WO2002065770A1

WO2002065770A1 - Chip for achieving the instant vod on the mon-direction cable tv network

Info

Publication number: WO2002065770A1
Application number: PCT/CN2001/001161
Authority: WO
Inventors: Zhongquan Xu; Naifeng Xu; Wei FENG; Aixi Zhu; Hong Zhu; Xianfeng Xu; Guangmeng Chen; Shiying Luo
Original assignee: Sarft Dszheng Information Scimce Science & Technology Co., Ltd.
Priority date: 2001-02-13
Filing date: 2001-07-09
Publication date: 2002-08-22
Also published as: CN1370008A; CN1159913C

Abstract

A Chip for achieving the instant VOD on the mon-direction cable TV network is characterized in comprising switch channel controller, program schedule controller, calculating processor, SDRAM and the controller of the same, data RAM (temporary memory) transmitting controller and I/O interface. The switch channel controller detects the video or other signals and sends the video signal to the program schedule controller which comparing the size of packet number, accessing the data RAM and sending the signal by the controller for archiving the result of VOD. This chip makes up the network in simple structure, easy in operating at low cost.

Description

Chip for realizing video on demand on cable unidirectional network

The present invention relates to an integrated circuit chip, and in particular, to a chip used in a current one-way network of a cable television to implement user-side program on-demand and a video on-demand on a cable television one-way network. Background technique

As an effective media means for disseminating information, cable television has been widely established in all provinces, cities, counties, townships and towns in China. Existing cable television networks are unidirectional broadcasting. Cable ¾ video bands generally use 5 IHz-634MHz (750MHz) to transmit programs. With 8MHz as a physical analog channel, the information transmitted is limited. Currently, S¾ one-way set-top boxes are widely used on cable television networks, although digital broadcasting and digital video and video broadcasting services can be realized, such as: one-way data services, digital payment. TV, digital scrambled TV, stock information, digital quasi-video on demand Wait. But only one-way transmission function, its signal flow is: RF input signal passes through the tuner, selects the channel, because the analog signal is transmitted on the network (HFC), so digital-to-analog conversion is added, and it is demodulated by QAM. Digital signal. After de-multiplexing, the video stream is converted into a program stream, and then video and audio decoding, encoding, and output are performed.

To enable users to achieve two-way interactive on-demand, a large number of network facilities and many servers and two-way interactive on-demand set-top boxes are required. This increases the cost, the equipment is complex, and the management level is increased. achieve. Summary of the Invention

The purpose of the present invention is to overcome the shortcomings of the existing two-way cable TV network on-demand complex structure and large equipment investment, and provide an on-demand on-demand by using the existing one-way cable TV network structure. The chip with the expanded coverage and unlimited capacity, easy on-demand, convenient and fast, is used in the set-top box of the client to realize the video on-demand on-demand on the cable unidirectional network.

The technical solution for achieving the purpose of the present invention is: a chip for realizing video on demand on a unidirectional network of cable television, which is characterized by including a switch channel controller, a process controller, an arithmetic processor, an SDRAM controller and SDRAM, and data RAM (temporary storage) sending controller, and input / output interface; the switch channel controller is used for identifying program video signals or other signals, and selecting The required video signal is sent to the process controller through the channel, and the signal not required by the user is sent to the motherboard through the output interface; the process controller receives the stream data packet output from the switch channel controller, and compares the received data packet The segment number is larger than the segment number of the currently playing data packet. Select a data packet that is larger than the currently playing segment number and save it, and then input the next segment data after the current segment data packet is output, so that the program data stream is continuously played; The arithmetic processor is used to send the code stream at a constant speed, and a reference clock is used to control the code stream transmission. The data RAM (temporary storage) transmission controller, wherein the data RAM is used to remove the header of the data stream, and then send the The controller sends it to the memory allocation table, and the memory allocation table quickly finds the segment number of the pre-cast data stream; the SDRM controller and the SDRAM are used to read and write control the data output by the process controller, and the SDRAM is used as the data stream Buffer, the data retrieved from the buffer is played slowly and written quickly to achieve the on-demand effect.

