High definition television
High Definition Television [ haɪ ˌdɛfɪˈnɪʃən ˈtɛlɪvɪʒən ] ( HDTV , English for high-definition television ) is a collective term that describes a series of television standards that are distinguished from Standard Definition Television (SDTV) by an increased vertical, horizontal or temporal resolution .
At different times, due to the current state of the art, resolutions other than high resolution were understood. Vertical resolutions of 720 pixels and 1080 pixels are currently used, which are differentiated by additional terms such as 720p , 1080p and 1080i . With Full HD , the ability of an HDTV-capable device (is TV , DVD player , video camera , set-top box , game console , smart phone ) called, spend a HD resolution of 1920 × 1080 pixels or to record. The older television standards of theCCIR (West) or OIRT (East) with the color modulation systems PAL and SECAM offer 576 lines for comparison; the North American NTSC 480 lines.
“HDTV” should not be confused with the 16: 9 aspect ratio in digital television ( DTV , in Europe in the DVB standard) or digital terrestrial television ( DTTV , in Europe DVB-T ), as was the case with the joint introduction in some countries happened.
|Full-size fish versus HDTV and SDTV resolutions|
|For comparison, the resolution of the fish to total image resolution of the same image section in each case is 16: 9 - aspect ratio in NTSC (480p), PALplus , and HDTV720 HDTV1080 shown.|
|One square corresponds to one pixel . HDTV with four times the number of pixels compared to SDTV.|
|One square corresponds to one pixel, SDTV resolution.|
|Both fish were converted up to the same size so that the number of pixels per unit area can be compared. The original dimensions of the fish correspond to the fish in the picture above with the TV resolutions. The sharpness effect depends much more on contrast ratios than on resolution.|
Since the HDTV standard is a summary of picture resolutions and frame rates, there is a basic nomenclature to differentiate between them. This is made up as follows:
|Number of lines||+||Image composition process||+||Refresh rate|
- Number of lines:
- For the number of lines, the vertical image resolution is specified in pixels (picture elements).
- Image composition method:
- The abbreviation “p” or “i” is used for the process of image construction. The abbreviation "p" stands for progressive and means the progressive frame , "i" stands for interlaced and says the interlaced or interlaced scanning .
- Refresh rate:
- There are two different conventions for specifying the frame rate in frames per second ( BpS or fps for "frames per second"):
1. 1080 i 60 = 1080 i / 30th = 1920 × 1080 pixels in the interlaced process and 60 fields per second 2. 1080 p 30th = 1080 p / 30th = 1920 × 1080 pixels in the full image process and 30 full images per second 3. 1080 p 24 = 1080 p / 24 = 1920 × 1080 pixels in the full image process and 24 full images per second 4th 720 p 50 = p / 50 = 1280 ×720 pixels in the full image process and 50 full images per second 5. 1152 i 50 = 1152 i / 25th = 2048 × 1152 pixels in the interlaced process and 50 fields per second (old HD-MAC standard)
In case of doubt, however, it is sufficient to know that the field frequency is between 50 and 60 Hz and the frame frequency between 25 and 30 Hz in the interlacing process.
With this regulation, there are two more properties of HDTV that have to be considered, which lead to different nomenclatures. On the one hand, it can happen that films available in full frames, primarily cinema productions, are transmitted in an interlaced manner, but the full-frame character can be reconstructed unchanged from these two fields. The paper would say 1080i50 or 1080i / 25 , for example , but it can also be displayed as 1080psf25 . The abbreviation for the image construction process is the Progressive Segmented Frame (PsF), which is written instead of the interlace abbreviation and only describes the type of transmission in more detail. As a result, however, the refresh rate must be halved. And secondly, the abbreviation 24p can also be found in digital cinema productions with HD cameras . This can mean 1080p24 , but digital cinema can also be a higher resolution ( e.g. 4K @ 24p).
HDTV is specified with 1080 active lines in interlaced mode or 720 lines in full screen mode with an aspect ratio of 16: 9 in the ITU-R BT.709. The term “high-definition” can refer to the specification of the resolution as well as to media with a sharpness similar to that of feature films.
The two usual HDTV image resolutions are 1280 × 720 pixels and 1920 × 1080 pixels in full format. The aspect ratio of the picture is 16: 9. The difference in resolution of 1280 × 720 compared to PAL (according to CCIR 601 ) is mathematically 2.2 times ((1280 × 720p) / (720 × 576i)) and 1920 × 1080 compared to PAL even 5 times ((1920 × 1080i) / ( 720 × 576i)), but optically it is only 1.25 times (720/576) or only 1.9 times (1080/576) vertically. A similar ratio is also calculated horizontally. Since the MPEG-2 compression used initially divides the image into blocks of 16 × 16 pixels, 1088 lines are actually transmitted at 1920 × 1080.
When comparing the resolutions of progressive formats with interlaced images, it should be noted that with the progressive format twice as much information is sent per unit of time as with the interlace process. Progressive and interlaced formats can only be compared to a limited extent, especially when there is a lot of movement in the picture. In the case of public TV broadcasters in Germany, Austria and Switzerland, it should be noted that most HD sources there are in 1080i format (international exchange format) and are only downscaled to 720p format at the broadcast output become. This means that the HDTV receiver at home receives the motion artifacts of the 1080i recording and the reduced 720p resolution together.
In practice, HDTV images often have to be rectified: The HF transmission of a 16: 9 image is often compressed into a 4: 3 ratio in the encoder, so that with 1080 lines only 1440 instead of 1920 points and with 720 lines only 960 instead of 1280 points are available.
The frame rates typically used are 23.976 Hz, 24 Hz, 25 Hz, 29.97 Hz and 30 Hz for full-screen display and 50 Hz, 59.94 Hz and 60 Hz for field display. If the capacity of the transmission medium allows, this is optional a full screen display with the field frequencies is also possible. However, the required data rate of 1080p50 and 1080p60 when using MPEG-2 exceeds the maximum provided by the transmission methods used (DVB and ATSC), and most TV production systems are not yet designed for double the data rate.
