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--- video_files:formulas [2025/05/16 21:54] – peter
+++ video_files:formulas [2025/05/17 07:24] (current) – peter
@@ Line 1: / Line 1: @@
 ====== Video Files - Formulas ======
+===== General =====
 <code>
@@ Line 18: / Line 20: @@
   * 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).
+  * Divide by 1,000 to to convert megabits (Mb) to megabytes (MB), or megabytes to gigabytes.
 <code>
@@ Line 25: / Line 27: @@
 </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>