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Digital monitoring technology industry is the main support codecs, network data
distribution, storage, pattern recognition, the mutual impact of technology to
each other constraints. Targeted against non-real-time, real-time targets, codec
technology is divided into two categories - non-real-time target for the
compression algorithms and real-time target for the compression algorithm. Two
types of algorithms are sent to protect it, the image quality scalable goals,
the core of each type of algorithm algorithm similar, only in the algorithm
complexity and compression efficiency of the balance between different, with the
development of IC manufacturing technology, Tend to use more sophisticated
algorithms, in exchange for higher compression efficiency, more flexibility in
dealing with countermeasures.
The pursuit of real-time image,
high-resolution, high-definition, available network bandwidth of 4 M / Road,
MPEG-2 compression format is a suitable candidate. Lower available network
bandwidth, low-resolution real-time images, you can choose H.263/H.264
compression format, H.263 compression algorithm mature, lower-cost, low
compression efficiency, a high degree of standardization, and H.264 Compression
algorithm continuously raise the level of standardization in the next period of
time this compression algorithm will become mainstream compression standard; As
for MPEG-7, MPEG-21 is the future will be more efficient compression algorithm.
Traditional Ethernet structure can not provide guaranteed quality
of service (QoS), difficult to adapt to the flow of video data. When the network
load heavier, the video data transmission network delay, transmission error
control has been unable to avoid the difficulties. In the image quality is the
premise, the server vendors use sophisticated compression algorithm to minimize
video data, reduce network load, to ensure that the network transmission latency
in the acceptable limits. Can provide the new service quality guarantee the
launch of the network protocol, will reduce network transmission latency,
transmission error control difficult, a corresponding reduction in the pressure
of increased compression efficiency, control the overall system cost. Placing
new data algorithm, retrieval algorithms, will effectively promote the video
data storage technology.
In fact, all kinds of different
compression algorithm the goal, not a reality in the compression algorithm can
unify the world, does not exist the so-called best suited to server compression
format. In a system of different channels, and even the same channel will have a
variety of compression format of the mixed operation, to take full advantage of
the characteristics of various compression formats to meet the requirements of
different scenes.
China's future digital surveillance products in
the technology will develop in the direction of the two: the first is the
direction of high-definition. With storage capacity growing, prices are lower,
and as NAS storage systems and applications mature, the image quality monitoring
requirements will become the preferred item, MPEG-4 + D1, H.264 + D1 or other
high-definition image compression standard The technology will become the
direction of the development of high-definition products will also become a
digital monitoring of key products. The second direction is the trend of network
monitoring, the network has become a daily life of an important component part
of, 100 M and 1000 M Ethernet, fiber-optic network can be seen everywhere,
people increasingly rely on the network. Based on MPEG-4, H.264 or update the
image compression standard will enable the digital surveillance network into a
new era.
Video Server After years of development, the compression
standard from the original M-JPEG and MPEG-1 to the present development of
MPEG-1, MPEG-2, MPEG-4, H.263, H.264 compression standards such as the
coexistence of Situation. For a long time in the actual development of the video
server as an open system, and there is no restriction on the use of which must
be a compression technology. At the same time that the video compression
standards of unrestricted, but also to promote the DVR system will continue to
assimilate the new compression technologies and research results from the
improved image compression quality, improve network performance, and other
aspects of continuous improvement to meet the needs of different users.
In fact, video server technology as digital audio and video of a
very simple application, and there is no restriction on the use of which must be
the necessary compression technology. First, as mentioned earlier, video server
is an open system, which can also be forthcoming from the video server in the
only national standard requirements of a unified testing methods and objective
evaluation of the standards on this point been confirmed. Second, the hardware
technology in the development of an objective to promote the system compress the
DVR and technological progress, from the initial use of MPEG-1 ASIC chips to
MPEG-4 compression and software, the combination of the past three years and
almost unified compression board of the world DSP-based hardware MPEG-4
compression board, the development of hardware technology almost played a
decisive role.
Judging from the current trends in the development of
servers, network applications will be the future monitoring system irreversible
direction for the development of this knowledge should be recognized by the
industry. Therefore, the video server in fact be charged with two tasks: the
local video and network monitoring. Taking into account the Chinese market on
the unique requirements of real-time, what kind of compression format was more
suitable for the future for both the network of real-time monitoring system .
