1. Computer Science 1 Week 11

2. This Week... QBasic While Loops QBasic While Loops Audio Basics Audio Basics

4. Incrementing Variables Added values to variables

5. Incrementing Variables It is very useful to increment variable It is very useful to increment variable  basically, you just add or subtract a value  this is very common in programming  some languages have special notation How? How?  assign a variable using itself +/- a value  It’s pretty easy to understand, but a little strange

6. LET var = var + 1 General Format Same Variable

7. LET x = 5 LET x = x + 1 PRINT x Increment Example: What Happens? 6

8. 6 Increment Example Output

9. LET x = 10 PRINT x LET x = x + 1 PRINT x Increment Example 2 11

10. 10 11 Increment Example 2 Output

11. INPUT "Guess:", guess IF guess = 2 THEN LET correct = correct + 1 END IF PRINT "Correct is"; correct Increment Example 3

12. Guess: 5 Correct is 0 Increment Example 3 Output

13. Guess: 2 Correct is 1 Increment Example 3 Output

15. QBasic While Loops While Loops

16. While Statement Repeats a block of statements Repeats a block of statements Condition to loop Condition to loop  each time an expression is examined  if True, the loop continues Think of it as an If Statement that loops Think of it as an If Statement that loops

17. If Statement vs. While Statement Uses a conditional expression If StatementWhile Statement Executes a block of statements Executes only onceExecutes multiple times

18. DO WHILE condition Statements LOOP While Statement Syntax

19. DO WHILE x <> 10 INPUT "Enter ten:", x LOOP PRINT "Done" While Loop Example

20. Enter ten: 7 Enter ten: 2 Enter ten: 10 Done While Loop Example Output

21. LET x = 10 DO WHILE x <> 10 INPUT "Enter ten:", x LOOP PRINT "Done" While Loop Example 2 Hmmm

22. Done While Loop Example 2 Output

23. INPUT Correct DO WHILE Guess <> Correct INPUT Guess LOOP PRINT "Done" While Loop Example 3

24. x = 1 DO WHILE x <= 5 PRINT x x = x + 1 LOOP While Loop Example 4

25. 1234512345 While Loop Example 4 Output

26. QBasic Lab While Loops – Secret Number Game

27. Lab: Secret Number Game Overview: Overview:  you will create a game  player guess a secret number Objectives: Objectives:  input a number from the user  use the While Loop  display "too high" or "to low"

28. Remember... Turn your program to Turn your program to  Lab9 in SacCT You must do your own work You must do your own work If you do not turn in your program, you will not get credit! If you do not turn in your program, you will not get credit!

30. Sequenced Music Sound Using Instructions

31. Sequenced Music Basics Think of it as an audio program Think of it as an audio program  it is equivalent to a music sheet!  contains notes, tempo, instruments, etc... Computers synthesize the sounds Computers synthesize the sounds  Wavetable contains pre-recorded sounds  e.g. piano, trumpet, violin, applause  not able to create vocals

32. Sequenced Music Basics Advantages Advantages  easy to edit – music sheet!  takes little space Sequencers Sequencers  are used to create sequenced music  many allow you to also use waveform audio  e.g. FL Studio, Adobe Audition,...

33. MIDI Musical Instrument Digital Interface Musical Instrument Digital Interface  way to connect musical instruments to a computer  still used today MIDI Files MIDI Files  standard also specifies a way to store music data  can be used in a webpage Extension: mid or midi Extension: mid or midi

34. Example Sequencer Adobe Audition

35. Waveform Audio How Sound is Represented

36. Waveform Audio Basics Digital representation of sound Digital representation of sound PCM PCM  Pulse-Code Modulation  data represents the vibrations that we hear Think of it as a "bitmap" of sound Think of it as a "bitmap" of sound  anything can be recorded as waveforms  however, like bitmaps, editing is difficult

37. Waveform File Types MP3 MP3  acronym for MPEG Level 3  created by Motion Pictures Expert Group  excellent compression – lossy  can be used for sound and video  extension: mp3

38. Waveform File Types Microsoft Wave File Microsoft Wave File  lossless compression – tends to be huge  extension: wav Windows Media Audio Windows Media Audio  lossy compression – competes with MP3  has better security and information features  extension:. wma

39. Adding a Waveform to Webpages Embed Tag Embed Tag   Background Sound Tag Background Sound Tag  Microsoft Extension to HTML  

40. Waveform vs. Sequenced Stored as raw data (PCM)Stored as instructions WaveformSequenced Files can be largeFiles tend to be small Difficult to editEasy to edit – music sheet Can store any soundCannot create vocals