CN1784005B - A method of accessing carousel data through the file system - Google Patents

Abstract

This invention relates to a method for addressing carousel by file, especially relating to a technology for random accessing data and effectively extracting data based on data carousel format and protocol in digital television receiving equipment. Said carousel data is a data transmitting technology applied in digital television field based on ISO/13818-6 data transmission protocol, but in standard large protocol it does not correspond with file system, the data accessing is complex. Said invention provides a method for storing data in buffer memory and corresponded with a kind of file system(such as virtual file system VFS) to obtain high speed data addressing.

Description

A method of accessing carousel data through the file system

technical field

The invention relates to a method for randomly accessing carousel data through files, in particular to a technology for randomly accessing and effectively extracting data based on data carousel format and protocol technology in a digital television receiving device. It belongs to the technical field of digital television reception.

Background technique

Digital TV receiving equipment generally refers to hardware equipment that can receive, decode and display digital TV signals. It is used in the field of digital TV and is the terminal for realizing the digitization of analog TV (see Figure 1). Digital TV receiving equipment receives digital image and data information. Therefore, unlike the reception and processing of traditional analog TV signals, digital TV receiving equipment receives and processes digital image information and data through its internal CPU and peripheral devices connected to it. The receiving system is to develop the application program applicable to digital TV receiving equipment on the basis of corresponding hardware and operating system; similarly, some professional digital broadcast content service providers also need to develop corresponding service software.

In the broadcasting equipment of a TV station or a TV operator, audio and video signals and data content are mixed through a front-end multiplexer to form a transport stream (TS stream). The transmission stream is modulated to form an electromagnetic signal and sent to the digital TV receiving device. The working principle of digital TV receiving equipment (set-top box) is as follows:

The tuning/selection module receives the electromagnetic signal and selects a certain range of bandwidth.

The demodulation module converts signals into data streams (Bitstreams).

解复用模块从数据流(Bitstreams)中抽出期望信息并将其以合适的方式提供给不同的解码器，它包括与条件接收模块合作的解扰器。

The demultiplexing module extracts the desired information from the data streams (Bitstreams) and provides them in a suitable way to different decoders, which includes a descrambler cooperating with the conditional access module.

The video decoding module converts the video bitstream in the displayed image sequence.

音频解码模块转换模拟音频信号中的音频位流。

The audio decoding module converts the audio bit stream in the analog audio signal.

图形引擎建立图形层在发送之前将其和对PAL/INTSC的模拟信号请求中的视频混合。

The graphics engine builds the graphics layer to mix it with the video in the analog signal request to PAL/INTSC before sending.

The front panel section is responsible for interpreting user commands via the receiver remote control, wireless keypad, or front panel.

The video bit stream and the audio bit stream are mixed with the image through the image processor to become an analog audio and video signal, which is output to the display screen (television). The data stream flows into the CPU through the demultiplexer and is processed by the system program running on the central processing unit (CPU). The processed results can be mixed with the audio and video streams and output to the display device.

Digital TV adds a large number of data services on the basis of the original audio and video services, and the data is circulated in a carousel mode together with digital TV signals and broadcast to digital TV receiving equipment through TS streams. The data carousel technology is specified in accordance with the ISO/IEC 13818-6 standard DSM-CC technology. There are two main data carousel modes: data carousel and object carousel. The data carousel used in digital TV broadcasting is based on the DSM-CC data carousel. The data in the carousel is sent in the form of modules, and each module is divided into multiple data blocks of the same size. The object carousel used in digital TV broadcasting is based on the DSM-CC object carousel. Each carousel represents a special service domain, which is composed of a collection of DSM-CC U-U objects. These objects include files, directories, events, and stream events. According to the ISO/I EC13818-6 standard, the data carousel protocol uses messages to encapsulate data and control information, and the directory structure information of the data to be broadcast is downloaded by the data table service to initialize the DSI (DownloadServerInitiate) message and the download information description DII (DownloadInfoIndirection) message Transmission, put the actual data file into the DownloadDataBlock (DDB) message defined by the data carousel protocol for transmission. In a data carousel, all data blocks of a module have the same length except the last data block of each module. A module is a collection of logically independent data. Multiple modules can form a group (Group), and multiple groups (Group) can form a supergroup (SuperGroup). The service download initialization DSI message describes the information of the group in the super group; the download information description DI I message describes the information of the modules in the group. The receiving device can decide which modules to receive according to the control message. The broadcast format of the carousel data is shown in Figure 2.

In modern computing technology, the organizational structure of data is generally realized through the file system. Virtual File System (VFS) is a commonly used file system organizational structure technology. In the field of digital TV, since the data broadcast by DSM-CC is broadcast in the form of a table structure, there is currently no specific technology on how to combine and associate the carousel data with the VFS file system.

