CN1322757C - Universal digital broadcast system and methods - Google Patents

Abstract

The present invention teaches methods and systems for providing full digital services such as VOD, digital broadcast, as well as a universal set-top-box (STB) capable of handling this variety of digital services. A plurality of hardware architectures and complimentary data transmission methods identifying the distinct services through an electronic program guide enable such transmission. The universal STB of the present invention is capable of distinguishing the different services based upon information received in the electronic program guide, and is designed with unique hardware architecture including a large buffer. The present invention further provides viewing options such as multiple broadcasts and virtual VCR time-shifting features including pause, recording, and freeze-framing a broadcast without suffering the volatility and poor quality of an Internet streaming broadcast. Still further, this variety of digital services is provided via a uni-directional communication link.

Description

General digital broadcasting system and method

technical field

The present invention relates to video-on-demand and digital broadcasting technologies. In particular, the present invention teaches methods and systems for providing all-digital services such as VOD, digital broadcasting, time shifting from any broadcasting medium, and set-top boxes (STBs) capable of handling all these kinds of data services.

Background technique

A variety of mechanisms are available for encoding and transmitting digital data. For example, the International Organization for Standardization (hereinafter referred to as "ISO/IEC") has introduced a standard (MPEG-2) for encoding moving pictures and associated audio. Due to the ubiquity of MPEG-2 and its relation to the present invention, some preliminary description is necessary.

The ISO/IEC MPEG-2 standard is stated in four documents. The document ISO/IEC 13818-1 (system) specifies the system code for this specification. This document defines a multiplex structure for combining audio and video data and a means of representing the timing information required for real-time playback of synchronized sequences. The document ISO/IEC 13818-2 (Video) specifies the coded representation of video data and the decoding process required to reconstruct the picture. The document ISO/IEC 13818-3 (Audio) specifies the coded representation of audio data and the decoding process required to reconstruct the audio data. The final document ISO/IEC 13818-4 (Conformity) specifies the characteristics used to determine the encoded bit stream and is used to detect compliance with the documents ISO/IE 13818-1, ISO/IE 13818-2, ISO/IEC 13818- The requirements stated in 3. These four documents (together the "MPEG-2 Standard") are hereby incorporated by reference.

In the context of digital broadcasting systems, a multiplexed bit stream conforming to the MPEG-2 standard is a "transport stream" constructed from "packetized elementary stream" (ie, PES) packets and packets containing other necessary information. A "packetized elementary stream" (ie, PES) packet is a data structure used to carry "elementary stream data". "Elementary stream" is a generalized term for either (a) encoded video, (b) encoded audio, or (c) in a sequence of PES packets with one and only one stream ID Other encoded bit streams carried. Transport Streams support the multiplexing of video and audio compressed streams from a program with a common time base.

Prior Art FIG. 1 illustrates the packetization process for packetizing compressed video data 106 of a video sequence 102 into a stream of PES packets 108 and then into a stream of Transport Stream packets 112 . Specifically, a video sequence includes headers 104 and associated compressed video data 106 . The video sequence 102 is parsed into variable-length segments, each segment having an associated PES packet header 110, to form a stream 108 of PES packets. The stream of PES packets 108 is then parsed into a plurality of segments, each segment being provided with a transport stream header 114 to form a transport stream 112 . Each transport stream packet of the transport stream 112 has a length of 188 bytes.

A transport stream allows one or more programs with one or more independent time bases to be combined into a single stream. Transport streams are useful in situations where data storage and/or transmission devices are noisy. The flow rate of transport streams and their constituent packet elementary streams (PES) can be fixed or variable. The stream rate is defined by the value and position of the Program Clock Reference (or PCR) field in the Transport Stream.

A PES packet, as defined in the MPEG-2 standard, includes a PES header that includes a 24-bit start code prefix field, an 8-bit stream identifier field, a 16-bit PES packet length field, a An optional PES header, and a payload, ie data portion 706. All these fields are described in the MPEG-2 standard.

