SDL_mix not working as expected

SDL Development
1

Hi,

I don’t know if this is the right place to ask, but I’m trying to
accompany my game with sound right now. I wrote a static SoundPlayer class
(I know static is bad, but I’m just learning right now) as a wrapper
around SDL_mix. It looks like this:

Header File:

#ifndef SOUNDPLAYER_H_INCLUDED
#define SOUNDPLAYER_H_INCLUDED

#include <SDL_mixer.h>

class SoundPlayer
{
public:

static void playSound(int id);
static void playMusic(int id);
static void closeMix();

private:

static Mix_Chunk* sound;
static Mix_Chunk* music;
static int channel;
static int musicChannel;
static bool eating;

};

#endif // SOUNDPLAYER_H_INCLUDED

Source file:

#include “soundplayer.h”

Mix_Chunk* SoundPlayer::sound;
Mix_Chunk* SoundPlayer::music;
int SoundPlayer::channel;
int SoundPlayer::musicChannel;
bool SoundPlayer::eating = false;

void SoundPlayer::playMusic(int id)
{
Mix_FreeChunk(music);

switch (id)
{
    case 1 : sound = Mix_LoadWAV("music/stage1.ogg"); break;
    default:
        break;
}

if(music == NULL)
    fprintf(stderr, "Unable to load WAV file: %s\n", Mix_GetError());

musicChannel = Mix_PlayChannel(1, sound, 0);

}

void SoundPlayer::playSound(int id)
{
if (Mix_Playing(channel) && !eating) return;

if (id == 1) eating = true;
else eating = false;

Mix_FreeChunk(sound);

switch (id)
{
    case 1 : sound = Mix_LoadWAV("sounds/Eat.ogg"); break;
    case 2 : sound = Mix_LoadWAV("sounds/1Up.ogg"); break;
    case 3 : sound = Mix_LoadWAV("sounds/Bite.ogg"); break;
    default:
        break;
}

if(sound == NULL)
    fprintf(stderr, "Unable to load WAV file: %s\n", Mix_GetError());

channel = Mix_PlayChannel(2, sound, 0);

}

void SoundPlayer::closeMix()
{
Mix_FreeChunk(music);
Mix_FreeChunk(sound);
Mix_CloseAudio();
}

Now what happens it this: When I call playMusic(1), the file
music/stage1.ogg is loaded and plays and expected. However, once I call
playSound(1), the sound for eating an egg is indeed played, but the music
just stops and doesn’t continue playing, even after the sound effect is
over.
I checked that SDL_mix uses the right channels by placing rather harsh
control statements (i.e. “if (channel != 2) exit(channel)”) which didn’t
trigger. So it uses channel 1 for music and channel 2 for sound.

Why does this happen? The whole point of using SDL_mix is being able to
play different sounds at the same time.

thanks,

Andreas

2

You are using the same variable to play both the music and audio effects:
In SoundPlayer::playMusic(int id), you are loading and playing using
"sound" as a pointer, not “music”.
In SoundPlayer::playSound(int id), you free the same pointer and loads
it again with the wanted sound effect.

I suggest you to use LoadMUS/Play_Music API provided by SDL_Mixer to
play background music, leaving the other channels for sound effects.

Leonardo

2010/3/8 :> Hi,

I don’t know if this is the right place to ask, but I’m trying to
accompany my game with sound right now. I wrote a static SoundPlayer class
(I know static is bad, but I’m just learning right now) as a wrapper
around SDL_mix. It looks like this:

Header File:

#ifndef SOUNDPLAYER_H_INCLUDED
#define SOUNDPLAYER_H_INCLUDED

#include <SDL_mixer.h>

class SoundPlayer
{
? ?public:

? ?static void playSound(int id);
? ?static void playMusic(int id);
? ?static void closeMix();

? ?private:

? ?static Mix_Chunk* sound;
? ?static Mix_Chunk* music;
? ?static int channel;
? ?static int musicChannel;
? ?static bool eating;
};

#endif // SOUNDPLAYER_H_INCLUDED

Source file:

#include “soundplayer.h”

Mix_Chunk* SoundPlayer::sound;
Mix_Chunk* SoundPlayer::music;
int SoundPlayer::channel;
int SoundPlayer::musicChannel;
bool SoundPlayer::eating = false;

void SoundPlayer::playMusic(int id)
{
? ?Mix_FreeChunk(music);

? ?switch (id)
? ?{
? ? ? ?case 1 : sound = Mix_LoadWAV(“music/stage1.ogg”); break;
? ? ? ?default:
? ? ? ? ? ?break;
? ?}

? ?if(music == NULL)
? ? ? ?fprintf(stderr, “Unable to load WAV file: %s\n”, Mix_GetError());

