high definition

high definition

HD, English for "high definition", means "high resolution". Generally speaking, HD has four meanings: HD TV, HD device, HD format, HD movie, etc.

File naming rules

The current HD resource publishing generally follows the following naming rules: movie name (Chinese + English), source, compression or processing mode, resolution, video coding, track format - name of production group or subtitle group @ publishing website. Due to the fact that all specifications are separated by a point separator (decimal point), H.264, for example, is often abbreviated as H264 or x264, so as not to affect reading. So what can we read from these naming rules?

Blu ray and HD

Dvd blu ray is the "Blu ray" disc that we are familiar with, or BD for short. In fact, from the technical point of view, BD and HDDVD both use the blue laser with the wavelength of 405nm as the reading and writing source.

Treatment method:

Hdremux, HDRE, HDRip (BD similar) hdremux, referred to as Remux, usually refers to the BD or HDDVD video and audio content extracted in a lossless way and packaged into a specific format (usually TS) file inside the processing method. It does not go through any way of re coding, video and audio pay attention to the "original.". However, Remux movies do not have the play menu and video clips on the original disc. Moreover, the movie capacity is very large, and it takes a long time to download in the network environment. hdre is to achieve a better balance in capacity, image quality and sound quality, and re encode the high-definition video stream. It does not re encode the audio stream, so it can maintain good sound quality. HDRE processing of the film can at least achieve 720p level resolution, so it also belongs to the ranks of high-definition films. hdrip re encodes both video stream and audio stream, and further reduces the volume. The image quality is slightly inferior to 720p, which is better than that of DVD Rip, and the volume is close to that of the latter. A complete HDRip movie generally only takes up 2GB to 4GB of storage space, which is convenient for the communication between audiophiles. Of course, HDRip is usually classified as "standard definition" because the image quality is a little worse than 720p.

Common resolution: 720p

1080i, 1080p, A1080, a720 and 816P are the key indicators used to identify the resolution of high-definition movies. Among them, I and P followed by the number are the abbreviations of interlaced scan and progressive scan respectively, and the number reflects the vertical resolution of high-definition film. For example, 720p refers to 1280 * 720 progressive scanning, 1080i is 1920 * 1080 interlaced scanning, which is a naming rule that abbreviates the horizontal resolution of signal source according to the conventional method. The resolution above 720p is the entry threshold of HD signal source. 720p standard is also called HD standard, while 1080i / 1080p is called full HD standard. the resolution of some films is a720 and A1080, which adopts deformation technology to obtain higher image quality. A1080 generally includes 1440 × 1080 and 1280 × 1080 specifications. The vertical resolution reaches 1080p standard. Through the horizontal expansion during playback, the definition close to full HD is achieved. A720 generally adopts 960 × 720 specifications, and some are lower than 852 × 720 specifications. And 816P is not a standard resolution, it is in the re coding, in order to effectively use, reduce capacity, use AVS software to cut off the upper and lower black edges. For example, the 1920 * 1080 resolution film ratio is 1.78:1, the actual content is 2.35:1 wide screen, and after removing the black edge, it is 1920 × 816. You can also use the deformation technology to reduce the horizontal pixels to 1440, and finally to 1440 * 816, to the full HD 1920 * 1080 launched by BSV LCD splicing technology.

Video coding: H.264, vc-1

MPEG-2 is widely used in BD and HDDVD. There are mainly three kinds of high-definition video coding formats: H.264, vc-1 and MPEG-2. In terms of compression rate and hardware performance requirements, H.264 > vc-1 > MPEG-2, but the image quality is not absolute. On the whole, vc-1 is relatively good. H. 264 is jointly developed by ITU-T (International Telecommunication Union) and ISO / iecmpeg, also known as AVC. There is another format called x264, which is actually a variant of H.264. It provides a free and open source encoder, commonly used in HDRE and HDRip formats. In short, H.264 is a standard, and x264 is a specific product that implements this standard. Vc-1 is a coding format dominated by Microsoft, which achieves a good balance between hardware performance requirements and video volume, while MPEG-2 is widely used in early HD field due to its mature technical foundation.

Track formats: DD5.1, DDplus, dolbytruehd, DTS, dtshd, lpcm

dd5.1: the traditional Dolby Digital 5.1 (Dolby Digital 5.1, AC-3), which can provide an entry-level three-dimensional one-line multi-channel experience. DD5.1 has a high compression rate and a low coding rate (up to 640kbps), which is hard to avoid in the high-definition audio applications. The two advantages of DD5.1 track are small footprint and easy network transmission. dts: DTS is the abbreviation of "digital theresystem", which belongs to lossy compression technology. Compared with DD5.1, the coding rate of DTS is more than 1.5mbps, which can achieve better audio playback effect. ddplus: Dolby Digital plus, which can also be written as "DD +", is a common audio technology in HD applications. It has 7.1 or more channels and has a wide range of coding rates, up to 6Mbps. DDplus can achieve both sound quality and capacity, which has been widely recognized by the HD industry and is suitable for broadcast level HD applications. dolby truehd: it adopts 100% lossless compression coding mode, supports up to 18mbps coding rate and eight 24bit / 96KHz full band channels. Due to the high coding rate, the storage space occupied by Dolby truehd audio track and the requirement of transmission bandwidth are also quite amazing, so it is difficult to be applied to the broadcasting system. dts-hd: starting from 7.1 channels, DTS-HD technology can support up to 32 channels of surround sound playback, with sampling rate from 8kHz to 192Khz and coding rate up to 1.5mbps. Dtshd is the most powerful competitor of Dolby truehd, and has a good prospect in the high-definition video and audio market. Lpcm: lpcm is the abbreviation of linear pulse code modulation (lpcm). It is an audio technology that converts analog signal into digital signal by continuous linear sampling. Lpcm audio without any compression, it can ensure good sound quality, but also bring a large amount of data.

Encapsulation format:

Tsavimkvwmv we usually understand the above four terms as the extensions of HD video files, but more accurately, these should be the four most common packaging formats of HD video. Theoretically, there is no necessary relationship between encapsulation format and video coding format or audio format. TS format has become the most widely used packaging format on the Internet, and it is often seen in "Remux" film source. Moreover, some high-end audio technologies, such as DTS-HD, can only be packaged in TS format. As for avi, we are most familiar with a packaging format, but it belongs to a relatively backward specification, and has poor compatibility with emerging video coding. Mkv and WMV are also rich in film sources, but generally speaking, they are not as good as TS format.

High definition television

HDTV, also known as "HDTV", is the standard format of HDTV determined by the American Association of motion picture and television engineers. Generally speaking, HDTV is the most popular term for HDTV. The definition of TV is measured by the number of horizontal scanning lines. the following are several common TV scanning formats: D1 is 480i format, with the same definition as NTSC analog TV, 525 vertical scanning lines, 480 visible vertical scanning lines, 4:3 or 16:9, interlaced / 60Hz, line frequency of 15.25khz. d2 is 480p format, same as progressive scan DVD, 525 vertical scan lines, 480 visible vertical scan lines, 4:3 or 16:9, resolution 640 × 480, progressive / 60Hz, line frequency 31.5khz. D