Digital television broadcasting system
[technical field]
The present invention relates to a kind of digital television broadcasting system, relate in particular to a kind of digital television broadcasting system based on the MPEG-4 technology.
[background technology]
1999, for MPEG-4 technology that International Standards Organization passed through is a new milestone in digital compression field, it is compared with the MPEG-2 technology, the MPEG-4 technology has higher compression efficiency, MPEG-4 is mainly in the low code stream business at present, be used widely as fields such as video telephone, IP-based video request programs, but also do not have a company to propose the MPEG-4 technology is applied to the digital TV Broadcasting Techniques field.
Abroad, the Moving Picture Experts Group-2 that digital TV Broadcasting Techniques adopts is because external digital television broadcasting standard was formulated between 1992~nineteen ninety-five, at that time, MPEG-4 standard and technology are all immature, and therefore, the digital television broadcasting standard has just adopted the signal source coding standard of MPEG-2.Digital television broadcasting system based on the MPEG-2 video compression standard has had a large number of users in western countries now.Digital television broadcasting system comprises wired digital television broadcasting system, digital video broadcast-satellite system, ground system of digital television broadcast etc.
Current, the existing both at home and abroad cable digital TV broadcast system based on the MPEG-2 technology as shown in Figure 1, Figure 1 shows that the embodiment system block diagram of digitlization HFC (Hybrid Fiber/Coax Network, HFC network) television system with 8MHz bandwidth for transmission 6-8 cover pal television program.
The partly total 6-8 cover of signal source PAL program, it adopts MPEG-2 video encoder 1 to carry out video compression coding and handles, this MPEG-2 video encoder 1 meets the MPEG-2/DVB standard, can support multiple image resolution ratio (PAL:720 * 576, NTSC:720 * 480), support PAL and ntsc television standard.
The MPEG-2TS signal bit stream that digital satellite signal transponder 2 is received digital satellite is converted to high-speed serial signals (DVBASI interface), sends into DVB multiplexer 3 again.
DVB multiplexer 3 meets the MPEG-2/DVB standard, can insertion inscribe a control information (ECM) or utilize the scrambling of control something that gives the game away (CW) in the MPEG-2 packet, and this is finished by management system 4.
QAM modulator 5 is modulated to radiofrequency signal with digital signal.Unidirectional or the two-way cable TV network network that hfc plant 6 is made up of optical fiber and coaxial cable and optical sender, optical receiver, amplifier, branch distributor, subscriber box etc.
DVB-C digital receiver 7 is set-top box that meet the DVB-C standard, and it forms (figure does not show) by three parts.Tuner is input as the CATV signal, is output as intermediate-freuqncy signal.Qam demodulator is reduced to digital signal with the intermediate-freuqncy signal demodulation, remove simultaneously the RS coding, again the TS data flow is sent TS data flow demodulation multiplexer, obtain the MPEG-2 compressed encoding signal of a certain programs, send the MPEG-2 decoder at last, can obtain NTSC/PAL NTSC television system NTSC Voice ﹠ Video signal, the Voice ﹠ Video signal directly send television set 8 to watch.
But above-mentioned cable digital TV broadcast system based on the MPEG-2 technology is owing to adopt the MPEG-2 source coding technique, so compression efficiency is low; In addition, after nineteen ninety-five, the IP technology has obtained widely using, and a large amount of program source is that the form with MPEG-4 leaves in the computer, and therefore above-mentioned cable digital TV broadcast system based on the MPEG-2 technology can not use the program source of the form of MPEG-4 not with the IP technological incorporation.
[summary of the invention]
The object of the present invention is to provide the digital television broadcasting broadcast system of a kind of MPEG-4 of fusion technology and IP technology.
Another object of the present invention is to provide the digital television broadcast receiving system of a kind of MPEG-4 of fusion technology and IP technology.
A further object of the present invention is to provide the digital television broadcasting system of a kind of MPEG-4 of fusion technology and IP technology.
For realizing purpose of the present invention, the technical solution adopted in the present invention is: a kind of digital television broadcasting broadcast system is provided, and it comprises MPEG-4 encoder, scrambling machine, IP traffic multiplexer and modulator that output is linked in sequence.
For realizing another object of the present invention, the technical solution adopted in the present invention is: a kind of digital television broadcast receiving system is provided, and it comprises tuner, demodulator, TS data flow demodulation multiplexer, descrambling machine and MPEG-4 decoder that output is linked in sequence.
For realizing a further object of the present invention, the technical solution adopted in the present invention is: a kind of digital television broadcasting system is provided, this digital television broadcasting system is made up of with the digital television broadcasting broadcast system and the digital television broadcast receiving system that are connected by this network network, described digital television broadcasting broadcast system comprises the scrambling machine, modulator, MPEG-4 encoder and IP traffic multiplexer, the output of this MPEG-4 encoder is connected with the input of this scrambling machine, the output of this scrambling machine is connected with the input of this IP traffic multiplexer, the output of this IP traffic multiplexer is connected with the input of this modulator, the output of this modulator is connected with network, and this scrambling machine is controlled its encryption to signal by management system; Described digital television broadcast receiving system comprises tuner, descrambling machine, demodulator, TS data flow demodulation multiplexer and MPEG-4 decoder, the output of this tuner is connected with the input of this demodulator, the output of this demodulator is connected with the input of this TS data flow demodulation multiplexer, the output of this TS data flow demodulation multiplexer is connected with the input of this descrambling machine, the output of this descrambling machine is connected with the input of this MPEG-4 decoder, and the output of this MPEG-4 decoder is connected with television set.。
The invention has the beneficial effects as follows that therefore digital television broadcasting system of the present invention compares the digital television broadcasting system compression efficiency height that adopts the MPEG-2 source coding technique owing to adopt the MPEG-4 source coding technique; In addition, because digital television broadcasting system of the present invention merges MPEG-4 technology and IP technology, therefore can use the program source of form of the MPEG-4 of IP mode.
