Odisha CHSE +2 Vocational Audio Video Technique common mistakes
Odisha CHSE +2 Vocational Audio Video Technique · Understand the traps and how to avoid them.
Writes that doubling the distance from a source reduces the level by 3 dB, and uses dB, dB SPL and dBFS as if they were interchangeable.
The candidate memorises '3 dB = double' without attaching it to power, voltage or sound-pressure reference quantities, so every dB question gets the same formula.
What to do instead
Anchor each scale: 0 dB SPL = 20 µPa; doubling distance in a free field gives about −6 dB; doubling power is +3 dB; doubling voltage or pressure is +6 dB; about +10 dB is heard as roughly twice as loud. Practise one numerical example for each rule and label the reference every time.
Explains a 24-bit/48 kHz recording as 'higher quality because it captures higher frequencies', and cannot state separately what the 48 kHz and the 24-bit values control.
Sample rate and bit depth are memorised as a single 'quality number' rather than as two independent axes of bandwidth and dynamic range.
What to do instead
Use the Nyquist rule: 48 kHz sampling can represent frequencies up to 24 kHz; bit depth sets the noise floor, roughly 6 dB of dynamic range per bit (about 96 dB at 16-bit, 144 dB at 24-bit). Draw a two-axis table and place 44.1/48/96 kHz and 16/24-bit on it.
Draws a cardioid polar pattern as a circle, and then selects an omnidirectional microphone for a noisy street interview 'to get more sound'.
Polar patterns are learned as names and sketches to copy, not as directional rejection that solves a real placement problem.
What to do instead
Sketch omni, cardioid, supercardioid and figure-8 with the rear null marked; state that omni picks up room and traffic from all sides while cardioid rejects the rear. For a noisy exterior, choose cardioid or supercardioid, work close, and use a windshield.
Sets the shutter to 1/1000 s at 25 fps for ordinary walking shots and expects the picture to become brighter because 'the shutter is faster'.
Shutter speed is confused with exposure gain or with phone auto-exposure, and the 180-degree shutter convention has been memorised without its motion rationale.
What to do instead
Apply the 180-degree rule: at 25 fps use about 1/50 s for natural motion blur. A faster shutter darkens the image and produces strobing, so compensate with iris, ND filter or lighting, not by treating shutter as a brightness control.
States that PAL is 525 lines at 60 fields per second and NTSC is 625 lines at 50 fields, and describes 4:2:2 as 'four times the luminance'.
The line and field standards are memorised as an unordered pair, and chroma subsampling notation is read as a multiplication rather than as a ratio of samples.
What to do instead
Build a firm comparison table: PAL 625/50, 25 fps; NTSC 525/60, about 30 fps. Read 4:2:2 as four luminance samples for two chroma samples on each of two consecutive lines, meaning chroma is half the horizontal resolution, not four times luminance.
Leaves gain at +18 dB and opens the iris to brighten a backlit subject, then white-balances on a coloured painted wall because it looks pale.
Gain is treated as free brightness, and white balance is treated as any action that makes the picture look less blue or orange, without checking the reference surface or the lighting source.
What to do instead
Keep gain at 0 dB where possible and control exposure with iris, ND filter and lighting; use zebras to protect highlights. White-balance on a white or grey card lit by the actual source, and re-balance when moving between daylight and tungsten.
Places the key light behind the subject, calls the fill light the main source, and says that adding more fill increases contrast.
The three lighting roles are memorised as a list of names rather than as functions in shaping shadow and separation.
What to do instead
Define by function: key is the main directional source, usually about 45 degrees to one side and above; fill softens shadow from the opposite side at lower intensity; backlight separates the subject from the background. More fill reduces the key-to-fill ratio and lowers contrast.
Writes the script as continuous prose with dialogue and camera directions mixed together, with no scene headings, shot numbers or duration column.
School essay writing habits carry over, and the script is treated as a story to read rather than as a production instruction sheet.
What to do instead
Use a two-column audio-video format: scene and shot number, location, video action and shot size on the left; dialogue, music, effects and duration on the right. Read the script aloud and check that every shot can actually be scheduled and recorded.
Imports footage and starts cutting before setting the sequence frame rate and resolution, adds a cross-dissolve to every cut, and exports without checking audio sync or levels.
Editing is learned as software button-pressing; the candidate follows the interface rather than a workflow from rushes to delivery.
What to do instead
Match the sequence to the source footage, log and label clips, and use straight cuts by default. Check sync on dialogue, keep peaks below clipping, and play the whole sequence on headphones and speakers before export. Test-export a short section first.
In the viva, recites textbook definitions of a cardioid microphone, a 50 mm lens or three-point lighting but cannot say why that choice was made in the candidate's own project.
The project was completed by copying steps or by one group member, so the candidate has output but no record of decisions, constraints or trade-offs.
What to do instead
Keep a project decision log: the goal, the constraint, the option chosen and why. Rehearse a three-sentence defence for each major choice, for example why a cardioid mic was used outdoors, and be ready to demonstrate the setup rather than only describe it.