Analysis of the development history of video disc players (1)
Video disc players are already one of the basic entertainment devices in the home. It has experienced several generations of product changes in technology, from VCD to From SVCD to DVD, as well as EVD, HVD, etc. whose prospects are still unclear, the performance of video disc players has been greatly improved, providing consumers with better and high-quality audio and video enjoyment. At the same time, my country's national disc player companies are gradually maturing through continuous research and development and market competition. This article discusses the main developments of the video disc player product line.
VCD was born in 1994 and has experienced the evolution of VCD1.0, 1.1, and 2.0. Version upgrades have increased interactivity, but the essential content has not changed. VCD uses MEPG1 fixed bit rate compression technology, the video is in 352*288 image format, and the effect is equivalent to VHS video tape. The audio uses two-channel stereo 44.1KHz, 16bit sampling, which is equivalent to the effect of an ordinary CD player. VCD2.0 adds menu interactivity based on the original VCD1.1, but the audio and video effects have not changed.
The advantage of VCD is obviously over VCR. VCD discs are much lighter and lighter than video tapes and are easy to store. They were welcomed by consumers as soon as they were launched. However, the shortcomings of VCD are also very obvious. The audio and video quality it provides does not meet consumers' expectations. In other words, the audio and video effects of VCD are not much different from those of video tapes, and its storage capacity is very limited. In response to these problems, upgraded products of VCD were quickly produced, and at the same time, opposition between the two camps of SVCD and CVD was formed.
SVCD, also known as Super VCD, is between DVD and VCD. Its images are the same as DVD, using MPEG-2, but the resolution of DVD is 720x576 (PAL) and 720x480. rate, while SVCD only uses 480x576 (PAL) and 480x480 (NTSC). The resolution of SVCD is 350 lines. SVCD can use VBR encoding to distribute the bitstream more efficiently, and can also use MPEG layer 1 or 2 audio. It is also theoretically possible to use multi-channel and VBR audio, but in practice this has never been implemented since there is no corresponding player that can output multi-channel audio (usually only two-channel output is available). VCD/SVCD are designed based on independent players (no computer required).
The birth of CVD technology has a certain historical background. In 1997, the American company C-CUBE had a premonition that the era of VCD was coming to an end, and DVD would enter the Chinese market on a large scale. It urgently needed to find a new hot spot to extend the life of VCD. This idea coincides with that of some domestic manufacturers. Due to technical reasons, these manufacturers are unable to research and produce DVD players at this stage. Facing the increasingly pessimistic VCD market, they are also in urgent need of a new selling point. Thus, CVD was born.
CVD itself is not much different from VCD, its storage capacity is 650MB. The only difference between the two is the compression method. CVD uses MPEG2's low-level/main class (MP/LL) compression method to increase image clarity at the expense of playback time. Due to the limited storage capacity of the disc, if the same DVD compression standard is used, the playback time will be reduced to 20 minutes per film, which is unacceptable to users. Therefore, CVD can only use the low-level compression method of MPEG2. Its video resolution will be slightly higher than VCD, reaching 350 lines, which is equivalent to the level of S-VHS. Compared with DVD, there is still a big gap. In addition, because the CVD machine must use a double movement, which is somewhat different from the original VCD movement, if the VCD movement is used to make CVD, the stability of the machine will be poor, which will bring disadvantages to consumers. To damage.
CVD and SVCD are upgrades after VCD. These two products eventually withdrew from the stage of history due to factors such as the sharp price reduction of DVD, the rapid spread of standards, and the huge abundance of film sources. .
Analysis of the development history of video disc players (2)
It is precisely because of the large capacity of DVD that DVD players have professional-level audio-visual performance.
In terms of audio, DVD can reach a signal-to-noise ratio of 110DB, which is comparable to professional-grade CD players. In terms of video, the high-definition exceeds 500 lines, which can fully demonstrate the performance of existing large-screen color TVs. The compression method of DVD is the MP/ML method of MEPG2, and the video image format is 720*576, which can basically match mainstream TV sets. DVD-5 can hold 135 minutes of movies, while DVD-17 can store up to 7 hours of movies. DVD provides parental management functions, multi-angle viewing functions and multi-subtitle functions, with good compatibility. At the same time, DVDs are also developing in the direction of multi-functions. In addition to ordinary home DVDs, there are also mobile DVDs, DVD mini speakers, car DVDs, etc., which greatly expands the use of DVDs. Due to the expansion of these functions, the pie in the video disc player market has become bigger.
Especially with the development of the high-definition TV industry, the audio-visual effects provided by DVD can no longer meet the needs of consumers, and the DVD technology itself needs to be upgraded. On the other hand, the biggest problem facing DVD is that our country's disc player companies have to pay a large amount of patent fees to the 6C organization for every disc player they produce. This makes the disc player industry, which has a low profit margin, even more unprofitable. my country's disc player market has seen sales increase while profits have declined. The introduction of new products and technologies has become imminent.
Starting in 1999, with the funding from the Ministry of Commerce and the Economic and Trade Commission of China, EVD began to be developed. A new generation of high-density digital laser video disc, an upgraded product of DVD, has a resolution five times that of DVD, reaching 1920 1080i or 1280 720P. For the first time in the world, the sound effects simultaneously achieve high fidelity and surround sound. An EVD disc can currently store approximately 110 minutes of audio and video programs. It can receive digital TV programs and has a unique rewritable function. It can record programs directly and burn the broadcast programs directly into discs. It is fully compatible with computers and is the development direction of DVD players in the Internet era. The EVD system (a new generation of high-density digital laser video disc system) makes it possible for our country to begin to get rid of the long-term situation of being controlled by others. The technical level of this EVD system is superior to that of DVD, with the highest resolution up to 1920*1080, and the image quality up to 5 times clearer than DVD; the audio compression algorithm with independent intellectual property rights can generate audio with Dolby AC-3 quality; in addition There are also flexible subtitle functions and strong interactive capabilities. The system also supports common video formats such as VCD, Super VCD, and DVD. The entire technical system includes 22 invention patents and 5 sets of software. Its standard specifications have been submitted to the International Electrotechnical Commission and the International Organization for Standardization as an international standard proposal. The expert appraisal committee believes that this system has obvious technical advantages compared with super VCD and DVD, filling the gap in domestic high-definition program optical disc storage and playback, and is a pioneering achievement in the country.
Competing with the EVD standard is HDV, whose Chinese name is "High Definition Digital Movie Player". It can play a variety of common discs and can also play "online movies". Its second-generation product It has the functions of browsing the web, sending and receiving emails, playing games and word processing. HDV multimedia high-definition digital movie player can not only play all common discs such as HDV, DVD, SVCD, VCD, CD, but also play movies in AVI format and browse JPEG pictures. HDV, like EVD, also plays the high-definition card. In addition, HDV pays more attention to the various new functions of video disc players and is a new generation of smart home appliances.
The discussion on standards has been going on for 4 or 5 years, but there has been no conclusion. However, the market cannot wait, and both HDV and EVD have reached a certain level of production. In the absence of a unified domestic industry standard and chaotic competition, whether the battle between SVCD and CVD will happen again, and finally a massive counterattack by foreign DVD technology, is the issue that worries most people in the industry.