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Hi Martin,

Probably you are looking into some kind of **Line Level** functions, I dont think IPP has such type of function.

Thanks,

Naveen Gv

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Hi,

You can use following code to find audio signal level

{

Ipp32f tmpMinS,tmpMaxS;

Ipp32f m_PeakAmpdB;

ippsMinMax_32f(fileData, sizeSamples, &tmpMinS, &tmpMaxS);

Ipp32f maxAbsSample = IPP_MAX(fabs(tmpMinS),fabs(tmpMaxS));

if(maxAbsSample > 0) {

m_PeakAmpdB = 20.f * log10(maxAbsSample / 32768.f);

} else {

m_PeakAmpdB = -91.f;

}

}

Regards,

Naveen Gv

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How does your code work? Could you explain where the 20.f and -91.f constants come from? Why do you measure dB negatively? I suppose -91dB represents silence whereas 0dB represents maximum volume; is that correct?

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You are right,

Amp(dB) = 20 lg(S/N), where S- random signal, N - noise

If S=1 then Amp(dB) = 20 lg(1/N) = -91 this is silence.

Thanks,

Naveen Gv

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What is mean of 32768.f here. Also this is you used for the 32 bit data. If I have 16 bit data what value we have to use.

Thanks,

Bharat Agarwal

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**>>**...Why do you measure dB negatively?

A signal strength is measured in dB ( dBm in case of a radio signal, likeWi-Fi, etc )and it means that

a -50 dBsignal is stronger than a-70 dB signal.

Here is anexample for some abstract signal:

-10 dB could be considered as"Excellent"

-25 dB could be considered as"Very Good"

-50 dB could be considered as"Good"

-70 dB could be considered as"Poor"

-90 dB could be considered as"No Signal"

Best regards,

Sergey

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Exactly, this is code for 16 bit data as32768.f is absolute maximum sample value for 16 bit sighned data.

You can change 32f function version to 16s to not doing data type convertion.

Igor S. Belyakov

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