This seems to be a more pressing issue. To answer this question, must return to
the practical application of.
Several mentioned earlier compression
standard represents a milestone in the development of compression technology,
but they all have in common is the foundation block transform technology, along
with the motion compensation technology is evolving, from the initial whole
pixels to the subsequent 1 / 2,1 / 4 pixels; Single-frame from the reference and then
to multi-frame reference. They support the Simple Profile I frame and P-frame,
and in the Advanced Profile support in the B-frame. We must recognize the
commitment to the server by the compression of the two tasks have
demand, the local video require a higher compression ratio and the need for
better network monitoring of real-time, the introduction of B-frame can raise
the compression ratio, and will be in Codec-bring the inherent delay.
Therefore, we can only say that the real-time monitoring server to
resolve the issue should not start from the standard, but should be considered
in resolving local video and network monitoring start of the conflict. Now, DSP
chip technology allows us to the development of the DSP with a complete
multi-channel CIF image of MPEG-4 compression, if we are to the local video
stream and network monitoring stream from the case, this conflict will be
solved. In addition, after the use of hardware compression technology, PC's CPU
resources are completely emancipated, in the performance of the CPU soaring
circumstances, do not take advantage of it is a waste. Our basic compression
board in the off-the CPU time under the support of real-time image capture, DVR
system software developers can fully capture the image of the real-time use of
sophisticated compression Codec compression, to meet the special needs of the
network transmission .
In short, opening up the video server can
continue to absorb new compression technology, but compression technology
standard is fixed, it is necessary to constantly meet the needs of users, the
most needed is a flexible use of technology.
"MPEG + D1 is monitoring
the development of business direction"
The application of different
markets with different requirements for quality, it is needless to the
challenge; depending on the requirements to apply a different definition
compression format, which is security video the best option. As we all know,
after the disk will be the only DVR use of controllable costs in space, then how
rational use of the limited disk space, optimize the hard drive to maximize the
use of products that customers buy, considered the highest priority of the key
factors One.
The first is to monitor the safety of existing,
followed by the application of management. Monitoring network applications is
the future direction of development, I also agree with this view, but the
current market, there are many manufacturers as a means of speculation in
Internet technology and image compression technology can not clear the image on
the transmission network in the state , We have too much speculation with a
certain concept to product, is in the show.
On the Chinese
mainland market for real-time images of the unique requirements, I think the
current compression technology, transmission technology discuss product
development, to achieve a clear video images at the same time protect the
real-time transmission, we must adopt a variety of compressed format on one, a
variety of plans As the format on one of the video screen and separate
monitoring network to do, to get our product in real-time video to clear, under
the premise of the protection network monitoring smooth and real-time.
In other words, the mere pursuit of networks, network resources and
the current image compression technology, often overlook the video and monitor
the fundamental, that is clear and collected high-quality images in order to
collect evidence; simple pursuit of clear, the evidence-gathering and security
Search the real, but the image is a transmission problem. The contradictions
between the two in technology applications are not completely resolve the
circumstances, we should be down-to-earth Security and pragmatic work, do not
forget the root of video surveillance.
Any image size and
compression format has its advantages and disadvantages. The purpose of the
video is evidence. Therefore, clear whether the video evidence, the key is to
choose the server. Currently the market is more use of the CIF screen video
format, in the general security projects, with CIF format performance image
quality is also fair, but in some sectors of the special requirements of the
situation, such as financial business, such as monitoring Certain places of
business-oriented video surveillance, these establishments frequent cash
transactions, and often disputes, the image quality is very high demand, CIF
picture on the fall far short of this requirement.
Obviously, MPEG
+ D1 format represents a new generation of screen images required standard, D1
(704 +576)-definition video as a new concept, the screen than CIF (352 +288)
increased four times, completely solve the business Site monitoring the video
image is not clear, ambiguous evidence this problem.
To say whether
this will become the future direction of development will depend mainly on the
people's understanding of the concept of security, the growing development of
science and technology, the existing security products will be used in people's
lives are increasingly common, and some of its focus on video evidence Some put
it as a management tool. However, the current application server market in
recent years, MPEG + D1 absolute control of business is the development
direction.
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