How does android implement SoundPool for playing sound effects in a short time?

Implementation Technology: android. media. SoundPool (manages and plays audio resources of applications and loads them directly to the memory ).

I. Basic Knowledge:

1. Create a SoundPool:

Let's take a look at the definition of the SoundPool function, as follows:

[Java]

Public SoundPool (

Int maxStream, // maximum number of streams simultaneously played

Int streamType, // stream type, which is generally STREAM_MUSIC

Int srcQuality // sampling rate conversion quality. No effect currently. Use 0 as the default value.

)

Public SoundPool (

Int maxStream, // maximum number of streams simultaneously played

Int streamType, // stream type, which is generally STREAM_MUSIC

Int srcQuality // sampling rate conversion quality. No effect currently. Use 0 as the default value.

) Eg.

SoundPool soundPool = new SoundPool (3, AudioManager. STREAM_MUSIC, 0 );

Creates a SoundPool that supports simultaneous playback of up to three streams and marks the type as music.

2. Load an audio file:

You can use either of the following methods:

[Java]

Int load (Context context, int resId, int priority) // load data from the APK Resource

Int load (FileDescriptor fd, long offset, long length, int priority) // load data from the FileDescriptor object

Int load (AssetFileDescriptor afd, int priority) // load data from the Asset object

Int load (String path, int priority) // load data from the complete file path

Int load (Context context, int resId, int priority) // load data from the APK Resource

Int load (FileDescriptor fd, long offset, long length, int priority) // load data from the FileDescriptor object

Int load (AssetFileDescriptor afd, int priority) // load data from the Asset object

Int load (String path, int priority) // load from the complete file path name. I currently use the first one, which is loaded from the APK Resource:

[Java]

Int load (

Context context, // the Context of the application, that is, the current Activity, which can be understood as who calls this method.

Int resId, // resource ID

Int priority // priority. Set this parameter to 1.

)

Int load (

Context context, // the Context of the application, that is, the current Activity, which can be understood as who calls this method.

Int resId, // resource ID

Int priority // priority. Set this parameter to 1.

)

3. Playback sound effects:

[Java]

Int play (

Int soundID, // the ID of the music to be played

Float leftVolume, // left audio volume

Float rightVolume, // right audio volume

Int priority, // priority, 0 is the lowest

Int loop, // number of cycles. 0 indicates no loop, and-1 indicates permanent loop.

Float rate // playback speed. The value ranges from 0.5 to 2.0, and 1 indicates the normal speed.

)

Int play (

Int soundID, // the ID of the music to be played

Float leftVolume, // left audio volume

Float rightVolume, // right audio volume

Int priority, // priority, 0 is the lowest

Int loop, // number of cycles. 0 indicates no loop, and-1 indicates permanent loop.

Float rate // playback speed. The value ranges from 0.5 to 2.0, and 1 indicates the normal speed.

)

4. Pause sound effects:

[Java]

Void pause (int streamID) // The parameter is the sound effect ID.

Void pause (int streamID) // The parameter is the sound effect ID.

Ii. Programming implementation:

1. Edit the interface (reslayoutmain. xml ):

[Java]

　　

Android: orientation = "vertical"

Android: layout_width = "fill_parent"

Android: layout_height = "fill_parent"

>

　　

Android: text = "Playing Sound 1"

Android: id = "@ + id/Button01"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

Android: text = "playback sound 2"

Android: id = "@ + id/Button02"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

Android: text = "Pause sound 1"

Android: id = "@ + id/Button1Pause"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

Android: text = "Pause sound 2"

Android: id = "@ + id/Button2Pause"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

　　

Android: orientation = "vertical"

Android: layout_width = "fill_parent"

Android: layout_height = "fill_parent"

>

　　

Android: text = "Playing Sound 1"

Android: id = "@ + id/Button01"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

Android: text = "playback sound 2"

Android: id = "@ + id/Button02"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

Android: text = "Pause sound 1"

Android: id = "@ + id/Button1Pause"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

Android: text = "Pause sound 2"

Android: id = "@ + id/Button2Pause"

Android: layout_width = "fill_parent"

Android: layout_height = "wrap_content">

　　

　　

LinearLayout defines a linear layout of vertical (vertical direction.

