point. 8. The method of claim 7, wherein the preview image description information comprises: The address information of the preview image and the time information corresponding to the preview image. 9. The method of claim 7 or 8, wherein the method further comprises: Generate preview images and preview image description information according to the preview image generation rules. 10. The method of claim 9, wherein the preview image generation rule comprises: Preview image interval time information and preview image resolution information. 11. A client device comprising: a receiver, for obtaining the index file of the video program from the server, the index file is the MPD file of the DASH protocol, and the index file includes the description information of the preview image; a processor, configured to obtain a preview image according to the description information of the preview image; display the preview image according to a user operation instruction; In the aspect of obtaining the preview image according to the preview image description information, the processor is specifically configured to: The stop position of the progress bar and the corresponding time point are obtained, the position information of the preview image corresponding to the time point is determined, and the corresponding preview image is downloaded from the server in real time according to the position information for display. 12. The client device according to claim 11, wherein the preview image description information comprises: The address information of the preview image and the time information corresponding to the preview image. 13. The client device of claim 11, wherein the processor is specifically configured to: When the user drags the playback progress bar, a corresponding preview image is displayed according to the position of the playback progress bar. 14. The client device of claim 12, wherein the processor is specifically configured to: When the user drags the playback progress bar, a corresponding preview image is displayed according to the position of the playback progress bar. 15. The client device according to any one of claims 11-14, wherein the processor is further configured to: download from the server according to the address information of the preview image before the user drags the playback progress bar preview. 16. The client device according to any one of claims 11-14, wherein the processor is further configured to: when the user drags the playback progress bar, according to the position of the playback progress bar and the The time information corresponding to the preview image is determined, the address information of the corresponding preview image is determined, and the preview image is downloaded from the server according to the determined address information of the preview image. 17. A server comprising: The transmitter is used to send the index file of the video program to the client, the index file is the MPD file of the DASH protocol, and the index file includes the description information of the preview image; The receiver is used to receive the client preview image download request; The transmitter is further configured to send the preview image to the client in response to the download request of the client; In the aspect of sending the preview image to the client in response to the download request of the client, the transmitter is specifically used for: Send a preview image corresponding to the location information in the preview image download request to the client, where the location information is determined by the client according to the stop position of the progress bar and a corresponding time point. 18. The server of claim 17, further comprising: The processor is used to generate a preview image and preview image description information according to the preview image generation rule. 19. The server of claim 18, wherein the preview image generation rule comprises: Preview image interval time information and preview image resolution information.

Images