Broadcasting quality controls

Today we had a lecture about quality controls when broadcasting. This was to help us understand what quality control tests we need our film to pass so that we can show it in our degree show.

This is what I learnt:

 - At the back of our eye, we have rods and cones. Rods can only see black and white and three cones in our eye can see colour - Red, blue and green.

 - If we add red, blue and green together, we get white light. When we mix red and green we get yellow, green and blue make cyan and red and blue make magenta.

 - At the beginning of each programme we have bars and tone, a clock and then the programme. The programme will internationally always start at the timecode 10:00:00:00, this is so the timecode can be less for the bars and tone and the clock. Time can never go backwards therefore the timecode cannot be negative.

 - the colour bars at the beginning are to show the different colours of light that RGB can produce.
Here are the colour bars:

The colours are at different brightnesses which are measured. Blue is at 11% brightness, red is at 30% brightness and green is at 59% brightness. This is easier to see if you change the the bars to black and white.

 - The brightness of colours has to be measured before it can be broadcast because in animation, we can produce artificial colours which can be too bright for broadcast. This is measured by using a vectorscope.  If the colours are too bright they will go beyond the boundary and this is classed as a fail so has to be adjusted before it can be broadcast.

 - The clock at the beginning before the programme starts must have the name of the item, name of the producers and have the duration. Some request that the description of the first and last shot must also be on there. Below is an example of the clock.

 - 20Hz is the lowest sound and 20,000Hz is the highest. Sound must be tested so that it is not too loud for broadcast. The BBC designed a meter called a Peak Programme meter which was an analog sound measurer. A PPM measures from 1 to 7 with PPM4 being at 0 db. Each number on the meter equals to 4db. Normal range is between PPM4 and PPM6. There is also a digital version that reads decibels. -18db is normal level and anything between -18 and -9 is fine for broadcasting. 

 - It must be tested for flashes using a Flash Panel Analyser. This tests wether the programme has too many flashes for it to be classed as suitable for broadcast. Res flashes are worse than white and is it goes above the line on the scale for any reason, then it fails.

 - When the resolution is 1080i that means it is interlaced and has 1080 horizontal lines. The programme will be at 25 frames per second. interlaced means that only half the fields or horizontal lines are shown at a time so all the odd ones will be shown and then all the even lines. This merges the first and second frames together to play. 

 - the BBC require all there programming to be in HD with 1920x1080 resolution and on HDCam SR tapes rather than digital.