The MPEG-2 standard focuses on the encoding and transmission of video and audio data. In general, the MPEG-2 standard uses compression algorithms so that video and audio data can be stored and transmitted more efficiently.

Prior Art FIG. 2 depicts a structural diagram of a digital broadcasting system 200, which includes a digital broadcasting server 202 and a set-top box 204 suitable for processing digital broadcasting data. Figure 2 illustrates not only the components of the system, but also the process flow for encoding, delivering (from digital broadcast system server 202 to set-top box 204), and decoding video and audio data according to the MPEG-2 standard. As is known, in a typical prior broadcasting method, an MPEG-2 standard transport stream is used in one stream.

At the digital broadcast server 202, the video data is provided to a video encoder 206 which encodes the video data according to the MPEG-2 standard (specified in document ISO/IEC 13818-2). The video encoder 206 transmits the encoded video 208 to a packetizer 210 , which groups the encoded video 208 . The packetized encoded video 212 provided by the packetizer 210 is then provided to a transport stream multiplexer 214 .

Similarly, at the digital broadcast server 202, audio data is provided to an audio encoder 214, which encodes the audio data according to the MPEG-2 standard (specified in document ISO/IEC 13818-3). The audio encoder 214 provides the encoded audio 218 to a packetizer 220 which groups the encoded audio 218 . The packetized encoded audio 222 provided by the packetizer 220 is then provided to the transport stream multiplexer 214 .

Transport stream multiplexer 214 multiplexes the encoded audio and video packets and transmits the resulting multiplexed stream to a set top box 204 via distribution infrastructure 224 . The distribution infrastructure 224, such as a telephone network and/or a cable television (CATV) system, may use fiber optics and employ the Asynchronous Transfer Mode (ATM) transmission protocol. At the set top box 204, on a remote side of the distribution infrastructure 224, a transport stream demultiplexer 230 receives the multiplexed transport streams. According to the packet identification number of a specific packet, the transport stream demultiplexer 230 decomposes the audio and video packets after encoding, and provides the video packet to a video decoder 232 through the link 238, and provides the audio packet through the link 240 Give an audio decoder 236.

Transport stream demultiplexer 230 also provides timing information to a clock control unit 236, which provides timing output to video decoder 232 and audio decoder 236 . Video coder 232 provides video data corresponding to the video data originally provided to video encoder 206 . Similarly, audio decoder 236 provides audio data corresponding to the audio data originally provided to audio encoder 216 .

In a traditional VOD architecture, a server and a server network communicate with clients in a standard hierarchical client-server mode. For example, a client sends a request to a server for a data file (eg, a video data file). In response to this request from the client, the server sends the requested data file to the client. In the standard client-server model, one or more servers fulfill a client's request for a data file. The client machine may have the ability to store any received data files locally in a non-volatile memory for later use. The standard client-server model requires a two-way communication infrastructure. Currently, two-way communication requires the construction of new infrastructure because existing cables can only provide one-way communication. Examples of two-way communication infrastructures are hybrid fiber coax (HFC) or all fiber infrastructure. Replacing existing cables is extremely expensive, and the resulting service may be out of the reach of most users.

Prior Art FIG. 3 depicts a simplified functional block diagram of a VOD system 300 . The central part of the system is video server 310, which routes digital movies residing in movie storage system 312 to distribution infrastructure 314, such as a telephone network and/or a cable television (CATV) The system can use optical fiber and adopt Asynchronous Transfer Mode (ATM) transmission protocol. The distribution infrastructure 314 distributes the movie to each home according to the routing information provided by the video server 310 .

The VOD system 300 also includes a plurality of VODSTBs 304 adapted to process VOD in the VOD system 300. Each STB 304 receives and decodes a digital film and converts it into a signal for playback on a television or monitor. In addition, the distribution infrastructure 314 also includes a "back channel" through which the viewer can sequence and control the playback of the digital movie. The back channel routes commands from the VOD STD 304 back to the video server 310 through the distribution network 314. The primary function of video servers 310 is to route compressed digital video streams from their storage units to requesting viewers.

