Re: [Sv1-devel] dBFS

[Christofer B. <tos...@ho...>]

Dear Mehmet,

Thanks a lot for your e-mail, the lines of code and the link. That is exactly my question. Is not the sample values proportional to the voltage? Then according to this website, 20 should be used instead of 10? Or am I misunderstanding what you mean? Thank you in advance!

Best regards,
Christofer

________________________________
From: me...@in... <me...@in...>
Sent: 20 January 2021 18:32
To: Christofer Bustad <tos...@ho...>; sv1...@li... <sv1...@li...>
Subject: Re: [Sv1-devel] dBFS

Hello,

Well, if you check the source code of Sonic Visualiser you could spot this lines..
AudioLevel - float dB = 10 * log10f(multiplier);
SpectrumLayer - value = 10.f * log10f(value);

so if you are saying why does Sonic Visualiser use 10 instead 20 you may check here :

https://www.cds.caltech.edu/~murray/wiki/index.php/Why_is_dB_defined_as_20log_10%3F



Regards,
Mehmet

20.01.2021, 17:12, "Christofer Bustad" <tos...@ho...>:
Hi there,

Thank you to all who contributed to this great and very useful piece of open-source software.

I wonder if someone may help me to understand something... If I generate a pure sine wave at say -20 dBFS in Adobe Audition, Sonic Visualiser displays the level -10 dBFS in the waveform view. Similarly, if I generate a sine wave at -40 dBFS in Adobe Audition, Sonic Visualiser displays the level -20 dBFS. Could it be the case that Sonic Visualiser calculates the dB values using 10*log10(input)? It was my understanding that dB values usually are calculated from sample values using 20*log10(input). Am I missing something in my understanding of this or could this be a bug in Sonic Visualiser? There also seems to be a similar difference in the spectrum view when I compare Sonic Visualiser to Adobe Audition.

Thank you very much in advance!

Best regards,
Christofer

,,

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