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Worked examples to calculate the file sizes of graphics, video and sound data., using the PLAN C 'worked Examples' approach.
Data Representation Worked Examples- Calculating File Sizes
Calculating the size of different types of data usually involves
Converting to different unit of measurement
Calculating total of data in suitable unit of measurement
Calculating overall file size
Rounding up to 2 decimal places
Study the following worked examples to see how to calculate the size of different types of data and then try to solve the related problem.
Calculating Image File Size
Calculate the backing storage required for an 8 bit colour image 400 pixels by 600 pixels.
Express your answer in Kilobytes.
Calculate total- number of pixels in image
400 pixels x 600 pixels = 24, 000 pixels
Calculate overall- image size in bits600 pixels400 pixels
24, 000 pixels x 8 bits per pixel = 240, 000 bits
Convert to bytes
240,000 bits/8 = 30,000 bytes
Convert to Kilobytes
30,000bytes / 1024 = 29.296875 Kb
Round Up to 2 d.p.
Calculate the backing storage required for a 16bit colour image 1024 x 1280 pixels. Express your answer in Megabytes. Show all working
Calculate the backing storage required for a 16 bit colour image 3 inches by 5 inches with a resolution of 40 d.p.i. Express your answer in Kilobytes. Show all working
Convert height and width to pixels
3 inches x 40 d.p.i = 120 pixels
5 inches x 40 d.p.i = 200 pixels
120 pixels x 200 pixels = 24, 000 pixels
Calculate overall- image size in bits
24, 000 pixels x 16 bits = 384, 000 bits
384, 000 ÷ 8 = 48,000 bytes
48, 000 ÷ 1024 = 46.875 Kb
Round Up to 2 d.p
46.875Kb = 46.88 Kb
Calculate the backing storage required for a 32 bit colour image 4 inches by 4 inches with a resolution of 200 d.p.i. Express your answer in Megabytes. Show all working
Calculating Video File Size
A single frameA video clip plays for 32 seconds and was recorded at 25 fps. Each frame has a resolution of 1280 x 720 and a colour depth of 24 bits. Calculate the size of the uncompressed video and write your answer in Gigabytes. Show all your working.
Calculate total- number of pixels in one frame
1280 pixels x 720 pixels = 921, 600 pixels per frame
Calculate total- one frame in bits
1280 pixels921, 600 pixels x 24 bits = 22, 118, 400 bits per frame
Calculate total- number of frames
32 seconds x 25 fps = 800 frames
Calculate overall- video clip size in bits
800 frames x 22, 118, 400 bits per frame = 17,694,720,000 bits
Convert to- Gigabytes
17, 694, 720, 000 /8 /1024 /1024 /1024 = 2.0599365234375 Gb
Round Up to- 2 d.p
2.0599365234375 = 2.06 Gb
A video clip plays for 14 seconds and was recorded at 12 fps. Each frame has a resolution of 640 x 480 and a colour depth of 16 bits. Calculate the size of the uncompressed video and write your answer in Megabytes. Show all your working.
Calculating Sound File Size
Calculate the storage required for an uncompressed 12 second sound which has been created by AQSound at a frequency of 48 kilohertz with a sampling depth of 2 bytes and 6 channels.
Write your answer in megabytes. Show all working.
Convert to samples per second
48kHz x 1000 = 48,000 samples per second
Calculate total- samples in one sound channel
48,000 x 12 seconds = 576, 000 samples
Calculate total- size of one sound channel
576,000 samples x 2bytes = 1, 152, 000 bytes
Calculate overall size of sound
1, 152, 000 bytes x 6 channels = 6,912,000 bytes
Convert to Megabytes
6, 912, 000 bytes ÷ 1024 ÷ 1024 = 6.591796875 Mb
Round Up to 2.d.p
6.591796875 Mb = 6.60 Mb
Calculate the storage required for an uncompressed 10 second sound which has been created by AQSound at a frequency of 24 kilohertz with a sampling depth of 1 bytes in stereo (2 channels).
Write your answer in kilobytes. Show all working.
AMcVey using PLAN C resourcesPage 1