The above-mentioned chip for implementing video on demand on a one-way network of a cable TV, wherein the segment number refers to a number crowned by each data packet using a code stream table, and the code stream table is based on a program length. , The size of the cache capacity, and the download rate, the overview of the drawings

The specific performance and characteristics of the present invention are further given by the following examples and their drawings.

FIG. 1 is a schematic diagram of a circuit principle of the present invention.

FIG. 2 is a schematic diagram of a signal flow direction of the present invention.

FIG. 3 is a schematic flow chart of the working principle when the present invention is used in a set-top box. Best Mode of the Invention

Please refer to FIG. 1 and FIG. 2. The on-demand on-demand chip is the core component of the set-top box to realize on-demand on-demand under the condition of unidirectional network. It is set between the common receiving digital video, information broadcasting set-top box's tuner QAM decoding and browsing motherboard. The chip for realizing video on demand on a unidirectional network of cable television of the present invention includes a switch channel controller, a process controller, a computing processor, an SDRAM (buffer) controller, a buffer (SDR I), and a data RAM (temporary storage). Sending controller, and input and output interfaces. The switch channel controller is used to identify the program video signal or other signals, and send the useful video signal to the process controller. The process controller compares the size of the data packet segment number, accesses it in the data buffer module, and sends it through the sending controller. The data stream is continuously and smoothly output to achieve the on-demand effect. among them:

The switch channel controller receives the digital signal selected by the tuner channel and demodulated by QAM, and identifies whether it is a user video-on-demand signal or other information. If it is a video-on-demand signal, let the signal enter the V0D process control. Device. If not, the signal goes straight from the input port to the STB browser board (motherboard).

The code stream data packet sent by the process controller from the switch channel controller is transmitted according to a pre-programmed code stream table, and the code stream table is based on the length of the on-demand program and the size of the buffer capacity. , And download speed, waiting time and other factors. The process controller receives a data packet with a segment number i. If i is smaller than the currently played segment number (indicating that it has been output), the segment is discarded, and the next one is received. If i is greater than the currently played segment number, If it is large, it is further judged whether the segment already exists in the buffer, if it is discarded, otherwise it is judged whether there is an empty cache, if it is, the packet is stored, if not, i is compared with the maximum segment number MAX in the cache, and the smaller one is discarded and the larger one is discarded. . Access in accordance with the above rules will ensure that the "0" segment is completed (the "0" segment below refers to the beginning of the program), and the "1" segment (the next segment smoothly connected to the beginning segment) must be stored in And after the "0" segment is finished, then the "1" segment is played to make the program play continuously. The segment number refers to the number given to each data packet by using a code stream table.

In order to send the code stream at a constant speed, the arithmetic processor uses a reference clock to control the code stream transmission. First get two values PCR (i) field and PCR (i + l) field, and get M by the counter (the total number of frames between two adjacent PCR fields),

According to the formula: T = PCR (i + l) — PCR (i) (1)

TF = T / M

Use the formula P (i, n) = PCR (i) + nXTF (2)

In the above two formulas, where:

PCR: program clock reference;

i: represents the count value of the PCR field, the initial value is 0;

M: the total number between two adjacent PCR fields;

n: represents the Nth frame data between two adjacent PCR fields, the initial value is 0, and the maximum value is M-1; PCR (i): represents the i-th PCR field value read from the TS stream;

TS stream: video transport stream; T: indicates the difference in playback time between two adjacent PCR fields;

TF: indicates the length of time required to send each frame of data in PCR (i) and PCR (i + l); P (i, n): indicates the time point of sending the n-th frame of data after the PCR (i) field;

T _sys : indicates the count value from the time when the first frame of data is sent. The initial value is PCR (0). Comparison: When T _sys <P (i, n), wait for data to be sent, and start to send the n-th frame of data when the times are equal;

When 1 ^ ₃ = P (i, n), start sending the n-th frame of data;

When D ^> P (i, n), write P (i, n) into T _sys , and the data will continue while T _sys and start to send the n-th frame of data.

