Broadcast-safe

Please help improve this article by expanding it. Further information might be found on the talk page. (February 2008)

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).

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 color bars.
  • 75% intensity corresponding to 100.0.75.0 color bars, also referred to as EBU Bars.

Variants

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

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.

Broadcast safe audio

Please help improve this article by expanding it. Further information might be found on the talk page. (June 2008)

Broadcast engineers in North America usually line up their audio gear to 0 db using a VU meter, in Europe equating to roughly +4 dBm (-18 dBFS) on a PPM ^[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

Video gear 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:

• VHS and 8 mm: Consumer devices generally lack time base corrrection, causing problems with genlock. They may also suffer from noticeably more noise and transmit less detail than is normal for standard definition TV.

• Older videogame systems: Before the sixth generation of videogame consoles, most videogames generated a video signal lacking the half scan line needed to make interlace happen. This subtle simplification caused NTSC sets to scan 240p instead of 480i, with similar results for PAL. While this actually improved picture quality for the kind of images that videogames of this era generated, such a signal would cause problems in a broadcast environment.

• VGA to NTSC converters: VGA runs at a true 60 frames per second, not the slightly slower rate of NTSC. Some low cost VGA to NTSC converters could not correct for this, and would generate an NTSC signal with accelerated timing. Most TVs had no problem displaying this, but such a signal would rapidly deteriorate if recorded onto analog VCRs that are unable to compensate for the increased framerate.

See also

Television portal

• 576i
• 480i
• VU meter
• Peak programme meter
• SMPTE color bars
• ProcAmp
• Safe area

External links

• More information about TV standards

References

v • d • e Digital Video Resolutions Designation Usage Examples Definition (lines) Rate (Hz) Interlaced (fields) Progressive (frames) Low; MP@LL LDTV, VCD 240; 288 (SIF)   24, 30; 25 Standard; MP@ML SDTV, SVCD, DVD, DV 480 (NTSC, PAL-M) 60 24, 30 576 (PAL, SECAM) 50 25 Enhanced EDTV 480; 576   60; 50 High; MP@HL HDTV, Blu-ray Disc, HDV 720   24, 30, 60; 25, 50 1080 50, 60 24, 30; 25 This table illustrates total horizontal and vertical pixel resolution via box size. It does not accurately reflect the screen or pixel shape (aspect ratio) of these formats, which is either 4:3, or 16:9.