? ?musicChannel = Mix_PlayChannel(1, sound, 0);
}

void SoundPlayer::playSound(int id)
{
? ?if (Mix_Playing(channel) && !eating) return;

? ?if (id == 1) eating = true;
? ?else eating = false;

? ?Mix_FreeChunk(sound);

? ?switch (id)
? ?{
? ? ? ?case 1 : sound = Mix_LoadWAV(“sounds/Eat.ogg”); break;
? ? ? ?case 2 : sound = Mix_LoadWAV(“sounds/1Up.ogg”); break;
? ? ? ?case 3 : sound = Mix_LoadWAV(“sounds/Bite.ogg”); break;
? ? ? ?default:
? ? ? ? ? ?break;
? ?}

? ?if(sound == NULL)
? ? ? ?fprintf(stderr, “Unable to load WAV file: %s\n”, Mix_GetError());

? ?channel = Mix_PlayChannel(2, sound, 0);
}

void SoundPlayer::closeMix()
{
? ?Mix_FreeChunk(music);
? ?Mix_FreeChunk(sound);
? ?Mix_CloseAudio();
}

Now what happens it this: When I call playMusic(1), the file
music/stage1.ogg is loaded and plays and expected. However, once I call
playSound(1), the sound for eating an egg is indeed played, but the music
just stops and doesn’t continue playing, even after the sound effect is
over.
I checked that SDL_mix uses the right channels by placing rather harsh
control statements (i.e. “if (channel != 2) exit(channel)”) which didn’t
trigger. So it uses channel 1 for music and channel 2 for sound.

Why does this happen? The whole point of using SDL_mix is being able to
play different sounds at the same time.

thanks,

Andreas

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

3

You should look at MixBox (http://code.bluedinosaurs.com/SDL.html), even if
only to get ideas. I think you’re trying some of the same things that it
does. If you’re just trying to learn more about SDL and SDL_mixer, then you
should keep improving your code.

Jonny DOn Mon, Mar 8, 2010 at 7:46 AM, Leonardo Guilherme < leonardo.guilherme at gmail.com> wrote:

You are using the same variable to play both the music and audio effects:
In SoundPlayer::playMusic(int id), you are loading and playing using
"sound" as a pointer, not “music”.
In SoundPlayer::playSound(int id), you free the same pointer and loads
it again with the wanted sound effect.

I suggest you to use LoadMUS/Play_Music API provided by SDL_Mixer to
play background music, leaving the other channels for sound effects.

Leonardo

2010/3/8 :

Hi,

I don’t know if this is the right place to ask, but I’m trying to
accompany my game with sound right now. I wrote a static SoundPlayer
class
(I know static is bad, but I’m just learning right now) as a wrapper
around SDL_mix. It looks like this:

Header File:

#ifndef SOUNDPLAYER_H_INCLUDED
#define SOUNDPLAYER_H_INCLUDED

#include <SDL_mixer.h>

class SoundPlayer
{
public:

static void playSound(int id);
static void playMusic(int id);
static void closeMix();

private:

static Mix_Chunk* sound;
static Mix_Chunk* music;
static int channel;
static int musicChannel;
static bool eating;
};

#endif // SOUNDPLAYER_H_INCLUDED

Source file:

#include “soundplayer.h”

Mix_Chunk* SoundPlayer::sound;
Mix_Chunk* SoundPlayer::music;
int SoundPlayer::channel;
int SoundPlayer::musicChannel;
bool SoundPlayer::eating = false;

void SoundPlayer::playMusic(int id)
{
Mix_FreeChunk(music);

switch (id)
{
case 1 : sound = Mix_LoadWAV(“music/stage1.ogg”); break;
default:
break;
}

if(music == NULL)
fprintf(stderr, “Unable to load WAV file: %s\n”, Mix_GetError());

musicChannel = Mix_PlayChannel(1, sound, 0);
}

void SoundPlayer::playSound(int id)
{
if (Mix_Playing(channel) && !eating) return;

if (id == 1) eating = true;
else eating = false;

Mix_FreeChunk(sound);

switch (id)
{
case 1 : sound = Mix_LoadWAV(“sounds/Eat.ogg”); break;
case 2 : sound = Mix_LoadWAV(“sounds/1Up.ogg”); break;
case 3 : sound = Mix_LoadWAV(“sounds/Bite.ogg”); break;
default:
break;
}

if(sound == NULL)
fprintf(stderr, “Unable to load WAV file: %s\n”, Mix_GetError());

channel = Mix_PlayChannel(2, sound, 0);
}

void SoundPlayer::closeMix()
{
Mix_FreeChunk(music);
Mix_FreeChunk(sound);
Mix_CloseAudio();
}

Now what happens it this: When I call playMusic(1), the file
music/stage1.ogg is loaded and plays and expected. However, once I call
playSound(1), the sound for eating an egg is indeed played, but the music
just stops and doesn’t continue playing, even after the sound effect is
over.
I checked that SDL_mix uses the right channels by placing rather harsh
control statements (i.e. “if (channel != 2) exit(channel)”) which didn’t
trigger. So it uses channel 1 for music and channel 2 for sound.

