10 basic common sense of home theater white introduction

1 What is a DVD?

DVD is a kind of optical disc storage technology. When it comes to DVD, it refers to Digital Video Disk (digital video disc), which is the DVD in our disc friends. Nowadays, DVD has long been used for this single purpose. The meaning of the DVD has also been extended to the Digital Versatile Disk (digital versatile disk), and now the popular DVD Audio and other products have shown the versatility of the DVD.


2 What is D5 D9

In fact, in addition to the familiar D5 and D9, the DVD family also has D10, and D18 and other categories that are not known to everyone. According to the physical characteristics, the scientific name of D5 disc is "single-sided single layer", D10 is "double-sided single layer", D9 is "single-sided double-layer" and D18 is "double-sided double-layer". Each layer can hold a certain amount of data, that is, the "single-sided single-layer" DVD has the smallest space, while the "double-sided double-layer" DVD has the largest space. The larger space can accommodate a larger amount of data, so the D9 can hold almost twice as much data as the D5, which is why the D9 disc usually has better sound quality and tidbits. (See DECSS for details)

Attachment: Capacity table (before the actual achievable capacity, nominal capacity in parentheses)

DVD-5 (12 cm, single-sided / single-layer) 4.37 GB (4.70 BB)

DVD-9 (12 cm, single/double) 7.95 GB (8.54 BB)

DVD-10 (12 cm, double sided/single layer) 8.74 GB (9.40 BB)

DVD-14 (12 cm, double-sided / mixed layer) 12.32 GB (13.24 BB)

DVD-18 (12 cm, double-sided / double-layer) 15.90 GB (17.08 BB)

3 What is NTSC PAL

NTSC and PAL are basically two different video formats. The main difference is that NTSC is 60 fields per second and PAL is 50 fields per second. Since the current TV adopts interlaced mode, NTSC can get 30 complete per second. Video frames, while PAL can get 25 full video frames per second.

What is the difference between the nuances of one frame per second in the performance of DVDs? As we all know, the speed of motion picture film is 24 frames per second, while the DVD made by PAL is one frame more than the film per second. In the same movie, PAL's screening speed will be increased by 1/24 than film; then NTSC can get 30 video frames per second. Is it faster than PAL? Actually, NTSC takes 3-2PULLDOWN technology to turn the movie. 30 frames per second. Movies of the same length, NTSC and PAL showtime conversion is: NTSC time X 24/25 = PAL time.

If you look at it this way, PAL seems to be a lot worse than NTSC, but there is still a key factor in it: PAL is 625 lines, and NTSC is 525 lines, that is: PAL lines are higher than NTSC This is why some disc friends recommend PAL: the number of lines is high, and the resolution is not high.


4 What is DeCSS

Some of the terms explained above come from industry-specified standards, while DeCSS is completely different. To say DeCSS, we must first talk about CSS.

The CSS (Content Scramble System) content scrambling system is designed to prevent digital copying. It was originally developed by Panasonic and Toshiba. The main purpose is to protect DVD discs from being illegally copied. However, in 1999, this complex encryption system was used by a Only the 16-year-old genius Norwegian teenager was cracked with a small software of tens of D, and the software was called DeCSS.

But in fact, the DeCSS that the disc friends are hanging on now has little to do with the software of the Norwegian teenager. The DeCSS that disc friends say is usually a concept opposite to lossy compression, which means that the disc is completely The original content is retained without any compression or deletion.

5 DVD tracks and subtitles

In a DVD movie, you can have 8 different audio tracks and 32 different subtitles for the viewer to switch at any time.

6 What is DTS AC3

DTS AC3 is a popular surround sound system, both of which use different encoding methods. Both use 6 channels (or 5.1 channels) such as left, center, right, left surround, right surround and sub-low frequency. The difference is that AC3 uses a digital compression ratio of 15:1, while DTS At only 6:1, the lower the compression ratio, the more space is needed, but the better the sound quality, which is why many disc friends prefer DTS tracks.


7 What is SB?

The so-called SB is actually the abbreviation of Super Bit. It is easy to see that the Super Bit represents the ultra-high bit rate. In fact, SB is a practice in which SONY has optimized the DVD9, the carrier of their audio and video products, to remove all unnecessary tidbits and ensure the quality of the film.

8 What is THX

THX is the acronym for Tomlinson Holman Experiment. It is not a sound standard like DTS or Dolby Digital sound. It is a certification, developed by Lucasfilm, designed for home theater quality assurance, and provides complete quality specifications for home audio-visual equipment (home theater). The THX standard is different from the international standard. Most standards have a tolerance range, but THX does not have a tolerance. There is only one minimum requirement, which must be exceeded to pass the test, eliminating the artificial trickiness.

