cs50 understanding tech (3- multimedia).txt

Audio:

- MIDI (Musical Instrumental Digital Interface): compuer-generated audio standard

- audio file formats: 
  - .WAV (uncomressed)
  - .mp3/.MPEG (compressed)
  - .AAC
  
  
- audio (recording) quality parameters:
  1- sample rate/freq.: no. of snapshots/second taken for digital recording
  2- bit depth: no. of bits used to store a snapshot of a digital recording
  
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  Graphic:
  
  - set of horizontal and vertical pixels (rectanglar) used to from a digital image 
  
  - colors can be represented by using RGB (Red-Green-Blue) format (on scale of 0-255)
    - black = 0 red + 0 green + 0 blue
    - white = 255 red + 255 green + 255 blue
    - red (for instance) = 255 red + 0 green + 0 blue
    
  - computer can represent 1 pixel of colored dot using 3 bytes (24 bits)
    1 byte for Red + 1 byte for Green + 1 byte for blue = 3 bytes = 24 bits 
    
  - hexadecimal system is used in representing color values (for simplicity)
    so we could represent the value 255 (max value for a color) as 0xff => 255
    (so we can say the red color is 0xff0000 succinctly)
  
  - Bitmap (.bmp) file fromat 
  - image resolution: no. of horizontal and vertical pixels used to format digital image
  
  - image formats (.bmp, .gif, .JPEG, .png, ...)
  
  - image formats could be lossy or lossy-less
 
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  Video:
  
  - video is a motion picture consists of set of frames (images) presented sequentially and quickly 
     (perhaps 24 frame per second or 30 frame/second for high quality videos)
     
  - file formats: (.avi, mp4, ....)
  
  - Codec file: is a way of encoding contents of video file (audio, frames, subtitles, ...)