Broadcast-safe

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Broadcast-safe video (broadcast legal or legal signal) is a term used in the broadcast industry to define video and audio compliant with the technical or regulatory broadcast requirements of the target area or region the feed might be broadcasting to. [1] In the United States, the Federal Communications Commission (FCC) is the regulatory authority; in most of Europe, standards are set by the European Broadcasting Union (EBU).

Contents

Broadcast safe video

Broadcast safe Standard Definition video

Broadcast safe 625 video

Broadcast safe standards for 625 lines of Standard Definition (Inaccurately referred to as PAL, a colour encoding that is usually used with such systems) video are: [2] [3]

  • Common name = 625/50i (576i) [4]
  • Commonly used digital SD SDI baseband signal = SMPTE 259M-C, 270 Mbit/s bitrate
  • Commonly used No. of Vertical Lines = 625 (576 visible active video)
  • Commonly used Frame rate = 25 Hz (25 interlaced frame/s)
  • Commonly used TV Resolution = 720 x 576 (576i)
  • Black levels = 0 mV or 0 IRE
  • White levels (Chrominance amplitude):
    • 700 mV p-p or 100 IRE - 100% intensity setting which corresponds to 100.0.100.0 SMPTE color bars.
    • 75% intensity corresponding to 100.0.75.0 color bars, also referred to as EBU Bars.
Variants
ResolutionAspect ratio Pixel aspect ratio Form of scanningFramerate (Hz)
VerticalHorizontal
5763524:3 or 16:9non-squareinterlaced25 (50 fields/s)
progressive25
4804:3 or 16:9non-squareinterlaced25 (50 fields/s)
progressive25
5444:3 or 16:9non-squareinterlaced25 (50 fields/s)
progressive25
7204:3 or 16:9non-squareinterlaced25 (50 fields/s)
progressive25
50

Broadcast safe 525 video

Broadcast safe standards for 525 lines of Standard Definition (System M, NTSC) video are: [5] [6] [7] [8] [9]

  • Common name = 525/60i (480i) [4]
  • Commonly used digital SD SDI baseband signal = SMPTE 259M-C, 270 Mbit/s bitrate
  • Commonly used Frame rate = 30 frame/s black and white, 29.97 interlaced frame/s color
  • Black level = 7.5 IRE for NTSC in the US, 0 IRE in Japan.
  • Blanking level = 0 IRE
  • White levels = 100 IRE, 714 mV
  • Maximum signal level = 120 IRE
  • Minimum signal level = -20 IRE
Variants
ResolutionAspect ratio Pixel aspect ratio Form of scanningFramerate (Hz)
VerticalHorizontal
4806404:3squareinterlaced29.97 (59.94 fields/s)
30 (60 fields/s)
progressive23.976
24
29.97
30
59.94
60
7204:3 or 16:9non-squareinterlaced29.97 (59.94 fields/s)
30 (60 fields/s)
progressive23.976
24
29.97
30
59.94
60

Broadcast safe High Definition video

Digital broadcasting is very different from analog. The NTSC and PAL standards describe both transmission of the signal and how the electrical signal is converted into an image. In digital, there is a separation between the subject of how data is to be transmitted from tower to TV, and the subject of what content that data might contain. While data transmission is likely to be a fixed and consistent affair, the content could vary from High Definition video one hour, to SD multicasting the next, and even to non-video datacasting. In the US, 8VSB transmits the data, while MPEG-2 encodes pictures and sound.

ResolutionAspect ratio Pixel aspect ratio Form of scanningFrame rate (Hz)
VerticalHorizontal
720128016:9squareprogressive23.976
24
25
29.97
30
50
59.94
60
1080192016:9squareinterlaced25 (50 fields/s)
29.97 (59.94 fields/s)
30 (60 fields/s)
progressive23.976
24
25
29.97
30

Broadcast safe audio

Broadcast engineers in North America usually line up their audio gear to nominal reference level of 0 dB on a VU meter aligned to +4dBu or -20dBFs, in Europe equating to roughly +4 dBm or -18 dBFS. Peak signal levels must not exceed the nominal level by more than +10 dB. [10]

Broadcast audio as a rule must be as free as possible of Gaussian noise, that is to say, it must be as close to the noise floor, as is reasonably possible, considering the storage or transmission medium.