Both the data carousel method and the object carousel method can transmit data in a carousel manner. However, to obtain these data, they need to be loaded on the fly and stored in the cache. However, for applications that need to use these data, the above method is very inconvenient, time-consuming and cumbersome. Method of the present invention is exactly the solution that proposes for the deficiency of traditional technology.

Contents of the invention

The technical problem to be solved by the invention is a method for a file system to access carousel data. The advantage of this method is that by setting a data buffer in the digital TV receiving device, the data transmitted through the carousel protocol obtained from the digital TV data signal is stored in the data buffer, and the data buffer is connected with the file system. Access data in the form of ordinary files, thereby eliminating the cumbersomeness of carousel data acquisition.

The present invention solves the above problems through the following technical solutions. The method of the present invention is to set a cache, which is associated with the cache through a traditional file system (such as through a virtual file system VFS). When it is necessary to obtain carousel data, it only needs to open and read the corresponding file, thereby Use to improve the response speed and data utilization efficiency of digital TV receiving equipment.

The technical solution of the present invention will be described in detail below.

Steps in this method:

The invention provides a transmission method based on a DSM-CC turntable, which acquires data through a directory file system. This method is applicable to both DSM-CC Data Carousel and Object Carousel. The difference between the two protocols is only reflected in the way the data is loaded. The following takes the data carousel (or data carousel) as an example to illustrate how to establish a cache and associate the file system with the carousel data, so as to achieve the purpose of effectively obtaining data through the file system.

To load the DSM-CC carousel data and associate them with the file system,

Generally, there are several sub-modules as follows:

1. Service Gateway: Responsible for providing external public interfaces and coordinating the task execution of each module of the system;

2. Cache: responsible for storing relevant file data, and providing technical search and deletion functions;

3. DSM FS: DSM file system, which provides an operation interface associated with the upper file system.

The role of Cache (cache): The cache is used to access the loaded data, so that the data does not need to be loaded frequently. When caching a Carousel, it will first receive all service download initialization DSI and download information description DII messages, and cache the entire file system structure. However, when an application calls a file, it will temporarily obtain it from the channel and cache it. When a file is used and closed, the memory it occupies can also be released. The structure of the Cache uses DDB as the basic unit of the cache. A Carousel corresponds to a Group linked list, each Group node points to a MoGule linked list, and each Module node points to a DDB linked list. The structure of Cache is shown in Figure 5.

Association with the file system (DSM FS): The DSM-CC data cache itself does not have a conventional file system. For the convenience of data acquisition, the cache data should be associated with a file system so that the data can be accessed through the file system. The organizational structure of the upper file system does not need to be the same as that of the Cache. DSM-CC and file systems (such as VFS) generally need to define the necessary data structures and functions associated with the file system.

The method of the present invention will be further described below by means of the accompanying drawings.

Description of drawings

Figure 1 is a block diagram of digital television equipment work. The digital TV signal enters the receiving device and is processed by the demodulation and demultiplexing module to separate the audio and video signal from the data signal. The event information carried in the data signal is processed and stored for display on the TV screen.

Figure 2 shows the organizational structure of the carousel data. In the data carousel, the transmitted data is stored in modules (Module); and each module is divided into several data blocks (Block). In a data carousel, all data blocks of a module have the same length except the last data block of each module. A module is a collection of logically independent data. Multiple modules can form a group (Group), and multiple buttons (Group) can form a supergroup (SuperGroup). The data carousel protocol uses messages to encapsulate data and control information. The data is carried by the DDB message; the control is carried by the download information description DII, service download initialization DSI and other messages. The service download initialization DSI message describes the group information in the super group; the download information description DII message describes the module information in the group. The receiving device can decide which modules to receive according to the control message.

Figure 3 shows the structure of the file system. In the present invention, the Flash module is a readable and writable storage module as a driver of the file system; DSMCC is readable and unwritable as another driver of the file system, because it is a circular carousel system, writing is pointless.

Figure 4 shows the module structure of DSM-CC data and its association with the file system. The Org.dvb.dsmcc module indicates through the SG interface that a certain carousel needs to be loaded into the Cache. Then VFS enables data access through common functions of the file system.

Figure 5 shows the organizational structure of Cache: Cache adopts a hierarchical storage structure, which is classified according to DSI (Carousel Node)->DI I (Group Node)->Module.

The present invention will be further described in detail below in conjunction with specific implementation examples.

Detailed ways

The specific implementation is as follows:

1. Obtain the information of carousel data

Load the program mapping table PMT, analyze the stream_identifier_descriptor descriptor, load the event information table EIT or business description table SDT, analyze the data_broadcast_descriptor descriptor, obtain the packet identifier PID information of the data broadcast and the type and level of the carousel.