The traditional frequency of 50 or 25 Hz is considered by some experts to be too low for the display of the much larger picture displayed, but this is not used in modern flat screens with at least twice the picture display frequency (100 Hz). The PAL- and SECAM-compatible 50 Hertz have the obvious disadvantage of a more noticeable flicker compared to the NTSC-compatible 60 Hertz on tube screens, but the advantage of a lower data rate with the same compression or vice versa. Cinema films in 24p are usually accelerated by four percent for conversion to PAL format (50 Hz); When converting to NTSC format (60 Hz), jerky movements can occur due to the commonly used telecine method ( 3: 2 pull-up ).
|Full frames (p)||Fields (i)||Pixel rate (descending)|
|1080p60||1920 × 1080 × 60 Hz
= 124.4 Mpx / s
|1080p50||1920 × 1080 × 50 Hz
= 103.7 Mpx / s
|1080p30||1080i60 (psf)||1920 × 1080 × 30 Hz
= 62.2 Mpx / s
|720p60||1280 × 720 × 60 Hz
= 55.3 Mpx / s
|1080p25||1080i50 (psf)||1920 × 1080 × 25 Hz
= 51.8 Mpx / s
|1080p24||1920 × 1080 × 24 Hz
= 49.8 Mpx / s
|720p50||1280 × 720 × 50 Hz
= 46.1 Mpx / s
|720p30||1280 × 720 × 30 Hz
= 27.6 Mpx / s
|720p25||1280 × 720 × 25 Hz
= 23 Mpx / s
|720p24||1280 × 720 × 24 Hz
= 22.1 Mpx / s
|The images indicate the ratio of the bandwidth to the maximum of 1080p60. The wedge shape reflects the field method, the cuboid shape the full image method or field with progressive segmented frame (PsF). The HD resolutions were sorted in descending order according to the required bandwidth. However, with regard to the bandwidth, it must still be taken into account that a film with 24 Hz as the source material is pulled up to 60 Hz, 50 Hz and 30 Hz and the missing images are calculated by interpolation and thus unnecessary images are transmitted as gap fillers and thus bandwidth is wasted. At 25 Hz a simple PAL speed-up of the source film can be made. The film is only played faster, but no images are interpolated. This means that the bandwidth is used more efficiently.|
For 1080i50 with MPEG-2 ( H.262 ) a bit rate of 27 Mbit / s is recommended (according to ITU ) (0.52 bit / px → approx. 5.4 Mbit / s with 576i50), with lower quality requirements 22 Mbit / s (0.42 bit / pixel → 4.4 Mbit / s). "Euro1080" / HD1 only sent at 18 Mbit / s, i.e. 0.35 bit / px, which is about 3.6 Mbit / s for SDTV or 3.75 Mbit / s at 1.85: 1- or 3 Mbit / s corresponds to 2.35: 1 DVD films ( Cinemascope ), with DVDs having the advantage of a dynamically adjustable bit rate.
There are several options for using the existing data rates as efficiently as possible. First, films with an original aspect ratio of 2.35: 1 to 16: 9 trimmed ( gecroppt ) and to the prescribed 16: 9 ratio can be accommodated. No black border is transferred at the top and bottom of the image, as it would not contain any visible image information and is therefore superfluous. However, there is no image information on the sides. Since static black areas can be compressed efficiently, there is only a small saving in data rates. For this purpose, the data rate is extended from a small required image area to a larger area and thus the data rate per area is reduced. Secondly, only the visible lines can be saved and the black bars to fill up the screen resolution can only be inserted during playback. Both methods are used when the aspect ratio deviates from the required 16: 9, i.e. becomes wider. A similar method would be conceivable for 4: 3 film material at 16: 9 and would replace the black borders ( pillar boxes ) on the sides. This was used by ProSieben HD and Sat.1 HD , for example .
Formats and HD ready
While the EBU currently recommends 720p / 50 to its members and, as a future option, 1080p50 / 60 on the production and broadcast side, especially since this suits the display devices that were widespread at the beginning, almost all active European HD providers have so far opted for 1080i50 (1080p / 25), but keep other options open. The EICTA seal HD ready takes this into account by requiring display devices to support the formats 1080i and 720p with 50 and 60 Hertz.
If the DRM data ( broadcast flag ) is set accordingly , the digital signal is only HDCP-encrypted, i.e. copy-protected, from the receiving device to the display device, which is not supported by all existing HD-capable screens, however. Critics also fear that the rights holders will force broadcasters and hardware manufacturers to set the DRM parameters in such a way that at unprotected HDTV outputs, i.e. normal DVI or analog (as with YPbPr - component video cable ), a lower quality or even lower quality no signal is output. In fact, future HDTV users will be able to see their films in the higher resolution, but recording will often not be permitted or only in poor quality (at best DVD-like) (keyword CI + ).
In principle, all sound formats used in digital television or on DVD are possible with HDTV , although Dolby Digital is becoming the norm. MPEG-1 Audio Layer 2 ( MP2 ) to Dolby Digital ( AC3 ) from mono to multi-channel sound can be used in the transport streams . Since HDTV is a premium offer, more bandwidth is made available for both the picture and the sound, and thus multi-channel sound is often offered.
Occasionally, films are still broadcast in stereo or even mono, whereby these are mostly older films for which there was no multi-channel sound process at the time of production and the source sound was not subsequently processed.
In Japan, some broadcasters use MPEG-2 Advanced Audio Coding (AAC). In the future, the further developments Dolby Digital Plus and DTS HD are to be used in television broadcasts and on data carriers, which should work more efficiently and allow more channels and additional functions.
At the moment transmission is mainly via satellite and cable, but terrestrial and Internet transmission ( IPTV ) are also possible. The distribution across these systems varies from country to country.