[description of drawings]
Fig. 1 is existing cable digital TV broadcast system block diagram based on the MPEG-2 technology.
Fig. 2 is the cable digital TV broadcasting broadcast system block diagram that MPEG-4 technology and IP technology are merged in the present invention.
Fig. 3 is the cable digital TV broadcast receiver system block diagram that MPEG-4 technology and IP technology are merged in the present invention.
Fig. 4 is the cable digital TV broadcast system block diagram that MPEG-4 technology and IP technology are merged in the present invention.
[embodiment]
Seeing also Fig. 2, is the cable digital TV broadcasting broadcast system that MPEG-4 technology and IP technology are merged in the present invention.This broadcast system comprises MPEG-4 encoder 9, DES scrambling machine 10, IP traffic multiplexer 12 and the QAM modulator 13 that output is linked in sequence.These devices all are integrated in the cabinet.
The partly total about 30 cover PAL programs of signal source, it carries out video compression coding by MPEG-4 encoder 9 handles, and becomes the MPEG-4 video flowing of IP mode; Then the MPEG-4 video flowing of IP mode being sent to DES scrambling machine 10 adopts the DES modes to encrypt by management system 11 controls; The MPEG-4 video flowing of the IP mode after will encrypting then is sent to IP traffic multiplexer 12 and the MPEG-4 video flowing of IP mode is broken into the TS data flow is sent to QAM modulator 13; By QAM modulator 13 digital signal being modulated to radiofrequency signal again transmits in hfc plant 14.Unidirectional or the two-way cable TV network network that hfc plant 14 is made up of optical fiber and coaxial cable and optical sender, optical receiver, amplifier, branch distributor, subscriber box etc.
Seeing also Fig. 3, is the cable digital TV broadcast receiver system that MPEG-4 technology and IP technology are merged in the present invention.This receiving system comprises tuner 15, qam demodulator 16, TS data flow demodulation multiplexer 17, DES descrambling machine 18 and the MPEG-4 decoder 19 that output is linked in sequence.These devices all are integrated in the cabinet.
Tuner 15 receives high-frequency signal from hfc plant 14, is output as intermediate-freuqncy signal; Deliver to qam demodulator 16 then the intermediate-freuqncy signal demodulation is reduced to digital signal, remove the RS coding simultaneously, again the TS data flow is sent to TS data flow demodulation multiplexer 17; The IP MPEG-4 data flow that TS data flow demodulation multiplexer 17 has broken into the TS data flow to IP MPEG-4 is demodulated to the MPEG-4 video flowing of IP mode, simultaneously, TS data flow demodulation multiplexer 17 also is responsible for the IP decryption key is separated out, and the MPEG-4 video flowing with the IP mode is sent to DES descrambling machine 18 then; The signal that DES descrambling machine 18 will have been encrypted is separated into deciphering MPEG-4 signal; MPEG-4 video after the deciphering flows to MPEG-4 decoder 19, and the signal after the decompression is ordinary audio and vision signal; Directly send television set 20 to watch the Voice ﹠ Video signal at last.In addition, DES descrambling machine 18 adopts the mode of separation between machine and card.
Seeing also Fig. 4, is the cable digital TV broadcast system that MPEG-4 technology and IP technology are merged in the present invention.This cable digital TV broadcast system is made up of with the above-mentioned cable digital TV broadcasting broadcast system and the cable digital TV broadcast receiver system that are connected by hfc plant 14 hfc plant 14.The signal source of about 30 cover PAL programs is sent to hfc plant 14 transmission through above-mentioned cable digital TV broadcasting broadcast system, be sent to above-mentioned cable digital TV broadcast receiver system via hfc plant 14 again, at last the Voice ﹠ Video signal be sent to television set 20 and watch.
The digital television broadcasting system of fusion MPEG-4 technology of the present invention and IP technology comprises wired digital television broadcasting system, three kinds of modes of wireless ground system of digital television broadcast and digital video broadcast-satellite system.If wireless ground digital television broadcast receiving system and digital video broadcast-satellite receiving system then increase antenna compared to above-mentioned cable digital TV broadcast system, receive high-frequency signal down by antenna, be sent to tuner, through double conversion, become the fundamental frequency signal of 8MHz, deliver to demodulator again.The modulator and demodulator that wireless ground system of digital television broadcast adopted is to adopt the COFDMT code encoding/decoding mode, and the modulator and demodulator that the digital video broadcast-satellite system is adopted is to adopt the QPSK code encoding/decoding mode.
The digital television broadcasting system of fusion MPEG-4 technology of the present invention and IP technology is compared with the present digital television broadcasting system based on the MPEG-2 technology, the efficient of the source encoding of broadcast television signal can be improved 6 times based on the digital television broadcasting system of MPEG-4 technology, in the cable television channels of an original 8MHz, as with existing former digital television broadcasting system based on the MPEG-2 compress technique, can transmit the TV programme of the single-definition about 6 covers, or transmit the TV programme of high definition about a cover, if and adopt the MPEG-4 compress technique, then can transmit the TV programme of the single-definition about cover more than 30 or the TV programme of the high definition about six covers, improve the utilization ratio of TV greatly frequency resource.