Why does this happen? The whole point of using SDL_mix is being able to
play different sounds at the same time.

thanks,

Andreas

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

4

Hi,

You are using the same variable to play both the music and audio effects:

Yeah, I already noticed that pretty much right after sending the email.
Stupid copy-paste error -.- It was quite embarassing to post such a stupid
mixtake to the mailing list xD

Thanks for pointing me towards the Play_Music API. Seems very nice,
especially because it takes care of stuff I was worried about, like
looping and fade-outs. I’m really just getting started, so I’m not aware
of many features just yet.

thanks,

Andreas> You are using the same variable to play both the music and audio effects:

In SoundPlayer::playMusic(int id), you are loading and playing using
"sound" as a pointer, not “music”.
In SoundPlayer::playSound(int id), you free the same pointer and loads
it again with the wanted sound effect.

I suggest you to use LoadMUS/Play_Music API provided by SDL_Mixer to
play background music, leaving the other channels for sound effects.

Leonardo

2010/3/8 <@aheld_at_uni-koblenz>:

Hi,

I don’t know if this is the right place to ask, but I’m trying to
accompany my game with sound right now. I wrote a static SoundPlayer
class
(I know static is bad, but I’m just learning right now) as a wrapper
around SDL_mix. It looks like this:

Header File:

#ifndef SOUNDPLAYER_H_INCLUDED
#define SOUNDPLAYER_H_INCLUDED

#include <SDL_mixer.h>

class SoundPlayer
{
? ?public:

? ?static void playSound(int id);
? ?static void playMusic(int id);
? ?static void closeMix();

? ?private:

? ?static Mix_Chunk* sound;
? ?static Mix_Chunk* music;
? ?static int channel;
? ?static int musicChannel;
? ?static bool eating;
};

#endif // SOUNDPLAYER_H_INCLUDED

Source file:

#include “soundplayer.h”

Mix_Chunk* SoundPlayer::sound;
Mix_Chunk* SoundPlayer::music;
int SoundPlayer::channel;
int SoundPlayer::musicChannel;
bool SoundPlayer::eating = false;

void SoundPlayer::playMusic(int id)
{
? ?Mix_FreeChunk(music);

? ?switch (id)
? ?{
? ? ? ?case 1 : sound = Mix_LoadWAV(“music/stage1.ogg”); break;
? ? ? ?default:
? ? ? ? ? ?break;
? ?}

? ?if(music == NULL)
? ? ? ?fprintf(stderr, “Unable to load WAV file: %s\n”, Mix_GetError());

? ?musicChannel = Mix_PlayChannel(1, sound, 0);
}

void SoundPlayer::playSound(int id)
{
? ?if (Mix_Playing(channel) && !eating) return;

? ?if (id == 1) eating = true;
? ?else eating = false;

? ?Mix_FreeChunk(sound);

? ?switch (id)
? ?{
? ? ? ?case 1 : sound = Mix_LoadWAV(“sounds/Eat.ogg”); break;
? ? ? ?case 2 : sound = Mix_LoadWAV(“sounds/1Up.ogg”); break;
? ? ? ?case 3 : sound = Mix_LoadWAV(“sounds/Bite.ogg”); break;
? ? ? ?default:
? ? ? ? ? ?break;
? ?}

? ?if(sound == NULL)
? ? ? ?fprintf(stderr, “Unable to load WAV file: %s\n”, Mix_GetError());

? ?channel = Mix_PlayChannel(2, sound, 0);
}

void SoundPlayer::closeMix()
{
? ?Mix_FreeChunk(music);
? ?Mix_FreeChunk(sound);
? ?Mix_CloseAudio();
}

Now what happens it this: When I call playMusic(1), the file
music/stage1.ogg is loaded and plays and expected. However, once I call
playSound(1), the sound for eating an egg is indeed played, but the
music
just stops and doesn’t continue playing, even after the sound effect is
over.
I checked that SDL_mix uses the right channels by placing rather harsh
control statements (i.e. “if (channel != 2) exit(channel)”) which didn’t
trigger. So it uses channel 1 for music and channel 2 for sound.

Why does this happen? The whole point of using SDL_mix is being able to
play different sounds at the same time.

thanks,

Andreas

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org