FLAC__StreamEncoderWriteCallback

Signature for the write callback.

A function pointer matching this signature must be passed to FLAC__stream_encoder_init*_stream(). The supplied function will be called by the encoder anytime there is raw encoded data ready to write. It may include metadata mixed with encoded audio frames and the data is not guaranteed to be aligned on frame or metadata block boundaries.

The only duty of the callback is to write out the \a bytes worth of data in \a buffer to the current position in the output stream. The arguments \a samples and \a current_frame are purely informational. If \a samples is greater than \c 0, then \a current_frame will hold the current frame number that is being written; otherwise it indicates that the write callback is being called to write metadata.

\note Unlike when writing to native FLAC, when writing to Ogg FLAC the write callback will be called twice when writing each audio frame; once for the page header, and once for the page body. When writing the page header, the \a samples argument to the write callback will be \c 0.

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

\param encoder The encoder instance calling the callback. \param buffer An array of encoded data of length \a bytes. \param bytes The byte length of \a buffer. \param samples The number of samples encoded by \a buffer. \c 0 has a special meaning; see above. \param current_frame The number of the current frame being encoded. \param client_data The callee's client data set through FLAC__stream_encoder_init_*(). \retval FLAC__StreamEncoderWriteStatus The callee's return status.