Currently in the IPTV service, the choice of audio and video codec technology presents a three-pronged situation, namely MPEG4 ASP, H.264 and AVS. The selection of the three standards will have an important impact on the IPTV industry.
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Three-legged
Currently in the IPTV service, the choice of audio and video codec technology presents a three-pronged situation, namely MPEG4 ASP, H.264 and AVS. Among them, MPEG4 and H.264 are international standards, and AVS is the Chinese national standard. As an important link in the IPTV industry chain, telecom operators such as China Telecom and China Netcom have similar development ideas for audio and video codec technology, and are pushing H.264. At the same time, they have shown a wait-and-see attitude towards AVS, indicating that it may be in the future. The IPTV equipment provider will be required to support AVS.
Compared with the H.264 and AVS technical standards, MPEG4 ASP has the earliest start-up in the streaming media and IPTV application market, and has the highest degree of industrialization, so it has received the widest support of IPTV equipment providers at this stage. In addition, another important link in the domestic IPTV industry chain, the broadcasting and television sector (content carrier) also tends to MPEG4. Among the three, AVS has the lowest degree of industrialization, followed by H.264.
From the market point of view, MPEG2 product technology is the most mature, widely used in the foreign IPTV market, and has been recognized and widely used in the domestic digital broadcast TV market. Because Microsoft's VC-1 or WM9 is a foreign manufacturer's standard, no matter from the perspective of the development of the IPTV industry or the digital broadcasting and television industry, it will not be recognized by the national standardization organization, nor will it be strongly supported by domestic operators. .
Standard setting
First, we need to understand the meaning of the various standards in the domestic IPTV industry. The current standards in the IPTV industry mainly refer to national standards, industry standards and enterprise standards. The national standards are formulated and promulgated by the standardization administrative department (the National Standardization Administration Committee), and the industry standards are formulated and promulgated by the competent ministries, and the enterprise standards are formulated by the enterprises themselves. National standards and industry standards can be divided into mandatory standards and recommended standards.
There is currently no IPTV national standard in the IPTV industry. The relevant departments of the Ministry of Information Industry are currently developing IPTV industry standards, which may become IPTV national standards in the future. AVS is a recommended national audio and video codec technology standard, which will be recommended and cited in the IPTV industry standard. The IPTV standards developed by China Netcom and China Telecom are all IPTV enterprise standards. If the radio and television departments also need to develop relevant IPTV industry standards, their specifications will also have an important impact on the choice of IPTV audio and video codec technology.
To be precise, the current contention of audio and video codec technology standards in the domestic IPTV industry is mainly reflected in the selection of video coding and decoding technology in the IPTV standard, and the selection of audio codec technology has not been used in the industry. More arguments and detailed considerations. In the IPTV system, the video and audio codec technology has relative independence. For example: Currently, IPTV system equipment of different manufacturers supports different audio codecs such as MPEG1 LAYER 2 (MP2), MPEG1 LAYER 3 (MP3), MPEG2 AAC, MPEG4 AAC, etc. One or several audio formats in technology.
Foreign or local?
Audio and video codec technology is a key technology for digital audio and video. It is widely used in digital TV, IPTV, mobile TV, VCD/DVD players, and other digital media terminal equipment industries. Based on plain economic reasons, the use of foreign audio and video codec technology standards will not only pay a huge patent fee, but also the standard as the most upstream of the industry chain, directly affecting the entire industry such as chips, software, front-end equipment, storage, transmission, terminal equipment, etc. chain. As a standard for China's independent intellectual property rights, AVS can not only prevent Chinese companies from plaguing patent fees, but also play a strategic role in protecting and promoting the healthy development of domestic digital audio and video related industries. It is against this background that in February 2006, AVS was officially promulgated as the national audio and video coding standard, and after the video part, audio, mobile video, systems, digital rights management and other parts will be completed and approved. Based on technology, economy, IPTV policy, industrial protection and many other reasons, the selection of mid-range audio and video codec technology in domestic IPTV industry involves not only IPTV equipment providers, telecom operators, content providers, chip providers, but also content carriers. The Ministry of Information Industry, the domestic AVS standards organization and other links are closely related.