In North America, ATSC is used as a terrestrial transmission. The maximum data transmission rate of 19.2 Mbit / s is stipulated there, but this cannot be maintained from the broadcaster to the end customer, as so-called independent networks are located within the transmission paths, which are allowed to change the signal in order to adapt it to their own conditions Adapt the power supply. This happens mainly with cable and terrestrial transmission. The video compression is MPEG-2, and the sound compression is MPEG Audio and Dolby Digital.
The DVB standard is used in Europe and is mainly broadcast via satellite. The cable companies are adopting some of these HD channels in their networks. In France, tests are currently being carried out with the DVB-T called TNT. In contrast to Germany, MPEG-4 / AVC ( H.264 ) is used there as video coding for HDTV and SDTV from the start . England's BBC feeds a BBC-HD variant into the Freeview-baptized DVB-T network in the London area. There is also a down push through Low Bandwidth Broadcasting tested.
In the early test period, DVB-S was used for satellite transmission, but later switched to DVB-S2 . Most of the current HD channels in Europe use DVB-S2 for regular operation; If new connections are announced, only DVB-S2 is mentioned. In contrast to DVB-S, it uses improved error correction during modulation and can therefore use the bandwidth up to 30% more effectively. DVB-C is retained in the cable network; no extended version, similar to the DVB-S2, is required. Effective video compression in accordance with MPEG-4 / AVC (H.264) is used for all of them.
In Australia, HDTV has been broadcast regularly since 2004 via DVB-T, but coded with MPEG-2. The German-French cultural broadcaster ARTE started its HDTV test broadcast for Germany in 720p on Astra 19 degrees east, for France in 1080i on 5 degrees west. According to a communication from the French Ministry of Culture and Communication, the program will be broadcast in MPEG-4 compression from October 30, 2008, unencrypted via DVB-T ("Télévision Numérique Terrestre") in 1080i and later via cable and DSL.
IP -based services are also available as a transmission path for HD content. There is a large number of fee-based and free VoD service providers (e.g. YouTube , Netflix ) which make films and series available as a stream or as a download in HDTV formats from 720p to Ultra HD . However, due to the digital rights management used, the reproduction of copyrighted content is often tied to special client applications provided by the service provider , the geographic region of the user and the respective user account or device. Such client applications are usually available in the form of web applications or application software. Depending on the provider, these services can be used with a personal computer , smart TV , mobile device or set-top box , provided that the end device has an internet connection that is sufficiently powerful for HD content and sufficient computing power to decode HD content. In addition, IP services are also available as a transmission path for conventional television programs in HD formats, in particular in the form of so-called triple play offers (e.g. Telekom Entertain ).
Table for terrestrial HDTV transmission systems
|Video||Main profile syntax of ISO / IEC 13818-2 ( MPEG-2 video)|
|Audio||ATSC standard A / 52 ( Dolby AC-3 )||ISO / IEC 13818-2 (MPEG-2 Layer-II audio ) and Dolby AC-3||ISO / IEC 13818-7 (MPEG-2 AAC audio)|
|External coding||RS (207, 187, t = 10)||RS (204, 188, t = 8)|
|External entanglement||52 RS block||12 RS block|
|Internal coding||Rate 2/3 trellis code||PCC : rate 1/2, 2/3, 3/4, 5/6, 7/8; Constraint length = 7, polynomials (octal) = 171, 133|
|Inside entanglement||12-to-1 trellis code||bit by bit, frequency, selectable time|
|Data randomization||Pseudo-random binary sequence with a length of 16 bits|
|modulation||8VSB (only used for terrestrial transmission)
16VSB (Designed for cable transmission but rejected by the cable industry; cable TV uses 64QAM or 256QAM modulation as the de facto standard )
QPSK , 16QAM and 64QAM
Hierarchical modulation: Multi-resolution constellation (16QAM and 64QAM)
Guard interval: 1/32, 1/16, 1/8 & 1/4 for the OFDM symbol
Two modes: 2k and 8k FFT
BST-COFDM with 13 frequency
segments DQPSK , QPSK, 16QAM and 64QAM
Hierarchical modulation: Choice between three different modulations for each segment
Guard interval: 1/32, 1/16, 1/8 & 1/4 to the OFDM symbol
Three modes: 2k, 4k and 8k FFT
SD devices with integrated DVB receivers are now standard in Europe. In the meantime, however, almost all new HD models from television manufacturers are available with either DVB-T (digital terrestrial), DVB-C (digital cable) and DVB-S (digital satellite reception). For ATSC receivers, the situation looked better before, as HDTV was introduced in the USA in 1998 and accordingly more devices were available on the market. The US regulatory authority FCC also used its powers to force manufacturers to install HDTV receivers in TV sets.
For the optimal display of HDTV, the display device must be capable of a physical resolution of 1920 × 1080 pixels , which is the case with most current devices ( full HD ). HD-ready devices with ( 1024 × 768 pixels ) are still occasionally offered.
LCD televisions and almost all other cathode ray tube-free devices benefit particularly from image signals that they do not have to convert to their native resolution, i.e. H. usually 720p60 or 1080i60.
With a PC, direct MPEG2 HDTV reception is possible using standard digital TV PCI cards and the corresponding software. However, integrated MPEG decoding chips (“full featured”) may be possible. d. Usually only designed for SDTV. While recording is also possible on somewhat weaker computers, viewing requires a relatively powerful computer (2 GHz processor) or special decoding chips that were previously hardly available. Converting to other formats has so far not been possible in real time without expensive special hardware.
The new European HDTV variant with DVB-S2 satellite signal and MPEG4 / AVC coding ( H.264 ) requires new reception converters / cards and very powerful image processing in the computer. Current graphics cards support MPEG4 / AVC decoding on the hardware side and thus relieve the CPU enormously. Such cards are marked with Nvidia PureVideo HD or ATI Avivo HD.
In the future, HDCP copy protection is also to be expanded to include receiver and graphics cards and computer monitors.
