High definition, in English, is "High Definition", which means "high resolution", as opposed to standard definition. Generally speaking, high-definition has four meanings: high-definition TV, high-definition equipment, high-definition format, and high-definition movies. HDTV is the abbreviation of Hign Definition Television, which means "high-definition television" when translated into Chinese. HDTV technology is derived from DTV (Digital Television) "digital television" technology. Both HDTV technology and DTV technology use digital signals, and HDTV The technology belongs to the highest standard of DTV, with the best video and audio effects. HDTV is different from the current traditional TV system that uses analog signal transmission. HDTV uses digital signal transmission. Since HDTV is digitized from the collection and production of TV programs to the transmission of TV programs and the reception to user terminals, HDTV brings us extremely high definition, with a resolution of up to 1920×1080 and a frame rate of up to 60fps is enough to put current DVDs to shame. In addition, the screen aspect ratio of HDTV has also changed from the original 4:3 to 16:9. If you use a large-screen display, you will have the feeling of being in a theater. At the same time, due to the use of digital technology, the signal's anti-noise capability has also been greatly enhanced. In terms of sound system, HDTV supports Dolby 5.1 channel transmission, bringing Hi-Fi level listening enjoyment. Compared with analog TV, digital TV has many advantages such as high-definition pictures, high-fidelity stereo sound, the ability to store TV signals, the ability to complete multimedia systems with computers, and full utilization of frequency resources. Many of these advantages will inevitably promote HDTV to become the first choice for home theaters. Main force.
The TV signals transmitted by HDTV can achieve higher resolutions than traditional TV signals (NTSC, SECAM, PAL) allow. In addition to the early analog signal formats in Europe and Japan, high-definition TV is transmitted through digital signals, so digital TV will also be introduced when introducing it.
HDTV is also the highest among DTV standards and has the best video and audio effects. DTV is a digital television technology and the successor to the current traditional analog television technology. The so-called digital TV means that all links from the studio to the launch, transmission, and reception processes use digital TV signals, or that all signal dissemination to the system is completed through a digital stream composed of binary digits. .
In addition, DTV technology can also be divided into LDTV (Low Definition Tele Vision) low-definition TV. Its image horizontal definition is greater than 250 lines, the resolution is 340×255, and the aspect ratio is 4:3. , mainly corresponding to the resolution level of the existing VCD; the standard definition TV (SDTV Standard Definition TeleVision) has an image horizontal resolution of 500--600 lines, with a minimum of 480 lines, and a resolution of 720×576, using 4: The aspect ratio of 3 mainly corresponds to the resolution level of existing DVDs. The video standards currently used in broadcast-level post-production are mainly SDTV and HDTV. Compared with analog TV, digital TV has many advantages such as high-definition pictures, high-fidelity stereo sound, the ability to store TV signals, the ability to complete multimedia systems with computers, and full utilization of frequency resources.
HDTV stipulates that the video must have at least 720 lines of non-interlaced (720p, often called progressive) or 1080 lines of interlaced interlaced (1080i, often called interlaced) scanning (DVD standard is 480 lines), the screen aspect ratio is 16:9. The audio output is 5.1 channel (Dolby Digital format) and is compatible with receiving other lower format signals for digital processing and playback.
HDTV has three display formats, namely: 720P (1280×720, non-interlaced, field frequency is 24, 30 or 60), 1080i (1920×1080, interlaced, field frequency 60) , 1080P (1920×1080, non-interlaced, field frequency is 24 or 30), but this is fundamentally just an algorithm inherited from analog video, mainly to correspond to the original TV video definition standard. For real HDTV, there are only two criteria that determine clarity: resolution and encoding algorithm.
Among them, 720P and 1080 i are the most common ones circulated on the Internet, and there are relatively many 1080P samples on the Microsoft WMV-HD site. There are two main high-definition standards in the United States, namely 1280×720p/60 and 1920×1080i/60; Europe tends to 1920×1080i/50; among them, 720p is the highest format and requires line frequency support of 45kHz, while 1080i The line frequency support for /60Hz only requires 33.75kHz, and the line frequency requirement for 1080i/50Hz is even lower, only 28.125kHz.
