Re: [hatari-devel] STe DMA sound

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On 13/04/2018 at 10:18, Nicolas Pomarède wrote:
In dmaSnd.c at line 530, can you force "DmaSnd_LowPass = true" to see if
the sound is better according to you ?

I have just forced that variable, and I can hear the effect.
I opened 2 Hatari windows to clearly hear the difference.

With that:
Low-pass filter is definitely enabled on drums. The samples lost some resolution, as if a treeble button was turned down. The original Hatari sound was more pleasant. But I don't know which version is more accurate, this should be compared with real hardware.

*BUT* that didn't fix the issue!
I can still hear the bogus-treeble which makes my ears bleeding.
Those annoying frequencies are definitely above the low-pass filter.

So something is trashing the sound at another level, adding unexpected high frequencies.

I attach a sample, recorded with "DmaSnd_LowPass = true". You can easily ear the annoying treeble. And with Audacity spectral analysis, you can even see it! There are bogus bars around 7 KHz.
Maybe they are added by something else? LMC1992 emulation?

Vincent Rivière

Attachment: lethal.wav
Description: Wave audio

Attachment: analysis.png
Description: PNG image

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