Two stationary game consoles each of the seventh and eighth generation, Xbox 360 and PlayStation 3 , Xbox One and PlayStation 4 support 1080p HD output via HDMI for games and films. Nintendo's Wii , on the other hand, does not offer HD output, but a maximum of 480p. The successor Wii U from the eighth generation also has 720p and 1080p support. In principle, the Xbox also already supports HDTV (1080i YPbPr), but the PAL version requires a modification using a mod chip ( enigma switch ). Similarly, some games with the 1080i YPbPr option were also offered for the NTSC version of the PlayStation 2 .
An HD-compatible set-top box is required to receive HDTV. This is a receiving device that can decode and process the signals. To receive Premiere HD (new name "Sky" since mid-2009), which was broadcast in HD (1080i50) at the 2006 World Cup, you have to ensure that it is compatible. This is just as much a matter of course as mastering the MPEG-4 compression standard (instead of just MPEG-2) and the DVB-S2 modulation standard (instead of just DVB-S), which is usually used for HDTV via satellite.
Since HDTV transmissions take place via satellite and cable, terrestrial or IPTV are also possible, there is a separate tuner or receiver for each of these reception channels, which is not compatible with the others. Double tuners for mixed operation are currently rarely available for SDTV and not at all for HDTV.
Analog and digital interfaces can be used to transmit the decompressed video and audio signals. This is only restricted by whether the interface can handle the required bandwidths and frequencies and whether these are approved by the rights holder of the signals, since certain interfaces are switched off by a broadcast flag and encryption and are switched on with the approved encryption.
The analog HD-capable video interfaces include VGA , including DVI-Analog and DVI-Integrated , and component video as well as the component video via SCART now offered by some manufacturers . A YUV output via the three RGB lines must be activated / preselected in the device menu, since no sensor signal is currently defined on SCART pin 16 for HDTV. The three-channel component connection can contain two different color levels; for standard TV sources, different level ratios between Y (brightness), Pb (blue) and Pr (red) apply to standard TV sources than for HDTV sources. In extreme cases that do not conform to the standard, this results in a color-falsified image output, e.g. B. if the analog output is switched down to SD quality for reasons of copy protection.
The digital video interfaces include DVI-Digital and DVI-Integrated , "Integrated" means additional connections for an analog VGA signal. The Serial Digital Interface is primarily found in digital studio equipment and projectors for digital cinemas - the HD-SDI variant also supports HDTV. In the computer sector, the DisplayPort is to be used instead of DVI and HDMI . FireWire is occasionally used for D-VHS recorders and HDV camcorders . Video data as well as audio data and control signals can be sent via the DVI-compatible HDMI . There are four variants of HDMI. HDMI 1.0, 1.2 and 1.3 only differ in the supported resolutions, color depths and sound standards. For example, HDMI 1.0 only directly supports the HDTV resolutions, 24 bit color depth and Dolby Digital, DTS and PCM . HDMI 1.3 also directly supports SDTV resolutions, 3D video, 48 bit color depth and Dolby Digital plus (including TrueHD ) and DTS HD. HDMI 1.3a uses "Lipsync" to correct any divergent image and sound data, should these have been switched via an AV receiver. The new audio formats can also use HDMI 1.0 or S / PDIF , but for this the signals must be converted in real time into normal Dolby Digital, DTS or even individual PCM streams. HDMI 1.4a establishes the 3D implementation in the home area through autom. Switching between "side-by-side" or "top-and-bottom" format and the highest resolution 4K (Ultra High Definition) with four times the HD resolution.
A problem has arisen when connecting different makes of playback devices and displays because the industry has often implanted the digital image level formats “DVI-PC” or “DVI-Video” (HDMI contains the same video format as DVI connections) in their devices without to think of a subsequent changeover option. The difference: While with DVI-PC (graphics cards) the brightness levels range from 0 to 255, with DVI-Video (home electronics) a buffer is reserved below and above the black and white level (level range 16 to 239). Only some video projectors and flat screens can be switched between PC level (extended / extended) and video level (standard / normal) via menu. Black is either too bright or lower areas of brightness are swallowed up, the white level is not maximum or is overdriven, all depending on the device combination. Only if the digital video level range in both devices happens to be the same is the range of contrast at the HDMI input, which cannot be changed using the brightness or contrast controls.
In the professional area, there are tape formats and HDCAM (SR) from Sony as well as DVCPro HD and D5 HD from Panasonic . HDCAM has held the lion's share of the market since 1999, D5 HD has been discontinued, and tape-based DVCPRO HD has become very rare. In 2005, hard disk , optical and card-based formats appeared. Sony's XDCAM HD family stands for optical recording, Panasonic's P2 memory cards and, since 2007, Sony's XDCAM EX with recording on SxS media. In addition to the dozen cameras from these manufacturers, cameras that record on hard drives have been around since 2007. RED is the most widespread, its resolution is higher than HD. Cineforms Aspect Ratio HD and DNxHD from Avid are each supported by a camera, the Ikegami Editcam HD or the SI-2K from P + S Technik.
The best known is certainly the Blu-ray Disc , it replaced D-VHS cassettes (aka D-Theater) and proprietary DVD-ROMs with films in WMV-HD format. The original competition format HD-DVD has after leaving Toshiba from the HD DVD market in February 2008, no future. As far as the frame rate is concerned, the Blu-ray Disc is not tied to the television standards; instead, cinema films are available here native with 1080p24, and the same often applies to TV series recorded with 24p. Modern televisions and projectors can receive such a signal via HDMI ; when playing back, each image is then usually projected several times in order to avoid flickering (if no interframe calculation is used). However, no specification has yet been planned for the Blu-ray Disc that allows more than 24 frames per second at 1080p, although it would be technically possible for both the capacity of the BD and the maximum HDMI bandwidth.
For amateur filmmakers, DV has been expanded to become the HDV standard; Corresponding video cameras are available and offer a resolution of 1440 × 1080 in anamorphic 16: 9 aspect ratio and 50 Hz or 60 Hz frame rate in interlaced mode.