As the IPTV industry standard setter, the Ministry of Information Industry's standards development work aims to protect the healthy development of the entire domestic industrial chain and promote the best social benefits, and the AVS Working Group itself has received key support from the Ministry of Information Industry, so it can It is foreseen that AVS will be the basic choice for the standard audio and video codec technology of the IPTV industry. At present, AVS is in the process of standardization to industrialization, and AVS-based codec chips, encoders, set-top boxes, etc. have not yet been commercialized.
Since the AVS standard has just been promulgated and productization has not yet begun on a large scale, we can easily understand why MPEG4 is more supported by the broadcasting and TV department and IPTV equipment providers at this stage. Compared with AVS and H.264, MPEG4 codec and streaming server applications are more mature and widely used, and the content stored in MPEG4 format is more extensive. However, although MPEG4 started earlier, the great development of MPEG4 is largely due to the launch of the domestic IPTV market.
For H.264, in addition to its technological advancement, another important reason for domestic telecom operators to push H.264 is because H.264 evades the patent charge from MPEG4 to operators, that is to say H.264 The patent fee collection method has dispelled the MPEG4 charge shadow that was originally shrouded in the domestic telecom operators. So even if the current H.264 cost is higher than the cost of MPEG4, H.264 still makes domestic telecom operators rejoice and jump.
In 2002, MPEG-LA announced the patent fee for MPEG4. In addition to the fixed codec fee, the content owner and content provider were charged according to the playing time. For the domestic IPTV industry, in addition to content operators, IPTV operators also need to pay related patent fees.
This caused an uproar in the industry and directly became an external factor in promoting the pace of the H.264 market. However, it is disappointing that in the first half of 2005, H.264 patent pool owners announced the procedures for charging through two authorized agents, MPEG-LA and VIA Licensing, and announced that they will be on January 1, 2006. Official fees are charged. It is hoped that the purpose of evading MPEG4 charges for IPTV operations through H.264 has not been achieved. What is even more discouraging is that the existence of two patent agency organizations also complicates the problem, and may even cause patent users to have to face both organizations at the same time, because they each represent a part of the patent owner.
Although chip manufacturers already know that the H.264 patents are intricate and the industrialization process will take some time, they obviously did not expect that the hunger for H.264 technology upgrades by operators and terminal manufacturers in the domestic IPTV market is so rapid that they are not ready enough. . However, as the upstream of the industry chain, chip manufacturers are always among the first to intervene in the H.264 field, so even though they are not willing to replace the MPEG4 chip with sufficient profit, it will be replaced by H.264 chip. Appeared, but still accelerated the development process of the H.264 chip.
From the perspective of chip implementation, the efficiency of H.264 is based on the high complexity of its implementation. For its Baseline, the decoder complexity will be about 3 times that of the H.263 decoder. The complexity of the encoder is up to 10 times more. In addition, since video processing is a data processing-based system, combined with video processing algorithms, implementing instruction operand loading and parallel computing will greatly improve data processing efficiency.
In H.264, motion estimation uses a multi-frame reference technique, which requires the processor architecture to have new considerations for the processor's data scheduling mechanism and the organization of on-chip and external memory. H.264 can perform parallel processing based on picture, slice, and macroblock levels as well as previous standards. H.264 also uses the RD algorithm for mode selection. All modes have no correlation in calculation, that is, they can operate in parallel. To adapt the parallel processing characteristics of H.264 encoder to the implementation of high-complexity H.264 algorithm, the processing chip architecture needs to evolve from a single-core architecture with insufficient processing capability to a dual-core, multi-core architecture. An effective way to improve the performance of multimedia processing chips in the next few years. However, it is followed that the software working difficulty of the multimedia processing chip (such as compiler, operating system task scheduling, etc.) will be greatly increased, extending the implementation cycle and product maturity cycle of the H.264 chip.
