WO2005109880A1

WO2005109880A1 - A method for accessing carousel data via file system

Info

Publication number: WO2005109880A1
Application number: PCT/CN2005/000626
Authority: WO
Inventors: Xiangzhong Fang; Hongtao Liao; Haisheng Sun
Original assignee: St Microelectronics Nv
Priority date: 2004-05-09
Filing date: 2005-05-08
Publication date: 2005-11-17
Also published as: CN1784005B; CN1784005A

Abstract

This invention discloses a method for accessing carousel data via file system, and especially discloses a technology of randomly accessing and effectively extracting data based on data carousel format and protocol in digital television receiver. It belongs to the digital television receiving field. Carousel data is the data transmission technology applied in digital television field based on ISO/13818-6 data transmission protocol, but in the standard protocol, it is not related to file system, so it is complicated in data acquirement. This invention provides a method for storing data in a buffer, and associating the data with a file system (e.g. virtual file system (VFS)). So, accessing the carousel data just as randomly as accessing the local file and accessing the data effectively and conveniently is achieved.

Description

Method for accessing carousel data through file system

The invention relates to a method for randomly accessing carousel data through a file, and particularly to a technology for performing random access and effective extraction of data in a digital television receiving device based on a data carousel format and a protocol technology. It belongs to the field of digital television receiving technology. BACKGROUND OF THE INVENTION Digital television receiving equipment generally refers to hardware equipment capable of receiving, decoding, and displaying digital television signals. It is applied in the field of digital television and is a terminal for the realization of digitization of analog television (see Figure 1). Digital television receiving equipment receives digital image and data information. Therefore, unlike traditional analog television signal receiving and processing, digital television receiving equipment receives and processes digital image information and data through its internal CPU. And peripheral devices connected to it. The receiving system is based on the corresponding hardware and operating system to develop applications suitable for digital television receiving equipment; Similarly, some professional digital broadcast content service providers also need to develop according to the hardware performance and functions of different digital television receiving equipment Corresponding service software.

In the broadcast equipment of a TV station or 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 transmitted to a digital television receiving device. The working principle of digital TV receiving equipment (set-top box) is as follows-

♦ The tuning / selection module receives electromagnetic signals and selects a certain range of bandwidth.

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

♦ The demultiplexing module extracts the desired information from the data streams (Bitstreams) and provides it to different decoders in a suitable way. It includes a descrambler that works with the conditional access module.

♦ The video decoding module converts the video bit stream in the displayed image sequence.

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

♦ The graphics engine creates the graphics layer and mixes it with the video in the PAL / NTSC analog signal request before sending it. ♦ The front control panel is responsible for interpreting user commands issued by the remote control, wireless keyboard or front panel. The video bit stream and audio bit stream are mixed with the image through the image processor, and become analog audio and video signals, which are output to the display screen (TV). 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. Data is circulated in a carousel manner and broadcasted to the digital TV receiving device in a TS stream with digital TV signals. The data carousel (Data Carousel) technology is based on the ISO / IEC13818-6 standard DSM-CC technology. There are two types of data carousel: data carousel and object carousel. The data turntable for digital TV broadcasting is based on the DSM-CC data turntable. The data in the turntable is sent in the form of modules, and each module is divided into multiple data blocks of the same size. The object turntable for digital television broadcasting is based on the DSM-CC object turntable. Each turntable represents a special service domain. This domain consists of a collection of DSM-CC UU objects. These objects include files, directories, events, As well as stream events. According to the ISO / IEC13818-6 standard, the data carousel protocol uses messages to encapsulate data and control information. The directory structure information of the data to be broadcast is transmitted by the data table DSI (DownloadServerlnitiate) message and DII (Downloadlnfolndirection) message, and the actual data file is transmitted. Put into a DownloadDataBlock (DDB) message as 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, and multiple groups can form a supergroup. The DSI message describes the information of the group in the super group; the DII message describes the information of the modules in the group. The receiving device can decide which modules to receive based on the control message. The transmission format of carousel data is shown in Figure 1.

In modern computing technology, the organization of data is generally implemented through a file system. Virtual File System (VFS) is a common file system organization technology. In the field of digital television, 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 transfer data through a carousel. However, to get To fetch these data, they need to be loaded instantly and stored in the cache. However, for applications that need to use this data, the above method is very inconvenient and time consuming.

The method of the present invention is a solution proposed for the deficiency of traditional technology. Summary of the invention

The technical problem to be solved by the present 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 from the digital TV data signal and transmitted through the carousel protocol is stored in the data buffer. The data buffer is associated with the file system and is directly applied during application. Access the data as a normal file, thereby eliminating the tedious acquisition of carousel data.

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 a virtual file system VPS). When the carousel data needs to be obtained, only the corresponding file needs to be opened and read, which is convenient Use, improve the response speed and data utilization efficiency of digital television receiving equipment.