In 2006, Sony and Panasonic also introduced AVCHD , a new camcorder standard for amateur filmmakers. The "AVC" stands for MPEG-4 / AVC and reproduces the recording codec used and the standard defines a resolution of 1920 × 1080 at 60 or 50 Hz in the interlaced process and 24 Hz in the full screen process.
Recordings of existing video cassettes can be played back by VHS video recorders on HDTV screens, but a D-VHS video recorder is required for recording new MPEG2-HD recordings. HD-compatible hard disk receivers in Europe were initially only available in Great Britain for Sky-HD (Pay TV). These devices are now also available in Germany.
In order to avoid license costs, separate storage media and codecs are being developed in Taiwan and China. In Taiwan, research is being carried out on the Finalized Versatile Disc (FVD), and players and films for the Enhanced Versatile Disc (EVD) are already available in China . Both formats have slightly more storage space than DVD, but provide for the more efficient codecs VC-1 from Microsoft (FVD) or VP5 and VP6 from On2 (EVD). Primarily, these media are replacements for the standard definition DVD DVD, but they are also intended for HD material. China is also developing its own version of HD-DVD. The FVD, EVD and China HD-DVD are intended exclusively for the Asian region and will not be sold in the rest of the world.
HDTV can also be distributed via video-on-demand (VoD) for PCs and hard disk recorders . The BBC is currently examining the market and the feasibility of broadcasting HD films in addition to the digital television stream using the downpush method and low bandwidth broadcasting in order to be able to distribute the HD films and offer them for simulcast .
The background to this is that the various companies in the US film industry in particular want to use the globally promoted conversion from low-definition (SDTV) to high-definition (HDTV) television as an opportunity to remove the exception regulations that exist almost everywhere on copyright protection for private recording of radio broadcasts on SDTV. Restricting resolutions or cutting them entirely - since HDTV requires different signal connections to SDTV anyway, these should be established in a digital form instead of in analog form, with the help of HDCP in a form protected from recording. The idea behind this is that by sending a broadcast flag, the receiving receiver is prompted to either switch off the high-resolution analog image signals completely or to reduce them to SDTV resolution. An image in HDTV resolution is then only available via the copy-protected digital image output, which at the same time activates HDCP encryption. Unprotected programs such as live broadcasts of sporting events could then still be recorded in HDTV resolution, but the broadcast of a Hollywood film could not be recorded or only in limited quality. This will be the case with the new HDTV platform (RTL HD, Pro7 HD, Sat1 HD) from the SES-Astra (see CI + ).
HDTV has nothing to do with copy protection, the name HDTV only stands for high definition television. However, HDTV sets usually bear the HD ready logo, and this in turn requires the HDCP copy protection . However, this mechanism is criticized by many consumer advocates as it can also prevent purely private copies. See also High-bandwidth Digital Content Protection .
All digital control, encryption, or assignment mechanisms that are already used in digital media can also be used. Digital rights management can be integrated for a targeted comparison of permissions, encryption of the signal within the hardware, among other things through digital transmission content protection, can be used to prevent unintentional access, and watermarks can also be set in images, audio or other areas. A content protection and copy management system (DVB-CPCM) is currently being developed for the new DVB version 3.0 , which encrypts the signal after reception and only allows it to be played by devices that are in the authorized domain .
These mechanisms are not provided for in the HDTV standard, but are used as with all digital media and the almost simultaneous appearance of these technologies on the market creates the impression that HDTV and the mechanisms mentioned are inevitably intertwined (keywords HD + and CI + ).
The higher resolution brings finer textures to the screen and thus sometimes unwanted details in the face and the rest of the body of people. In order to cover this up, more emphasis must be placed on the mask than is the case with SDTV. Where the overall picture could be further improved by superficial changes such as covering and powders in SDTV be in HD productions new method as airbrushing - make-up applied, put only such image settings, keep the unwanted parts hidden, or blur filter is placed automatically on image areas with skin tones, to specifically lower the resolution in a limited part of the image. In this way, any shortcomings can be concealed. By Phillip Swann an HD leaderboard with the ten prettiest and ugliest people was created.
In contrast to conventional film cameras, HD cameras manage without extensive illumination of the environment, but the image noise increases , which must be compensated for by adjusting the signal-to-noise level. These good night-time recording properties were also decisive for the choice of HD cams for the films Collateral and Miami Vice by Michael Mann , whose actions take place at night.
There are also differences to SDTV broadcasts when it comes to setting sets or stages . In many cases, it is not enough to take over the backdrop, as a building style that is sufficiently rough for SDTV or any damage that was not visible with SDTV only appears in HDTV or is more clearly visible. The set-up is therefore usually carried out at the same time as the conversion to HD technology, as was evident from The Late Show with David Letterman in August 2005.
In Star Trek: Enterprise , another side effect of HDTV came to fruition. In the episode “In the Dark Mirror - Part 2” there is a scene in which the biographical background information of two main characters was shown on a screen. Only a small part of it was reproduced in the dialogues and the rest could not be deciphered in the SDTV transmission. However, the author Michael Sussman was not aware that the text displayed in HDTV was completely decipherable and therefore legible. As a result, Star Trek fans took screenshots of it and became aware of some errors in the text that did not correspond to the strict Star Trek canon (recognized facts and chronology within the fictional Star Trek universe). Among other things, the date of Captain Archer's assumption of command of the Enterprise was incorrectly stated. Although this is only noticed by die-hard fans, it makes it clear that more emphasis must be placed on backdrops in order to avoid such mistakes or to use them as Easter eggs .
Movies and many series used to be recorded exclusively on film. If these films are still available as interpositive or duplicate negatives , high-resolution transfers can also be made from old films and series. The film has to be scanned with a digital film scanner . Cinema screening copies on celluloid , cellulose acetate or polyester can usually not be taken over directly because of existing damage, but must first be restored at great expense . The chemical cleaning of the film strip before scanning and a subsequent digital image processing is very time-consuming and costly and is therefore not used with every old film. It has already been carried out for some DVD releases so that these films could already be broadcast in HD and are waiting for a release in the successor DVD format. Many films do not have the HDTV-compliant aspect ratio 16: 9, but still offer the higher resolution (depending on the condition of the original master). Classic films like The Wizard of Oz and series like A Cage Full of Heroes have already been broadcast in HD in the USA.
