Transcript Multimedia Notes

Int 2 Multimedia Revision
Digitised Sound
• Analogue sound recorded from person, or
real instruments
Digitised Sound Data
• Sound card
– Circuit board managing recording and
playback of sound
– Own processor and memory to help CPU.
• Microphone (input)
– Captures sound
• Speakers (output)
– Playback sound
Storage of Sound Data
• RAW
– Uncompressed file format
• WAV
– Lossless compression file format
• MP3
– Lossy compression file format
Terms
• Lossy Compression
– Reduces file size, but also reduces quality
• Sampling depth / resolution
– No of bits to store sample of sound
– More bits = better quality = larger file size
• Sampling frequency (Hz)
– No of samples of sound per second
• Sound time
– Duration in seconds
Features of Sound Editing
• Crop
– Shortens track length
• Decrease Sampling depth
– less bits = poorer quality = smaller file size
• Decrease Sampling frequency
– poorer quality & smaller file size
• Volume
– Adjust loudness
• Reverse
– Playing track backwards
• Special effects
– Echoes, reverberation
Synthesised Sound
• Artificially produced by computer
MIDI (Musical Instrument Digital Interface)
• Record synthesised music on computer
system.
• Midi keyboard used to play music
• Each note described by attributes (bit like
vector graphics)
MIDI Attributes
• Instrument
– Produces different sounds to represents various
instruments – violin, flute…
• Pitch
– Frequency of note
• Volume
– How loudly or softly music note is played
• Duration
– Length of note
• Tempo
– Speed of music
Macros
• Recording series of actions and then assigning
this to a set of keystrokes
• Used to customise a package.
Advantages
• Saves time
• Always playback accurately
• Customises a package
Examples
• Changing page layout
• Automating mail merge
Standard Algorithms
•
Input validation
– To ensure that data entered falls within a
valid range
Example
1. Loop
2.
Get value from user
3.
If value not in range then
4.
Display error message
5.
End if
6. Until value in range
Standard Algorithms
• Counting Occurrences
– Counts no of times a value appears in a list
• Linear Search
– Finds a value within a list
• Finding Maximum
– Finds the highest number within a set
• Finding Minimum
– Finds the smallest number within a set