Function projectm_playlist_insert_presets 

pub unsafe extern "C" fn projectm_playlist_insert_presets(
    instance: projectm_playlist_handle,
    filenames: *mut *const c_char,
    count: u32,
    index: c_uint,
    allow_duplicates: bool,
) -> u32

@brief Adds a single preset to the playlist at the specified position.

To always add a file at the end of the playlist, use projectm_playlist_add_preset() as it is performs better.

@note The files are not checked for existence or for being readable.

@param instance The playlist manager instance. @param filenames A list of local preset filenames. @param count The number of files in the list. @param index The index to insert the presets at. If it exceeds the playlist size, the presets are added at the end of the playlist. @param allow_duplicates If true, the preset filenames will always be added. If false, a preset is only added to the playlist if the exact filename doesn’t exist in the current playlist. @return The number of files added to the playlist. Ranges between 0 and count.