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Topic: Line at 18 or 20 kHz in spectogram (Read 997 times) previous topic - next topic
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Line at 18 or 20 kHz in spectogram

Hi,

in quite a few higher resolution files I have found a line exactly at 20 kHz, but I have also seen it at 18k.

What may be the cause of this?

Thx

X

And while we're at it, the following, above 20k, that's just random high frequency noise? I've also seen it before in a 358k SACD conversion to 96k FLAC.

X

Re: Line at 18 or 20 kHz in spectogram

Reply #1 –
Lines can be noise from CRT monitors.

Re: Line at 18 or 20 kHz in spectogram

Reply #2 –
CRT noise that high? They're usually hovering at around 15 kHz.
Second one is sort of standard for how SACD work, as far as I understood.
TAPE LOADING ERROR

Re: Line at 18 or 20 kHz in spectogram

Reply #3 –
Quote from: Squeller on
And while we're at it, the following, above 20k, that's just random high frequency noise? I've also seen it before in a 358k SACD conversion to 96k FLAC.
That's dither with shaped noise.

Re: Line at 18 or 20 kHz in spectogram

Reply #4 –
The 20kHz line to me looks like some dsp or filtering artifact.
 

Re: Line at 18 or 20 kHz in spectogram

Reply #5 –
Quote from: danadam on
That's dither with shaped noise.
Thank you, I'd guess it may be a DSD transfer to PCM? Thanks for the key word "shaped noise", I looked into DSD a bit[1], it wouldn't be my choice. Just from the technical idea. As I understand it (and for sure it is limited understanding) they work around dynamic range obstacles by signitificantly altering the signal? "The art of noise shaping"? However, I am pretty sure, in a PCM transfer this kind of noise is just useless weight to the file sizes and can/should be filtered. There's no natural sound above 22k.

I now have that habit to look into the spectogram of >48khz files. Some have natural frequencies above 22k, some a big NOTHING, some just randomness.

[1] OMG, 99 years old people on Youtube telling the audience that DSD "just sounds better".