Audio and Video Production
What the exam tests
Digital audio sampling and file-size calculation, codecs and containers, video frame rate and resolution, and basic editing workflow.
Core rules
- Sampling converts a continuous waveform into discrete samples; sample rate is samples per second; bit depth is bits per sample; channels multiply data.
- Nyquist rule: sample at least twice the highest frequency to reconstruct it. CD audio is 44.1 kHz, 16-bit, stereo.
- Lossless audio (WAV, FLAC) preserves samples; lossy (MP3, AAC, Ogg Vorbis) removes perceptual detail.
- A container (MP4, MKV, WebM) holds streams; a codec (H.264, VP9, AAC) encodes them. They are not the same thing.
- Editing terms: cut/trim, ripple delete, transition, title, keyframe, render/export.
Worked example
60 s stereo, 44.1 kHz, 16-bit PCM: 44,100 samples/s × 2 bytes × 2 channels × 60 s = 10,584,000 bytes ≈ 10.1 MB. If exported to MP3 at 128 kbps, size ≈ 128,000 bits/s × 60 / 8 = 960,000 bytes ≈ 0.92 MB. The MP3 is smaller because it is lossy.
Traps
Do not confuse sample rate with bit depth. Do not call MP4 a codec. Do not assume higher resolution always means better quality if bitrate is starved. Check whether the question asks for bytes or bits. Mono uses one channel, not two.