Mpega_demo

Since I could not find the correct header files for using
mpega.library on AmigaOS 4 I banged my head against an
alignment issue in the library/mpega.h file for 3 days.

Now that I finally found the solution I decided to update
the MPEGA_demo.c example, distributed with the original
mpega.library for 68k, for OS4 with corrected headers for
OS4.

All needed headers except proto/mpega.h are included. The
proto had copyright text in it so I dared not include it.
Besides, that one seems already be updated and included
for OS4.

Changes
~~~~~~~
* FIX * Added #pragma pack(2) to the libraries/mpega.h file.

* FIX * Fixed the pcm buffer parameter for MPEGA_decode_frame() in
        interfaces/mpega.h to take an array of pointers to WORD,
        instead of just a WORD pointer which is incorrect.

* FIX * Fixed the demo so it works with OS4. Using SDI_hook.h
        to define the hook now. Made a tiny makefile for it.

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Other programs by Deniil 715! can be found on OnyxSoft homepage at:

 http://www.onyxsoft.se/

Feel free to mail me if you found bugs or have suggestions!