Sound, Basic: Play random sound effects

[Scott Ferguson]

The Sound component is ideal for adding sound effects to your project.

It is intended for short sounds of perhaps 5 seconds or less.

For longer sounds you should use the Player component.

In this exercise we will make a project that plays random sound effects using the basic functionality of the Sound component.

Create a new project named lrn_snd_basic.

Screen Designer:

Copy all six wav files to the Media list in the Screen Designer.

Change the Screen1.Title to Random sound effects.

Drag and drop a Button component onto the Viewer.

Set Button1.Text to Play.

Drag and drop a Sound component onto the Viewer.

It will appear below the Non-visible components heading.

The instance created is named Sound1.

Note also that the six sound files have been uploaded to the Media list.

Blocks Editor:

We will create a global variable to hold our list of sound files.

Drag and drop a [def variable as] block onto the BE canvas.

Change it's name to sounds.

 - this variable will hold the list of sound effects

Attach a list from csv row block to the [def sounds as] block.

 - this block accepts text data separated by commas and converts it to a list

Attach a text block to the list from csv row block.

Change it's text to baby.wav,door.wav,heartbeat.wav,gong.wav,meow.wav,owl.wav.

 - this data will populate our list and the group of blocks will simplify operations later on

Drag and drop a Screen1.Initialize event block onto the BE canvas.

 - we will use this to pre-load all of the sound effect files before they are played (necessary to avoid an error message)

Drag and snap a foreach block into Screen1.Initialize.

 - it will be used to loop through the sounds list and initialize the sound files

  - the [name var] block will hold each file name in turn as the loop executes

Drag and click a [global sounds] variable block to the in list socket.

 - this completes the shell of the loop

 - the [global sounds] block provides the list for the foreach loop to iterate through

Drag and click a [set Sound1.Source to] block inside the foreach block.

Drag and attach a [value var] block to the to socket of Sound1.Source.

 - the foreach loop begins with the first item in the sounds list and ends with the last item in the list

 - each time through the foreach loop, the Sound1.Source property will be set to the file name stored in the var argument

Drag and drop a Button1.Click block onto the BE canvas.

 - this block will be used to load and play a random sound effect

Drag and drop another [set Player1.Source to] block.

Snap a pick random item block to it and attach a [global sounds] block to it.

 - these blocks will pick a random sound effect file name from the sounds list and set the Sound1.Source block to that value

 - note that [set Player1.Source to] and [set sounds to] look similar as they both contain values that can be read or written, but the 'Source' variable is special in that it is always associated with a Player component

Drag and snap a Sound1.Play block below the Sound1.Source block.

 - now when the user presses the Play button (Button1) a random sound effect will play

 - (Sound1.Play looks different from Sound1.Source because it is a special procedure block that uses the value stored in Sound1.Source to play the sound effect)

 

END.

Now test your project with the emulator or device.

Challenge: The [set Screen1.Title to] block allows us to put data in the Title bar. Can you think of a way to put the file name in Sound1.Source in the Title bar each time the user presses the Play button?

[M. Hossein Amerkashi]

Great work.

Do you have a tutorial on like a soundboard where it can record / play multiple sounds at the same time?

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[Taifun]

I think, Gareth has an example?

see here https://groups.google.com/forum/#!topicsearchin/programming-with-app-inventor/soundboard$20AND$20authorname$3AGareth%7Csort:date%7Cspell:true

Taifun

[Scott Ferguson]

As Taifun says, Gareth has an example if he will share it with you. The only way that I know to get multiple sounds to play at exactly the same time is to have an ImageSprite collide with other ImageSprites simultaneously firing their CollidedWith blocks. Inside those blocks I have the blocks to play piano note chords on my Piano Composer app/project. 

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Scott