The stream position is the position seen by the user, not the position of the file already streamed into the Stream Manager's memory. The stream position is updated when buffers are released, using AK::IAkAutoStream::ReleaseBuffer().
戻り値:
The file position in bytes of the beginning of the first buffer owned by the user. If the user does not own a buffer, it returns the position of the beginning of the buffer that would be returned from a call to AK::IAkAutoStream::GetBuffer().