Resource Manager

Demonstrates how you can use the resource manager to manage loaded sounds.

This example loads the first sound specified on the command line via the resource manager and then plays it using the low level API.

You can control whether or not you want to load the sound asynchronously and whether or not you want to store the data in-memory or stream it. When storing the sound in-memory you can also control whether or not it is decoded. To do this, specify a combination of the following options in ma_resource_manager_data_source_init():

  • MA_RESOURCE_MANAGER_DATA_SOURCE_FLAG_ASYNC - Load asynchronously.
  • MA_RESOURCE_MANAGER_DATA_SOURCE_FLAG_DECODE - Store the sound in-memory in uncompressed/decoded format.
  • MA_RESOURCE_MANAGER_DATA_SOURCE_FLAG_STREAM - Stream the sound from disk rather than storing entirely in memory. Useful for music.

The object returned by the resource manager is just a standard data source which means it can be plugged into any of ma_data_source_*() APIs just like any other data source and it should just work.

Internally, there's a background thread that's used to process jobs and enable asynchronicity. By default there is only a single job thread, but this can be configured in the resource manager config. You can also implement your own threads for processing jobs. That is more advanced, and beyond the scope of this example.

When you initialize a resource manager you can specify the sample format, channels and sample rate to use when reading data from the data source. This means the resource manager will ensure all sounds will have a standard format. When not set, each sound will have their own formats and you'll need to do the necessary data conversion yourself.

#define MA_NO_ENGINE        /* We're intentionally not using the ma_engine API here. */
#define MINIAUDIO_IMPLEMENTATION
#include "../miniaudio.h"

#ifdef __EMSCRIPTEN__
#include <emscripten.h>

void main_loop__em(void* pUserData)
{
    ma_resource_manager* pResourceManager = (ma_resource_manager*)pUserData;
    MA_ASSERT(pResourceManager != NULL);

    /*
    The Emscripten build does not support threading which means we need to process jobs manually. If
    there are no jobs needing to be processed this will return immediately with MA_NO_DATA_AVAILABLE.
    */
    ma_resource_manager_process_next_job(pResourceManager);
}
#endif

void data_callback(ma_device* pDevice, void* pOutput, const void* pInput, ma_uint32 frameCount)
{
    ma_data_source_read_pcm_frames((ma_data_source*)pDevice->pUserData, pOutput, frameCount, NULL);

    (void)pInput;
}

int main(int argc, char** argv)
{
    ma_result result;
    ma_device_config deviceConfig;
    ma_device device;
    ma_resource_manager_config resourceManagerConfig;
    ma_resource_manager resourceManager;
    ma_resource_manager_data_source dataSource;

    if (argc < 2) {
        printf("No input file.");
        return -1;
    }


    /* We'll initialize the device first. */
    deviceConfig = ma_device_config_init(ma_device_type_playback);
    deviceConfig.dataCallback = data_callback;
    deviceConfig.pUserData    = &dataSource;    /* <-- We'll be reading from this in the data callback. */

    result = ma_device_init(NULL, &deviceConfig, &device);
    if (result != MA_SUCCESS) {
        printf("Failed to initialize device.");
        return -1;
    }


    /*
    We have the device so now we want to initialize the resource manager. We'll use the resource manager to load a
    sound based on the command line.
    */
    resourceManagerConfig = ma_resource_manager_config_init();
    resourceManagerConfig.decodedFormat     = device.playback.format;
    resourceManagerConfig.decodedChannels   = device.playback.channels;
    resourceManagerConfig.decodedSampleRate = device.sampleRate;

    /*
    We're not supporting threading with Emscripten so go ahead and disable threading. It's important
    that we set the appropriate flag and also the job thread count to 0.
    */
#ifdef __EMSCRIPTEN__
    resourceManagerConfig.flags |= MA_RESOURCE_MANAGER_FLAG_NO_THREADING;
    resourceManagerConfig.jobThreadCount = 0;
#endif

    result = ma_resource_manager_init(&resourceManagerConfig, &resourceManager);
    if (result != MA_SUCCESS) {
        ma_device_uninit(&device);
        printf("Failed to initialize the resource manager.");
        return -1;
    }

    /* Now that we have a resource manager we can load a sound. */
    result = ma_resource_manager_data_source_init(
        &resourceManager,
        argv[1],
        MA_RESOURCE_MANAGER_DATA_SOURCE_FLAG_DECODE | MA_RESOURCE_MANAGER_DATA_SOURCE_FLAG_ASYNC | MA_RESOURCE_MANAGER_DATA_SOURCE_FLAG_STREAM,
        NULL,   /* Async notification. */
        &dataSource);
    if (result != MA_SUCCESS) {
        printf("Failed to load sound \"%s\".", argv[1]);
        return -1;
    }

    /* In this example we'll enable looping. */
    ma_data_source_set_looping(&dataSource, MA_TRUE);


    /* Now that we have a sound we can start the device. */
    result = ma_device_start(&device);
    if (result != MA_SUCCESS) {
        ma_device_uninit(&device);
        printf("Failed to start device.");
        return -1;
    }

#ifdef __EMSCRIPTEN__
    emscripten_set_main_loop_arg(main_loop__em, &resourceManager, 0, 1);
#else
    printf("Press Enter to quit...\n");
    getchar();
#endif

    /* Teardown. */

    /* Uninitialize the device first to ensure the data callback is stopped and doesn't try to access any data. */
    ma_device_uninit(&device);

    /*
    Before uninitializing the resource manager we need to uninitialize every data source. The data source is owned by
    the caller which means you're responsible for uninitializing it.
    */
    ma_resource_manager_data_source_uninit(&dataSource);

    /* Uninitialize the resource manager after each data source. */
    ma_resource_manager_uninit(&resourceManager);

    return 0;
}
Copyright © 2022 David Reid
Developed by David Reid - mackron@gmail.com