Get various current decoder/stream state information.
\param mh handle
\param key the key to identify the information to give.
\param val the address to return (long) integer values to
\param fval the address to return floating point values to
\return MPG123_OK on success
Get various current decoder/stream state information. \param mh handle \param key the key to identify the information to give. \param val the address to return (long) integer values to \param fval the address to return floating point values to \return MPG123_OK on success