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, NTSC-J, PAL-M) 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, 0 IRE for NTSC-J in Japan and PAL-M in Brazil.
  • 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, to SD multicasting the next, and even to non-video datacasting. For ATSC 1.0, 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
50
59.94
60

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 +4 dBu or -20 dBFS, 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 far from 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.[ citation needed ]

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.[ citation needed ]

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

<span class="mw-page-title-main">NTSC</span> Analog television system

NTSC is the first American standard for analog television, published in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170.

<span class="mw-page-title-main">PAL</span> Colour encoding system for analogue television

Phase Alternating Line (PAL) is a colour encoding system for analog television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields per second, and associated with CCIR analogue broadcast television systems B, D, G, H, I or K. The articles on analog broadcast television systems further describe frame rates, image resolution, and audio modulation.

<span class="mw-page-title-main">Standard-definition television</span> Digital TV with similar definition to analog broadcasts

Standard-definition television is a television system that uses a resolution that is not considered to be either high or enhanced definition. Standard refers to offering a similar resolution to the analog broadcast systems used when it was introduced.

<span class="mw-page-title-main">Interlaced video</span> Technique for doubling the perceived frame rate of a video display

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 characteristics of the human visual system.

<span class="mw-page-title-main">Rec. 601</span> Standard from the International Telecommunication Union

ITU-R Recommendation BT.601, more commonly known by the abbreviations Rec. 601 or BT.601, is a standard originally issued in 1982 by the CCIR for encoding interlaced analog video signals in digital video form. It includes methods of encoding 525-line 60 Hz and 625-line 50 Hz signals, both with an active region covering 720 luminance samples and 360 chrominance samples per line. The color encoding system is known as YCbCr 4:2:2.

<span class="mw-page-title-main">ATSC standards</span> Standards for digital television in the US

Advanced Television Systems Committee (ATSC) standards are an International set of standards for broadcast and 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, South Korea and Trinidad & Tobago. Several former NTSC users, such as Japan, have not used ATSC during their digital television transition, because they adopted other systems such as ISDB developed by Japan, and DVB developed in Europe, for example.

<span class="mw-page-title-main">Serial digital interface</span> Family of digital video interfaces

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.

<span class="mw-page-title-main">SMPTE color bars</span> Widely used NTSC television test pattern

SMPTE color bars are a 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, and created by test pattern generators. 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.

Broadcasttelevision systems are the encoding or formatting systems for the transmission and reception of terrestrial television signals.

<span class="mw-page-title-main">YPbPr</span> Color space used in analog video

YPbPr or Y'PbPr, also written as YPBPR, is a color space used in video electronics, in particular in reference to component video cables. Like YCBCR, it is based on gamma corrected RGB primaries; the two are numerically equivalent but YPBPR is designed for use in analog systems while YCBCR is intended for digital video. The EOTF may be different from common sRGB EOTF and BT.1886 EOTF. Sync is carried on the Y channel and is a bi-level sync signal, but in HD formats a tri-level sync is used and is typically carried on all channels.

<span class="mw-page-title-main">480i</span> Standard-definition video mode

480i is the video mode used for standard-definition digital video in the Caribbean, Japan, South Korea, Taiwan, Philippines, Myanmar, Western Sahara, and most of the Americas. The other common standard definition digital standard, used in the rest of the world, is 576i.

<span class="mw-page-title-main">576i</span> Standard-definition video mode

576i is a standard-definition digital video mode, originally used for digitizing analogue 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 legacy colour encoding systems, it is often referred to as PAL, PAL/SECAM or SECAM when compared to its 60 Hz NTSC-colour-encoded counterpart, 480i.

576p is the shorthand name for a video display resolution. The p stands for progressive scan, i.e. non-interlaced, the 576 for a vertical resolution of 576 pixels. Usually it corresponds to a digital video mode with a 4:3 anamorphic resolution of 720x576 and a frame rate of 25 frames per second (576p25), and thus using the same bandwidth and carrying the same amount of pixel data as 576i, but other resolutions and frame rates are possible.

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.

<span class="mw-page-title-main">Pixel aspect ratio</span> Proportion between the width and the height of a pixel

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

Analog high-definition television has referred to a variety of analog video broadcast television systems with various display resolutions throughout history.

MUSE, commercially known as Hi-Vision was a Japanese analog high-definition television system, with design efforts going back to 1979.

High-definition television (HDTV) describes a television or video system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since at least 1933; in more recent times, it refers to the generation following standard-definition television (SDTV). It is currently the standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television.

<span class="mw-page-title-main">625 lines</span> Analog television resolution standard

625-line is a late 1940s European analog standard-definition television resolution standard. It consists of a 625-line raster, with 576 lines carrying the visible image at 25 interlaced frames per second. It was eventually adopted by countries using 50 Hz utility frequency as regular TV broadcasts resumed after World War II. With the introduction of color television in the 1960s, it became associated with the PAL and SECAM analog color systems.

<span class="mw-page-title-main">525 lines</span> 1940s American analog standard-definition television resolution standard

525-line is an American standard-definition television resolution used since July 1, 1941, mainly in the context of analog TV broadcast systems. It consists of a 525-line raster, with 480 lines carrying the visible image at 30 interlaced frames per second. It was eventually adopted by countries using 60 Hz utility frequency as TV broadcasts resumed after World War II. With the introduction of color television in the 1950s, it became associated with the NTSC analog color standard.

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