The above discussion shows that prior solutions cannot provide both VOD and digital broadcasting in a single system. In contrast, prior solutions are limited by several factors. A major limiting factor is that prior art streams use MPEG-2 transport streams. Additionally, prior art VOD systems required a two-way communication link in order to operate. It is desirable to be able to provide a system in which digital broadcasting and on-demand services can be provided to a large number of clients over almost any transmission medium without replacing existing infrastructure. What is also needed is a way to provide viewers with viewing options (e.g., multiple broadcasts) and virtual VCR time-shifting features (e.g., pause, record, freeze a broadcast's picture) without choppy and poor Internet streaming broadcast quality Methods. It is also desirable to provide this functionality over a one-way communication link.

Contents of the invention

The present invention teaches methods and systems for providing fully digital services such as VOD, digital broadcasting, time shifting from any broadcasting medium, and a universal set top box (STB) capable of handling all these kinds of digital services.

A first embodiment of the present invention describes a universal broadcast system providing all digital services over multiple channels through a unidirectional communication link. These channels are suitable for providing either VOD or digital broadcasting. Other channels may be used for other purposes, so further services are not excluded by the invention.

The general broadcast system includes digital broadcast circuitry adapted to transmit digital broadcast data on a first channel of the general broadcast system. The digital broadcast circuit includes a plurality of digital broadcast data sources providing data to be broadcast on a first channel, a plurality of digital data encoders, a first data combining device, a first channel server, and a First channel upconverter. Each digital data encoder is coupled to a corresponding, unique data source and is operable to encode received data into a digital program stream format. A first data combining device is coupled to the digital data encoder and is operable to combine data received in a digital program stream format into first combined digital stream data.

A first channel server is coupled to the data combining device and is operable to generate a first modulated intermediate frequency signal based on the first combined digital stream data. The first up-conversion device is coupled to the first channel server, and is operable to convert the first modulated IF signal into a first radio frequency signal.

The universal broadcast system also includes a combiner amplifier coupled to the first channel circuit. The combiner amplifier is operable to amplify, condition and combine received radio frequency signals, eg, the first radio frequency signal. The output of the combiner amplifier is suitable for providing multiple channels of a general broadcast system across a unidirectional communication medium.

According to another embodiment of the present invention, the general broadcast system is also adapted to provide data on demand through a second channel. This is achieved by the following components: a central control server, a central storage device storing data to be supplied on-demand, and a data-on-demand circuit for the second channel. The data-on-demand circuit includes a second-channel server with a second-channel server CPU, local memory, a modulator and a network interface. The second channel server is operable to generate a second modulated intermediate frequency signal based on the digital data stored in the local memory.

The data-on-demand circuit also includes a second channel up-conversion device coupled to the second channel server, the second up-conversion device operable to convert the second modulated intermediate frequency signal into a second radio frequency signal provided to the combiner amplifier.

The central control server is operable to select the second channel and calculate a delivery matrix for transmitting data files stored on the central storage device on the second channel. The second central control server is also operable to provide offline addition, deletion, and modification of data file information on the second control server.

One aspect of the present invention relates to a computer-implemented general digital broadcast method adapted to transmit digital broadcast data in one channel and data on demand in another channel in a digital broadcast system. The method includes providing a first channel server adapted for transmission of digital broadcast data over a first channel. And including providing a second channel server, the second channel server is suitable for transmission of data on demand through a second channel. Before data broadcasting, the method also tells about preparing a first channel server for the transmission of data-on-demand information; transmitting an electronic program guide (an electronic program guide includes information indicating that "the first channel contains digital broadcast data". Electronic program guide also includes information indicating "the second channel contains digital data on demand"); and combining and transmitting the data from the first channel and the second channel.

Description of drawings

Prior Art Fig. 1 graphically illustrates the grouping process of grouping compressed video data into a packet stream and a transport packet stream.

Prior Art Fig. 2 is a block diagram of a system conforming to the MPEG-2 standard.

