Broadcast Health and Safety (ANI304)

Today, we had a lecture about technical standards for the Degree Show with Mike Dixon. 


BBC technical standards for TV programmes from Moodle
http://learn.rave.ac.uk/moodle/mod/resource/view.php?id=35623

High Definition Format

All material delivered for UK HD TV transmission must be:

1920 x 1080 px in an aspect ratio of 16:9

25 fps (50fields) interlaced* - 1080i/25

colour sub-sampled at a ratio of 4:2:2

*Interlaced video is a technique of doubling the perceived frame rate without consuming extra bandwidth.

Sound Quality

Sound must be recorded with appropriately placed microphones, giving minimum background noise and without peak distortion.
The audio must be free of spurious signals such as clicks, noise, hum and any analogue distortion. The audio must be reasonably continuous and smoothly mixed and edited.
Audio levels must be appropriate to the scene portrayed and dynamic range must not be excessive. They must be suitable for the whole range of domestic listening situations.
Stereo audio must be appropriately balanced and free from phase differences which cause audible cancellation in mono.
The audio must not show dynamic and/or frequency response artefacts as a result of the action of noise reduction or low bit rate coding systems.

Tolerance of out of gamut signals


In practice it is difficult to avoid generating signals slightly outside this range, and it is considered
reasonable to allow a small tolerance, which has been defined as follows under EBU Rec103:

RGB components must be between -5 % and 105% (-35 and 735mV)
therefore
Luminance (Y) must be between -1% and 103% (-7mV and 721mV)

Slight transient overshoots and undershoots may be filtered out before measuring, and an error will only be registered where the out of gamut signals total at least 1% of picture area. Many monitoring devices are designed to detect errors to this specification.


Blanking

HD images must fill the active picture area (1920 x 1080 pixels). No ‘blanking errors’ are permitted on new, up-converted, or archive material.
However a two pixel tolerance will be permitted during CG or complex overlay sequences where key signals, graphic overlays or other effects do not fully cover the background image. Where animated key signals or overlays cause moving highlights at the edge of the active image it is preferable to blank these pixels completely. A note of the timecodes and reasons for these errors should accompany the delivered programme.


Photosensitive Epilepsy (PSE)

Flickering or intermittent lights and certain types of repetitive visual patterns can cause serious problems for viewers who are prone to photosensitive epilepsy. Children & teenagers are particularly vulnerable.

All UK Television channels are subject to the Ofcom BROADCASTING CODE 2009 which states:
Section 2: Harm and Offence:
            2.12 Television broadcasters must take precautions to maintain a low level of risk to
                    viewers who have photosensitive epilepsy. Where it is not reasonably practicable
                    to follow the Ofcom guidance (see the Ofcom website), and where
                    broadcasters can demonstrate that the broadcasting of flashing lights and/or
                    patterns is editorially justified, viewers should be given an adequate verbal and
                    also, if appropriate, text warning at the start of the programme or programme
                    item.
The Ofcom guidance is at: http://stakeholders.ofcom.org.uk/binaries/broadcast/guidance/813060/section22009.pdf

2.9.1 Testing for flashes and patterning

All programmes for tape delivery must be tested using the Harding Flash Pattern Analyser v2.54b on an SD down converted SDI feed. Any failure whatsoever will result in rejection of the programme, and any affected sections must be repaired and re-tested before acceptance.
Broadcasters will, at their discretion, either test the programme during the Quality Control process, or will require a relevant Harding FPA pass certificate to be delivered with the tape.

2.9.2 PSE-broadcast warnings

Verbal or on-screen text warnings at start of programme may only be used in exceptional
circumstances when:

           The relevant content is completely integral and necessary to the context of the
           programme and,
        
           Permission to use the relevant content has been cleared by the relevant broadcaster
           and documented in writing by those responsible for commissioning /editorial content.

Advance notification and planning requirements will vary by broadcaster.



Mike showed us the pokemon video clip as an epileptic example.