====== Video Files - Formulas ======

===== General =====

<code>
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)
</code>

<WRAP info>
**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.

<code>
1/8 * 60 / 1000 = 0.0075.
</code>

</WRAP>

----

===== Picture File Size =====

<code>
File Size = width x height x colour depth x frame rate x duration
</code>

<WRAP info>
**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.

</WRAP>

----

===== Sound File Size =====

<code>
Sound File Size = sample rate x duration x bit depth x number of channels
</code>

<WRAP info>
**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.

</WRAP>

----

===== Bitrate =====

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

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

Video Bitrate = Total Bitrate - Audio Bitrate
</code>

----

===== Duration =====

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

----

===== Filesize =====

<code>
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)  
</code>

----

===== 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.

<code>
audio bitdepth = audio bitrate / audio_channels / audio sample rate
</code>

<WRAP info>
**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.
</WRAP>

----

===== Sound Bitrate =====

<code>
bit rate = audio sample rate * audio channels * audio bit depth
</code>

----

===== Sound File Size =====

<code>
Sound File Size = sample rate x duration x bit depth x number of channels
</code>