Type Definition flac_sys::FLAC__StreamDecoderMetadataCallback

type FLAC__StreamDecoderMetadataCallback = Option<unsafe extern "C" fn(decoder: *const FLAC__StreamDecoder, metadata: *const FLAC__StreamMetadata, client_data: *mut c_void)>;

Signature for the metadata callback.

A function pointer matching this signature must be passed to one of the FLAC__stream_decoder_init_() functions. The supplied function will be called when the decoder has decoded a metadata block. In a valid FLAC file there will always be one \c STREAMINFO block, followed by zero or more other metadata blocks. These will be supplied by the decoder in the same order as they appear in the stream and always before the first audio frame (i.e. write callback). The metadata block that is passed in must not be modified, and it doesn't live beyond the callback, so you should make a copy of it with FLAC__metadata_object_clone() if you will need it elsewhere. Since metadata blocks can potentially be large, by default the decoder only calls the metadata callback for the \c STREAMINFO block; you can instruct the decoder to pass or filter other blocks with FLAC__stream_decoder_set_metadata_() calls.

\note In general, FLAC__StreamDecoder functions which change the state should not be called on the \a decoder while in the callback.

\param decoder The decoder instance calling the callback. \param metadata The decoded metadata block. \param client_data The callee's client data set through FLAC__stream_decoder_init_*().