The word THX was produced by George Lucas' first science fiction film "Five Hundred Years Later (THX 1138)". As early as 1982, Lucasfilm established the THX studio, specializing in film recording projects. Actively assisted the cinema to improve the sound system; in 1986 Lucasfilm was fully engaged in the coordination of audio manufacturers, and invested in the research of the quality specifications of home theater equipment. In 1990, it proposed THX certification services (including home theater equipment, films, recording studios, computers, games, etc.). ).


Lucasfilm mainly hopes that the future home theaters will have a common set of standards, so that the recording project has the same standard and feasible; for the rigorous testing of the THX certification standard, the product is granted by the THX department of Lucasfilm, and This product is labeled "THX Certification Mark" as a reference for consumers to purchase.

Lucas originally had this plan because he noticed that the sound from the cinema's audio equipment was not good, and that the sound was not the same when playing movies in every movie theater. Lucas feels that every movie-loving audience should have the right to demand good sound. No matter which cinema, the sound effects of the movie should be as good as real. Therefore, THX certification has also followed. There are many cinemas in the world that have passed this certification. Unfortunately, no cinema in mainland China or Hong Kong has passed THX certification. Currently, only one Warner cinema in Taiwan has passed THX certification. of.

Since THX is a company, it is natural to cover the cost. For all THX-certified products, LucasFilm pays a certain fee each year. For example, the THX certification procedure in cinemas is strict: the cinemas that require certification apply to Lucas, and the company sends personnel to inspect the standards and propose changes. After everything is done, the company will come out to test it in the field. The cinema is eligible to hang the THX logo for one year after the standard is reached. After half a year, the company will confirm it again. If it still meets the requirements, it will continue to be listed in the second half of the year. In the second year, if you want to list, you have to re-certify. These are all to pay the company.

The popularity of the DVD has given Lucas a big THX-certified world. In fact, the company's THX division has completed the THX standard for DVD discs and DVD players, and released a THX DVD test disc. In 1997, the first THX-certified disc "Twister" was launched. In 1998, the first THX-certified DVD player Pioneer Elite DV-09 was officially launched. THX started to get involved in DVD certification.

The standard for home THX DVD players consists of three parts: video quality, audio quality and reliability.

The so-called weight of the control function refers to the order of consideration of the various control functions of the DVD player. Some operating functions are often used, they must be set to be eye-catching, the operation is straightforward, and some are rarely used, and it is difficult to use, so it should be placed in a hidden place to avoid misuse.

The family of THX audio standards in DVD players rigorously examines basic audio standards such as distortion, noise, frequency response and D/A conversion performance, as well as an important set of standards for home theater environments. In addition, some special standards for audio DVDs have been added, including output level, output impedance, damping, spurious components and phase response. The most important thing is of course the video quality standard for DVD player restoration. In order to test these standards, high-quality test discs are required. For this reason, Lucas has released a DVD test disc.

If there is THX certification, there will be some THX test items in the DVD movie, including the video system and audio system. This is also a way to determine if it is a THX certification. Provide a URL to query the THX-certified DVD that has been released - THX Certified Video Enquiry

9 What is a variable width screen?

If you want to explain the variable width screen in the simplest way, I would say: Variable width screen is a technology that can output the most suitable image ratio according to your device. In practice, when you watch a DVD with a 4:3 display device, the upper and lower parts of the 16:9 image are automatically decorated with black borders to maintain the best display, and when you use a 16:9 display device The image is automatically displayed again at a 16:9 aspect ratio.

10 What is a B-film?

The so-called B-level film refers to a special film with low production cost, subject matter and director's techniques to cater to the audience (for which it is often not to avoid bloody, pornographic, and violent plots). This type of film is usually played at midnight because its stimulating images and themes make it easy for the audience to fall asleep even when they are extremely sleepy. After the next file, they are usually spread in the form of videotapes. For many years, B-rated films have always had a group of loyal followers. But in the Chinese world, the concept of B-level films is not universal, and Chinese people are also relatively unfamiliar with this kind of film.

In the era of American blockbusters, it refers to the low-cost movies produced by second-rate movies. The movies usually have no big stars, but the types are like everyone, such as thriller films and horror movies.

This is a standard explanation, but now the interpretation of the B-level film is broader. Most of Stephen King’s films are B-rated. The Hong Kong-made films basically belong to the B-level film, even the first episode of Mummy. All belong to the B-level film, click to view more "Home Theater Introduction Knowledge", WeChat: cnhifi.

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