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MPEG hardware
for the AMIGA
Hardware based MPEG audio decoder for the Amiga printer port.
What is MPEG audio?
MPEG audio is a compression procedure for audio data. It is also well-known under the names MP2 or MP3. By this procedure it is possible to reduce music pieces to a data quantity of approx. 1/10. That means, a music piece of 30 MB size shrinks to 3 MB without a loss of hearing quality. With this comparatively small data quantity, it will be attractive to play ones music pieces on the computer.
Why a hardware for decoding?
The Amiga of course is also able to play MPEG compressed music pieces. However each Amiga has still the old Custom chip "Paula" on the motherboard. This audio chip is only able to produce 8 bits. But if you manipulate the software, it produces 14 bits (with approx. 27 kHz). However to achieve CD quality during playback, a 16-Bit sound card and at least a 68060 processor with 50 MHz is needed. PowerPC owner (like my fewness) will sneer to this problem because they have enough performance available. However most Amiga owners have still an older model located in the corner, which can be converted with few expenditure to an MPEG Player. The advantage of an Amiga computer is that it can be attached to each TV set. Thus it is possible to select the titles visualy, and to place the Amiga for example near the stereo system.
This is how my handwired prototype looks like
For whom is this circuit suitable?
This circuit is suitable for all who want to convert their old Amiga with small expenditure to an MPEG Player. Because of the hardware based decoding a standard 68000 should be sufficient. A sound card for the Amiga is not necessary, because the DAC (digital analog converter) on the circuit fulfills this function. Playback takes place with 18 bits at 44100 Hz (CD quality).
Which Amiga computer are compatible?
This circuit works with all Amigas, which possess a parallel port. My software addresses the port chip (CIA 8520) directly to reduce time. That should not cause problems, because all Amigas possess this chip (except the Amiga clone "Draco").
The following devices are particularly suitable:
Amiga 600 HD:
The A600 is very small and has an internal IDE controler, from which a fixed disk can be operated. The music titles can be stored on the fixed disk. Because it is only as small like a keyboard without numeric key block, it can be transported very well.
Amiga CDTV:
This is an Amiga 500 in a black CD-Player case. It has a built-in CD ROM drive and it looks rather smart. The titles could be read directly from a data CD.
Amiga CD32:
The Amiga play console possesses a CD ROM drive. It must be upgraded with the extension module SX32 to give the device a parallel interface. Onboard the SX32 module is also an IDE controler, from which a fixed disk can be operated.
Of course all other Amigas can also be used. Only to the A1000 is to note that it has another allocation at the parallel port.
Here is my software, which is needed for playing the music.
NOTE! The software works only with the HARDWARE described above!
Additionally the software is in development and not finished yet!
In the case someone ruins his Amiga, I AM NOT RESPONSIBLE FOR ANY DAMAGE! Anyone who is stimulated to tinker, solders on his own risk!
Much fun with soldering!
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