Prior Art Figure 3 is a simplified functional block diagram of a VOD system.

Fig. 4 is a block diagram of a digital broadcast server according to the first embodiment of the present invention.

Fig. 5 is a structural diagram of a VOD server according to another embodiment of the present invention.

Fig. 6 is a block diagram of a general digital data server according to another embodiment of the present invention.

Fig. 7 is a block diagram of a channel server adapted to transmit VOD data according to the first embodiment of the present invention.

FIG. 8 is a structural diagram of a general-purpose STB hardware architecture according to yet another embodiment of the present invention.

Detailed ways

Embodiments will be described in detail below with reference to the accompanying drawings, which are an integral part of each embodiment. The drawings illustrate by way of example embodiments in which the invention may be practiced. These examples are described in detail to enable those skilled in the art to practice the invention. It is to be realized that other embodiments may be utilized, and structural, logical, and electrical changes and other modifications may be made without departing from the spirit and scope of the present invention.

The present invention teaches methods and systems for providing fully digital services such as VOD, digital broadcasting, and a generic set-top box (STB) capable of handling all these kinds of digital services. Multiple hardware architectures and complementary data delivery methods identify different services through an electronic program guide enabling such delivery. The universal STB of the present invention is able to distinguish between different services based on the information received in the electronic program guide, and is designed using a good hardware architecture including a large buffer. The present invention also provides viewing options such as multicast and virtual VCR time-shifting features including pausing, recording, freezing a broadcast without choppy and poor Internet streaming broadcast quality. Additionally, these diverse services are provided over a one-way communication link.

The discussion of broadcast servers will begin with Figure 4, which illustrates a digital broadcast server suitable for providing digital broadcast programming consistent with the present invention. Turning next to FIG. 5, a VOD server according to another embodiment of the present invention will be described. In FIG. 6, a general digital server providing multi-channel digital broadcasting and VOD will be described. Next, referring to FIG. 7, a channel server suitable for VOD transmission will be described.

Turning directly to FIG. 4, a single channel portion of a digital broadcast server 400 includes a plurality of video sources 402, a plurality of digital data encoders 404, a data merging device 408, a channel server 410, an upconverter 412, and a combiner Amplifier 414. Video source 402 may provide analog video data (eg, from a camera, VCR, television program) or digital video data (eg, MPEG files, MPEG transport streams). Typically each digital data encoder 404 is an MPEG encoder/converter hardware device, although other encoding standards are available, and encoding can be implemented in software.

The MPEG program stream output of digital data encoder 404 is provided to data combining device 408 for generating a combined data stream 416 . Data combining device 408 may take any form suitable for a particular application, for example, if digital data encoder 404 output and channel server 410 input are Ethernet compatible, then data combining device 408 may be an Ethernet switch. Likewise, the data merging facility 408 can be implemented in a computer system having an appropriate interface.

The channel server 410 operates on the combined data stream 416 to generate an output 418 consisting of packets with subchunks and chunks. In a preferred embodiment, the block number will increase sequentially, and finally reaching a block number of 32 bits, 64 bits wide or larger (i.e. 2 ³² -1, 2 ⁶⁴ -1 or 2 ⁿ -1), the Return to zero. Each packet generated by the channel server 410 will include a corresponding program ID which will validate a common STB so that the nature of the received data packet can be determined later, e.g. digital broadcast data or Data On Demand.

In the preferred embodiment of the invention, each data consolidation device 408 and associated channel server 410 is built into a single device 406, but these devices could be manufactured as stand-alone devices.

Figure 5 illustrates the architecture of a VOD server 450 consistent with one embodiment of the present invention. VOD server 450 includes a plurality of channel servers 411, a plurality of upconverters 412 (each corresponding to a channel server 411), a combiner amplifier 414, a central control server 502, and a central memory 504 (as illustrated, is coupled via a data bus 506). As will be described immediately below, the central control server 502 controls the off-line operation of the channel server 411 and initiates real-time transmission once the channel server 411 is ready. Central storage 504 stores data files in digital format.