Although the existing IPTV set-top box using the Ti DM642 processor can support standard-definition decoding of H.264, for the IPTV value-added services that broadband operators have been expecting, such as videophones, etc., which require set-top box encoding audio and video services, Existing multimedia processing chips are limited by performance and do not provide good support, which makes such services impossible, and brings considerable technical risks to the IPTV service. Moreover, the cost of the set-top box supporting H.264 is relatively high at present, which greatly increases the market input cost of the IPTV service and increases the market risk of the IPTV service.
In contrast, MPEG-4 ASP, since the MPEG organization first announced MPEG-4 technology in November 1998, has been a development foundation for quite some time, and a large number of mature chips have been born and put into large-scale applications. Most of these chips used in MPEG-4 have undergone a long period of technical inspection and have good compatibility and stability. In addition to the continuous improvement of technology, in terms of price, the average unit price has gradually decreased. With these chip support, broadband operators can launch similar value-added services as soon as possible.
Because of this, if H.264 cannot be applied on a large scale in the domestic IPTV market, MPEG4 chips still have the advantage of hardware and software development costs compared with H.264 chips. H.264 still needs huge cost investment. In addition, chip manufacturers still need time to stabilize and improve existing H.264 chips. It is the consideration of cost and stability that has restricted and affected the large-scale commercial use of H.264.
Market decides the way out
It is predicted that by 2008, China's broadband subscribers will increase to 100 million, and if 20% of them become IPTV users, the number of IPTV subscribers will reach 20 million; if current cable TV subscribers are 20% before 2008 As a network TV user, the number of users will reach 20 million; mobile users will be estimated to exceed 400 million by the end of 2005. If 5% of them become Internet TV users before 2008, the number of users will reach 20 million. Household. On this basis, it is estimated that the total number of IPTV users will reach 60 million by 2008.
Let us take a look at the selection of domestic traditional radio and television market codec technology that has the greatest impact on the industrialization of audio and video codecs. The CCTV digital TV channel uses the foreign MPEG-2 standard. The reason is that in order to ensure the fidelity of signal transmission, MPEG-2 has a long development time and mature technology; the second is for copyright protection, because CCTV wants to introduce many foreign digital TV programs, and the other party agrees The MPEG-2 codec standard feels that this can protect its copyright. In addition, there are currently more than 1 million cable digital TV users in the country, which also use the MPEG-2 standard. If you replace the AVS standard, there must be a cost of replacing the set-top box.
Observe the market situation of audio and video codec technology from the perspective of application. In terms of broadcast and DVD applications, MPEG2 is still in the mainstream, but in mobile TV, video conferencing, video surveillance and video telephony, H.264 and MPEG4 technologies are widely used. From the product application level, DVD is currently the largest application market for codec, and the next stage of growth momentum is expected to occur in the video application field of mobile terminals, such as watching digital TV, personal media players, etc. with handheld devices. H.264 in these areas will have a wider range of applications than MPEG4.
On the whole, H.264 is supported by telecom operators and equipment providers. Whether in the Internet or other applications, H.264 has the status of occupying the mainstream in the future market. For the IPTV industry, H.264 is a foregone conclusion in place of MPEG4, but the commercial cost of H.264 will still hinder its large-scale application in the short term. For AVS, because of its advantages of reducing patent fees for domestic companies and the support of the Chinese government, the application in China is worth looking forward to.
From a development perspective, audio and video codec technology is always in the process of continuous evolution. Therefore, what is placed in front of the IPTV equipment provider is not the question of which audio and video codec technology to choose, but whether the IPTV system and solution can be implemented in the media transport layer regardless of the codec format transparency. Sexual aspects can be quickly and seamlessly upgraded to support current and future codec technologies.
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