Table of Contents

Video Files - Formulas

General

File size = bitrate * number of minutes * .0075
Bitrate = file size / (number of minutes * .0075)
Number of minutes = file size / (bitrate * .0075)

otherwise

GB = mbps * minutes * .0075
mbps = GB / (minutes * .0075)
minutes = GB / (mbps * .0075)

NOTE: The .0075 is derived from the following:

  • As there are 8 bits per byte, it is required to device by 8 to determine the bits.
  • To convert the number of minutes to seconds, multiply by 60.
  • Divide by 1,000 to to convert megabits (Mb) to megabytes (MB), or megabytes to gigabytes.
1/8 * 60 / 1000 = 0.0075.

Picture File Size

File Size = width x height x colour depth x frame rate x duration

NOTE:

  • width: In pixels.
  • height: In pixels.
  • color depth: The number of bits used to encode the colour of one pixel.
    • A 1-bit colour depth means that the graphic can only include 2 colours (e.g. 1 = black, 0 = white).
    • A 8-bit colour depth means that the graphic can include up to 256 colours.
    • A 3-Byte colour depth (RGB code) would include 16,777,216 colours.
      • RGB would have a color depth of 3 (24 bits; 8 bits for Red, 8 bits for Green, 8 bits for Blue).
    • A 4-Byte color depth (RGBA) can also be used. (32 bits; 8 bits for Red, 8 bits for Green, 8 bits for Blue; 8 bits for Alpha).
  • frame rate: in fps (frame per seconds).
  • duration: in seconds.

Sound File Size

Sound File Size = sample rate x duration x bit depth x number of channels

NOTE:

  • sample rate: The number of samples being recorded per second; (such as 48,000 samples per second).
  • duration: In seconds.
  • bit depth: The number of bits used to record one sample.
  • channels: 1 is mono, 2 is stereo, 6 is dolby-surround.

Bitrate

Bitrate = file size / (number of minutes * .0075)

Bitrate = (file size * 8) / (duration in seconds)

Video Bitrate = Total Bitrate - Audio Bitrate

Duration

Number of minutes = file size / (bitrate * .0075).

Filesize

file size = bitrate * number of minutes * .0075

file size = duration × frame rate × frame size
  frame size = H × V × color depth
  color depth = 8bitxRGB = 8*3 = 24

Picture File Size = colour depth x width in pixels x height in pixels
  colour depth = RGB=3 bytes; RGBA=4 bytes
  
file size = bitrate * time

file size = duration × file size per sec / 8
  file size per second = fps × frame size

Video File Size = (Bitrate / 8) × Duration

File Size (in Bytes)=(Video Bitrate × Duration)+Audio Bitrate
File Size (in Bytes)=(Video Bitrate × Duration)+((Audio Bitrate x Audio Size)/Audio Channels*6)

Compressed Video File Size (GB) = (Bitrate (Mbps) * Total Time (seconds)) / (8 * 1024)

Sound Bitdepth

See bits per raw sample field.

An approximation of the sound bitdepth can be calculated by using variables: audio sample rate, audio channels and audio bitrate. 

audio bitdepth = audio bitrate / audio_channels / audio sample rate

NOTE: The audio bitrate may need to be multiplied by 1,000 to be in bits.

  • This formula should produce a value such as 1, 2, 3 or 4; which is the number of bytes.
    • When these bytes are multiplied by 8 to convert them to bits, this will result in 8, 16, 24, or 32 bits.

Sound Bitrate

bit rate = audio sample rate * audio channels * audio bit depth

Sound File Size

Sound File Size = sample rate x duration x bit depth x number of channels