George Lucas had the old Star Wars trilogy scanned in high resolution as a precaution in order to have the best possible source material and to avoid the costs of reworking for future HDTV versions. But he also produced some digital HD scenes for “Star Wars Episode I” with the first available 1080p24 cameras from Sony. Texas Instruments supplied the matching digital cinema technology with the first DLP projectors.
For high-resolution broadcasting and utilization on HD-DVD, the sci-fi series Star Trek: The Original Series not only scanned the material shot on film, including restoration, but also compared the special effects and models from the 1960s with current, Exchanged visual effects from the computer. This remastering mainly affects the space scenes with exterior views of the spaceships. If the seasons on HD-DVD sell well, such revisions could also be extended to other Star Trek series in order to be able to publish them again, this time in high resolution.
Perception and image reproduction
Because of the higher resolution of HDTV is the viewing distance from which the picture is out of focus, with the same image size and screen size smaller than with SDTV. More details can only be perceived with HDTV if you sit close enough to the picture. At a large viewing distance, the resolution of HDTV cannot be distinguished from a lower resolution. With regard to perception, the maximum viewing distance results from the resolution of the human eye with approximately one angular minute limits of about 2.3 times (resolution 1280 × 720) and 1.6 times (1920 × 1080) the respective image diagonals. The higher resolution is therefore particularly advantageous for beamers (if they can display the resolution) and large playback devices.
With HDTV, the risk of line flicker is reduced ( 1080i ) or disappears entirely ( 720p ). 720p is used in eye tests on normal size screens; H. up to a screen diagonal of about one meter, preferred by most people over 1080i. The EBU recommends 720p to its members because of the lower data rate required and also because deinterlacing is only necessary once in the broadcast center and there with professional hardware .
Artifacts (also known as macroblocking) can arise in digital television if the ratio of new image resolution and bandwidth is too low or if the provider (broadcaster, media authors) does not use efficient compression algorithms and equipment. This "block formation" then occurs especially in fast scenes with a high density of image movement. Even if a higher bandwidth and newer more efficient codecs (MPEG-4 / AVC) are used in contrast to SDTV, artifacts can still occur due to bandwidth constraints.
Picture dropouts ( glitch ) in connection with HDTV were reported with the first HD receivers. This could be traced back to the early firmware of the devices, the higher bandwidth of the transmitter and the use of HDCP. Since the HDCP encryption has to be checked and activated when switching to a station that requires this, it could happen that brief picture dropouts followed in the first moments after the TV picture appeared, followed by other side effects such as green cast or artifacts.
When playing HD recordings ( DVR caching ) it can happen that not all data is loaded due to the high bandwidth and an insufficiently powerful playback device, although the data is actually undamaged and complete. If the data is incomplete during the recording due to a disturbed reception signal, for example due to thunderstorms or technical problems with the transmitter, it is extrapolated during playback - which can also lead to glitches.
If only one converter module is used for image generation for reasons of cost and convergence, i. H. If all three primary colors are scanned on a CCD, this can lead to clearly recognizable scanning errors. To put it simply, an imbalance in the color scanning leads to recurring image errors, which are particularly noticeable when the scanned image has an unfavorable ratio to the image sensor resolution. This image defect occurs less often with 3-CCD solutions.
The higher the resolution of an image and the higher the level of detail in the image, the higher the probability of the moiré effect . This effect occurs when periodically repeating image patterns are superimposed. This can be seen on television in people with plaid clothing ("herringbone pattern"). This effect is likely to be even more pronounced in HDTV because of the higher details, provided that the presenters' clothing, sets, etc. are not chosen accordingly.
Various devices can convert received or read SD signals into HDTV resolutions and output them at their interfaces. For example, in DVD players, a DVD film with PAL resolution (720 × 576 pixels) is extrapolated and usually output to the monitor via digital outputs (DVI, HDMI). If a display device receives a resolution via its inputs that it cannot display natively , the always integrated upscale unit must adapt the signal. Some devices with a high display resolution are criticized for the fact that all incoming signals are subjected to a scaling, whereby the intermediate resolution sometimes does not correspond to the native resolution and thus the sharpness of detail is lost. A third variant is specialized external devices that are connected between the receiver and display device and are exclusively responsible for signal conversion. The results achieved with home equipment can vary considerably, depending on the type of application used and the performance of the equipment.
Upscaling is also carried out by many broadcasters in order to broadcast SD programs within an HDTV offering. The professional devices used for this generally achieve better results than standard end-user equipment and the signal usually benefits from the higher data rate available compared to parallel SD broadcasting (almost DVD quality, "near DVD"), but the quality of they do not reach real HD sources.
Scaling may also be necessary if, for example, the aspect ratio of the 4: 3 signal and the 16: 9 screen do not match. The "hard" insertion of black bars ( letterbox , above and below, or pillarbox , left and right) is only necessary to a limited extent in digital television, namely for formats wider than 16: 9, but is still done by some broadcasters because the black ones Compress areas very efficiently. In addition to black bars, there are also other methods of adapting signals with different aspect ratios in end devices, including cropping ( pan and scan ), linear inflation ( zoom ) or compression in one direction, possibly in an intermediate format (16:10, 14: 9 , 5: 3) and non-linear inflation, in which the center of the image is less distorted than the outer areas.
The chips that provide these and other functions are produced by companies such as Faroudja or Pixelworks and built into televisions, projectors and encoders, for example.
At CeBIT 2006, a prototype with four times the number of pixels (3840 × 2160 pixels) from HDTV was presented. These displays should preferably be used in areas in which extremely detailed digital images are required, such as technical drawings or X-rays . The double number of rows and columns makes it easier to upscale HDTV, as each pixel of the 1080i / p source corresponds to exactly four pixels of the Quad HDTV resolution. Although this interpolation does not bring any new picture details, it does solve the interpolation problem from PAL to HDTV, since there no integer multiplications are possible.
