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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: leirbag28 on November 12, 2007, 06:40:10 PM
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Was wondering if anyone has the MP3@64 MP3 decoder for C=64 and Amiga?
Is it any good? does it take all the load off the CPU? can it be controlled by CLI commands? does it work with AMPlifier?
Im interested in buying one but dont know jack squat about it.
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MP3@64 is a good decoder to any Amiga. Works almost exactly as a MAS-Player (DIY project).
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http://www.schoenfeld.de/inside/Inside_MP3AT64.txt probably answers most of your questions.
The host just provides a MP3 stream and the MAS ASIC takes care of the rest. When it comes to software, I'm as uninformed as you are (familiar with the concept, not the particular hardware).
With C64 support, this could be a candidate for the "Blue Monday on a Floppy" project, although you'd need something like a SFD-1001 to be vintage on the storage end.
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Also a very informative thread here (http://eab.abime.net/showthread.php?t=29989) on the subject
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Thanks people!
But still got a few questions:
Is this better than the MAS player?
also how can it use 5% system resources...........in my opinion it should use 0% because if it works on a C=64 with minimal CPU usage, it should darn well work on an Amiga with wayyyyyy less CPU usage.
They mentioned a half a second delay..............delay on what? on the graphical display? or the actual song playing?
Also would this work with a Quadddra port or some sort of Clockport splitter as long as I disable any other Clockport cards (e.g subway USB)?
WHat I mean is I leave both the Subwway and MP3@64 connected, but just turn off the Subway via the Poseiden software and then use the MP3@64....will this work without issues?
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leirbag28 wrote:
also how can it use 5% system resources...........in my opinion it should use 0%
Presumably the 5% CPU usage is taken up by the player app, which has to present a UI and then feed the file to the MP3@64.
leirbag28 wrote:
because if it works on a C=64 with minimal CPU usage, it should darn well work on an Amiga with wayyyyyy less CPU usage.
I expect the UI on the C64 version is less complex. And also, there is no nice audio driver API on the C64 which makes it easier (but less CPU efficient) to write a player for the Amiga. The C64 one probably bashes the hardware directly.
leirbag28 wrote:
They mentioned a half a second delay..............delay on what? on the graphical display? or the actual song playing?
On the song playing from the sound of the thread posted above - though I've never tried the hardware myself.
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moto
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> Is this better than the MAS player?
It's basically the same.
> also how can it use 5% system resources...........in my opinion it should use 0%
You need to transfer the MP3 data stream to the card, which will obviously use up more than 0% of your CPU time. Then again, somebody "forgot" to connect the interrupt pin to the MAS' "buffer full" indicator, which means it needs to poll very often, if more data can be sent as the buffer is *very* small (~260 bytes). This interrupt polling overhead is causing some CPU usage, that you won't be able to measure e.g. with Scout as its not spent with a task.
Also the serial latching of the bytes is very slow, so it needs waitstates between every bytes. Maybe on C64, you will send a few byte at each raster interrupt or whatever, but causing an interrupt for every byte is no option on the Amiga.
> Also would this work with a Quadddra port or some sort of Clockport splitter as long as I disable any other Clockport cards (e.g subway USB)?
AFAIK you don't even have to disable either clockport card. Both drivers support all four Quaddddroport clockports.