Broadcast audio must have a good signal-to-noise ratio, where speech or music is a bare minimum of 16db above the noise of the recording or transmission system. For audio that has a much poorer signal-to-noise ratio (like cockpit voice recorders), sonic enhancement is recommended.

Non-standard video

Although almost any video gear can create problems when broadcast, equipment aimed at consumers sometimes produces video signals which are not broadcast safe. Usually this is to reduce the cost of the gear, since a non-standard video signal in the home might not create the problems that one might find in a broadcast facility. Potential flaws exist with:

In digital television only environments

In nations that have fully converted to digital television, broadcast safe analogue television takes on a slightly different meaning. All broadcasting systems will have been mostly converted to digital only outputs, leaving fewer entry points for analogue television signals.

What this means is that all devices that feed to the television transmitter must take in and feed standard analogue television signals into the transmission chain. Mostly it is up to the switcher to notify if there is non-broadcast safe video to the programmer. However, due to the limitations of many switchers for DTV and HDTV it ultimately is up to the automation systems to alert the programmer of non-broadcast safe video inputs.

As a matter of broadcast engineering practice, 4:3 analogue television signals will always pose the most problems with broadcast safe compliance. The use of portable and cheap timebase-genlock systems for analogue television inputs in the digital television studio will be clearly mandatory for the next 50 years.[ original research? ]

See also

Related Research Articles

NTSC Analog color television system developed in the United States

NTSC, named after the National Television System Committee, is the analog television color system that was introduced in North America in 1954 and stayed in use until digital conversion. It was one of three major analog color television standards, the others being PAL and SECAM.

PAL Colour encoding system for analogue television

Phase Alternating Line (PAL) is a colour encoding system for analogue television used in broadcast television systems in most countries broadcasting at 625-line / 50 field per second (576i). It was one of three major analogue colour television standards, the others being NTSC and SECAM.

Standard-definition television Original analog television systems

Standard-definition television is a television system which uses a resolution that is not considered to be either high or enhanced definition. SDTV and high-definition television (HDTV) are the two categories of display formats for digital television (DTV) transmissions. "Standard" refers to the fact that it was the prevailing specification for broadcast television in the mid- to late-20th century.

Video Electronic moving image

Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode ray tube (CRT) systems which were later replaced by flat panel displays of several types.

Interlaced video

Interlaced video is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured consecutively. This enhances motion perception to the viewer, and reduces flicker by taking advantage of the phi phenomenon.

Composite video Analog video signal format

Composite video is an analog video signal format that carries standard-definition video as a single channel. Video information is encoded on one channel, unlike the higher-quality S-video and the even higher-quality component video. In all of these video formats, audio is carried on a separate connection.

Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that standard, is used mostly in the United States, Mexico, Canada, and South Korea. Several former NTSC users, in particular Japan, have not used ATSC during their digital television transition, because they adopted their own system called ISDB.

Serial digital interface

Serial digital interface (SDI) is a family of digital video interfaces first standardized by SMPTE in 1989. For example, ITU-R BT.656 and SMPTE 259M define digital video interfaces used for broadcast-grade video. A related standard, known as high-definition serial digital interface (HD-SDI), is standardized in SMPTE 292M; this provides a nominal data rate of 1.485 Gbit/s.

SMPTE color bars

SMPTE color bars are a trademarked television test pattern used where the NTSC video standard is utilized, including countries in North America. The Society of Motion Picture and Television Engineers (SMPTE) refers to the pattern as Engineering Guideline EG 1-1990. Its components are a known standard. Comparing it as received to the known standard gives video engineers an indication of how an NTSC video signal has been altered by recording or transmission and what adjustments must be made to bring it back to specification. It is also used for setting a television monitor or receiver to reproduce NTSC chrominance and luminance information correctly.