Among the three formats of high-definition signals, 1080i/50Hz and 1080i/60Hz have exceeded 1,000 scanning lines, but they all use interlaced scanning mode, and 1080 lines pass through twice. Completed by scanning, the actual number of scan lines in each field is only half, that is, 1080/2=540 lines. Since a complete picture requires two scans to display, there are still slight flickering and crawling phenomena when displaying fine pictures, especially still pictures, due to the limitations of this interlaced scanning technology principle. But 720p/60Hz is different. It uses progressive scanning mode. A complete picture is displayed at one time. The number of single scanning lines can reach 720 lines, and the horizontal scanning can reach 1280 points. At the same time, because the field frequency is 60Hz, the picture is stable and clear. No flickering.
The HDTV resolutions we often see are 1280×720 and 1920×1080, which is indeed a big test for today’s monitors. If the resolution is further improved, it will be difficult to display it today. Better picture quality can be obtained on some monitors, because the bottleneck at this time is the display device. In addition, it is also certain that for screens below 32 inches, the 1920×1080 resolution has basically reached the human eye’s resolution limit for dynamic video clarity. In other words, no matter how high the resolution is, it can only be used on large-screen displays. Only then can the advantages be shown.
In addition to resolution being the key to HDTV, encoding algorithms are also a link that cannot be ignored. HDTV can basically be divided into three algorithms: MPEG2-TS, WMV-HD and H.264. Different encoding technologies naturally have differences in compression ratio and image quality. Relatively speaking, the "compression ratio" of MPEG2-TS is poor, while WMV-HD and H.264 are more advanced. It is very easy to understand that encoding technology with poor "compression ratio" also has relatively low requirements for the decoding environment, which means that the requirements for hardware equipment can be reduced. Blu-ray or Blu-ray Disc (abbreviated as BD) uses a shorter wavelength (405nm) blue laser to read and write data, hence its name. Traditional DVDs require a light head to emit a red laser (wavelength 650nm) to read or write data. Generally speaking, a laser with a shorter wavelength can record or read more information per unit area. Therefore, Blu-ray has greatly improved the storage capacity of optical discs. For optical storage products, Blu-ray provides an opportunity for leapfrog development.
So far, Blu-ray is the most advanced large-capacity optical disc format. The huge progress of BD laser technology allows you to store 25GB-50GB document files on a single disc. This is several times that of existing (single-disc) DVDs. In terms of speed, Blu-ray allows recording speeds of 1 to 2 times, or 4.5 to 9 megabits per second.
Blu-ray discs have an extremely strong layer that protects the important recording layer inside the disc. Philips' Blu-ray discs use advanced vacuum linking technology to form a uniformly thick 100µ m security layer. Philips Blu-ray Discs can withstand frequent use, fingerprints, scratches and dirt, ensuring the storage quality and data security of Blu-ray products.
Technically, the Blu-ray burner system is compatible with various optical disc products that have appeared before. The huge capacity of Blu-ray products brings possibility and convenience to high-definition movies, games and large-capacity data storage. Will promote the development of high-definition entertainment to a great extent.
At the end of 2007, Sony launched the first high-definition player equipped with Blu-ray DVD in China: BDP-S300/BM Blu-ray player opened up the commercial application of Blu-ray in China, and achieved the success of the previous PlayStation 3 The impressive results have laid the foundation for the standard battle between Blu-ray and HD-DVD. However, the price of this DVD of up to 5000 RMB has put many consumers away. The shackles of cost mean that there is still a long way to go before the popularization of BlueRay.
BDP-S300/BM Blu-ray player performance standard
7.1 surround channel
1080 signal output
24 frames per second Movie-like playback frames
x.v.Colour color gamut standard
BRAVIA Theater Sync theater synchronization function HD DVD (or: High Definition DVD) is a blue digital optical storage format Beam disc products are formulated and developed by the HD DVD Promotion Group. HD DVD is similar to its competitor Blu-ray Disc. The discs are optical digital storage media the same size as CDs (120 mm in diameter) and use blue light with a wavelength of 405 nanometers.
HD DVD is promoted by the HD DVD Promotion Association composed of Toshiba, NEC, Sanyo Electric and other companies. HP (also supports BD), Microsoft and Intel have successively joined the HD DVD camp, while the mainstream studio Universal Pictures Yip is also a member.
