Audio output through multiple devices

Samples Directory

/CRIWARE/SDK/pc/samples/criatomex/multi_device

Sample Description

This sample shows how to play sound through multiple audio devices.
It differs from the "select_device" sample in that the audio is output simultaneously through multiple devices.

When playing back the sound, it is necessary to prepare an independent mixer for each device. Therefore, an additional ASR rack must be created as a mixer.

In this sample, we created 4 ASR racks (the default ASR and 3 additional ASRs) and assign the output of each ASR rack to a different device.
The program flow is as follows:

1. Enumerate devices by calling the criAtom_EnumAudioEndpoints_WASAPI function.
2. Assign the devices found from CRIATOM_SOUND_RENDERER_HW1 to CRIATOM_SOUND_RENDERER_HW4 by calling the criAtom_SetDeviceId_WASAPI function.
3. Initialize the Atom library and set the output of the default ASR rack to CRIATOM_SOUND_RENDERER_HW1.
4. Create three additional ASR racks and set the output of each ASR rack from CRIATOM_SOUND_RENDERER_HW2 to CRIATOM_SOUND_RENDERER_HW4.
5. At the start of the audio playback, specify the destination ASR rack by calling the criAtomExPlayer_SetAsrRackId function.

Some sample code to do this is shown below:

/* Max number of devices */
#define MAX_DEVICES                     (4)
 
/* Number of actually found devices */
static CriSint32 num_devices = 0;
 
/* Type of hardware sound renderer assigned to each device */
static const CriAtomSoundRendererType sound_renderer_table[MAX_DEVICES] = {
    CRIATOM_SOUND_RENDERER_HW1,
    CRIATOM_SOUND_RENDERER_HW2,
    CRIATOM_SOUND_RENDERER_HW3,
    CRIATOM_SOUND_RENDERER_HW4
};
 
/* Main process */
main()
{
        :
    /* Enumerate the audio devices */
    criAtom_EnumAudioEndpoints_WASAPI(user_endpoint_callback, NULL);
        :
 
        :
    /* Initialize the library */
    criAtomEx_SetDefaultConfig_WASAPI(&lib_config);
    lib_config.asr.sound_renderer_type = CRIATOM_SOUND_RENDERER_HW1;
    criAtomEx_Initialize_WASAPI(&lib_config, NULL, 0);
 
    /* Create ASR racks for additional devices */
    for (i = 1; i < MAX_DEVICES; i++) {
        criAtomExAsrRack_SetDefaultConfig(&asr_rack_config);
        asr_rack_config.sound_renderer_type = sound_renderer_table[i];
        app_obj->asr_rack_id[i] = criAtomExAsrRack_Create(&asr_rack_config, NULL, 0);
    }
        :
 
        :
    /* Assign the destination ID of the ASR  */
    criAtomExPlayer_SetAsrRackId(app_obj->player, app_obj->selected_device);
 
    /* Start playback */
    app_obj->playback_id = criAtomExPlayer_Start(app_obj->player);
        :
}
 
/* Callback triggered when a device is detected */
static void CRIAPI user_endpoint_callback(void *object, IMMDevice *device)
{
        :
    /* Get device ID */
    device->GetId(&device_id);
 
    /* Link sound renderer and hardware */
    criAtom_SetDeviceId_WASAPI(sound_renderer_table[num_devices], device_id);
 
    /* Free device ID area */
    CoTaskMemFree(device_id);
        :
}

Attention

CRIATOM_SOUND_RENDERER_HW1 and CRIATOM_SOUND_RENDERER_NATIVE refer to the same sound renderer.
Therefore, after assigning a device to CRIATOM_SOUND_RENDERER_HW1, if you also assign a device to CRIATOM_SOUND_RENDERER_NATIVE, the setting for CRIATOM_SOUND_RENDERER_HW1 will be overwritten.
(Please use only one of them in the application.)