In the human society is about to enter information society today,
telecommunications network and computer network development greatly changed the
whole society, people's life style, and lifestyle changes and turn on the
computer network and telecommunications network service ability put forward
higher request.
Since the 1990s, with the rise of the personal computer and the Internet
popularization of Internet users, and the data represented by IP explosive
growth, and business there appear a large number of new business requirements,
such as: video conference, e-commerce, VOD VOD video etc. These new business
needs to network bandwidth to put forward new requirements. Because OA and
technological progress, and DWDM ATM technology, MPLS technology, Tbps level for
transmission, routers exchange and the upgrading of means, provides timely
bandwidth bottlenecks in the access.
Based on different with different system and transmission medium of
various schemes, such as the emergence and development based on twisted-pair
cable (xDSL, HomePNA), based on digital lines, based on wireless (WLL), based on
the coaxial cable (HFC, CableModem) and based on optical fiber (OAN) system,
broadband access to enjoy unprecedented development.
The development of broadband access, and promoted the new business needs
and development. Remote monitoring is one of them.
Second, the remote monitoring and image compression
Remote monitoring past only bank financial institutions, enterprises and
units will superiority as the business needs, based on the traditional access,
using DDN, v. 90Modem, ISDN, etc, in Banks access method of financial
institutions and operators of telecommunication room on the remote computer
centralized monitoring, etc.
But now, with broadband access, remote monitoring for the family is no
longer an unreachable, it will be with the development of the broadband access
and access the new business developed vigorously, and bring new family feeling.
As the main contents of remote monitoring and control, because of its
image data and the key solution, if consider image problem solved, other data
such as family security personnel records, such problems will be solved.
1, image compression
At present, image compression method, also is quite rapid development, the
classic Huffman coding method such as arithmetic coding, coding, forecast
coding, transform domain coding etc. Considering the characteristics of visual
perception and statistical significance of information distribution, and raises
the so-called "perception entropy theory", at the same time with mathematical
theory, such as wavelet transform and related subjects, the development of
modern coding method, analysis and synthesis method. Based on the above two
coding method, according to different purposes and various image compression of
the international standards have been introduced.
To sum up, h. 261, h.263 h.264, suggestion, JPEG standard and MPEG - 1-2,
MPEG mpeg-4 standard etc. MPEG still MPEG - 7, MPEG - 21. The MPEG - 1/2/4 is
system of standard, they not only have video coding, also have audio coding
system and the content of the agreement, including layer when synchronization,
reuse and etc. And h. 261, h.263 just a video coding standard, must with other
relevant international standards and Suggestions.
H. 261 is mainly applied to the videophone/meeting TV, h.263 line is
mainly used for simulating the videophone/TV conference, and JPEG mainly aimed
at the high resolution image transmission and low resolution image transmission.
And h. 341/3 with series of h. 262 and MPEG common as the ISO/IEC13818 draft
standards. The draft standards is mainly used in digital storage, video
broadcasting and telecommunications. Storage media can be directly connected to
the decoder, also can through the bus, a local area network (LAN) or telecom
such communications link connection.
The MPEG - 1 standard for digital storage body image and sound coding
activities, its digital rate for 1.5 Mbps. The MPEG - 1 in h. 261 basis do great
improvement, in order to satisfy the random access and high compression ratio,
the image scanning formats for SIF (SourceInputFormat) format, and to the
standard VCD CD.
Mpeg-2, called "the activity of the title of the image and related sound
information", can understand generic coding for MPEG - 1 on the basis of further
expanded and improved. At present, mpeg-2, has been acknowledged as the voice
and image, it is the basic standard digital signal widely applied. Introduces
"scalable Scalability ()" video coding concepts realize classification. RBT -
including the main class ITU. 601 / D1 format, senior level HDTV widescreen
display format etc. / narrow
In 1998, through the mpeg-4 (ISO/IEC14496) standard not mpeg-2,
substitute. It focus on different applications, the very low rate of digital
64kbps) (less than the activity, the image coding technique based on the model
of the coding method, morphological and fractal method, different from the MPEG
- 1/2, and fault tolerance. In digital control system (DVR) in a lot of
application.