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

Steps of the method:

The present 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 different data loading methods. The following uses the data carousel (or data carousel) as an example to explain 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 DSM-CC carousel data and associate them with the file system, there are generally the following sub-modules:

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 related file data, and providing search and delete functions; 3. DSM FS: DSM file system, which provides an operation interface associated with the upper file system.

The role of cache (cache): cache is used to access already loaded data, so that there is no need to load data frequently. When a Carousel is cached, all DSI and DII messages will be received first, and the entire file system structure will be cached, but when an application calls a certain file, it will temporarily obtain it from the channel and cache it. After a file is used and closed, the memory occupied by it can 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 Module linked list, and each Module node points to a DDB linked list. The structure of the cache is shown in Figure 3.

Association with 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) need to define the data structures and functions necessary for file system association.

The method of the present invention will be further described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 2 shows the organization of carousel data. In a data carousel, the transmitted data is stored in modules; each module is divided into several data blocks. 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, and multiple groups can form a supergroup. The data carousel protocol uses messages to encapsulate data and control information. Data is carried by DDB messages; control is carried by DII, DSI and other messages. The DSI message describes the information of the group in the super group; the DII message describes the information of the modules 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 used as a driver of the file system, which is a readable and writable storage module; DSMCC is used as another driver of the file system, which is readable but not writable because it is a circular carousel System, writing is meaningless.

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 carousel needs to be loaded into the cache. VFS can then access data through common functions of the file system.

Figure 5 shows the organizational structure of the Cache: Cache uses a hierarchical storage structure and is classified by DSI (Carousel Node)-> DII (Group Node)-> Module.

The present invention will be further described in detail below with reference to specific implementation examples. DETAILED DESCRIPTION Specific implementations are as follows:

Get information about carousel data

Load the PMT table, analyze the stream_identifier_descriptor descriptor, load the EIT or SDT table, analyze the data_broadcast_descriptor descriptor, and obtain the PID information of the data broadcast, the type of the carousel, and the level of the carousel.

Call MBT— SilGetCarousellnfo () to get the required data — broadcast — descriptor descriptor.

Associated carousel

When the DSM-CC module is started, according to the obtained data_broadcast_descriptor descriptor, call

MBT—DlAttachGateway () mounts the corresponding data carousel on the VFS file system.

々 Call MBT__DlDetachGateway () to cancel the association and unmount the DSM-CC file system.

When correlating carousel data, DSI and DII tables need to be loaded to obtain specific data organization structure. When associated with a virtual file system VFS, the following operations need to be performed: a) Define the type of DSM-CC file system: Its name is: "dsmfs"; b) Define the structure of file system spuer- block and inode; c) Define three methods of file system super- operation operation: void (* read — Inode) (struct inode *), void (* put_super) (struct super— block *), int (* statfs) (struct super— block *, struct statfs *. Int)

d) Define the four methods required for file inode operations on the file system: dsmfs_file— operations, dsmfs—file—inode—create ,, dsmfs— inode— lookup, dsmfs— inode— unlink e) Define the three required dir inode operations for the file system Methods: dsmfs—dir— operations, dsmfs_inode_looku, dsmfs_inode_ unlink f) Three methods to define the file system file—operation read and write: dsmfs— file— read, dsmfs— file— write, dsmfs— file— readdir \

g) Define the read method of the file system dir operation: dsmfs— dir— readdir h) Define the DSM — CC file system Register with the VFS file system: register_filesystem (& dsmfs_fs_type)

i) Define the method of unregistering the DSM_CC file system: unregister_ filesystem (& romfs_fs_type) According to the above steps, by implementing the described structure and method, the DSM_CC and VFS file system are associated.

3. File operations

The function of the VFS file system operation is called to access the file, and DDB messages are loaded at this time to provide specific data. What should be explained at last: 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 rather than 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 invention can still be modified or equivalently replaced without any modification or partial replacement that departs from the spirit and scope of the invention, which should be covered by the rights of the invention Among the requirements.

Claims

Rights request

1. A method for accessing carousel data through a file system, comprising: setting a data buffer in a digital television receiving device, and acquiring data transmitted from a digital television data signal and transmitting data through a carousel protocol in the data buffer, The data buffer is associated with the file system, and the data is accessed directly as a normal file when applied.

2. A method for accessing carousel data through a file system according to claim 1, characterized in that it constructs a DSM file system by defining corresponding data formats and data reads, so that data functions are associated with the file system It makes the upper application directly call the function of the file system to access the data.

3. A method for accessing carousel data through a file system according to claim 1 or 2, characterized in that the specific data carousel format and protocol it processes can be in accordance with the ISO / 13818-6 standard Data carousel and object carousel may also be data in other formats transmitted through other transmission protocols.

4. The method for accessing carousel data through a file system according to claim 1 or 2, characterized in that the upper-layer file system used for association can be a general virtual file system or other tree-shaped files system.