In 2012 the Consumer Electronics Association approved the upcoming standard and thus the successor to Full HD, Ultra HD (4K). The image format is exactly twice as wide and twice as high as a 1080p Full HD image. This means that Ultra HD has a resolution of 3840 × 2160 pixels, which corresponds to around 8 megapixels. Corresponding hardware was presented by all well-known manufacturers at the Consumer Electronics Show 2013 in early 2013 .
Super hi-vision TV
In Japan, the TV broadcaster NHK is already testing a further development of HDTV called Super Hi-Vision . The picture format is exactly four times as wide and four times as high as a regular HDTV picture. This means that a Super Hi-Vision picture has 16 times the resolution of an HDTV picture. Super Hi-Vision has a resolution of 7680 × 4320 pixels ( 8K ), is designed exclusively for 60 full frames per second and supports up to 24 audio channels. Although the format was developed for television use, it also closes the gap between television and digital cinema, as HDTV does not have sufficient resolution for large screens. To enable easy scaling, the number of rows and columns in HDTV has simply been quadrupled. Super Hi-Vision is in the early stages of development. Before it can be used in regular broadcasting operations, the high bandwidth requirements must be met and more efficient compression methods developed.
When switching from analogue cinema with films on polyester or another carrier material to digital cinema with digital films, feeds and projection, proposals were also made to integrate the HDTV resolutions into the emerging digital cinema standard. The ITU-R SG 6 committee of the International Telecommunications Union, which is a UN organization , represented the broadcast side and, among other things, developed the HDTV standard 1080i. The ITU tried to establish the HD standard 1080p24 as the basis for D-Cinema. Even if this standard was not established and the distributors rejected this project, since the image quality of HD is not sufficient for large cinema projection, almost without exception all digitally produced cinema films are created in 1080p24 (see also digital cinema camera ).
In September 2004, the Digital Cinema Initiative (DCI) specified a storage and transport format for digital film in version 1.0 of its 'non-binding technical specification' and communicated this to the SMPTE . The master resolution is 2K and 4K : According to DCI 1.1., Section 188.8.131.52. and 184.108.40.206 the resolution is:
- with an aspect ratio of 1.85: 1998 × 1080 pixels for 2K and 3996 × 2160 for 4K.
- with an aspect ratio of 2.39: ( Cinemascope ) 2048 × 858 at 2K and 4096 × 1716 at 4K.
Nevertheless, the 1080p24 picture resolution represents the lion's share of digital cinema films, although HDTV picture resolutions were rejected as inadequate. The lion's share of digital projectors in cinemas are 1080p or 2K, 4K projectors are only currently being installed in cinemas - while there are thousands of 1080p / 2K cinemas (over 3000 in the USA alone), there are just a few hundred in 4K. Current film and even advertising productions are increasingly being produced in 4K resolution. The cinema can benefit from HDTV broadcasts, since additional sources of income can be developed outside of the core business . Special events such as sports broadcasts and concerts can be broadcast live in cinemas, as receivers for digital signals can be easily integrated into the existing digital cinema equipment. And even if the resolution of HDTV does not match that of 4K, it can still be better than if the signal of a conventional television broadcast or a 720p broadcast were projected onto the screen .
Stereoscopy (3D TV)
Under stereoscopy is any technique that is capable of transmitting three-dimensional visual information with two-dimensional images and awaken the impression of real spatial depth in the viewer. The spatial impression in photos or films is created by two superimposed single images that were taken from two slightly different positions (usually eye relief). In the cinema or television, these 3D films were only rarely used for special presentations, because firstly, the production of the 3D films is more complex and therefore more expensive and because special anaglyph, polarizing or electronically controlled 3D glasses had to be used to view these films . that not every viewer owns and does not want to wear for every broadcast. In the 1950s, 3D cameras were popular for horror films and documentaries were primarily filmed in stereo 3D. These films can also be transferred from celluloid to digital media and in HD resolution, or they can be recorded digitally in HD. From spring 2007, for example, there was a 3D cinema in Cologne's Cinedom with hourly films similar to the IMAX-3D, but projected with a 3D-DLP digital projector. The 3D glasses used there (initially electronic LCD shutter, now Dolby 3D in four halls) are very light and can almost be confused with polarization glasses. The loss of light is similarly high, but the reproduction is now absolutely flicker-free and of high quality, regardless of the position of the head.
On November 21, 2005, the US television broadcaster NBC broadcast the episode "Still Life" of the HDTV series Medium - Nothing Remains Hidden But 3D Video, in which some scenes were enhanced with 3D effects.
There are also attempts to bring 3D HD signals to "autostereoscopic" 3D displays , on which the viewer can see the three-dimensional effect without 3D glasses. Autostereoscopic displays are often referred to as 3D LC displays (single user display) if the special screen can only respond to one pair of eyes. Philips showed a prototype at CeBIT 2006, on which 3D material from KUK Filmproduktion GmbH could also be seen (development by Philips has since been discontinued). The horizontal resolution is reduced by the technology used (barrier mask or lenticular lenses).
The images can be transmitted either as a video signal stream in which both perspective partial images are sent with an anaglyphemous color offset (usually red / cyan, outdated), or as full-color interlaced fields (field sequential - halved vertical resolution) or as full-color "Side-by-side" method (partial images side by side 2: 1 horizontally compressed - half horizontal resolution). Other methods require two separate signal streams for the perspective sub-images, and thus twice the bandwidth is required. HDMI high-speed cable offers enough bandwidth reserves to transfer 1080p24 data streams in frame-packing format from the 3D Blu-ray player to the display. In order to ensure perfect playback, the synchronization between the two separate signals and, if necessary, the 3D shutter glasses must be maintained. The medium that contains this separate information must also have sufficient capacity and guarantee twice the output speed, just like the "HighSpeed" HDMI cable. At the end of 2009, ETSI established the 3D Blu-ray standard with the extended HDMI1.4a interface, the 3D playback method (for passive 3D polarization glasses with half the vertical resolution or for active 3D shutter glasses) remains the 3D TV - and left to 3D projector manufacturers.
