Sound Effects and Music Using DSL

//Using SDL, SDL_image, SDL_mixer, standard IO, and strings
#include <SDL.h>
#include <SDL_image.h>
#include <SDL_mixer.h>
#include <stdio.h>
#include <string>

SDL_mixer is a library use to make audio playing easier (because it can get complicated). to set it up just like set up SDL_image. Like before, it's just a matter of having the headers files, library files, and binary files in the right place with your compiler configured to use them.

     //Initialize PNG loading
                int imgFlags = IMG_INIT_PNG;
                if( !( IMG_Init( imgFlags ) & imgFlags ) )
                {
                    printf( "SDL_image could not initialize! SDL_image Error: %s\n", IMG_GetError() );
                    success = false;
                }

                 //Initialize SDL_mixer
                if( Mix_OpenAudio( 44100, MIX_DEFAULT_FORMAT, 2, 2048 ) < 0 )
                {
                    printf( "SDL_mixer could not initialize! SDL_mixer Error: %s\n", Mix_GetError() );
                    success = false;
                }

To initialize SDL_mixer need to call Mix_OpenAudio. The first argument sets the sound frequency, and 44100 is a standard frequency that works on most systems. The second argument determines the sample format, which again here using the default. The third argument is the number of hardware channels, and here using 2 channels for stereo. The last argument is the sample size, which determines the size of the chunks use when playing sound

bool loadMedia()
{
    //Loading success flag
    bool success = true;

    //Load prompt texture
    if( !gPromptTexture.loadFromFile( "21_sound_effects_and_music/prompt.png" ) )
    {
        printf( "Failed to load prompt texture!\n" );
        success = false;
    }

    //Load music
    gMusic = Mix_LoadMUS( "21_sound_effects_and_music/beat.wav" );
    if( gMusic == NULL )
    {
        printf( "Failed to load beat music! SDL_mixer Error: %s\n", Mix_GetError() );
        success = false;
    }

Here load our splash texture and sound.
To load music call Mix_LoadMUS and to load sound effect call Mix_LoadWAV. 

    //Load sound effects
    gScratch = Mix_LoadWAV( "21_sound_effects_and_music/scratch.wav" );
    if( gScratch == NULL )
    {
        printf( "Failed to load scratch sound effect! SDL_mixer Error: %s\n", Mix_GetError() );
        success = false;
    }
 
    gHigh = Mix_LoadWAV( "21_sound_effects_and_music/high.wav" );
    if( gHigh == NULL )
    {
        printf( "Failed to load high sound effect! SDL_mixer Error: %s\n", Mix_GetError() );
        success = false;
    }

    gMedium = Mix_LoadWAV( "21_sound_effects_and_music/medium.wav" );
    if( gMedium == NULL )
    {
        printf( "Failed to load medium sound effect! SDL_mixer Error: %s\n", Mix_GetError() );
        success = false;
    }

    gLow = Mix_LoadWAV( "21_sound_effects_and_music/low.wav" );
    if( gLow == NULL )
    {
        printf( "Failed to load low sound effect! SDL_mixer Error: %s\n", Mix_GetError() );
        success = false;
    }

    return success;
}

In the event loop, play a sound effect when the 1, 2, 3, or 4 keys are pressed. The way to play a Mix_Chunk is by calling Mix_PlayChannel. The first argument is the channel you want to use to play it
 //Handle key press
                    else if( e.type == SDL_KEYDOWN )
                    {
                        switch( e.key.keysym.sym )
                        {
                            //Play high sound effect
                            case SDLK_1:
                            Mix_PlayChannel( -1, gHigh, 0 );
                            break;
                         
                            //Play medium sound effect
                            case SDLK_2:
                            Mix_PlayChannel( -1, gMedium, 0 );
                            break;
                         
                            //Play low sound effect
                            case SDLK_3:
                            Mix_PlayChannel( -1, gLow, 0 );
                            break;
                         
                            //Play scratch sound effect
                            case SDLK_4:
                            Mix_PlayChannel( -1, gScratch, 0 );
                            break;

play/pause the music on a 9 keypress and stop the music on a 0 keypress.

When the 9 key pressed first check if the music is not playing with Mix_PlayingMusic. If it isn't,start the music with Mix_PlayMusic. The first argument is the music play and the last argument is the number of times to repeat it. Negative 1 is a special valu to loop it until it is stopped.

 case SDLK_9:
                            //If there is no music playing
                            if( Mix_PlayingMusic() == 0 )
                            {
                                //Play the music
                                Mix_PlayMusic( gMusic, -1 );
                            }
                            //If music is being played
                            else
                            {
                                //If the music is paused
                                if( Mix_PausedMusic() == 1 )
                                {
                                    //Resume the music
                                    Mix_ResumeMusic();
                                }
                                //If the music is playing
                                else
                                {
                                    //Pause the music
                                    Mix_PauseMusic();
                                }
                            }
                            break;
                         
                            case SDLK_0:
                            //Stop the music
                            Mix_HaltMusic();
                            break;
                        }
                    }