In terms of audio, HD DVD supports up to two-channel 24-bit/192kHz or up to eight-channel 24-bit/96kHz encoding. All HD DVD players must support linear PCM (uncompressed), Dolby Digital AC-3, Dolby Digital EX, DTS, Dolby Digital Plus and Dolby TrueHD decoding. If the HD DVD has a second audio track, the audio track can be stored in the above format, or using DTS-HD High Resolution Audio and DTS-HD Master Audio.
To enjoy the highest definition sound, HD DVD manufacturers can choose linear PCM, Dolby TrueHD or DTS-HD Master Audio encoding. However, because the bandwidth requirements of linear PCM are very high, the distortion-free Dolby TrueHD format is usually used for distortion-free sound in HD DVD discs.
In terms of images, HD DVD supports many different resolutions, from the lowest CIF to the highest SDTV, and from DVD standard storage images to 720p, 1080i, 1080p of high-definition TV. In terms of encoding, HD DVD can use DVD-supported MPEG2 or the newly supported, more efficient AVC and VC-1.
But in 2008, as Warner, which originally supported HD DVD, announced its departure from HD DVD, and several US chain stores decided to support Blu-ray products, Toshiba finally officially announced on February 19 that it would terminate HD DVD business. This also means that HDDVD has completely failed in the next-generation war with BD. High Definition Television (English: High Definition Television), often called HDTV in Mainland China and high-definition TV in Taiwan, is a new product in the TV business. The original iTU-R is called High Definition Television. The following definition is: "High-definition television shall be a transparent system such that a viewer with normal vision at a distance three times the height of the system's display screen shall obtain an image of the same quality as when viewing the original scenery or performance. the impression obtained”. Its horizontal and vertical clarity is about twice that of a regular TV, and it comes with multi-channel surround sound.
High-definition television refers to the transmission of television signals that can achieve a resolution higher than that allowed by traditional television signals. In addition to the early analog signal formats in Europe and Japan, high-definition TV is transmitted through digital signals, so digital TV will also be introduced when introducing it.
Historically, the term "high definition television" was used for the television standard developed in 1930 to replace an earlier experimental system. Although Philo T. Farnsworth, John Logie Baird, and Vladimir Zworkin each developed different TV systems after this, resolution was not the main indicator to distinguish their technologies. In the late 1920s and 1930s, only patent disputes and lawsuits were brought to the noisy market. Most patents have basically expired after World War II. There is no unified TV standard in the entire world, and the market is blank. PAL, EDSC and other analog signal standards have been used for more than half a century. 1. HD TV ≠ HD TV
HD TV is just one of the devices for viewing HD channels. Users who only purchase a high-definition TV are not guaranteed to receive high-definition channels, because viewing high-definition channels also requires a high-definition set-top box. Only when you use a high-definition set-top box to watch high-definition channels, the high-definition TV can come in handy. Otherwise, the high-definition TV is just a decoration in the living room.
2. HD channel ≠ SD channel
HD channel is a kind of restoration of the scene, which is a revolutionary and subversive audio-visual upgrade. The SD channel is an extension and supplement to the public channel. It has richer content and fewer advertisements. HD channels and SD channels have their own advantages. HD TVs can watch SD channels, but only watching SD channels is a waste of HD TVs. Only by using high-definition televisions to watch high-definition channels can high-definition televisions be useful.
3. True HD TV = HD TV + HD set-top box + HD channel
A true HD TV must have three components: HD TV, HD set-top box and HD channel Conditions, one of the three is indispensable. Only by using a high-definition set-top box to receive signals and using a high-definition TV to display the effect of high-definition channels can you watch real high-definition TV.
4. The difference between true high-definition and pseudo-high-definition
True high-definition refers to the faithful restoration of high-definition video and audio signals transmitted in wired networks through high-definition TVs, set-top boxes and other equipment. For example: If a user has a high-definition TV and audio equipment that supports 5.1 channels at home. If you purchase our high-definition products and install the set-top box equipment, you can fully present the CHC high-definition channels transmitted in the cable network. Users can not only see the 1920*1080 display screen, but also experience the 5.1-channel Sound effects.
If the user directly uses the high-definition TV set at home and the audio equipment that supports 5.1 channels to watch ordinary cable TV programs, since the program itself only has a resolution of 720*576 and a mono sound source, the user What you see is a pseudo 1920*1080 image processed by the TV itself, and the six surround speakers used to broadcast 5.1 channels can only broadcast the same sound at the same time, so there is a mismatch between such equipment and content. It's a huge waste.