Broadcast television systems are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main analog television systems in use around the world until the late 2010s (expected): NTSC, PAL, and SECAM. Now in digital terrestrial television (DTT), there are four main systems in use around the world: ATSC, DVB, ISDB and DTMB.

Enhanced-definition television, or extended-definition television (EDTV) is a Consumer Electronics Association (CEA) marketing shorthand term for certain digital television (DTV) formats and devices. Specifically, this term defines formats that deliver a picture superior to that of standard-definition television (SDTV) but not as detailed as high-definition television (HDTV).

720p Video resolution

720p is a progressive HDTV signal format with 720 horizontal lines and an aspect ratio (AR) of 16:9, normally known as widescreen HDTV (1.78:1). All major HDTV broadcasting standards include a 720p format, which has a resolution of 1280×720; however, there are other formats, including HDV Playback and AVCHD for camcorders, that use 720p images with the standard HDTV resolution. The frame rate is standards-dependent, and for conventional broadcasting appears in 50 progressive frames per second in former PAL/SECAM countries, and 59.94 frames per second in former NTSC countries.

480i Standard-definition video mode

480i is the video mode used for standard-definition analog or digital television in the Caribbean, Myanmar, Japan, South Korea, Taiwan, Philippines, Laos, Western Sahara, and most of the Americas. The 480 identifies a vertical resolution of 480 lines, and the i identifies it as an interlaced resolution. The field rate, which is 60 Hz, is sometimes included when identifying the video mode, i.e. 480i60; another notation, endorsed by both the International Telecommunication Union in BT.601 and SMPTE in SMPTE 259M, includes the frame rate, as in 480i/30. The other common standard, used in the other parts of the world, is 576i.

576i Standard-definition video mode

576i is a standard-definition video mode originally used for terrestrial television in most countries of the world where the utility frequency for electric power distribution is 50 Hz. Because of its close association with the colour encoding system, it is often referred to as simply PAL, PAL/SECAM or SECAM when compared to its 60 Hz NTSC-colour-encoded counterpart, 480i. In digital applications it is usually referred to as "576i"; in analogue contexts it is often called "625 lines", and the aspect ratio is usually 4:3 in analogue transmission and 16:9 in digital transmission.

Low-definition television (LDTV) refers to TV systems that have a lower screen resolution than standard-definition TV systems. The term is usually used in reference to digital TV, in particular when broadcasting at the same resolution as low-definition analog TV systems. Mobile DTV systems usually transmit in low definition, as do all slow-scan TV systems.

A video signal generator is a type of signal generator which outputs predetermined video and/or television oscillation waveforms, and other signals used in the synchronization of television devices and to stimulate faults in, or aid in parametric measurements of, television and video systems. There are several different types of video signal generators in widespread use. Regardless of the specific type, the output of a video generator will generally contain synchronization signals appropriate for television, including horizontal and vertical sync pulses or sync words. Generators of composite video signals will also include a colorburst signal as part of the output.

Pixel aspect ratio

Pixel aspect ratio is a mathematical ratio that describes how the width of a pixel in a digital image compares to the height of that pixel.

MUSE, was an analog high-definition television system, using dot-interlacing and digital video compression to deliver 1125-line high definition video signals to the home. Japan had the earliest working HDTV system, which was named Hi-Vision with design efforts going back to 1979. The country began broadcasting wideband analog HDTV signals in 1989 using 1035 active lines interlaced in the standard 2:1 ratio (1035i) with 1125 lines total. By the time of its commercial launch in 1991, digital HDTV was already under development in the United States. Hi-Vision continued broadcasting in analog until 2007.

High-definition television (HD) describes a television system providing an image resolution of substantially higher resolution than the previous generation of technologies. The term has been used since 1936, but in modern times refers to the generation following standard-definition television (SDTV), often abbreviated to HDTV or HD-TV. It is the current de facto standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television and Blu-ray Discs.

Black and burst Analogue synchronization signal used in broadcasting

Black and burst, also known as bi-level sync and black burst, is an analogue signal used in broadcasting. It is a composite video signal with a black picture. It is a reference signal to synchronise video equipment, in order to have them output video signals with the same timing. This allows seamless switching between two video signals.

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