In an exemplary embodiment, the data files stored in the central storage 504 can be accessed by any authorized computer, such as the central control server 502 connected to the network, through a standard network interface (eg, Ethernet connection). The channel server 411 may provide data files retrieved from the central storage 504 according to instructions from the central control server 502 . The retrieval of digital data for VOD and the scheduling of transmission of digital data are performed "off-line" so that each channel server 411 is fully prepared for real-time data transmission. Each channel server 411 tells the central control server 502 when it is ready to provide VOD, that is, when the central control server 502 can control the channel server 411 to start VOD transmission.

In a preferred embodiment, the central control server 502 includes a graphical user interface (not shown in the figure) to enable the service provider to schedule the transmission of data through drag and drop operations. In addition, the central control server 502 confirms and controls the channel server 410 to start or stop according to the transmission matrix. In Khoi Hoang's patent application entitled "System and Method for Providing Video-on-Demand Services for Broadcasting Systems", filed May 31, 2000, application serial number 09/584,832, describes methods for providing one-way VOD Systems and methods for broadcast matrices. This patent is hereby incorporated by reference.

The central control server 502 automatically selects a channel, and calculates transmission matrices for data files transmitted in the selected channel. The central control server 502 provides offline addition, deletion, and modification of data file information (eg, duration, category, ranking, and/or brief description). In addition, the central control server 502 also controls the central storage 504 by modifying the data files and databases stored in the central storage 504 .

Each channel server 411 is assigned to a channel and coupled to an upconverter 412 . The output of each channel server 411 is a quadrature amplitude modulation (QAM) modulated intermediate frequency (IF) signal having an appropriate frequency for the corresponding upconverter 412 . The QAM modulated IF signal depends on the standard used. In the United States, the currently adopted standard is the "Data Specification Over Cable System Interface (DOCSIS)" standard, which requires an IF frequency of approximately 43.75 MHz. A recommended channel server 411 will be described in more detail below with reference to FIG. 7 .

The up-converter 412 converts the IF signal received from the channel server 104 into a radio frequency signal (RF signal). The RF signal (including frequency and bandwidth) depends on a desired channel and the standard used. For example, in the United States, under the current standard for one cable television channel 80, an RF signal has a frequency of approximately 559.25 MHz and a bandwidth of approximately 6 MHz.

The output of upconverter 412 is applied to combiner/amplifier 414 . Combiner/amplifier 414 amplifies, conditions, combines the received RF signal, and outputs the signal to a transmission medium.

Figure 6 illustrates a general broadcast server 500 in accordance with one embodiment of the present invention. Universal broadcast server 500 provides both on-demand and digital data broadcasts in a single broadcast server. The general broadcast server 500 includes a plurality of video sources 402, a plurality of digital data encoders 404, a plurality of digital broadcast devices 406, (each having a data consolidation device 408 and a channel server 410), a plurality of channel servers 411, a plurality of Upconverter 412, a combiner amplifier 414, a central control server 502, and a central memory 504 (coupled by a data bus 506) are shown in the figure.

The central control server 502 controls the data merging device 408 , the channel servers 410 and 411 . Remarkably, digital broadcasting is performed in real time by combining streaming program data, while VOD service includes off-line preparation of the channel server 411 . In this manner, the general broadcast server 500 provides all-digital services such as VOD and digital broadcasting.

Figure 7 illustrates an exemplary channel server 411 consistent with one embodiment of the present invention. Channel server 411 includes a CPU 550, a QAM modulator 552, a local memory 554, and a network interface 556. The server controller 602 controls the overall operation of the channel server 411 by instructing the CPU 550 to divide the data file into blocks (further divided into sub-blocks and packets); A transmit matrix that selects data blocks for transmission; encodes the selected data; compresses the encoded data; and transmits the compressed data to the QAM modulator 552.