In this layout, fill in four button controls, including the text, id, layout_width, and layout_height parameters.

The interface layout is as follows:

2. code editing (srcwyfzclMyActivity. java ):

[Java]

Package wyf. zcl;

Import java. util. HashMap; // introduce related packages

Import android. app. Activity;

Import android. media. AudioManager;

Import android. media. SoundPool;

Import android. OS. Bundle;

Import android. view. View;

Import android. widget. Button;

Import android. widget. Toast;

Public class MyActivity extends Activity {

/** Called when the activity is first created .*/

SoundPool sp; // gets a sound pool reference

HashMap spMap; // get a map reference

Button b1; // specifies the audio playback control Button.

Button b1Pause; // specifies the pause control Button.

Button b2; // audio playback control Button

Button b2Pause; // specifies the pause control Button.

@ Override

Public void onCreate (Bundle savedInstanceState ){

Super. onCreate (savedInstanceState );

SetContentView (R. layout. main );

InitSoundPool (); // initialize the sound pool

B1 = (Button) findViewById (R. id. Button01); // audio playback control Button instantiation

B2 = (Button) findViewById (R. id. Button02); // audio playback control Button instantiation

B1Pause = (Button) findViewById (R. id. Button1Pause );

B2Pause = (Button) findViewById (R. id. Button2Pause );

B1.setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

PlaySound (); // play the first sound effect, loop through it

Toast. makeText (MyActivity. this, "Playing Sound 1", Toast. LENGTH_SHORT). show ();

}});

B1Pause. setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

Sp. pause (spMap. get (1 ));

Toast. makeText (MyActivity. this, "Pause sound 1", Toast. LENGTH_SHORT). show ();

}});

B2.setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

PlaySound (); // play the second sound, loop it over

Toast. makeText (MyActivity. this, "Playing Sound 2", Toast. LENGTH_SHORT). show ();

}});

B2Pause. setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

Sp. pause (spMap. get (2 ));

Toast. makeText (MyActivity. this, "Pause sound 2", Toast. LENGTH_SHORT). show ();

}});

}

Public void initSoundPool () {// initialize the sound pool

Sp = new SoundPool (

5, // maxStreams parameter, which is used to set the number of sound effects that can be played at the same time

AudioManager. STREAM_MUSIC, // streamType parameter. This parameter sets the audio type, which is usually set to STREAM_MUSIC in games.

0 // srcQuality parameter, which sets the quality of the audio file. Currently, no effect is available. Set it to 0 as the default value.

);

SpMap = new HashMap ();

SpMap. put (1, sp. load (this, R. raw. attack02, 1 ));

SpMap. put (2, sp. load (this, R. raw. attack14, 1 ));

}

Public void playSound (int sound, int number) {// playback sound. The parameter sound is the id of the playback sound, and the parameter number is the number of playback sound effects.

AudioManager am = (AudioManager) this. getSystemService (this. AUDIO_SERVICE); // instantiate the AudioManager object

Float audioMaxVolumn = am. getStreamMaxVolume (AudioManager. STREAM_MUSIC); // returns the maximum volume of the current AudioManager object.

Float audioCurrentVolumn = am. getStreamVolume (AudioManager. STREAM_MUSIC); // return the volume of the current AudioManager object.

Float volumnRatio = audioCurrentVolumn/audioMaxVolumn;

Sp. play (

SpMap. get (sound), // the id of the music to be played

VolumnRatio, // left audio volume

VolumnRatio, // right-channel volume

1, // priority, 0 is the lowest

Number, // number of cycles. 0 indicates no loops, and-1 indicates no permanent loops.

1 // playback speed. The value ranges from 0.5 to 2.0. 1 indicates the normal speed.

