Is it possible to use init_file/init_file_w with resource manager?

[bjorn-nesby]

I'm working on a wrapper around the OS-provided decoder in macOS (Audio Toolbox framework), and have a quick question with regard to this:

Our implementation is using the miniaudio resource manager to handle loading files. When supplying a custom decoder, I'm wondering if it would be possible to somehow instruct the resource manager to invoke the init_file or init_file_w methods when it's initializing the decoder?

The reason I'm asking is that the audio toolbox framework has some very handy (high level) methods for decoding compressed files, but these methods only accept file path.
And yes, I guess I'm basically sidestepping the resource manager by doing this. But someone told me that lazyness is a virtue when programming, and the alternative here seems to be to re-implement a lot of the audiotoolbox functionality using its (callback-based) lower level API :-)

[mackron]

Does ma_resource_manager_data_source_init_w() not call ma_decoder_init_file_w() internally?

[mackron]

Let me go into more detail there. When using ma_resource_manager_data_source_init/init_w(), I thought it should call the equivalent ma_decoder_init_file/init_w method. When using init_file() I thought it would try calling the onInitFile callback in the decoding vtable, and if you used init_file_w() it would call onInitFileW if it's been implemented. That's indeed why those callbacks are available in the decoding vtable.

[bjorn-nesby]

It doesn't seem so - in my code, it's specified like this:

static ma_decoding_backend_vtable g_ma_decoding_backend_vtable_macmedia =
{
    ma_decoding_backend_init__macmedia,
    ma_decoding_backend_init_file__macmedia, 
    NULL, // onInitFileW() 
    NULL, // onInitMemory() 
    ma_decoding_backend_uninit__macmedia
};

The init_file method is just a stub which look like this:

static ma_result ma_decoding_backend_init_file__macmedia(void* pUserData, const char* pFilePath, const ma_decoding_backend_config* pConfig, const ma_allocation_callbacks* pAllocationCallbacks, ma_data_source** ppBackend)
{
  return MA_NOT_IMPLEMENTED;
}

When I run the example, the regular init method is called just fine, but init_file seems to be ignored.

[mackron]

I had a look at the code and you're absolutely correct. Those onInitFile/W callbacks are not being used at all (neither is onInitMemory). I'll have to have a look at that, because certainly the whole point of those callbacks even existing in ma_decoding_backend_vtable was to give custom decoders an opportunity to do an optimized implementation for those scenarios. I think this was an oversight on my part.

I'll convert this to an issue so I don't forget about it.

[bjorn-nesby]

Thanks! I'm happy to test any solution you come up with :-)