QAM modulator 552 accepts data for transmission via a bus (ie, PCI, CPU local bus) or Ethernet connection. In an exemplary embodiment, QAM modulator 552 may include a downstream QAM modulator, an upstream quadrature amplitude modulation/quadrature phase shift keying (QAM/QPSK) burst demodulator (with forward error correction decoding tuner, and/or an upstream tuner). The output of the QAM modulator 552 is an IF signal that can be applied directly to the upconverter 412 .

The network interface 556 connects the channel server 411 to other channel servers 411 and the central control server 502 to execute dispatching and control instructions from the central control server 502, report status to the central control server 502 in turn, and receive information from the central storage 504. data file. Any data files received from the central storage 504 may be stored in the local memory 554 of the channel server 411 prior to processing the data files according to instructions from the central control server 502 . In an exemplary embodiment, the channel server 411 can send one or more DOD data streams, these DOD data streams depend on the bandwidth of a cable channel (for example, 66.5 or 8 MHz), QAM modulator (for example, QAM 64 or QAM 256), and a compression standard/bit rate for DOD data streams such as MPEG-1 or MPEG-2.

Multiple digital programs can be broadcast on one analog channel depending on the channel bandwidth, modulation scheme, and required program bit rate (MPEG). For example, in a 6MHz CATV channel using QAM64. The maximum throughput of the channel is 27Mb/s. If the required bit rate is 2Mb/s, 13 digital programs can be sent on one analog channel in theory. Because of protocol overhead, the actual number of programs is less.

Figure 8 illustrates a generic STB 600 consistent with one embodiment of the present invention. STB 600 includes a QAM demodulator 602, a CPU 604, a local memory 608, a decoder 612 with video and audio decoding capabilities, a graphics overlay module 614, a user interface 618, a communication link 620, A fast data bus 622 is coupled to the devices as illustrated. The CPU 602 controls the overall operation of the general-purpose STB 600 to select data in response to a client's request, decode the selected data, decompress the decoded data, reassemble the decoded data, store the decoded data in local memory 608 or buffer memory 610 , and transfer the stored data to decoder 612 . In an exemplary embodiment, local memory 608 includes non-volatile memory (eg, a hard drive), and buffer memory 610 includes volatile memory.

In a first embodiment, QAM demodulator 602 includes transmitter and receiver modules, and one or more of the following: dedicated encryption/decryption module, forward error correction decoder/encoder, tuner control processors, downstream and upstream processors, and CPU and memory interface circuits. QAM demodulator 602 receives the modulated IF signal, samples, and demodulates the signal in preparation for data recovery.

In an exemplary embodiment, when access is allowed, the decoder 612 decodes at least one data block to convert the data block into an image playable on an output screen. Decoder 612 supports commands from a subscribing client, such as play, stop, step, rewind, forward, etc. Decoder 612 provides the decoded data to output device 624 for use by the client. Output device 624 may be any suitable device, eg, a television, a computer, any suitable display monitor, a VCR, and the like.

Graphics overlay module 614 enhances the quality of displayed graphics by providing alpha blending or picture-in-picture capabilities, for example. In an exemplary embodiment, graphics overlay module 614 may be used for graphics acceleration during game play mode, for example, when a service provider provides on-demand game services using a system consistent with the present invention.

User interface 618 enables a user to operate STB 600 and can be any suitable device, for example, a remote control, a keyboard, a smart card, etc. Communication link 620 provides an additional communication connection. This can be coupled to another computer and can also be used to enable two-way communication. It is preferred to have data bus 622 be a commercially available "fast" data bus suitable for performing data communications in a real-time manner as claimed by the present invention. Suitable examples include USB, firewalls, and the like.

In an exemplary embodiment, although the data files are broadcast to all cable television subscribers, only those DOD subscribers who have a compatible STB 600 are able to decode and enjoy the data-on-demand service. In a first exemplary embodiment, permission to retrieve data files on request may be obtained through a smart card system in user interface 618 . Smart cards can be recharged at a local store or at vending machines installed by the service provider. In another exemplary embodiment, a flat fee system provides subscribers with unlimited access to all available data files.

