Bool wxReadMediaGlobalHeader (wxMediaStreamIn& in)
Reads data from in to initialize for reading buffers from the stream. The return value is TRUE if the read succeeds, or FALSE otherwise. One or more buffers can be read from the stream by calling the buffer's ReadFromFile method. (The number of buffers to be read must be known by the application beforehand.) When all buffers are read, call wxReadMediaGlobalFooter. Calls to wxReadMediaGlobalHeader and wxReadMediaGlobalFooter must bracket any call to ReadFromFile, and only one stream at a time can be read using these methods or written using wxWriteMediaGlobalHeader and wxWriteMediaGlobalFooter.