Custom data source format

[SmartFoxServer]

We are trying to implement a custom data source for playback using ma_engine.
The datasource reads data from an ma_audio_buffer (in our tests filled with data loaded from a raw audio file).
If we set the format (inside my_data_source_get_data_format and ma_device_config_init) to ma_format_f32, everything works as expected and the sound is played correctly.
If we set the format to ma_format_s16 or any other format, we get the following results:

• MacOS: the sound can be somehow heard but with a lot of noise.
• Windows: program exits when the playback should start; no errors reported
• Linux: crash with malloc error when the playback should start

How can we use a format different from ma_format_f32?
Showing below how we initialize device, engine, sound, custom data source and data source read method.
Thank you for your help.

int main(void)
{
	//--- Create DEVICE --- --- ---  ---  ---  ---  ---  ---  ---  ---  --- 
	deviceConfig = ma_device_config_init(ma_device_type_playback);
	deviceConfig.playback.format   = ma_format_s16;
	deviceConfig.playback.channels = 2;
	deviceConfig.sampleRate        = 44100;
	deviceConfig.dataCallback      = device_data_callback;
	
	if (ma_device_init(NULL, &deviceConfig, &device) != MA_SUCCESS) {
		return -3;
	}

	//--- Create ENGINE --- --- ---  ---  ---  ---  ---  ---  ---  ---  --- 
	engineConfig = ma_engine_config_init();
	engineConfig.pDevice = &device;
	
	result = ma_engine_init(&engineConfig, &engine);
	if (result != MA_SUCCESS) {
		return result;  // Failed to initialize the engine.
	}
	
	result = stream_ds_init(&stream, 10);
	if (result != MA_SUCCESS){
		return 1;
	}
	
	// Start playback device
	if (ma_device_start(&device) != MA_SUCCESS) {
		return result;  // Failed to start playback
	}
	
	// Load raw audio file in memory
	loadRawAudio(str, &audioBuffer, &audioSize);

	ma_audio_buffer_config config = ma_audio_buffer_config_init(format, channels, audioSize / ma_get_bytes_per_frame(format, channels), audioBuffer, NULL);
	ma_audio_buffer_init(&config, &ma_buffer);
	
	ma_sound sound;
	result = ma_sound_init_from_data_source(&engine, &stream, 0, NULL, &sound);
	if (result != MA_SUCCESS) {
		return result;
	}
	
	ma_sound_start(&sound);
	
	// Hold the main thread
	printf("\nPress key to quit");
	getchar();
	
	// TODO uninit stuff
	return 0;
}

ma_result stream_ds_init(stream_ds* pDataSource, int stream_id)
{
	ma_result result;
	ma_data_source_config baseConfig;
	
	baseConfig = ma_data_source_config_init();
	baseConfig.vtable = &stream_ds_vtable;
	
	result = ma_data_source_init(&baseConfig, &pDataSource->base);
	if (result != MA_SUCCESS) {
		return result;
	}
	
	// ... do the initialization of your custom data source here ...
	pDataSource->stream_id = stream_id;
	
	return MA_SUCCESS;
}

void device_data_callback(ma_device* pDevice, void* pOutput, const void* pInput, ma_uint32 frameCount)
{
	ma_engine_read_pcm_frames(&engine, pOutput, frameCount, NULL);
}

static ma_result stream_ds_read(ma_data_source* pDataSource, void* pFramesOut, ma_uint64 frameCount, ma_uint64* pFramesRead)
{
	ma_uint64 framesRead = ma_audio_buffer_read_pcm_frames(&ma_buffer, pFramesOut, frameCount, MA_FALSE);
	
	if (framesRead < frameCount) {
		printf("We have reached the end of the memory stream.\n");
	}
	
	*pFramesRead = framesRead;
	
	return MA_SUCCESS;
}

static ma_result stream_ds_get_data_format(	ma_data_source* pDataSource, ma_format* pFormat, ma_uint32* pChannels, ma_uint32* pSampleRate, ma_channel* pChannelMap, size_t channelMapCap)
{
	*pFormat = ma_format_s16;
	*pChannels = 2;
	*pSampleRate = 44100;
	// pChannelMap	 ??
	
	return MA_SUCCESS;
}

[mackron]

It's because you've configured your device to use ma_format_s16, but ma_engine_read_pcm_frames() only returns samples in ma_format_f32 format. An individual data source can be s16 in which case the engine will convert it automatically, but the backing device must be ma_format_f32, or you need to manually convert the data returned from ma_engine_read_pcm_frames() from f32 to s16.

If you change deviceConfig.playback.format = ma_format_s16; to deviceConfig.playback.format = ma_format_f32; it should work fine. You can leave stream_ds as ma_format_s16.