On the TV satellite Eutelsat 9A , the HD program “3DSatTV” had been freely available on 11747 MHz since the beginning of 2009 (double images “side-by-side” next to each other). At the beginning of July, a 30-minute loop with spatial animations, real 3D, ran - Recordings from the 24-hour race at the Nürburgring, fashion photos, impressions from Venice and NASA scientific films about the stereo satellite mission to the sun (animations and real 3D videos!). The 3D films are broadcast in "side-by-side" format in an HDTV channel with 1920 × 1080 pixels and show two partial images side by side that have been squeezed horizontally 2: 1 anamorphically. The 3D image display device at home must turn this into a full-format 120 Hz 3D video with two superimposed partial images in 16: 9 format so that the LCD shutter glasses synchronized via an infrared signal can display the two stereoscopic partial images for the correct eye 60 Hz cycle can switch through. For the first time, the International Radio Exhibition Berlin 2009 was dominated by 3D HDTV with several providers of suitable TV screens, almost all of which favored the mature 120 Hz LCD shutter glasses technology. From the beginning of 2010 the first inexpensive “3D-ready” DLP projectors (resolution 720p) were available, which are controlled by suitable PC graphics cards via HDMI1.3 interfaces with a 120 Hz 3D video signal. Matching 3D shutter glasses can be synchronized via infrared control (Nvidia “3D-Vision”) or with a special white pulse (“DLP-Link”), as with 3D TV sets.
In 2012 there are several free 3D TV demo programs on Astra 19 ° Ost , the pay TV channel “Sky 3D” can usually be received unencrypted in the mornings with demo films and 3D cinema film trailers. Some companies are introducing the first 4K 3D TVs that offer full HD spatial resolution with passive polarization 3D glasses.
- The world's largest 720p display is in Hard Rock Stadium , the football stadium of the Miami Dolphins . It serves as a display and advertising board, has a screen diagonal of 44.5 m (1750 inches) and is composed of LEDs.
- The world's largest 1080p display is on the Tokyo Racecourse. It has the dimensions of 66.5 m × 11.3 m (751.45 m², diagonal 67.45 m or 2656 inches). Three video overlays can be displayed side by side on this at the same time. The display panel was composed of 35 Mitsubishi Aurora Vision LED displays; the displays are fed with analog hi-vision HD signals directly from the racetrack. With an aspect ratio of 5.89: 1, it is less suitable for HD films , as this is not a common aspect ratio, unless several films are also shown next to each other.
- Enhanced Definition Television (EDTV)
- High Definition Audio Vision (HDAV)
- Resolution (photography)
- W. Wunderlich: Digital television HDTV, HDV, AVCHD for beginners and those switching. Auberge-tv Verlag, 2007, ISBN 978-3-00-023484-2
- Charles A. Poynton: Digital Video and HDTV - Algorithms Interfaces. Morgan Kaufmann Publishers, 2003, ISBN 1-55860-792-7
- Dominique Hoffmann: High Definition TV - Theory and Practice. Hüthig Verlag, 2005, ISBN 3-7785-3985-X
- Claudia Udenta: HD 1080 / 24p - The new dimension of film (s) s. Mediabook-Verlag Reil, 2002, ISBN 3-932972-11-2
- Armin Gärtner: Radio and video in medical technology, volume 4 series medical technology and information technology. TÜV Media Verlag, Cologne 2007, ISBN 978-3-8249-1045-8
- Armin Gärtner: High-Definition Television in Medical Technology. In: mt medical technology. TÜV Media Verlag Cologne, No. 2, 2007, pp. 52-65
- Gerhard Mahler : The basics of television technology. Springer-Verlag, 2005, ISBN 3-540-21900-5 , pp. 79-81
- High Definition for Europe - a progressive approach , EBU article (English, PDF, 207 kB)
- Current HD channels worldwide
- HDTV channels via satellite in Germany and Europe
- Link catalog on the subject of HDTV (television) at curlie.org (formerly DMOZ )
- HDTV test image download ( Memento from April 1, 2010 in the Internet Archive )
- Linowsat: List of European HDTV channels and their data rates
- What is 3D or Full HD 3D technology?
- Document EBU Tech 3299, High Definition (HD) Image Formats for Television Production , accessed December 15, 2013
- EBU-Tech 3312: Digital Terrestrial HDTV Broadcasting in Europe (PDF; 228 kB) on: www.ebu.ch, Genoa, February 2006 (English)
- Mask for HD video: Are they ready for a high-definition close-up? on: telegraph.co.uk . March 12, 2005
- hi-def video limits: Paul Cameron and Dion Beebe, ACS push hi-def video to its limits for Collateral, which chronicles a hit man's nocturnal killing spree. on: theasc.com, Jay Holben, 2004 (English)
- Setting : Star Trek: Biography details of Archer and Sato on: dailytrek.de
- Star Trek: TOS-Remastered: Star Trek - Remastered Trek on Blu-ray? Rumors About That & Other Hi-Def Trek on: tvshowsondvd.com, David Lambert, August 1, 2007
- HDTV in the cinema: England fans watch match in cinema on: en: wikinews, June 21, 2006 (English)
- DCI cinema specification: DCI Cinema System Spec 1.1 ( Memento from July 1, 2007 in the Internet Archive ) (PDF; 1.4 MB) on: dcimovies.com
- Largest 720p display: Dolphin Stadium 720p HDTV (worlds largest) unveiled ( memento of the original from September 3, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. on: hdbeat.com, Richard Lawler, April 9, 2006 (English)
- Largest 1080p display: the world's largest HDTV display with 751 square meters ( memento of the original from January 14, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. on: chip.de, July 29, 2006