In the preferred embodiment, the data-on-demand interactive feature allows a client to select an available data file at any time. The time difference between when the client presses a selection key and when the selected data file starts playing is called the response time. When more resources (such as bandwidth, server capacity) are allocated to provide DOD services, the response time will be shortened. In an exemplary embodiment, the response time can be determined based on resource allocation and an estimate of the desired quality of service.

The above examples illustrate some exemplary embodiments of this invention, and those skilled in the art will appreciate that other embodiments can be derived from these embodiments and that modifications and variations can be made from these embodiments. Accordingly, the invention is not limited to the specific embodiments discussed above, but is defined by the following claims.

Claims (22)

1, general purpose public address system, this general purpose public address system provides digital service by a unidirectional communications link on a plurality of channels, and each above-mentioned channel provides one of VOD or digital broadcasting, and this general purpose public address system comprises:

At the first digital broadcasting circuit of one first channel of above-mentioned general purpose public address system, the first above-mentioned channel is a digital broadcast channel, and this first digital broadcasting circuit comprises:

A plurality of first digital broadcast data sources, the data that each first digital broadcast data source provides preparation to play on the first above-mentioned channel in the digital broadcasting mode;

A plurality of digital data coding devices, each digital data coding device is coupled in data source correspondence, unique in above-mentioned a plurality of data sources, and each above-mentioned digital data coding device operationally becomes a digital program stream format to the digital coding that is received;

First data merge equipment, and these first data merge device coupled in above-mentioned a plurality of digital data coding devices, and these data merge equipment and operationally the data that receive by the digital program stream format are merged into the first digital stream data that merge;

First channel server, this first channel server is coupled in above-mentioned data and equipment, and this first channel server operationally generates the intermediate-freuqncy signal of one first modulation according to the first above-mentioned digital stream data that merge;

First up-conversion device, this up-conversion device are coupled in the first above-mentioned channel server, and this first up-conversion device operationally converts the intermediate-freuqncy signal of the first above-mentioned modulation to one first radiofrequency signal; And

A combiner amplifier, this combiner amplifier is coupled in the first above-mentioned channel circuit, this combiner amplifier operationally amplifies, regulates and makes up the radiofrequency signal that is received, and the output of this combiner amplifier is applicable to that crossing over an one-way communication media transmits above-mentioned a plurality of channels;

This general purpose public address system also comprises:

A center Control Server;

The central storage device of the data of data-on-demand supply is pressed in a storage preparation;

At the first data-on-demand circuit of a second channel of above-mentioned general purpose public address system, above-mentioned second channel is a data-on-demand channel, and this first data-on-demand circuit comprises:

The second channel server, this second channel server has a second channel server CPU, local internal memory, a modulator and a network interface, and this second channel server operationally generates one second intermediate-freuqncy signal of modulating according to the numerical data that is stored in the above-mentioned local internal memory; And

The second channel up-conversion device, this second channel up-conversion device is coupled in above-mentioned second channel server, and this second up-conversion device operationally converts the intermediate-freuqncy signal of the second above-mentioned modulation to second radiofrequency signal that offers above-mentioned combiner amplifier.

2, general purpose public address system as claimed in claim 1, wherein, at least one in above-mentioned a plurality of first digital broadcasting sources is analog video source.

3, general purpose public address system as claimed in claim 2, wherein, above-mentioned analog video source is an analog video camera.

4, general purpose public address system as claimed in claim 2, wherein, above-mentioned analog video source is an analog video boxlike video tape recorder.

5, general purpose public address system as claimed in claim 2, wherein, above-mentioned analog video source is a tv programme source.

6, general purpose public address system as claimed in claim 1, wherein, at least one in above-mentioned a plurality of first digital broadcasting sources is digital video source.

7, general purpose public address system as claimed in claim 6, wherein, above-mentioned digital video source is a mpeg data file.

8, general purpose public address system as claimed in claim 6, wherein, above-mentioned video source is a mpeg transport stream.

