Ability to play a file from a custom file handle.

[deadlocklogic]

Hi,
I am trying to play a file with a custom handle (for example a file from external storage on Android).
So I can obtain a file stream from the required path but how to plug it into miniaudio?
I found Custom Data Sources in the documentation but it is not clear how to easily use it without manually decoding the stream.
So I want to be able to manipulate the stream using the registered decoders without much effort of manual decoding whatsoever.
Is there any example, snippets?
Thanks.

[mackron]

Are you using ma_decoder directly? If so, you'll need to use ma_decoder_init() and implement the reading and seeking callbacks yourself. There is a pUserData parameter for passing in your custom data to support your callbacks. The read callback corresponds to fread() and the seek callback corresponds to to fseek().

If you're using the engine and the resource manager the only way would be to implement a VFS and do all of your file handling through that. You implement the callbacks in ma_vfs_callbacks and then pass it into the pResourceManagerVFS variable in the ma_engine_config struct. Take a look at the implementation of ma_default_vfs() and ma_default_vfs_init() in miniaudio.h for an example of implementing a VFS.

[deadlocklogic]

Ok, so just for the sake of testing, this works:

ma_vfs_callbacks callback;
callback.onOpen = &ma_default_vfs_open;
callback.onOpenW = &ma_default_vfs_open_w;
callback.onClose = &ma_default_vfs_close;
callback.onRead = &ma_default_vfs_read;
callback.onWrite = &ma_default_vfs_write;
callback.onSeek = &ma_default_vfs_seek;
callback.onTell = &ma_default_vfs_tell;
callback.onInfo = &ma_default_vfs_info;

engineConfig = ma_engine_config_init();
engineConfig.pResourceManagerVFS = &callback;

I can now provide my own implementation instead of the defaults.

By the way this library feels so rich, but lacks a bit of online documentations about few features.
Thanks.

[deadlocklogic]

Just a question:
Is it safe to change the engine's config at runtime after already done?
For instance I want to alternate which vfs to use, because ma_default_vfs_open1 doesn't take a pUserData so it is not feasible to select a vfs at runtime. (Consider I want to play a file from internal memory or memory card for instance each method has its own vfs implementation).

[mackron]

No that's not safe. If you want to dynamically switch things around you'd need to implement that within your custom VFS implementation.

Typically the way you would do a custom VFS is to "extend" the ma_vfs_callbacks object by making it the first member of your structure:

struct my_custom_vfs
{
    ma_vfs_callbacks cb;
    /* Custom members go here. */
};

That way you can cast between ma_vfs* and my_custom_vfs* and get access to your custom members from within your callbacks.