Call MBT_SilGetCarouselInfo() to obtain the required data_broadcast_descriptor descriptor.

2. Associate carousel

在DSM-CC模块启动时，根据获得的data_broadcast_descriptor描述子，调用MBT_DIAttachGateway()将对应的数据轮播挂载到VFS的文件系统上。

When the DSM-CC module starts, according to the obtained data_broadcast_descriptor descriptor, call MBT_DIAttachGateway() to mount the corresponding data carousel to the VFS file system.

Call MBT_DIDetachGateway() to disassociate and unmount the DSM-CC file system.

When associating the carousel data, it is necessary to load the service download initialization DSI and download information description DII table to obtain the specific data organization structure. When associating with the virtual file system VFS, the following operations are required:

a) Define the type of DSM-CC file system: its name is: "dsmfs";

b) Define the structure of the file system super_block and inode;

c) Define three methods of file system super_operation: void(*read_inode)(structinode*), void(*put_super)(struct super_block*), int(*statfs)(struct super_block*, struct statfs*, int)

d) Define four methods required for file system file inode operations: dsmfs_file_operations, dsmfs_file_inode_create, dsmfs_inode_lookup, dsmfs_inode_unlink;

e) Define three methods required for file system dir inode operations: dsmfs_dir_operations, dsmfs_inode_lookup, dsmfs_inode_unlink;

f) Define three methods for reading and writing file system file_operation: dsmfs_file_read, dsmfs_file_write, dsmfs_file_readdir\

g) Define the reading method of the file system dir operation directory operation: dsmfs_dir_readdir;

h) Define the method of registering the DSM-CC file system to the VFS file system:

register_filesystem(&dsmfs_fs_type);

i) Define the method of logging out of the DSM-CC file system:

unregister_filesystem(&romfs_fs_type).

According to the above steps, by implementing the structure and method, the DSM-CC is associated with the VFS file system.

3. File operation

Call the function of the VFS file system operation to access the file, and load the DDB message at this time to provide specific data.

Finally, it should be noted that: the present invention provides a method for accessing carousel data through a file system and its design concept. The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. The invention has been described in detail, and those of ordinary skill in the art should understand that: the present invention can still be modified or equivalently replaced, and any modification or partial replacement without departing from the spirit and scope of the present invention should be covered by the rights of the present invention. within the required range.

Claims (7)

1. A method for accessing carousel data through a file system, comprising: 1) Obtain carousel data information through the Service Gateway module; 2) According to the Service Gateway module interface instruction, load the obtained carousel data information into the Cache cache data module, and associate the carousel data with the file system module; 3) Data access through the file system module; Wherein, the file system is a virtual file system VFS; The operations for associating the carousel data with the virtual file system VFS include: A. Define the type of DSM-CC file system; B. Define the structure of the file system super_block and inode; C. Define the method of file system super_operation operation; D. Define the method of file system file inode operation; E. Define the method of file system dir inode operation; F. Define the method of reading and writing the file system file_operation; G. Define the reading method of the file system dir operation directory operation; H. Define the method for registering the DSM-CC file system to the virtual file system VFS; I. Define the logout method of the DSM-CC file system. 2. A method for accessing carousel data through a file system according to claim 1, wherein the acquisition of carousel data information in said 1) includes: loading program mapping table PMT, analyzing stream_identifier_descriptor descriptor, Load the event information table EIT or the service description table SDT, analyze the data_broadcast_descriptor descriptor, obtain the packet identifier PID information of the data broadcast, the type of carousel and the level of the carousel; call the MBT_SilGetCarouselInfo function to obtain the required data_broadcast_descriptor descriptor. 3. A method for accessing carousel data through a file system according to claim 1, characterized in that, when the obtained carousel data information is loaded into the Cache data module in said 2), at first load the service Download Initialization DSI and Download Information Description DII messages. 4. A method for accessing carousel data through a file system according to claim 1, wherein associating the carousel data with the file system in said 2) comprises: when DSM-CC starts, According to the obtained data_broadcast_descriptor descriptor, call the MBT_DlAttachGateway function to mount the corresponding carousel data to the file system. 5. A method for accessing carousel data through a file system according to claim 4, characterized in that calling the MBT_DIDetachGateway function to cancel the association between the carousel data and the file system and uninstall the file system. 6. A method for accessing carousel data through a file system according to any one of claims 1-5, wherein the file system is a tree file system. 7. A method for accessing carousel data through a file system according to any one of claims 1-5, characterized in that, the specific data carousel format and protocol processed by the method conform to ISO/IEC 13818-6 The data carousel and object carousel regulated by the standard or data in other formats transmitted through other transmission protocols.

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