9, general purpose public address system as claimed in claim 1, wherein, at least one in above-mentioned a plurality of digital data coding devices is mpeg encoder.

10, general purpose public address system as claimed in claim 1 wherein, is configured to a single equipment to above-mentioned first data merging equipment and the first above-mentioned channel server.

11, general purpose public address system as claimed in claim 1, wherein, the first above-mentioned digital broadcasting circuit is a digital broadcast circuit in a plurality of digital broadcasting circuit, and as the part of above-mentioned a plurality of channels of above-mentioned general purpose public address system.

12, general purpose public address system as claimed in claim 1, wherein, above-mentioned center Control Server is operationally selected above-mentioned second channel, and for transmitting a transmission of the data file calculating matrix on the above-mentioned central storage device that is stored on the above-mentioned second channel.

13, general purpose public address system as claimed in claim 12, wherein, above-mentioned center Control Server also operationally provides the off line of the data file information on above-mentioned second channel server is added, deleted and revises.

14, general purpose public address system as claimed in claim 1, wherein, the above-mentioned file of center Control Server managed storage on above-mentioned central storage device.

15, general purpose public address system as claimed in claim 1, wherein, the VOD data are one-way transmissions.

16, general purpose public address system as claimed in claim 15 wherein, is configured to a single equipment to above-mentioned first data merging equipment and the first above-mentioned channel server.

17, general purpose public address system as claimed in claim 17, wherein, the first above-mentioned digital broadcasting circuit is in above-mentioned a plurality of digital broadcasting circuit, and is a part that is used for a plurality of channels of above-mentioned general purpose public address system.

18, general purpose public address system as claimed in claim 15, wherein, above-mentioned center Control Server is operationally selected above-mentioned second channel, and for transmitting a transmission of the data file calculating matrix on the above-mentioned central storage device that is stored on the above-mentioned second channel.

19, general purpose public address system as claimed in claim 18, wherein, above-mentioned center Control Server also operationally provides the off line of the data file information on the second above-mentioned Control Server is added, deleted and revises.

20, general purpose public address system as claimed in claim 15, wherein, the above-mentioned file of center Control Server managed storage on above-mentioned central storage device.

21, general purpose public address system, this general purpose public address system provides digital service by a unidirectional communications link on a plurality of channels, and each above-mentioned channel provides one of VOD or digital broadcasting, and this general purpose public address system comprises:

A plurality of digital broadcasting circuit, wherein each is used for a counterpart of a plurality of channels of described general purpose public address system, and each all is a digital broadcast channel, and each digital broadcasting circuit all can produce digital broadcast data on the channel of correspondence;

A center Control Server;

A central storage device, this central storage device storage prepares to press the data of data-on-demand supply;

Be used for a plurality of data-on-demand circuit of a counterpart of a plurality of channels of above-mentioned general purpose public address system, each above-mentioned data-on-demand circuit is used for generating data-on-demand on the channel of a correspondence; Each data-on-demand circuit comprises the channel server of a correspondence, this channel server has a channel server CPU, local internal memory, a modulator and a network interface, wherein above-mentioned center Control Server is operationally selected a concrete data-on-demand channel, and for one of the data file calculating of transmitting on the above-mentioned central storage device that is stored on the above-mentioned data-on-demand channel transmits matrix, and provide off line interpolation, deletion and modification to the data file information on the second above-mentioned Control Server.

22, computer implemented universal digital broadcast method, this method comprises following action:

One first channel server is provided, and this first channel server is adapted to pass through one first Channel Transmission digital broadcast data;

A second channel server is provided, and this second channel server is adapted to pass through a second channel transmission data-on-demand;

Transmit an electronic program guides, this electronic program guides comprises that the first above-mentioned channel of indication comprises the information of digital broadcast data, and this electronic program guides also indicates above-mentioned second channel to comprise data-on-demand; And

Combination and transmission are from the data of first above-mentioned channel and above-mentioned second channel;

Wherein data-on-demand broadcasting is finished with one way system.

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