Open an audio device for playback.
int Mix_OpenAudio(SDL_AudioDeviceID devid, const SDL_AudioSpec *spec);
|devid||the device name to open, or 0 for a reasonable default.|
|spec||the audio format you'd like SDL_mixer to work in.|
Returns 0 if successful, -1 on error.
An audio device is what generates sound, so the app must open one to make noise.
This function will check if SDL's audio system is initialized, and if not, it will initialize it by calling
SDL_Init(SDL_INIT_AUDIO) on your behalf. You are free to (and encouraged to!) initialize it yourself before calling this function, as this gives your program more control over the process.
If you aren't particularly concerned with the specifics of the audio device, and your data isn't in a specific format, you can pass a NULL for the
spec parameter and SDL_mixer will choose a reasonable default. SDL_mixer will convert audio data you feed it to the hardware's format behind the scenes.
That being said, if you have control of your audio data and you know its format ahead of time, you may save CPU time by opening the audio device in that exact format so SDL_mixer does not have to spend time converting anything behind the scenes, and can just pass the data straight through to the hardware.
The other reason to care about specific formats: if you plan to touch the mix buffer directly (with Mix_SetPostMix, a registered effect, or Mix_HookMusic), you might have code that expects it to be in a specific format, and you should specify that here.
This function allows you to select specific audio hardware on the system with the
devid parameter. If you specify 0, SDL_mixer will choose the best default it can on your behalf (which, in many cases, is exactly what you want anyhow). This is equivalent to specifying
SDL_AUDIO_DEVICE_DEFAULT_OUTPUT, but is less wordy. SDL_mixer does not offer a mechanism to determine device IDs to open, but you can use SDL_GetAudioOutputDevices() to get a list of available devices. If you do this, be sure to call
SDL_Init(SDL_INIT_AUDIO) first to initialize SDL's audio system!
If this function reports success, you are ready to start making noise! Load some audio data and start playing!
When done with an audio device, probably at the end of the program, the app should close the audio with Mix_CloseAudio().
This function is available since SDL_mixer 3.0.0.