As a new generation of multimedia coding h.264, the technology is MPEG4 /
h.263 continuator.
H.264 itu-t is the video coding VCEG (group) and ISO/IEC MPEG (group) the
combination image coding video group (JVT: jointvideoteam) development of a new
digital video coding standard, it is both itu-t h.264, and ISO/IEC mpeg-4 first
10 parts. In January 1998, started the draft and September 1999, completed the
first draft, May 2001 established its test mode the TML - 8,2002 in June fifth
session of JVT through the h.264 FCD plate, the formal finalized in March 2003.
H.264 standard, and the former DPCM is also add transform coding hybrid
coding mode. It adopts "the return of the basic", concise design, many options
than h.263 + + much better compression performance, To strengthen the ability to
adapt to all kinds of channel, adopting "friendly" network structure and
grammar, and packet loss of error handling, Wide application target, to meet the
different rate and different resolution and different transmission (storage)
occasions needs, It is the basic system of open, use without copyright.
Technically, the h.264 standard have multiple flash, such as the symbol of
unity, high precision and coding based on the displacement of the estimated 4 *
4 pieces of integer transform, layered coding grammar etc. These measures to
make the h.264 algorithm has very high coding efficiency, in the same image
quality, can save more than h.263 about 50% of the code rate. H.264 of streaming
network structure, strong adaptability increased error recovery capacity, is
able to adapt to the IP and wireless networks. Can say, the h.264 compression
ratio is the highest standards of video compression. In digital control system
has been applied.
2 and the realization of image compression
Although different manufacturer USES a different image compression coding
method, but from the above analysis, MPEG is aimed at the special general
activity image coding, so the image remote monitoring using MPEG with congenital
advantage. Practical system, network application environment change as large,
choose the strongest, fault of the adaptive mpeg-4 standard (MEPG - 4Part2, MPEG
- 4Part10 = h.264), can be used not only to the image compression with high
quality, and can be used in low quality of image compression. But in the network
environment is good (more than 2Mbps), usable mpeg-2, standard, in order to
achieve the purpose of high quality image transmission.
Concrete as the image compression solutions, CCD camera video signal
output analog video server to the video capture IPEncoder (card), video
sampling, A/D conversion, video signals into digital simulation signal. After
processing unit to calculation, and finally the compression MPEG compressed
video signal into the digital network interface, the network transmission to the
remote.
Third, remote monitoring based on the realization of the broadband access
1, ADSL/CableModem point-to-point realization
Based on ADSL/CableModem point-to-point way of remote monitoring system
structure. If there is a PC households families, in a video capture PC card, can
access a 4-1 road simulated camera signal. And ADSL transmission unit ATU - user
can act as video processing network interface, the engine with the ISP
twisted-pair DSLAM digital subscriber line access the multiplexing ATU - C
(room) the associated with ADSL transceiver unit. Resident family without PCS,
video capture card can be used to compress integration with MPEG video together
constitute a server. Remote users using ADSL/CM/LAN access method, Modem/as
Internet access, according to the IP address of the residents under ADSL found
within the family PC or video server, extraction of compressed image signal by
MPEG, home to old person, child, patient image observation and language
exchange. But residents must be in digital image on the Internet, so to be
limited by the rate of ADSL uplink rate (640kbps a64k -). CableModem through
work, basic same, just for CableModem, ATU - R, but for DSLAM CMTS HFC image can
speed up 1.5 Mbps, rate of maximum uplink rate than ADSL, but the existing
problem of HFC bandwidth sharing.
Because CableModem according to the service provider with ADSL, provided
the IP address is probably dynamic, but every time after startup IP address is
constant. So far end users according to this IP address can be found in the
video server within the family households, the resident family PC after startup
fixed to the distal users send told the IP address of the method to realize the
Internet. If the household PC security control software is installed inside
special through serial, receiving the host family alarm signal can upload RS232
family security system of remote monitoring and control (fortification/removal,
etc.).
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