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Atari demoscene BBS
| Re: Amanita |
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Posted by: evil
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Mar,12.2010-13:23
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The datas are shifted 3 bits in the first 10k of the files, this is to prevent them to play on PC or Macs.
Why? Because the files are of unstandard sample frequency. MPEG 1 supports 44100 or 48000Hz and the Falcon wants 49170Hz. So to prevent people to play the tunes and hear them wrongly on their PC or Mac, we decided to do corrupt the files a little bit. Of course the demo itself de-corrupt the files before playing :)
Here's the code snippet from the mp2 loader in the demo:
move.l mp2_adr,a0
move.w #1024*10-1,d7
.decrypt:
move.b (a0),d0
ror.b #3,d0
move.b d0,(a0)+
dbra d7,.decrypt
Nothing advanced, but does the trick.
About the DSP DMA transfer skew, I don't know why and what happens, but I know Noring worked on that a bit until he got it to work.
--
Anders Eriksson
ae@dhs.nu
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Topic
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Posted by
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Date
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Amanita
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ggn
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Mar,02.2010-15:37
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Re: Amanita
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Grey
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Mar,02.2010-19:34
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Re: Amanita
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mikro
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Mar,02.2010-21:29
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Re: Amanita
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ChrisTOS
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Mar,02.2010-23:32
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Re: Amanita
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macFalcon
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Mar,03.2010-10:45
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Re: Amanita
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Cyprian
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Mar,03.2010-16:29
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Re: Amanita
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PeP
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Mar,03.2010-13:44
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Re: Amanita
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Leonard
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Mar,03.2010-15:17
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Re: Amanita
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evil
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Mar,03.2010-15:46
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Re: Amanita
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Leonard
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Mar,03.2010-23:13
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Re: Amanita
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CiH
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Mar,04.2010-02:15
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Re: Amanita
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evil
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Mar,04.2010-09:37
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Re: Amanita
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Sallafranque
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Mar,10.2010-23:14
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Re: Amanita
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evil
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Mar,12.2010-13:23
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Re: Amanita
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Sallafranque
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Mar,15.2010-14:21
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Re: Amanita
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evil
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Mar,16.2010-11:02
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Re: Amanita
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proteque
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Mar,30.2010-22:28
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Re: Amanita
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Simon Sunnyboy / Paradize
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Mar,07.2010-19:32
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What's the anti-troll code?
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