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Atari coding BBS
| Re: STE LMC1992 |
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Posted by: dml
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Nov,22.2013-13:33
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Thanks everyone for the responses - it's all helpful.
This is slightly complicated by the fact I have not properly tested playback on STE hardware. The noise is noticeable at low volumes when the data is played back on my PC or via STeem, but OTOH those don't have real 8-bit DACs and the frequency base is different so aliasing/stepping in the sample is probably being amplified instead of softened by the host hardware (?).
Filtering the sample hasn't had too much impact, and the sample data doesn't indicate obvious presence of noise on inspection, but it is easy to see the aliasing steps at lower volumes. Only quiet samples are affected.
However in case it doesn't magically go away when I test on the real machine, it seems good to have a backup plan and a second way to deal with noise generally.
LMC vs DAC linearity - yes I figured there would be a complicated overlapping of the two so a map would need to be made which combine the two terms to get the expected output level, renormalize the sample and minimize state changes to the LMC.
At first I though a table could be hacked up by emitting all DAC/LMC combinations to a WAV via emulator and then make a new map with reverse-lookups but that relies too much on emulation accuracy :) better to do it properly with calculation and confirm.
Cheers
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Topic
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Posted by
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Date
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STE LMC1992
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dml
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Nov,20.2013-15:36
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Re: STE LMC1992
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dml
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Nov,20.2013-15:40
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Re: STE LMC1992
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Cyprian
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Nov,20.2013-18:14
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Re: STE LMC1992
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dml
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Nov,20.2013-18:21
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Re: STE LMC1992
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Cyprian
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Nov,20.2013-23:57
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Re: STE LMC1992
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dml
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Nov,21.2013-00:11
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Re: STE LMC1992
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Cyprian
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Nov,21.2013-13:47
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Re: STE LMC1992
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gwEm/PHF
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Nov,21.2013-14:44
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Re: STE LMC1992
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RA/pdx
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Nov,22.2013-12:47
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Re: STE LMC1992
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dml
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Nov,22.2013-13:33
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Re: STE LMC1992
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ggn
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Nov,22.2013-17:15
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Re: STE LMC1992
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dml
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Nov,23.2013-13:02
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Re: STE LMC1992
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gwEm
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Dec,02.2013-01:13
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What's the anti-troll code?
That's your personal code to be able to add comments and messages on the dhs.nu site.
Don't have a code or forgot it? Fix it here.
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