Video File Calc
A video has:
Calculate the raw file size in bytes.
100×100×8×10×10=800,000 bits 800,000÷8=100,000 bytes
The process of taking measurements of an analogue sound wave at regular intervals.
What is sampling?
1280 × 720 resolution, 24-bit colour depth, 30 fps. Calculate raw data per second.
1280×720×24×30 =663,552,000 bits/s
The process of mapping each sampled amplitude to the nearest available digital amplitude level.
What is quantisation?
920 × 1080, 24-bit colour depth, 30 fps, 10 seconds. Calculate file size in MB.
1920×1080×24×30×10 =14,929,920,000 bits
14,929,920,000÷8=1,866,240,000 bytes
1,866,240,000÷1024=1,822,500 KB
1,822,500÷1024=1779.79 MB
A stereo recording uses 48 kHz sampling, 24-bit depth, and lasts 5 minutes. Ignoring compression, this is the approximate amount of storage required.
What is 86.4 MB?
48,000×24×2×300 bits
= 691,200,000 bits
÷ 8 = 86,400,000 bytes
≈ 86.4 MB (decimal)
Video A = 1920 × 1080
Video B = 3840 × 2160
Both have 24-bit colour and 30 fps. How many times more raw data does B require?
Width doubles:
1920×2=3840
Height doubles:
1080×2=2160
Therefore pixels increase by:
2×2=4
Everything else stays the same.
An audio system changes from 8-bit to 16-bit. This is how many times more amplitude levels it can represent.
What is 256 times more?
(answer in photos)
3840 × 2160, 24-bit colour depth, 60 fps, 2 minutes. Calculate file size in GB.
2×60=120 s
3840×2160×24×60×120 =143,327,232,000 bits
143,327,232,000÷8=17,915,904,000 bytes
17,915,904,000÷1024=17,496,000 KB
17,496,000÷1024=17,085.94 MB
17,085.94÷1024=16.69 GB
Two recordings use the same sampling rate, but one uses 8-bit depth and the other uses 16-bit depth. The 16-bit recording represents amplitudes more accurately because it has this many more possible levels.
What is 65,280 more levels?
65,536−256=65,280
(answer in photos)