Cracks in the sound (YM+DMA)

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dma
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Cracks in the sound (YM+DMA)

Postby dma » Sat Feb 23, 2013 5:20 pm

Hi,

Here attached is a .zip archive containing a test .snd file (along with .ttp player for it) which gives cracks in the sound on Hatari when all 3 voices are played along DMA mono beat.
It only occurs when the bassdrum is playing.

You can hear it at 17 seconds when playing the .snd file.
I also included a recording (as .ogg) from Hatari where you can also hear this problem.

Maybe it only occurs on my Hatari setup ? I cannot test it on another computer here.
So it would be nice if someone else could check this.
You do not have the required permissions to view the files attached to this post.

Hippy Dave
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Re: Cracks in the sound (YM+DMA)

Postby Hippy Dave » Sat Feb 23, 2013 8:07 pm

I think the LMC1992 volume or bass or treble register is turned up too high and causing distortion.
This can happen on a real STe too. Real STe distortion is caused by clipping; Hatari distortion is
caused by overflow because saturation mathematics is not used. Hatari should distort at about the
same point as a real STe, but may sound different.

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dma
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Re: Cracks in the sound (YM+DMA)

Postby dma » Sat Feb 23, 2013 9:31 pm

Actually, the test .snd file i provided sounds correct my STe.
Sorry that i forgot to mention that.

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Re: Cracks in the sound (YM+DMA)

Postby Hippy Dave » Sat Feb 23, 2013 9:53 pm

EDIT:
I found and solved the problem. YM + DMA sound samples exceeded 16 bits at one point in the code.
I also made a patch to do clipping instead of overflow for LMC1992 distortion.

-Following experiment cancelled.
Try this experiment:
Turn down the volume to see if the noise goes away on Hatari.
Maybe turn up volume on Real STe to find where it gets worse.
I'll think about the results, if you can tell me some levels.

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Re: Cracks in the sound (YM+DMA)

Postby dma » Sun Feb 24, 2013 8:08 am

Ah that's marvellous. Is there any chance i could get a windows (32bits xp) build binary with this patch somewhere?

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Re: Cracks in the sound (YM+DMA)

Postby Hippy Dave » Sun Feb 24, 2013 5:20 pm

dma wrote:Ah that's marvellous. Is there any chance i could get a windows (32bits xp) build binary with this patch somewhere?

Check this link to see when the patch is applied.
http://hg.tuxfamily.org/mercurialroot/hatari/hatari

Download from CHS' automated Windows Hatari build link
the next day (first link on page).
http://hatari.tuxfamily.org/links.html

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Re: Cracks in the sound (YM+DMA)

Postby dma » Sun Feb 24, 2013 5:56 pm

Oh i didn't knew about the automated build, great!

I can't wait for the patch (literally, as it blocks my "out of the house" work on some tunes ;)).
Thanks again for such a fast job.

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Re: Cracks in the sound (YM+DMA)

Postby npomarede » Sun Mar 17, 2013 10:23 pm

Hello,
I applied the ym+dma patch made by David to the dev version, so it should appear soon in the windows' daily builds.

Nicolas

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Re: Cracks in the sound (YM+DMA)

Postby dma » Mon Mar 18, 2013 8:56 am

Ah that's great, thanks, no more problem on my track(s).


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