The role of the data RAM (temporary storage) V0D sending controller is: TS stream is the data stream of the packet header, the packet header is removed via the data RAM, and the first broadcast segment is quickly found using the memory allocation table.

The SDRAM controller and the SDRAM, according to the V0D process controller, perform read-write control on the SDRAM, and the SDRAM serves as a buffer of the data stream, and the data taken out from the buffer is slowly played and written quickly to achieve on-demand effect.

The working principle flow when the present invention is used in a set-top box is shown in Figure 3:

After booting, according to the channel selection status, it is determined whether the data to be sent is selected by the switch, flowed to the process controller, or directly sent to the STB motherboard for processing; if it is a video-on-demand signal, let its signal enter the V0D process controller. If not, the signal goes straight from the input to the STB browser board (motherboard).

When in the first-in-first-out (FIFO) state, there are two concurrent workflows, one is sending the CS segment data being played to the output port, and the other is the data segment received by the receiving port;

Receiving data flow: In the first-in-first-out (FIFO) state, the entire storage area is cleared, and the data is received from the video stream PID (packet information identifier) in the "0" segment. After the "0" segment is received, the "0" segment starts to play, other segments are received, and a data frame with a segment number CI is received. If the CI is smaller than the currently played segment number CS (meaning that it has been output), the segment will be played. Discard and receive the next one. If the CI is greater than the currently playing segment number CS, then judge whether the segment exists in the buffer, discard it, if not, otherwise judge whether there is an empty buffer, if yes, store the packet, and compare the CI and The maximum segment number CM size in the cache. Keep the smaller one and discard the larger one.

Process of sending data: Change the PID number of the video stream, that is, restore the PID to its original state. Judge CS 'segment is If it has already been sent, it will continue to play. If it is not completed, it will continue to play. If it is completed, it will continue to send CS + 1 data, and clear the buffer occupied by CS data.

It is determined whether the currently played segment number CS + 1 is greater than the maximum segment number MAX of the entire transmission, and if not, the transmission procedure is continued. Otherwise, the end of the on-demand signal will be sent after the end of playback. Industrial applicability

Since the present invention uses a process controller and a sending controller to continuously receive and update the video stream, as long as the downlink signal is continuously received, the two-way on-demand function can be completed, eliminating a series of costs and operations such as the transmission and transmission of the uplink signal. At the same time, due to the use of unidirectional video stream broadcasting, there is no need to modify the existing network structure, which saves a lot of manpower and material resources for rebuilding the network, and the number of users is unlimited. It can be expanded with the expansion of the coverage of the wired network Quick and easy on-demand.

Claims

Claim

1. A chip for implementing video-on-demand on-demand on a cable unidirectional network, which is characterized by comprising a switch channel controller, a process controller, an arithmetic processor, a buffer controller and a buffer, and a data temporary transmission controller. And the input and output interfaces; the switch channel controller is used to identify program video signals or other signals, and selects the video signals required by the user to be sent to the process controller through the channel, and the signals not required by the user are sent to the process interface through the output interface. The main board; the flow controller receives the stream data packet output from the switch channel controller, and compares the size of the received data packet segment number with the segment number of the currently played data packet, and selects a data packet that is larger than the currently played segment number. Save it, and then input the next segment of data in sequence after the output of the current segment data packet, so that the program data stream is continuously played; the arithmetic processor is used to send the code stream at a constant speed, and a reference clock is used to control the code stream transmission The data temporary storage controller, wherein the data temporary register is used to remove the header of the data stream, The sending controller sends the data to the memory allocation table, and the memory allocation table quickly finds the segment number of the pre-cast data stream. The buffer controller and the buffer are used to read and write control the data output by the process controller. The buffer As a buffer of the data stream, the data retrieved from the buffer is played slowly and written quickly to achieve the on-demand effect.

2. The chip for implementing video-on-demand on-demand on a one-way network of cable television according to claim 1, wherein the segment number refers to a number crowned by each data packet by using a code stream table, and The code stream table is compiled according to the length of the program, the size of the buffer capacity, and the download rate.