);

}

}

Package wyf. zcl;

Import java. util. HashMap; // introduce related packages

Import android. app. Activity;

Import android. media. AudioManager;

Import android. media. SoundPool;

Import android. OS. Bundle;

Import android. view. View;

Import android. widget. Button;

Import android. widget. Toast;

Public class MyActivity extends Activity {

/** Called when the activity is first created .*/

SoundPool sp; // gets a sound pool reference

HashMap spMap; // get a map reference

Button b1; // specifies the audio playback control Button.

Button b1Pause; // specifies the pause control Button.

Button b2; // audio playback control Button

Button b2Pause; // specifies the pause control Button.

@ Override

Public void onCreate (Bundle savedInstanceState ){

Super. onCreate (savedInstanceState );

SetContentView (R. layout. main );

InitSoundPool (); // initialize the sound pool

B1 = (Button) findViewById (R. id. Button01); // audio playback control Button instantiation

B2 = (Button) findViewById (R. id. Button02); // audio playback control Button instantiation

B1Pause = (Button) findViewById (R. id. Button1Pause );

B2Pause = (Button) findViewById (R. id. Button2Pause );

B1.setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

PlaySound (); // play the first sound effect, loop through it

Toast. makeText (MyActivity. this, "Playing Sound 1", Toast. LENGTH_SHORT). show ();

}});

B1Pause. setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

Sp. pause (spMap. get (1 ));

Toast. makeText (MyActivity. this, "Pause sound 1", Toast. LENGTH_SHORT). show ();

}});

B2.setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

PlaySound (); // play the second sound, loop it over

Toast. makeText (MyActivity. this, "Playing Sound 2", Toast. LENGTH_SHORT). show ();

}});

B2Pause. setOnClickListener (new View. OnClickListener (){

@ Override

Public void onClick (View v ){

Sp. pause (spMap. get (2 ));

Toast. makeText (MyActivity. this, "Pause sound 2", Toast. LENGTH_SHORT). show ();

}});

}

Public void initSoundPool () {// initialize the sound pool

Sp = new SoundPool (

5, // maxStreams parameter, which is used to set the number of sound effects that can be played at the same time

AudioManager. STREAM_MUSIC, // streamType parameter. This parameter sets the audio type, which is usually set to STREAM_MUSIC in games.

0 // srcQuality parameter, which sets the quality of the audio file. Currently, no effect is available. Set it to 0 as the default value.

);

SpMap = new HashMap ();

SpMap. put (1, sp. load (this, R. raw. attack02, 1 ));

SpMap. put (2, sp. load (this, R. raw. attack14, 1 ));

}

Public void playSound (int sound, int number) {// playback sound. The parameter sound is the id of the playback sound, and the parameter number is the number of playback sound effects.

AudioManager am = (AudioManager) this. getSystemService (this. AUDIO_SERVICE); // instantiate the AudioManager object

Float audioMaxVolumn = am. getStreamMaxVolume (AudioManager. STREAM_MUSIC); // returns the maximum volume of the current AudioManager object.

Float audioCurrentVolumn = am. getStreamVolume (AudioManager. STREAM_MUSIC); // return the volume of the current AudioManager object.

Float volumnRatio = audioCurrentVolumn/audioMaxVolumn;

Sp. play (

SpMap. get (sound), // the id of the music to be played

VolumnRatio, // left audio volume

VolumnRatio, // right-channel volume

1, // priority, 0 is the lowest

Number, // number of cycles. 0 indicates no loops, and-1 indicates no permanent loops.

1 // playback speed. The value ranges from 0.5 to 2.0. 1 indicates the normal speed.

);

}

}

The first few imports are used to import related packages on which the program depends;

Then there is the Activity class, which is equivalent to registering the callback function of our interface. @ Override refers to the onCreate () function of the Activity. This method is called when MyActivity (that is, our window) is created.

The initSoundPool () function initializes the sound pool;

FindViewById instantiate the button control;

@ Override: the Key listening function setOnKeyListener ().

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